Self Help

The Story of the Human Body - Daniel Lieberman

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Matheus Puppe

· 94 min read



Here is a summary of the content and copyright information:

  • This book is titled “The Story of the Human Body: Evolution, Health, and Disease” and was written by Daniel E. Lieberman.

  • Copyright for the book is held by Pantheon Books, a division of Random House. The book was published in 2013.

  • The book explores how the human body evolved over time from early hominins to modern humans. It examines how bodies adapted through evolution and how current health issues relate to mismatches between our evolved physiology and modern environments/lifestyles.

  • The copyright notice indicates that the book and its content are protected by copyright law. It provides publishing details like the publisher, year of publication, ISBN numbers, and that the book jacket design was done by Matt Dorfman.

  • In summary, the copyright information establishes that Daniel Lieberman holds the rights to this published work exploring human evolutionary biology and its implications for health, while Pantheon Books published and distributed the copyrighted material.

Here is a summary of the core argument:

  • Humans have evolved over millions of years to be well-adapted to the environments of our hunter-gatherer ancestors, not modern conditions of abundance.

  • As a result, we are prone to chronic diseases when living with today’s food supplies and lifestyles which our bodies did not evolve to handle. Things like processed foods, sedentary work, lack of exercise are mismatched to our evolutionary biology.

  • This mismatch is driving epidemics of obesity, diabetes, heart disease and other chronic illnesses. It is also imposing huge healthcare costs on societies.

  • To address this, we need to find ways to nudge and sometimes oblige people to eat whole, unprocessed foods and get regular physical activity - lifestyle patterns we evolved to follow as hunter-gatherers. Doing so would help prevent chronic disease and respect our biological nature.

The key point is that modern environments and behaviors are unhealthy for us because we did not evolve to function optimally under such conditions, given the environments and lifestyles of our evolutionary past as hunter-gatherers. Returning to more ancestral-like diets and activity patterns could help resolve this mismatch and improve health.

Here are the key points about what a healthy lifestyle means and what drawbacks there may be:

  • An ancestral or hunter-gatherer lifestyle is often considered healthier since humans evolved eating whole, unprocessed foods and being physically active by hunting and gathering.

  • However, humans have also adapted to new foods like dairy and grains through evolution. Our bodies aren’t necessarily only adapted to ancestral diets.

  • Some drawbacks of fully adopting an ancestral lifestyle include difficulty accessing wild foods and limited dietary variety. It can also be impractical for modern life.

  • Specific healthy changes could include eating more whole foods like fruits, vegetables, nuts and seeds while limiting ultra-processed junk foods and refined carbs.

  • Physical activity levels should aim to mimic our evolutionary past with both aerobic activity like walking/running and strength training with bodyweight movements.

  • Too much sedentary time spent sitting should be reduced through taking breaks and incorporating incidental movement into daily life.

  • Moderation is key - a balanced lifestyle that incorporates some healthy ancestral principles may be most sustainable long-term over an extreme change.

The main challenge is adapting our evolved needs to modern environments and lifestyles in a pragmatic way that supports long-term well-being. Both evolution and our current realities must be considered.

  • Adaptations evolve to help organisms survive and reproduce under specific environmental conditions. What contexts matter most for the evolution of adaptations are those where survival and reproductive success can vary greatly.

  • Adaptations often involve tradeoffs, as no single trait can optimize an organism for all contexts. The evolution of adaptations tends to result in imperfect compromises rather than perfection, as environments constantly change.

  • Over time, organisms accumulate multiple interacting adaptations through natural selection. The human body can be viewed as a “palimpsest” containing layers of adaptations that provide functional flexibility across a range of conditions.

  • Adaptations evolve to maximize reproductive success, not necessarily health, longevity or happiness. Many human traits that cause problems today evolved because they improved survival and fertility in the past.

  • Understanding human evolutionary history is important for explaining why the human body is designed the way it is. It also provides insights into what environments and lifestyles humans are well-adapted or maladapted to, which is crucial for preventing and treating diseases. Disease susceptibility can often be traced to mismatches between modern and ancestral environments.

In summary, contextual factors that impact survival and reproduction have driven the evolution of imperfect, tradeoff-involving adaptations in humans and other species. Knowledge of evolutionary history helps explain human traits and diseases.

Here are the key points about who is more at risk of type 2 diabetes and why it’s difficult to encourage healthier behaviors:

  • Certain groups are genetically predisposed to type 2 diabetes, such as some racial/ethnic groups whose ancestors evolved in environments with different diets/activity levels.

  • From an evolutionary perspective, our bodies were adapted for conditions as hunter-gatherers, not modern sedentary lifestyles and diets high in sugar/processed foods. This mismatch is a root cause of rising diabetes rates.

  • Humans evolved to crave energy-dense foods and efficiently store fat, which provided advantages in past environments but now contributes to obesity/diabetes risk with modern diets.

  • Sedentary lifestyles are also evolutionary novelties that our bodies were not adapted for. Physical activity was an everyday part of life as hunter-gatherers.

  • It’s difficult to encourage healthier behaviors because our evolved preferences for sugar/fat and tendencies towards sedentary behaviors are deeply ingrained and take conscious effort to override. Modern environments also heavily promote obesity/diabetes.

So in summary, certain groups are genetically predisposed, but more fundamentally, modern diets/lifestyles mismatch our evolutionary adaptation, making diabetes more common and behaviors to reduce risk harder to adopt on a large scale. Our biology evolved for conditions no longer present today.

  • Human evolution is far from over due to rapid cultural change acting as the dominant evolutionary force on the human body today.

  • Cultural evolution and our evolved biological traits now interact in complex ways. Cultural changes sometimes create novel environments that our bodies are poorly adapted for, leading to non-infectious diseases.

  • Efforts to prevent these “mismatch diseases” often fail because the novel environmental causes are difficult to change, and sometimes diseases are unintentionally perpetuated by treating only the symptoms.

  • This allows a vicious cycle where the disease remains common. This is a form of cultural evolution, not biological evolution, as the environments and behaviors causing the diseases are passed on, not the diseases themselves.

  • To understand these interactions, we must first examine human evolutionary history over the past 6 million years to understand what the human body is truly adapted for. This exploration involves looking at how early human ancestors evolved bipedalism in Africa and becoming adapted to an upright posture.

  • The earliest known hominins include Sahelanthropus tchadensis from Chad dating to 6-7 million years ago, Orrorin tugenensis from Kenya at 6 million years old, and two species of Ardipithecus from Ethiopia - A. kadabba from 5.8-5.2 million years ago and A. ramidus dated to 4.5-4.3 million years ago.

  • Fossils of these early hominins are sparse but provide clues about the transition from chimp/gorilla-like LCA to bipedal hominins. They have small brains and retain many apelike features but also show signs of bipedalism.

  • Ardipithecus ramidus is particularly informative, represented by a partial skeleton of a female (“Ardi”) that shows adaptations for both bipedal walking and tree climbing.

  • While bipedalism in humans may seem uniquely challenging, it is not exceptionally rare across the animal kingdom. Occasional bipedalism is common, and the transition to habitual bipedalism in early hominins likely occurred gradually over several million years.

  • The passage discusses key anatomical adaptations that enabled early hominins like Ardi to walk upright in a bipedal fashion, even though it was different from modern human walking.

  • Features like a reshaped pelvis with a shorter, sideways-facing ilium allowed for better torso stabilization while walking. An S-shaped spine and lumbar vertebrae positioned the torso above the hips.

  • The foot had traits indicating it could generate effective forward propulsion, like a partially stiffened midfoot and toes that could bend upward. However, the foot also retained adaptations for tree climbing.

  • Ardi and these early hominins were occasional bipeds that walked upright in a non-human manner when on the ground. Their gait was likely more efficient than apes but less than modern humans.

  • They were also adept climbers that spent time in trees. Their gait when walking was odd, stepping to the sides of long, inward feet with short strides.

  • Dietary adaptations included slightly larger teeth than apes, better able to process low-quality foods in addition to fruit. But their faces and teeth were generally apelike.

So in summary, the key points are the anatomical evidence for emerging bipedalism in early hominins like Ardi, along with retention of climbing abilities, and subtle dietary differences from apes.

  • Early hominins like Ardi and Toumaï had slightly more forward-placed cheekbones and more vertical faces compared to chimpanzees. This positioned their chewing muscles to produce higher bite forces for breaking down tougher foods like plant stems and leaves.

  • Their canine teeth were also smaller and less dagger-shaped than male chimpanzees, likely adapting them to chew tougher foods rather than fighting conspecifics.

  • Taken together, this evidence suggests early hominins were adapting to eat less desirable but more fibrous foods when preferred fruits became scarce, due to climate changes shrinking forests into woodlands.

  • Bipedalism evolved initially to help hominins forage more efficiently as climate change caused food sources to become more dispersed. Standing and walking upright may have allowed accessing foods like fruits in trees more easily.

  • More importantly, bipedalism was likely under strong selection because it was energetically far more economical than chimpanzee-like knuckle walking. Hominins could travel much farther on two legs using the same energy, aiding search for scarce foods over larger areas as habitats changed. This made bipedalism highly advantageous for surviving periods of environmental stress and scarcity.

  • Bipedalism evolved in early hominins like Ardipithecus to help them forage more efficiently for fallback foods when fruit was scarce, as the climate in Africa was cooling.

  • Initially bipedalism provided only a modest advantage, but natural selection gradually enhanced features like lumbar vertebrae that improved upright walking and running.

  • Bipedalism freed the hands but did not immediately lead to tool use - that took millions of years. However, it did create new challenges like unstable pregnancy and loss of speed.

  • Pregnancy while bipedal imposed additional stresses, and hominin females evolved adaptations like extra lumbar vertebrae to cope. Loss of speed made early hominins more vulnerable to predators.

  • While disadvantageous in some ways, the benefits of bipedalism like more efficient foraging outweighed the costs, allowing hominins to survive for 2 million years. It set the stage for later adaptations like tool use and brain expansion in response to new challenges.

  • The australopiths, who lived between 4-1 million years ago, played a pivotal role in human evolution through changes to their diet and locomotion.

  • Compared to earlier hominins like Ardipithecus, the australopiths relied more heavily on foods that were hard and tough to chew, like tubers, seeds, and plant stems, rather than fruit. This is evidenced by adaptations like larger teeth, more robust jaws, and wider faces suited for powerful chewing muscles.

  • Their walking style also became more human-like, with features like wider hips, arched feet, and alignment of the big toe, allowing for more efficient bipedalism. However, some australopith species may have still been adept climbers.

  • Variations in diet and locomotion among different australopith species were likely driven by climate changes in Africa during the Pliocene, which led to more open habitats with less abundant fruit.

  • By partially weaning off fruit and becoming proficient bipeds adapted to tougher foods and long-distance travel on foot, the australopiths set the stage for later evolution of the genus Homo and many key features of the modern human body.

  • Climate change made Africa drier during the time of the australopiths, expanding open woodland and savanna habitats. This created a “fruit crisis” as fruit became more scarce and scattered.

  • This placed strong selective pressure on australopiths to access alternative/fallback foods when preferred fruits were unavailable. Fallback foods can mean the difference between life and death.

  • Evidence suggests australopith diets included fruits when available, as well as edible leaves, stems, and seeds. It is likely they also started digging for underground storage organs (USOs) like tubers, bulbs and roots, which were highly nutritious fallback foods.

  • USOs require effort to extract but are rich in calories, nutrients and available year-round. Relying on USOs would have provided important dietary benefits over chimp-like fallback foods.

  • The large, flat teeth with thick enamel seen in australopiths, especially robust species, were adaptations for chewing tough, fibrous foods like raw USOs. Their teeth were specialized for forceful, grinding chewing to break down hard fallback foods.

  • Accessing and eating fallback foods, through adaptations like robust dentition, influenced the evolution of australopith bodies and abilities under strong natural selection pressures to acquire sufficient nutrition.

  • Australopiths, early human ancestors, had large, thick teeth shaped like millstones that were well-adapted for grinding tough, fibrous foods like tubers. They needed these big teeth to chew unprocessed, uncooked foods for much of the day.

  • As australopith cheek teeth and chewing muscles evolved to be larger, their front teeth like incisors and canines became smaller to make room. This reflected their declining reliance on fruit and increasing consumption of tougher fallback foods.

  • Large chewing muscles required heavy muscle attachments and thick skulls/faces in australopiths to provide strength and resist damage from forceful chewing. Their skulls show features indicating powerful jaw muscles.

  • Thick, robust jaws and faces in australopiths helped withstand the stresses of chewing tough foods all day without fracturing.

  • While diets varied, climate change likely increased australopith reliance on tougher,starch-rich underground storage organs like tubers as fruits became less available.

  • Foraging further for dispersed fallback foods required australopiths to evolve more efficient bipedal walking adaptations to travel longer distances compared to tree-dwelling apes. Features like straightened lower limbs increased walking efficiency.

  • Australopithecus afarensis and A. africanus had short, sturdy big toes aligned with the other toes, adapted for bipedal walking. They also had a partial longitudinal arch in the foot.

  • This stiffened arch and upwardly oriented toe joints indicate they could push off effectively during walking, like humans.

  • A. afarensis specifically had a large, flat heel bone adapted to coping with high impact forces from heel striking during walking - implying an extended leg stride like humans.

  • However, A. sediba had smaller, less stable heels and likely walked with a turned-in foot and shorter stride without significant heel striking.

  • Australopiths had inward-facing femurs allowing a narrow stance without side-to-side swaying. Their hip and knee joints were robust to handle forces of bipedalism.

  • They also had more stable, human-like ankle orientations compared to chimps. Wide pelves and curved lumbar spines helped stabilize the upper body during bipedal walking.

  • Species like A. afarensis were fairly efficient walkers, though not identical to humans. They retained some climbing adaptations like long arms and curved fingers/toes.

  • Bipedalism in australopiths allowed long-distance traveling in search of foods, helping survival when resources were scarce. This set the stage for later hominin evolution.

  • The evolution of Homo erectus and early humans is linked to climate change during the Ice Age between 3-2 million years ago, as Earth’s oceans cooled by 2 degrees Celsius on average.

  • In eastern Africa, this led to shrinking forests and expansion of grasslands/woodlands as habitats changed. Finding food became more challenging as preferred fruits became scarcer.

  • Early humans like H. erectus evolved new behaviors to cope, including hunting/gathering in addition to plant foraging. This involved eating more meat, using tools, and cooperating in tasks like food sharing.

  • H. erectus, dated to 1.9 million years ago in Africa, had a modern human-like body plan with traits adapted for hunting/gathering. Though their brains and faces were intermediate between australopiths and humans.

  • H. erectus dispersed out of Africa and survived for almost 2 million years, indicating hunting/gathering was successful. Their body proportions allowed for long distance movement to access varied food sources.

  • The evolution of hunting/gathering underlies the evolution of the human genus Homo and its characteristic physical traits, more so than enlarged brain size initially. This lifestyle enabled survival of early humans as climate changed.

  • Early humans began gathering plant foods like tubers, nuts, berries, and honey around 2-3 million years ago in open African habitats. This required traveling long distances (6+ km per day) to find scarce, seasonal foods that were difficult to extract from hard shells, underground, etc.

  • Meat eating began by at least 2.6 million years ago, as evidenced by cut-marked animal bones. Meat was an important high-calorie, nutrient-dense supplement to the plant-heavy diet.

  • Hunting and gathering required intensive cooperation, including food sharing between mates, offspring, extended families, and community members. This was essential for survival given the risks and uncertainties of this way of life.

  • Mothers were unlikely able to regularly hunt or scavenge while pregnant/nursing and caring for toddlers, so a division of labor emerged where females gathered and males hunted and provisioned the family/group.

  • Food processing using simple tools was also necessary to make tough, fibrous plant and animal foods more easily chewed and digestible. Without this, early humans would have spent all their time eating and digesting with no time left for other activities.

The transition to hunting and gathering selected for several adaptations that enabled early humans to walk long distances in search of food. Homo erectus had longer legs than australopiths, which reduced the energy costs of walking. Their feet developed a full arch and modern striding gait. Leg bones became thicker and joints larger to withstand the higher forces of bipedal walking.

Walking upright helped dissipate heat by reducing solar exposure compared to quadrupeds. H. erectus also had a taller, longer-limbed body shape that increased surface area for sweating and cooling. An external nose created turbulence to warm inhaled air before reaching the lungs, aiding thermoregulation. These adaptations allowed early humans to walk long distances foraging during the hottest parts of the day when other animals rested, expanding their range and diet. The combination of technological, social and anatomical changes enabled the evolution of hunting and gathering as a novel human survival strategy.

  • The external nose evolved in early humans to humidify air before it reaches the lungs. Its unusual anatomy causes inhaled air to swirl in chaotic vortices, increasing contact with mucus membranes that humidify the air.

  • This humidification is important to prevent the lungs from drying out when breathing hot, dry air. The nose turbulence also helps recapture moisture when exhaling.

  • Early humans like Homo erectus evolved abilities for running long distances at moderate speeds in hot conditions. This helped them hunt and scavenge on the savanna.

  • Persistence hunting, chasing prey until it overheats, was likely used since early humans lacked weapons for close-range kills. Sweating and loss of body hair helped dissipate heat during runs.

  • Structural adaptations like spring-like tendons and muscles appeared in H. erectus, improving running efficiency and endurance. These enabled hunting and survival in hot, open habitats through running-based strategies.

  • Running uses springs in the legs and feet to store and release energy, lowering the calorie cost. The human arch and Achilles tendon act as effective springs.

  • Running is less stable than walking, so humans evolved adaptations to stabilize the body while running. These include an enlarged gluteus maximus muscle, larger semicircular canals in the inner ear, and the nuchal ligament connecting the head and arms.

  • Other running adaptations include relatively short toes, narrow waists and shoulders allowing independent hip and torso movement, and leg muscles with many slow-twitch fibers for endurance.

  • Many running adaptations like the gluteus maximus and nuchal ligament don’t benefit walking, showing selection for running ability in early humans.

  • Running capabilities may have driven early humans to become less capable climbers, focusing on hunting and scavenging via long distance running instead.

So in summary, humans evolved many anatomical adaptations geared towards efficiently storing and releasing energy while running, as well as stabilizing the body during the less stable running gait - adaptations that helped early humans hunt and scavenge over long distances through persistent running.

  • The majority of a throw’s energy comes from the shoulder, which acts like a catapult by cocking the arm behind the head. With precise timing, humans can throw projectiles like spears at up to 100 mph. Effective throwing requires anatomical developments seen in Homo erectus.

  • Early humans needed tools not just for hunting but also for basic food processing like cutting, grinding and tenderizing. This reduced chewing/digestion time and improved calorie extraction. It also allowed smaller teeth and chewing muscles in Homo erectus.

  • Brains and guts share similarities as expensive tissues consuming about 15% of energy. In humans they are similarly sized at around 1 kg each, unlike most mammals where guts are twice brain size.

  • Aiello and Wheeler proposed Homo shifted energy from large guts to large brains by switching to higher quality diets from hunting/gathering. This enabled the 33% larger brain size of H. erectus compared to australopiths, likely through smaller gut size as well.

  • Larger brains provided advantages for the intense cooperation required for hunting/gathering, involving skills like theory of mind, communication, reasoning, memory. Bigger brains then allowed further evolution once this lifestyle provided more energy.

So in summary, hunting/gathering enabled shifts in human anatomy, development and energetics through food processing, diet changes and brain-gut tradeoffs, culminating in the increased brain size and cognitive abilities of Homo erectus.

  • Homo erectus was the first hominin species to migrate out of Africa, dispersing across the Old World around 1.9 million years ago. Early H. erectus populations were small and lived at low densities, allowing them to gradually spread over wide areas without significantly increasing population density.

  • H. erectus began colonizing temperate regions during the Pleistocene Ice Ages, which consisted of repeated cycles of extreme cooling and glacial expansion followed by rapid warming and glacial retreat. During cold periods, much of Europe was uninhabitable tundra but areas like southern Europe and Africa experienced less drastic climate changes.

  • Glacial cycles altered plant and animal distributions, forcing hominin populations to migrate in response. Wet or warm periods allowed expansion into new territories while dry or cold periods may have caused geographic contractions. This created an “ecological pump” effect that periodically redistributed hominin populations across Africa and Eurasia over time.

  • Despite facing challenging and changing environments during the Ice Ages, H. erectus was able to survive and spread widely, becoming the first hominin species to establish populations on multiple continents outside Africa. This suggested early adaptations for coping with variable climates.

  • Homo erectus likely spread out of Africa through the Middle East and into Europe and Asia. However, periods of warmer and colder climate caused fluctuations in available habitats.

  • During drier periods when the Sahara expanded, H. erectus populations in Africa were isolated. Colder glacial periods in Europe and Asia also posed challenges, potentially causing local extinctions.

  • As H. erectus dispersed, isolation led populations to diverge over time through natural selection and genetic drift. Later H. erectus populations showed some variation in size, with bigger brains becoming more common.

  • Descendants like Homo heidelbergensis and other populations classified as “archaic Homo” exhibited larger brains and faces than H. erectus. Neanderthals evolved in Europe/Western Asia, while Denisovans inhabited Asia.

  • Archaic humans were skilled hunter-gatherers who controlled fire and invented stone spear points, improving hunting. Fire allowed for cooking, warmth, and safety from predators.

  • Climate fluctuations challenged archaic humans, sometimes isolating or causing extinction of northern populations that later re-dispersed when conditions improved. Neanderthals and modern humans diverged but remained closely related.

  • Neanderthals were a species of archaic human that lived in Europe and western Asia between about 200,000-30,000 years ago.

  • They had large brains (average 1500 cc) and were well-adapted physically to survive cold climates. Skull features included prominent eyebrow ridges and no chin.

  • Neanderthals were skilled hunter-gatherers who made complex stone tools. However, they showed less evidence of symbolic behavior like art compared to modern humans.

  • Genetic evidence indicates Neanderthals and modern humans diverged genetically 400,000-800,000 years ago, though there was some interbreeding. Neanderthals were close cousins but not direct ancestors of modern humans.

  • Brain size increased significantly in human evolution, nearly doubling in the genus Homo over the ice ages. Neanderthals had brains slightly larger than modern humans on average.

  • Larger brains impose high energy and metabolic costs, requiring adaptations for protection, thermoregulation, birth canal size, etc. The dividends of increased cognition enabled human ancestors to evolve and support larger brains despite these costs.

  • Human birth is difficult due to the tight pelvis and baby needing to make a 90-degree turn in the birth canal. Most human mothers require assistance to give birth.

  • Bigger brains are costly for animals to develop and maintain. However, the benefits of increased intelligence in early humans outweighed these costs. Bigger brains allowed for enhanced cooperation, scientific thinking, and other skills not detectable in archaeological records.

  • Key benefits of bigger brains included improved ability to cooperate in large groups through communication, impulse control, understanding others, and complex social interactions. Bigger brains also enabled better scientific thinking and naturalist knowledge required for hunting.

  • Humans mature gradually over 18+ years compared to other mammals, which incurs fitness costs but allows for prolonged learning and skills development. This prolonged development evolved to support our large, complex brains.

  • Humans added a novel childhood stage after weaning but before full independence. We also significantly stretched out the juvenile and adolescent stages compared to other primates. Our extended development pace cannot be attributed just to larger body size and instead relates to time needed for our big brains to mature.

  • Early human ancestors like Australopiths and early Homo erectus grew their brains at a similar pace to chimpanzees. Their brain sizes were also comparable.

  • Neanderthals attained adult brain size slightly faster than modern humans, between 5-6 years compared to 6-7 years. But a 6-year-old human child still has more developing to do.

  • The Nariokotome Boy fossil showed that H. erectus had a longer childhood than chimps, taking 8-9 years to attain an equivalent skeletal maturity to a 13-year-old human. This suggests juvenile and adolescent periods developed more recently.

  • Evidence suggests Neanderthals may have matured similarly to H. erectus, with adolescence lasting 1-2 years beyond dental maturity. Modern humans likely have the longest adolescence.

  • As brains got larger, the critical infant/childhood development period extended to support growth. This imposed an energetic burden on mothers to nurse and care for infants while still pregnant or caring for toddlers.

  • Humans store more body fat than other primates, likely to fuel expensive brain growth/development and provide reserves during times of shortage. Fat babies and children helped ensure a reliable energy supply.

  • Growing larger brains and longer development periods required acquiring more energy or reallocating energy budgets. Evidence points to both strategies through increased food quality/quantity and diverting energy from other functions to support growth and reproduction.

  • The basal metabolic rate (BMR) of humans and other mammals is mostly dependent on body mass. BMR refers to the minimum calorie needs of the body when at rest.

  • Archaic humans like Homo erectus likely had a relatively smaller gut size compared to their brain size. A smaller gut enabled them to process and digest high quality, meat-rich diets with less energy expenditure.

  • Modern hunter-gatherers have higher total daily energy expenditures (TEEs) than would be expected based solely on body size, averaging 2000-3000 calories due to physically active lifestyles. Archaic humans likely had similar activity levels and TEEs.

  • However, adult hunter-gatherers generally acquire more daily energy (DEP) than they expend on average, yielding a surplus of 1000-2500 calories. This came from efficient hunting, gathering high-quality foods, and food processing/cooking technologies.

  • Having reliable energy surpluses fed a positive evolutionary feedback loop in archaic humans. Surplus could be invested in brain and body growth, reproduction, and supporting larger populations with social cooperation.

  • Gradual increases in brain and body size over millions of years support the energy surplus feedback hypothesis for human evolution. However, unreliable access to food and energy shortfalls also led to the extinction of some archaic human populations.

  • On the isolated island of Flores, archaic humans displayed an extreme case of this evolutionary pressure. The “Hobbit” species Homo floresiensis exhibited dwarfism, likely due to energetic constraints of the small island environment.

  • The discovery of the Tasaday tribe in the 1970s presented the idea that hunter-gatherers lived peaceful, leisurely lives without wanting for anything. However, this turned out to be an orchestrated hoax.

  • While hunter-gatherer lives were not as difficult as often portrayed, they were also not entirely leisurely. Hunter-gatherers had to work many hours each day to obtain enough food through intense cooperation, walking, carrying, digging, etc.

  • However, hunter-gatherers only needed to work enough to satisfy daily needs. They then had free time for rest and social activities. This aspect of their economic system offers some benefits compared to modern stresses.

  • A few true hunter-gatherer groups still exist today, but none are truly “pristine” as they have interacted with farmers/herders for millennia. Studying them provides some insight but not the full picture of human evolution.

  • To understand what modern human bodies are adapted for and why Homo sapiens survived while others went extinct, we must look back in time to examine the origin of our own species and the environmental/social changes that occurred.

  • Modern humans (Homo sapiens) evolved in Africa around 200,000-300,000 years ago from archaic human ancestors.

  • Genetic evidence from comparisons of human DNA globally indicates we all descended from a small ancestral population in Africa.

  • Fossil evidence also traces the origin and dispersal of early Homo sapiens out of Africa starting around 100,000-80,000 years ago.

  • Anatomically, early modern humans had smaller faces that sat more inward beneath the braincase compared to archaic humans like Neanderthals. Our skulls also became more rounded/globular in shape.

  • Behaviorally and culturally, Homo sapiens displayed a unique and unprecedented capacity for innovation, cultural change and transmission of ideas/technology compared to other human species.

  • Starting around 50,000 years ago, a major cultural and technological revolution occurred that enabled Homo sapiens to rapidly colonize the entire planet.

  • Wherever Homo sapiens spread, archaic human species like Neanderthals eventually went extinct, likely due to competitive advantages from our enhanced cognitive/cultural abilities rather than purely physical differences.

  • Modern human skulls are more spherical and globular in shape compared to archaic human skulls, which were longer and more elongated. Modern skulls have a higher forehead and more rounded contours.

  • One distinguishing feature of modern humans is the chin. True chins are not found in archaic humans.

  • Below the neck, the differences between modern and archaic humans are more subtle. Modern hips are slightly less flared and birth canals are narrower. Skeletons are also slightly less robust.

  • While anatomical differences are minor, archaeological evidence shows greater behavioral differences over time. Early modern humans showed signs of long-distance trade and symbolic artifacts.

  • Around 50,000 years ago, the Upper Paleolithic revolution occurred, with innovations like blade toolmaking, bone tools, housings, weapons, and a broader diet. Sites increased in number and density.

  • A key change was cultural - Upper Paleolithic peoples regularly expressed themselves symbolically through art, carvings, and elaborate burials. Cultures also changed over time versus remaining static.

  • While Neanderthals were intelligent, they lacked the propensity for cultural innovation seen in modern humans. Brain size was similar, so differences may lie in brain organization or genetics rather than size.

  • The passage argues that Neanderthals were likely intelligent, with differences between them and modern humans being more subtle in brain structure and wiring.

  • One key difference is that modern humans have 20% larger temporal lobes, which are important for language, memory, and potentially spirituality. Parietal lobes are also relatively larger and involved in sensory processing, symbol understanding, and abstract thinking.

  • The prefrontal cortex may be 6% larger in humans and involved in coordination, planning, social behavior, and impulse control.

  • Larger temporal and parietal lobes may have contributed to a rounder human skull shape.

  • Differences in brain structure could explain enhanced cooperation, communication, tool use, and foraging abilities in modern humans.

  • Human brains may develop thicker neocortexes and have more complex and prolonged wiring, allowing for greater skill acquisition.

  • Genetic differences likely underlie structural brain differences, but specific genes have not been identified yet, though FOXP2 is one candidate.

  • Modern human speech abilities, due to shorter face anatomy, would have enhanced communication of ideas, information, emotions and intentions. This was a key development for modern human culture and technology.

  • The uniquely shaped human vocal tract, with equally long horizontal and vertical portions, produces vowels whose frequencies are more distinct, requiring less precision to produce clearly identifiable sounds. This would make human speech easier to understand.

  • However, this vocal tract configuration also comes at a cost. In humans, the space behind the nose and mouth is not divided into separate tubes for air and food, unlike in other mammals. This means humans risk choking when swallowing food, as it can block the airway, unlike other species where food and air take different paths.

  • These unique traits of human speech and swallowing emerged due to humans having a lower, more retracted face shape compared to other primates like chimpanzees. While archaic humans like Neanderthals could still communicate to some degree, modern human speech was likely clearer.

  • The biological factors making humans cognitively and behaviorally modern have profound consequences because they are manifested primarily through culture. Culture spreads ideas and practices more rapidly than biological evolution alone. Cultural evolution has been a powerful driver of human change over thousands of generations.

  • Self is not a biological trait, but humans have biological adaptations that enable cultural behaviors and the use/modification of culture. These cultural capacities appear to be uniquely developed in modern humans.

  • In contrast to Homo sapiens, Neanderthals and Denisovans likely would not have changed their hunter-gatherer ways much over 100,000 years if they were the only human species left.

  • For Homo sapiens, cultural changes have accelerated biological changes through behaviors like diet, activities, and clothing that influence body growth and function. This doesn’t cause evolution directly but can drive natural selection over time.

  • As modern humans spread globally, cultural innovations allowed survival in diverse environments but also exposed populations to new selection pressures. Physical adaptations developed like shorter limbs and stockier builds in colder climates.

  • Cultural adaptations buffered environments’s effects on genetics but also enabled new selection pressures to operate. Over thousands of years, this contributed to phenotypic variations between human populations.

  • While culture transformed human success, hunter-gatherer lives still required physical effort and abilities. Human evolution should not be seen as purely a triumph of brains over brawn. Both cultural and physical adaptations contributed to the evolutionary success of Homo sapiens.

  • Hunter-gatherer lifestyle was physically demanding but not excessively so. Hunter-gatherers typically worked 6 hours per day procuring food and resources.

  • The transition to agriculture began around 12,000 years ago. Farming enabled population growth through greater food availability but also required new forms of labor and transformed diets. It opened the door to new diseases and social problems.

  • Civilization and modern technology have provided many advantages like longer lifespans, increased prosperity, and enjoyable conveniences. However, they have also caused novel health challenges that were rare for hunter-gatherers, like certain diseases, obesity, diabetes, and mental illnesses.

  • Progress has not always been gradual or continuous. For much of the last few thousand years after the agricultural revolution, farmers generally had to work harder than hunter-gatherers, experienced worse health, and died younger on average despite producing more food.

  • In summary, while civilization has clear upsides, it has also created environmental and lifestyle “mismatches” from our evolutionary past that contribute to new disease burdens. The transition from foraging to farming and modern industrial society brought both benefits and unintended consequences for human health and well-being.

Here are the key points:

  • Significant biological evolution has continued in humans since the Paleolithic, contrary to previous assumptions. Natural selection is still occurring due to genetic variations and differences in reproductive success.

  • Recent studies using large genomic datasets have found evidence of recent natural selection over the past few thousand years, including selection for genes related to reproduction, immunity, metabolism, thermoregulation, etc.

  • However, relatively less natural selection has occurred in humans in the last few thousand years compared to earlier periods, due to the small number of generations and cultural factors buffering selection.

  • Cultural evolution has been a more powerful force of change than natural selection over the past few thousand years. Changes to diets, lifestyle, environments, etc. have altered developmental trajectories and interactions between genes and environment.

  • While human genes have changed modestly, cultural changes have transformed environments in important ways, leading to a different type of “evolutionary change” through altered developmental plasticity rather than natural selection.

So in summary, biological evolution via natural selection has continued but slowed, while cultural evolution has accelerated changes to human physiology and health through environmental/developmental impacts on the interaction of genes and environment.

  • The human body has changed in various ways due to cultural changes, such as maturing faster, having smaller teeth/jaws, thinner bones, flatter feet, and more cavities. People also tend to sleep less and experience more stress/anxiety.

  • We face new infectious diseases that were previously rare or nonexistent. These changes have a genetic basis but are mostly due to interactions between genes and our changing environments.

  • Type 2 diabetes provides an example, as certain genes make some people more susceptible but it is spreading globally due to new Western lifestyles interacting with ancient genes. Evolution occurs through gene-environment interactions changing rapidly due to cultural changes in our environments.

  • An evolutionary perspective is useful for medicine. Diseases like cancer represent aberrant evolutionary processes within the body. Evolutionary mismatches can also cause health problems when genes are poorly adapted to new environments.

  • Considering human evolution is important for topics like treating infectious diseases, using antibiotics appropriately, fighting cancer effectively, rethinking symptoms as adaptations, understanding why diets/fitness programs often fail, and preventing/treating evolutionary mismatches. The field of evolutionary medicine provides insights into disease etiology and improving health outcomes.

  • Mismatch diseases result from modern behaviors and environments that our bodies are poorly adapted for due to human evolution over millennia. Our genes and physiology are matched to the Paleolithic environment but conflict with some modern conditions.

  • Examples include diseases from eating sugar/carbs instead of the diverse fiber-rich diet we evolved on, or skin cancer from moving to sunny climates without adaptation for high UV exposure.

  • Mismatch can occur when stimuli are too much, too little, or novel compared to what we’re adapted for. Examples include diseases from overeating fat, under eating fat, or eating new types of unnatural fats.

  • Causes of mismatch include migration to new environments, cultural changes altering diets/activities/pollutants, and shifts in life history like living longer or earlier puberty.

  • It’s difficult to definitively identify mismatch diseases due to complex gene-environment interactions and lack of hunter-gatherer health data, but candidates include type 2 diabetes, heart disease, skin cancer, autism, MS, ADHD, and more.

  • An evolutionary perspective considering our adapted environment may help address and prevent mismatch diseases, which are major contributors to disease burden and healthcare costs globally.

  • Other researchers have studied health among hunter-gatherer and subsistence farming populations, but these studies are limited in sample size and data quality. They suggest type 2 diabetes, myopia, and some heart diseases are rare in these groups. Little is known about other diseases like cancer, depression, Alzheimer’s.

  • Table 3 lists diseases hypothesized to be “evolutionary mismatches” - more prevalent, severe, or occurring earlier because modern environments differ from what humans evolved with. This is only a partial list and more data is needed.

  • While these diseases may alarm, not all are definitely caused by mismatch and many are just hypothesized. However, it is clear most diseases today are triggered or intensified by post-hunter-gatherer environmental factors.

  • Some mismatch diseases like scurvy were eliminated by preventing causes, but others like cavities remain common because we treat symptoms but not underlying causes like sugar consumption. This creates a “vicious circle of dysevolution” where we pass on disease-causing environments rather than preventing diseases.

  • Dysevolution is a harmful form of cultural change over time that maintains mismatch diseases, as opposed to treating their root causes to eliminate them over generations. Cavities are given as an example that remains prevalent through this process.

  • The transition from hunter-gatherer to agricultural lifestyles, which began around 10,000 years ago, represented a major mismatch for humans. It marked the end of Eden-like existence for our ancestors.

  • Farming required much more labor and toil compared to the relatively leisurely lifestyle of hunter-gatherers. Humans had to work hard in the fields to grow crops and raise livestock rather than simply foraging for readily available wild foods.

  • This transition subjected humans to various health mismatches. Sedentary agricultural work and new diets high in starchy grains led to problems like malnutrition, obesity, dental cavities, and infectious diseases. Life expectancy declined with the rise of farming.

  • Some scholars argue agriculture was “the worst mistake in human history” as it brought about misery, disease and hardship despite enabling bigger populations through stable food sources. While farming allowed more reliable calorie sources, it imposed physical and biological costs on humans.

  • The biblical story of Adam and Eve being expelled from the Garden of Eden and condemned to toil on the land can be seen as an allegory for humankind losing its original hunter-gatherer existence and having to adapt to the labor and hardships of agricultural living. This transition marked the beginning of major human physiological and health mismatches.

Farming originated independently in multiple locations around 10,000-12,000 years ago as the last Ice Age ended. Rising populations put pressure on hunter-gatherers to find more stable sources of food. The warmer, more predictable climate of the Holocene era made plant cultivation more feasible on a large scale.

Early farmers domesticated plants like wheat and legumes by selectively breeding larger, easier to harvest varieties. They also domesticated animals like sheep and pigs. This led to permanent settlements and dependence on cultivation rather than migratory hunting and gathering.

The transition to farming brought benefits like more predictable food sources but also led to negative health consequences. Farmers had lower quality diets and were more susceptible to infectious diseases in dense populations. They also suffered from “mismatch diseases” as the human body adapted for hundreds of thousands of years of hunting and gathering was now eating cultivated plants and domesticated animals.

Some of the mismatch diseases that arose included nutrition deficiencies, disabilities from harder work, and weaknesses to pathogens evolved from living closely with domesticated animals. However, civilization and population growth were ultimately enabled by the agricultural revolution. Societies responded by developing new food processing and storage techniques to improve nutrition.

  • Farming originated independently in several parts of the world starting around 10,000-9,000 years ago following the end of the last ice age.

  • In the Middle East, the first domesticates included wheat, barley, peas, lentils, and flax. Farming then spread throughout the region and into Europe, Asia, and Africa. Many modern humans have genes originating from these early farmers.

  • In East Asia, rice and millet were first domesticated around 9,000 years ago in China. Asian farming began after pottery was invented, which helped store and boil food for hunter-gatherers.

  • In Mesoamerica, squash was domesticated around 10,000 years ago, followed by corn around 6,500 years ago. Maize agriculture then slowly spread throughout the Americas. Other early domesticates in the Americas included potatoes in the Andes over 7,000 years ago and seed plants in eastern North America by 5,000 years ago.

  • In Africa, domesticates like millet, rice and sorghum emerged south of the Sahara around 6,500 years ago. Yams and taro were likely domesticated in New Guinea between 10,000-6,500 years ago.

  • Domesticated animals spread farming’s impact. Sheep, goats and cattle were domesticated in the Middle East over 10,000 years ago. Pigs were domesticated in Europe and Asia between 10,000-9,000 years ago. Other regional domesticates followed, like llamas in the Andes and chickens in Asia.

  • Farming populations grew rapidly due to higher birth rates and childhood survival compared to hunter-gatherers. This population growth drove farming’s spread worldwide as farmers interacted and exchanged genes with hunter-gatherers.

A Paleolithic hunter-gatherer transported to a modern supermarket would be astounded by the bounty and variety of food available. Before the era of agriculture, transportation and refrigeration, people’s diets were much more limited and monotonous.

Early farmers relied heavily on a few staple crops like wheat, barley and rye for calories. This provided more consistent calories than hunter-gathering but was poorer in nutrients. Farmer diets were more prone to deficiencies and “mismatch diseases” from lack of variety. They also faced risks of famine from crop failures in ways hunter-gatherers did not.

The development of agriculture and processes like refining grains removed fiber and nutrients. Starchy farmer diets promoted dental cavities and issues with blood sugar levels over time. While agriculture supported larger populations, it introduced new health tradeoffs and vulnerabilities compared to hunter-gatherer lifestyles. A modern supermarket’s diversity would seem incredibly abundant and appealing to a Paleolithic visitor accustomed to scarce seasonal foods.

  • Farming led to population growth as more calories allowed larger families and higher birth rates. But larger, denser populations also fostered new kinds of infectious diseases.

  • Plagues require large populations, which didn’t occur until farming started. Even modest increases in birth rates from farmer families resulted in exponential population growth compared to hunter-gatherers. World population grew over 100-fold from 5-6 million 12,000 years ago to 600 million at Jesus’ birth.

  • Plagues also require permanent settlements with high population densities. Farmers lived in villages that grew over time, increasing densities from just 1 person per sq km for hunter-gatherers to over 50 people per sq km in towns.

  • Dense, aggregated populations in villages and towns became ideal places for infectious diseases to thrive and spread from host to host. This made settlements dangerous places for human hosts in terms of contagion. More calories and population growth from farming thus had both benefits and costs in terms of new mismatches like infectious diseases.

  • Farming allowed for population growth and density that facilitated the spread of infectious diseases. It introduced humans to new pathogens like tuberculosis, leprosy, syphilis, plague, smallpox, and influenza.

  • Permanent settlements led to poor sanitation with contaminated drinking water and soil, as well as rodents and insects carrying diseases. This included rats, mice, mosquitoes spreading malaria, and flies/lice carrying typhus and plague.

  • Close contact with domesticated animals exposed humans to zoonotic diseases like TB, measles, diphtheria, leprosy, influenza, plague, and smallpox.

  • However, farming also allowed for population growth, civilizations, and overall human achievements. It was advantageous from an evolutionary perspective of having more children.

  • Initially after the agricultural revolution, human health and height increased in some areas as nutrition improved. But over time, stresses like diseases and malnutrition led to declining height and health indicators in many farming populations.

So in summary, farming introduced major diseases but aided population and civilization growth. The impact on human health was mixed, with initial benefits followed by increasing stresses as populations grew and diseases spread. It was largely driven by evolutionary pressures for population growth above all costs.

  • The transition to agriculture initially led to benefits like increased height, but over longer periods, health generally declined as farming intensified. Skeletal evidence shows higher rates of disease, malnutrition, and dental problems among agricultural populations.

  • Farming drove natural selection by altering diets, pathogens, workloads, and population sizes, providing more mutations for selection to act on. Studies have identified over 100 genes selectively favored due to agriculture, many related to immunity against diseases like malaria, plague and tuberculosis.

  • Genes also evolved to help digest dairy and process carbohydrates from domesticated foods. However, cultural innovations like making nixtamalized corn flour had a greater buffering impact on mismatch diseases than genetic adaptations alone. While some cultural responses cleverly solved problems, others only treated symptoms.

  • Overall, while agriculture intensified natural selection, many cultural innovations insulated humans from the strongest selection pressures and negative health impacts of the agricultural lifestyle. Cultural evolution has been a more dominant force than genetic adaptation since the origins of farming.

The passage describes the paradox of human health in the industrial era. While advances in healthcare, sanitation, and education since the Industrial Revolution dramatically improved health and life expectancy, new “mismatch” diseases have emerged that were rare or unknown historically.

The Industrial Revolution transformed the world economically and technologically as humans harnessed fossil fuels to power machines for manufacturing and transportation. This led to fundamental shifts like new sources of energy to produce goods, specialization of labor, and globalization of trade and food production.

While this increased wealth and living standards, it also disrupted traditional lifestyles and communities. Modern illnesses like diabetes, heart disease, and cancer have become prevalent, as people’s diets, activities, and environments changed radically in just a few generations due to industrialization.

To understand current health issues, the passage argues we must view the industrial era through an evolutionary lens - examining both how it solved problems from agriculture but also created new mismatches between our ancient genetics and modern environments and behaviors.

  • The Industrial Revolution led to new types of manufacturing jobs like operating machines in mills, plowing fields with machines, and transporting goods. It also enabled new industries like beer brewing.

  • It drove a transition to capitalism and specialization of labor. Workers shifted from farms to factories performing more specialized roles, requiring more coordination and new organizations.

  • Factories drew many people to cities, changing family structures and social classes. New services and institutions evolved to support the growing middle class.

  • Science became increasingly important, with engineers and chemists playing key roles in industrialization. Scientists like Pasteur also helped advance public health.

  • While factory jobs were very physically demanding initially, technology has reduced activity levels over time. Many jobs now primarily involve sitting, standing, or light activity compared to farming work.

  • As economies developed, manufacturing shrank and service sector jobs focusing on information, administration, and research grew, further reducing activity levels for many workers.

The Industrial Revolution significantly reduced the amount of physical activity people engage in, both at work and in daily life. Many modern inventions like cars, elevators, appliances, etc. have made tasks more efficient by reducing the physical effort required. As a result, the average amount of daily physical activity for office workers has decreased by around 15% compared to farmers and manual laborers.

The Industrial Revolution also transformed our diets and food system. Food production became highly industrialized and efficient, allowing for abundant, cheap sources of calories like sugar, fat, starch and salt. Portion sizes increased significantly over time as well. As a result, the modern diet tends to be more calorie-dense and less varied or nutritious than historical diets. Industrial meat production in particular relies on large-scale, intensive farming methods to lower costs and increase output, often at the expense of environmental impacts and animal welfare. Overall, industrialization made highly processed, calorie-dense foods widely and cheaply available, contributing to positive and negative nutritional changes.

  • Industrial agriculture practices like concentrated animal feeding operations (CAFOs) can promote disease in animals due to high densities and waste. Animals require constant antibiotics to treat chronic diarrhea and prevent death. CAFOs also generate large amounts of pollution.

  • Food industrialization has significantly changed human diets. Processed foods are engineered to be appealing, convenient and shelf-stable but are often low in nutrients and fiber and high in sugar, fat and salt. This contributes to obesity and diseases like diabetes.

  • Industrial diets differ greatly from hunter-gatherer diets. They contain higher carbohydrates, especially refined starches and sugars. They are lower in protein and fiber but higher in saturated fat. Vitamins and minerals are also lower except for salt.

  • Industrialization supported medical and sanitation advances through new technologies, funding and infrastructure. This helped populations explode and drove more demand. A key revolution was discovering microbes and combating pathogens through practices like sanitation, hygiene, vaccines and antibiotics. This improved health and supported the Industrial Revolution’s success in enabling more people to work and consume goods.

  • In the 1700s, Edward Jenner brazenly scratched the arm of a boy with smallpox pus from a human, but the boy did not get infected. This showed exposure to cowpox provided protection against smallpox.

  • In 1856, Louis Pasteur proved microbes caused infections when he discovered bacteria contaminated wine and heating it killed the microbes, preventing vinegar formation. This led to pasteurization and breakthroughs in microbiology.

  • Pasteur developed vaccines against anthrax, chicken cholera and rabies. He also saved the silk industry by identifying the source of a plague killing silkworms. This created the new field of microbiology.

  • Later in the 1800s, scientists discovered other disease-causing bacteria, malaria-causing protozoa, and viruses. Paul Ehrlich developed the first effective antibacterial drugs in the 1880s. Penicillin was accidentally discovered in 1928 but mass produced during World War 2, saving hundreds of millions of lives.

  • Advances in medicine, sanitation, hygiene, food storage and refrigeration greatly reduced disease transmission and improved public health during the Industrial Revolution. This showed how scientific and industrial progress reinforced each other.

  • Traditionally, humans rarely slept alone or in isolated conditions. People usually slept in close proximity and shared beds with family members.

  • Hunter-gatherer societies typically took daily naps and had an earlier bedtime than modern societies. They also often had a “first and second sleep” pattern, waking up briefly in the middle of the night.

  • The Industrial Revolution transformed sleep patterns by providing entertainment like lights, radio, and TV that encouraged people to stay up later. It also increased stress levels.

  • Isolating ourselves in insulated bedrooms may disrupt natural sleep processes by minimizing sensory stimuli humans evolved with, like sound and smell.

  • Around 10% of people in developed nations regularly experience serious insomnia due to changes in lifestyle and sleeping environment.

  • Lack of sleep has negative health impacts by disrupting hormone levels related to growth, metabolism, appetite and more.

  • Historically, better sleep quality correlated with higher socioeconomic status as wealth reduced stress levels.

So in summary, modern sleep patterns differ significantly from traditional hunter-gatherer practices and may contribute to increasing rates of insomnia and associated health problems. The Industrial Revolution disrupted evolutionary sleep adaptations.

  • Over the last millennium, Europeans steadily increased in height until the 20th century when they reached the same heights as cavemen. Dutch males were once shorter than American males but are now the tallest due to further increases in height.

  • Weight has also generally increased due to more calories from plentiful food and less physical activity. The average BMI of American males has risen from healthy to overweight levels over the last century. However, birth weights have not increased and low birth weight is still an issue, especially for Black populations.

  • Longer lifespans, increased fertility, and decreased infant mortality fueled a population boom over the Industrial era. World population has more than doubled from 3 to 7 billion people since 1960. Urbanization has also increased as more people move to cities.

  • While progress was made against infectious diseases of poverty, the epidemiological transition has brought rising rates of noncommunicable diseases as more people live longer. Lower mortality has been accompanied by higher rates of chronic illness and disability in older populations. Overall, industrialization led to both improvements in some measures of health but also new health issues and disparities.

  • Senior citizens today generally live much longer than their grandparents/great-grandparents did in the early 20th century. In the 1930s, life expectancy was around 60-64 years but people can now expect to live 18-20 years longer on average.

  • However, seniors today are also more likely to experience a slower, more painful death due to chronic illnesses rather than acute illnesses that were common historically.

  • The leading causes of death have shifted from respiratory/infectious diseases to heart disease and cancer, which often involve lingering illnesses over many years rather than quick deaths. Other chronic illnesses like Alzheimer’s, diabetes, arthritis are also more prevalent.

  • This “extension of morbidity” as seniors live longer but with illnesses is contributing to rising healthcare costs as the large Baby Boomer population ages.

  • Looking at it from an evolutionary perspective, the rise in chronic diseases cannot be fully explained as an inevitable tradeoff of living longer. Hunter-gatherers who avoid modern lifestyles do not experience many chronic diseases common today even into old age.

  • This suggests that aspects of modern environments and lifestyles are evolutionary “mismatches” that promote chronic disease more than simply aging itself. Factors like diet, activity levels, etc. may play a role.

  • Obesity is one of the biggest health problems today, with two-thirds of adults in developed nations being overweight or obese.

  • While humans are well-adapted to store fat, excess belly fat in particular can lead to diseases like type 2 diabetes, heart disease, and some cancers. These are examples of mismatch diseases caused by too much of a stimulus (energy intake) that humans are not well-equipped to handle.

  • The body converts food like carbohydrates and fats into energy molecules called ATP through cellular processes like burning fuels. Energy balance is determined by intake vs expenditure of ATP.

  • Excess energy intake beyond expenditure is stored as fat. Humans are very adapted to gain weight and store fat, but not well-adapted to excess belly fat.

  • The high prevalence of obesity-related diseases increasing now may be due to environments providing relentless excess energy intake that humans struggle to cope with metabolically.

  • Treating obesity-related diseases sometimes creates feedback loops that compound the problems, by not addressing the underlying causes of excess energy intake. An evolutionary perspective provides insights into these issues.

  • Energy balance is a measure of how much energy one takes in from food versus how much energy is expended over a given period of time. In the short term, one is usually in either positive or negative energy balance after eating or not eating.

  • Over longer periods like days, weeks or months, being in energy balance means not gaining or losing weight. Weight gain or loss occurs from extended periods of positive or negative energy balance.

  • Organisms regulate energy balance in two main ways - how much they eat and how much they expend. The resting metabolism accounts for a large portion of daily energy expenditure to support essential functions. Physical activity burns additional calories depending on intensity.

  • When food is consumed, carbohydrates, proteins and fats are broken down. Carbohydrates and fats are stored or burned for energy, but in different ways. Glucose from carbs is used immediately while fructose and excess carbs are stored as fat. Fat provides more dense energy storage as triglycerides.

  • Insulin regulates blood glucose and stimulates storage of excess carbs and glucose as fat. Glucagon and cortisol trigger the release of stored energy from fat and glycogen during periods of need.

  • The body functions like a fuel bank, storing energy from food intake and withdrawing it through hormonal control of fat and carb fluxes to organs as needed to maintain energy balance and activity levels.

  • Humans evolved to store fat readily due to its evolutionary importance for survival and reproduction. Having extra body fat provided an energy reserve for times of scarcity.

  • Natural selection favored genes making it easy for humans, especially women, to store fat. This “thrifty genotype” helped humans store calories when food was plentiful to survive tough times.

  • The “thrifty genotype hypothesis” proposes populations like Native Americans are prone to obesity today due to retaining these genes, which are mismatched with modern plentiful diets.

  • However, studies found no clear evidence of “thrifty genes” or regular famines during human evolution as the hypothesis predicted.

  • The “thrifty phenotype hypothesis” better explains patterns by focusing on developmental interactions between genes and environment. It notes babies exposed to malnutrition in the womb often become obese adults due to metabolic changes adapting them to scarcity.

  • This mismatch makes them prone to diseases like diabetes in today’s calorie-rich environments, as their bodies struggle to process excessive, easy-to-digest modern foods lacking fiber. Overall biological and developmental factors better explain human obesity trends than genetics alone.

  • The thrifty phenotype hypothesis explains the prevalence of metabolic syndrome among low birth weight babies and small-bodied populations as an adaptation to scarce resources. However, it does not explain why many children born to healthy or overweight mothers also develop these diseases.

  • Most people in developed countries who develop metabolic syndrome were not small at birth but rather were born with high birth weights. Instead of developing thrifty phenotypes, they develop “prodigal phenotypes” where they are born large due to excessive body fat.

  • Excessive weight gain during childhood relative to height is a strong risk factor for future metabolic syndrome. Overweight children develop and retain more fat cells throughout life, often in the abdominal area around organs.

  • Visceral (belly) fat behaves differently than other body fat by being more metabolically active and dumping fatty acids directly into the liver, impairing its function and increasing metabolic disease risk.

  • While people have always stored extra energy as fat, modern environments provide too much energy that humans did not adapt to. Changes in diet, particularly increased consumption of rapidly digestible sugars and high fructose corn syrup, have driven surging obesity rates since the 1970s by promoting higher and prolonged insulin and fat storage.

  • The liver can readily process fructose from whole fruits and vegetables at a leisurely pace. However, it can become overwhelmed by high amounts of fructose from processed foods consumed too quickly.

  • When this happens, the liver converts excess fructose to fat, some of which builds up in the liver and blocks insulin activity. This drives more insulin release, storing even more glucose and fat.

  • The average American consumes much more fructose today (55g) versus pre-WWI (15g), often from soda and processed foods containing high-fructose corn syrup.

  • Diet plays a dominant role in obesity rates rising globally. While genes can increase susceptibility, weight-gaining genes long predate current obesity levels. Changing environments, not genes, best explain the epidemic.

  • Other contributing environmental factors include increased stress/cortisol levels, sleep deprivation, physical inactivity, and changes to gut bacteria from modern diets and antibiotic overuse.

  • Exercise leads to modest weight loss primarily by promoting healthier metabolic function rather than direct calorie burning. Maintaining activity helps prevent weight gain.

  • Multiple factors interacting together can overwhelm the body’s ability to maintain energy balance, leading to excess fat storage and weight gain over time.

  • Type 2 diabetes is caused by insulin resistance, where cells become less sensitive to insulin’s effects and cannot uptake glucose from the blood properly.

  • Insulin resistance is strongly associated with high levels of visceral fat, especially fatty liver, and high triglycerides. People with abdominal obesity are most at risk.

  • Excessive consumption of sugars and refined carbs, especially fructose, promotes fatty liver and visceral fat buildup through increased triglycerides. Lack of physical activity also contributes.

  • Genetics and prenatal environment play some role, but diet and physical activity levels are the main controllable factors that determine risk. Losing weight and vigorous exercise can sometimes reverse early-stage type 2 diabetes by reducing visceral fat and improving insulin sensitivity.

  • Type 2 diabetes is considered preventable because excess visceral fat and insulin resistance can be avoided through diet and exercise lifestyle changes that maintain healthy weight and fat distribution. It has become more common due to lifestyle changes associated with modern obesogenic environments.

  • Studies show that when obese adolescents exercise moderately for 12 weeks, their insulin resistance decreases significantly. Increased physical activity and reduced visceral fat can reverse early type 2 diabetes.

  • In one remarkable study, 10 Aboriginal Australians with type 2 diabetes saw almost complete disease reversal after 7 weeks of returning to a hunting and gathering lifestyle through diet and exercise changes.

  • More research is needed on long-term effects of diet and exercise interventions for type 2 diabetics. However, these studies suggest that vigorous physical activity and improved diets can prevent or slow disease progression.

  • The biggest challenges are environmental factors like unhealthy abundant foods high in sugar/carbs and lack of physical activity due to modern conveniences. By the time obesity and diabetes develop, lifestyle changes are difficult.

  • While medication alongside moderate diet/exercise shifts helps manage symptoms long-term, lifestyle changes alone are nearly twice as effective. Resigning to primarily symptom management perpetuates the problem. Reversing causes through preventing obesity and insulin resistance is key to solving the diabetes epidemic.

  • Atherosclerosis (hardening of the arteries) is an inevitable result of aging, as damage accumulates in the arteries over time. Studies of ancient mummies show evidence of atherosclerosis, confirming it as a natural aging process.

  • However, modern lifestyles have greatly increased the risk factors for cardiovascular disease beyond normal aging. Factors like physical inactivity, poor diet, obesity, smoking, drinking, and stress all contribute.

  • Physical activity is important for cardiovascular health as it strengthens the heart and regulates fat storage/use. Studies show even moderate activity like walking lowers heart disease risk.

  • Diet quality also matters. Saturated fats raise LDL but unsaturated fats raise HDL. While all fats were consumed historically, traditional diets emphasized unsaturated fats which are healthier. Excess salt intake beyond natural levels from meat also contributes to risk.

  • Simply reducing fat intake may not be enough - the type of fats and carbohydrates consumed make a difference. High glycemic carbohydrates and excess fructose raise triglycerides and visceral fat, increasing disease risk.

So in summary, while atherosclerosis itself is natural, modern environmental factors have greatly increased cardiovascular disease risk above normal aging levels through unhealthy lifestyle patterns. Both diet quality and physical activity levels are important protective factors.

  • Chronic stress, through the autonomic nervous system, elevates blood pressure which damages arterial walls over time, leading to plaque formation and inflammation. Chronic emotional stress has similar effects.

  • Too little fiber intake from processed foods fails to effectively remove saturated fats from the digestive system, keeping LDL cholesterol levels high.

  • Moderate alcohol lowers blood pressure and improves cholesterol ratios, but excessive intake damages the liver’s ability to regulate fat and glucose. Tobacco also harms the liver and inflames artery walls.

  • Research indicates hunter-gatherers have much lower risk of heart disease than modern Westerners due to their active lifestyles and natural diets. They had low cholesterol and little evidence of heart issues in autopsies.

  • Heart attacks and strokes are largely evolutionary mismatches caused by agricultural/industrial diets combined with sedentary lifestyles. Physical farmers also have low risk. Risk increased with civilization and more sedentary upper classes.

  • Around 40% of Americans will be diagnosed with cancer in their lifetimes, making it the second leading cause of death. Cancers are caused by chance mutations that cancerous cells exploit to proliferate uncontrollably.

  • Cancer rates are undoubtedly higher today than in the past. Research from the 1800s found cancer rates were at least 10 times lower historically.

  • Reproductive cancers are linked to long-term positive energy balance/obesity through increased cumulative exposure to estrogens and other hormones from more frequent menstrual cycles and less breastfeeding among modern women. This mismatch drives higher rates of these cancers.

  • Reproductive cancer rates have increased with the spread of birth control and affluence. Birth control reduces women’s lifetime exposure to progesterone and estrogen, which promotes cell turnover and cancer suppression.

  • Obesity contributes to higher reproductive cancer risk, as obese women have 40% higher estrogen levels. Rates of these cancers strongly correlate with obesity after menopause.

  • Reproductive cancers are also linked to higher testosterone levels in men, which the body produces more of in states of frequent positive energy balance.

  • Physical activity lowers reproductive cancer risk by reducing levels of reproductive hormones like estrogen. Studies show exercise lowers rates of breast, uterine, and prostate cancers.

  • From an evolutionary perspective, increased access to resources elevates reproductive hormone levels, driving reproductive cancer risk upwards. Thus, these cancers are mismatch diseases ultimately caused by excess energy availability.

  • While some prevention is possible through lifestyle changes, current cancer treatment approaches are generally sensible for fighting the disease. However, treating the underlying causes more could significantly reduce rates. Considering cancers from an evolutionary perspective may also help develop more effective treatments.

  • Condemnations of obesity are often linked to poverty, as obesity is strongly correlated with low socioeconomic status. Being overweight or obese does not necessarily mean someone is unhealthy.

  • Too much focus on fighting obesity may stigmatize people unnecessarily and waste resources. However, where one stores fat, diet, and physical activity levels are more important predictors of health than weight alone.

  • One study found that lean men who did not exercise had twice the risk of death compared to obese men who were regularly physically active, showing the benefits of fitness even at a higher weight.

  • “Diseases of disuse” arise from having insufficient physiological capacity to meet environmental demands, unlike diseases of affluence from excess. They result from too little of a stimulus that was previously common, like physical activity.

  • Phenotypic plasticity allows the body to adapt its characteristics in response to environmental stresses as it develops. However, relying on these adaptations can lead to mismatches when critical environmental cues are altered or reduced, as in modern times.

  • Bones need mechanical stresses/loads while growing to develop proper shape, size and strength. Lack of stress leads to weaker, more fragile bones.

  • Factors like genes, nutrition and hormones also influence bone growth. But ability to respond to mechanical loads is especially important for adaptation.

  • Bones reach peak size in late teens/early 20s. After that, little can be done to make them bigger. Bones begin losing mass for life.

  • Regular stress from movement causes bone deformations which signals repair, keeping bones healthy. Less use leads to loss of bone mass.

  • Osteoporosis causes fragile, breakable bones in older people, especially postmenopausal women. Risk factors include lack of exercise during development, low calcium/vitamin D, smoking.

  • Sedentary modern lifestyles mean bones don’t experience stresses evolution expected, resulting in osteoporosis - a mismatch disease not prevalent in archaeological records. Proper stress signals during growth is important for strong bones later in life.

  • Osteoporosis is a disease caused by an imbalance between bone resorbing cells (osteoclasts) and bone forming cells (osteoblasts). As we age, osteoblast activity decreases while osteoclast activity increases, causing bone loss.

  • Several factors contribute to osteoporosis. Insufficient physical activity during youth and aging leads to lower peak bone mass. Post-menopausal women experience rapid bone loss due to dropping estrogen levels. Low calcium and vitamin D intake from modern diets also decreases bone health.

  • Hunter-gatherers historically experienced less osteoporosis risk factors. Girls reached puberty later, allowing more time to build bone. Their diets contained more calcium. Regular physical activity maintained bone density with age.

  • Osteoporosis is considered a mismatch disease. Our bodies did not evolve for modern sedentary lifestyles and calcium-deficient diets. This exacerbates age-related bone loss and leads to higher rates of osteoporosis compared to our evolutionary past.

  • Impacted wisdom teeth also result from evolutionary mismatches. Hunter-gatherers rarely had issues with wisdom tooth eruption, but agricultural diets led to tooth crowding in recent populations, causing more impactions.

  • Traditional food preparation techniques required extensive chewing, which helped jaws and teeth develop properly through mechanical loading and interaction of genes.

  • Extensive chewing stresses bones and muscles in the face, causing jaws to adapt and grow thicker/larger over time. This allows teeth to be properly positioned and fit together well.

  • Soft, processed modern diets mean less chewing force and stress on jaws during development. This can lead to smaller jaws, misaligned teeth, and impacted wisdom teeth requiring orthodontics/surgery.

  • The microbiome and exposure to pathogens plays an important role in developing a robust immune system during childhood. Extensive sterilization and antibiotic overuse may hinder this development and increase risk of immune-related diseases. Nursing provides immunological support as the immune system matures amid environmental exposures.

So in summary, modern diets and hygiene practices disrupt the co-evolutionary development of jaws/teeth and the immune system that relied on mechanical loading/stress and controlled exposure to microbes during childhood. This mismatch may contribute to increased orthodontic issues and immune dysfunction.

The passage discusses the hygiene hypothesis, which suggests that a lack of exposure to certain pathogens and microorganisms due to increased sanitation may be contributing to higher rates of allergic and autoimmune diseases. It provides background on how the immune system develops antibodies in response to antigens, which can cause inflammatory allergic reactions.

The original hypothesis was that limited childhood exposure to infections allows too many T-helper 2 cells to develop, increasing the risk these cells will target harmless substances as antigens. However, this does not fully explain rising allergy rates as some viral infections do not protect against allergies.

The “old friends” hypothesis proposes that humans coevolved with many microbes/pathogens in the environment, and disrupting this equilibrium through modern hygiene practices has caused the immune system to become overactive. Exposure to a diverse microbiome is associated with lower allergy rates. The passage suggests this imbalance may also explain evidence that exposure to some parasites can treat autoimmune disorders.

In summary, allergies could be mismatch diseases caused by too little exposure to microorganisms early in life, disrupting the immune system’s normal balance and function. While genetics also play a role, environmental disruptions like pollution are likely additional contributing factors to higher rates of immune-related diseases in developed nations.

  • The passage discusses various “diseases of disuse” - health problems caused by a lack of physical activity and stress on the body. Examples given are osteoporosis (weak bones), impacted teeth, and allergies.

  • These diseases have become more prevalent in modern times as people lead increasingly sedentary lives with more comforts and conveniences that reduce physical demands. However, the body needs various stresses to develop properly.

  • While medicines help treat symptoms, the root causes - lack of exercise, overly sterile environments, processed foods - are not adequately addressed. These diseases normally don’t impact fertility either.

  • The solution is not to abandon modern advances, but to reconsider how and when we use technologies like antibiotics. Modest levels of physical activity and exposure to dirt/germs are important for development.

  • Human bodies evolved through interactions with the environment, not in isolation. Allowing reduced stress leads to health issues down the line. Prevention through diet and exercise is key, but changing habits is challenging.

  • The passage then introduces the concept of “diseases of novelty” - how becoming accustomed to new aspects of our environment can make us overlook potential harms, like chemicals in products or vehicles. Questioning norms is difficult but important for health.

  • Many everyday comforts and novelties that humans commonly engage in, like wearing shoes, reading, and sitting, are actually evolutionary mismatches that can be potentially harmful in excess.

  • Our bodies aren’t well-adapted to these activities since they are relatively recent introductions, unlike behaviors we engaged in for millions of years as hunter-gatherers like walking barefoot.

  • However, we often confuse comfort with well-being and assume anything comfortable must be good for us. Things like overly soft beds, sedentary lifestyles, and cushy shoes can indeed lead to issues like back pain if taken to an extreme.

  • Three everyday activities looked at more closely are wearing shoes, reading, and sitting. Shoes limit sensory feedback from our feet and impact how we run or walk. Cushioned shoes encourage heel striking which can be injurious for running. Reading and sitting are largely sedentary.

  • The key is adopting an evolutionary perspective to help design better footwear, reading material, and seating that avoids the downsides of these modern conveniences while retaining the benefits of comfort. Moderation is important.

  • Landing on the balls of the feet or midfoot when running, known as a forefoot strike, helps absorb impact without generating noticeable impact peaks, making it less stressful on the body than heel striking.

  • Many experienced barefoot runners tend to forefoot or midfoot strike when running long distances on hard surfaces to avoid pain from impacts. Shod runners also switch to a forefoot strike when barefoot.

  • Heel striking allows for an easier, longer stride but generates hard, forceful impacts that can lead to injuries over many miles of running per week or year.

  • Shoes with arch supports, stiff soles, and toe springs make foot muscles weaker by doing the work for them. This can lead to flat feet and plantar fasciitis from the plantar fascia compensating for weak foot arch muscles.

  • Orthotics and other treatments relieve symptoms but don’t address the underlying cause of weak foot muscles. Strengthening foot muscles through barefoot activity is healthier.

  • Aspects of many shoes like narrow toe boxes and high heels can also cause foot problems like bunions, misaligned toes, and injuries.

  • Minimal shoes that don’t interfere with natural foot function may be healthier options and help adapt those with weak feet. Encouraging barefoot time for children helps their feet develop properly.

  • Many people today experience foot pain and treat it with orthotics, comfortable shoes, surgery, medications, and other products from pharmacies. As long as shoes remain comfortable, podiatrists will continue to have many patients to treat foot issues caused by modern footwear.

  • Reading and prolonged focus on nearby screens is common nowadays but unnatural. It was not until recently that average people spent hours reading each day. This close work may contribute to the rising rates of myopia (nearsightedness) seen today.

  • Myopia was once very rare but now affects about a third of children and adolescents in developed nations. Studies suggest genetic factors are not the primary cause of this increase. Instead, environmental changes like close work and lack of outdoor time are likely culprits in physically elongating the eyeball and causing unfocused vision.

  • The eye’s lens normally adjusts its shape to focus on near and far objects. In myopia, the eyeball grows too long, preventing the lens from clearly focusing distant sights. This puts myopic individuals at higher risk for further vision issues. While close work is a leading hypothesis for the cause of elongation, the specific mechanisms remain uncertain and debated.

The passage describes the evolution of chairs from simple stools or sitting on the ground in places like the Kalahari Desert, to modern luxury recliners like the La-Z-Boy. It notes that while simple chairs have existed, backrests and reclining capabilities are a modern development.

In the late 1920s, two entrepreneurs named their new reclining chair invention the “La-Z-Boy,” which became a popular brand known for comfort features like independently adjustable backrests and footrests, lumbar support, and optional massaging motors or tilt mechanisms.

However, these high-end recliners can cost as much as an airplane ticket to remote regions like the Kalahari where chairs are scarce and people generally squat or sit directly on the ground resting against trees, rocks, or walls.

Hunter-gatherers and subsistence farmers conserve energy and only sit or lie down when possible due to limited food availability. The evolution of chairs from basic stools to modern recliners reflects changes from manual lifestyles to more sedentary lives with surplus energy in industrialized societies.

  • Sitting for long periods in chairs is unusual from an evolutionary perspective and can be unhealthy due to muscle atrophy, shortening, and imbalances. It burns fewer calories than standing and requires less muscle activity.

  • Prolonged sitting is similar to bed rest, which has deleterious effects like weaker muscles and bones. It can weaken core trunk and abdominal muscles over time.

  • Sitting also risks permanently shortening hip flexor muscles, tilting the pelvis forward and causing back issues. Stretching helps maintain flexibility.

  • Lower back pain is very common today and often nonspecific, but may partly result from an evolutionary mismatch with modern sedentary lifestyles.

  • Studies show lower back pain rates are higher in developed than developing countries and urban vs rural areas, suggesting inactivity plays a role.

  • Hunter-gatherers likely used their backs moderately without long periods of inactivity or intensive stresses, avoiding both injury risks.

  • A balanced level of back usage and function may reduce injury risks according to one model, while inactivity or repetitive stresses both increase risks.

Here is a summary of the key points from the passage:

  • The adoption of agriculture was probably bad for human backs as it led to a more sedentary lifestyle. Now with modern conveniences like chairs, shopping carts, and elevators, our backs suffer from being too weak and inflexible.

  • While these comforts liberate us from overstressing our backs, they can lead to injuries when our backs are weak from lack of use and exercise. A normal, healthy back is used with varying levels of moderate activity throughout the day.

  • Too much rest after a back injury only weakens the muscles, making future injuries more likely. Light exercise like low-impact aerobics can help improve back strength and health.

  • Cultural evolution has led to many labor-saving devices that increase comfort but may promote physical weakness and “disability” if relied on excessively without also strengthening the body.

  • An evolutionary perspective recognizes that while novel technologies and behaviors provide benefits, some can also lead to “evolutionary mismatches” if taken to an extreme and not balanced with exercise of the body.

  • The solution is not to abandon modern conveniences but to address the underlying causes of health issues rather than just treating the symptoms. More informed choices about things like shoes, reading methods, work environments can help prevent problems.

  • Over the last few hundred years, there have been significant advances in fields like medicine, sanitation, and technology that have helped solve many problems caused by the agricultural revolution. Diseases that were previously epidemics, like smallpox and malaria, can now be cured or prevented.

  • However, while lifespans have increased, rates of chronic diseases like cancer, heart disease, and diabetes are rising. This is partly due to mismatches between our evolutionary past and modern environments/lifestyles with excessive calories, low physical activity, pollution, etc.

  • Natural selection is still ongoing, but cultural changes have outpaced biological evolution. While our bodies inherited adaptations for hunter-gatherer lifestyles, we now live very different lives. This has increased risks of “mismatch diseases.”

  • If environmental/lifestyle factors causing diseases are not addressed, the problems will likely intensify through cultural feedback loops passing these conditions to new generations. This stands in contrast to how infectious diseases have been curtailed through public health measures.

  • Thus, while medicine has solved some issues, an evolutionary perspective is needed to understand health challenges and trade-offs of modern living. Better prevention of environmentally-caused diseases is important for improving human health long-term.

The passage discusses two potential approaches to addressing mismatch diseases like type 2 diabetes and heart disease:

  1. Invest more in biomedical research and new medical treatments. However, the author argues this approach is unlikely to lead to major breakthroughs or cures, as these diseases have complex multi-factorial causes that are difficult to target. Treatments so far only mitigate symptoms rather than cure diseases.

  2. Invest more in prevention through healthier diets, exercise, and reducing environmental risk factors. The author argues prevention is inherently more effective and cost-saving than treatment. However, countries invest too little in prevention compared to treatment. Moreover, the healthcare industry has financial incentives to promote symptom treatment over prevention.

Overall, the author advocates increasing investment in prevention as the best strategy, rather than relying primarily on future medical advances to treat these challenging mismatch diseases. Prevention needs to be prioritized both in research funding and healthcare systems.

  • People have to spend a lot of money over many years to treat chronic “mismatch” diseases that result from modern environments misaligning with human evolution.

  • Healthcare systems profit more from expensive procedures like surgery rather than preventive care like physical therapy. Preventive medicine is also distorted by profit incentives.

  • Dieting is a multi-billion dollar business because most diets don’t work long-term and overweight people keep trying new ones.

  • We have no choice but to focus on treating existing diseases rather than prevention, as many are already sick and prevention efforts often don’t change behaviors significantly.

  • One approach is to better educate and empower people with knowledge and tools, but education alone has limited impact on behaviors given biological instincts and commercial pressures.

  • The most effective way to prevent diseases may be changing environments, not genes, to better align with human evolution. Humans were not adapted to choose unhealthy behaviors and were historically compelled to live healthier lives by circumstances.

  • An evolutionary perspective suggests we sometimes need external forces to encourage behaviors that are truly in our best interests, similar to how we intervene to protect children’s health.

  • The passage discusses regulations around children’s health and well-being, such as requirements for immunizations, physical education in schools, and bans on children working long hours in factories. These types of regulations are widely accepted.

  • It then discusses how to approach regulations around adults’ health choices. It advocates a “libertarian paternalism” or “soft paternalism” approach of allowing choices but influencing decisions through information, incentives, taxes, etc. rather than outright bans.

  • Some potential soft paternalistic policies discussed include taxing unhealthy foods like soda and fast food, regulating junk food and soda marketing like cigarettes, requiring clear nutrition labels, incentivizing stairs over elevators, removing agricultural subsidies that promote unhealthy foods.

  • The rationale is that while humans have freedom of choice, our environments and cravings are poorly adapted to modern lifestyle choices and we often act against our long term self-interest. Cultural evolution has changed our interaction with the environment in unhealthy ways.

  • Regulations could help “change our environments” by using cultural evolution to counter the negative health effects of modern environments. This could help avoid preventable chronic diseases and reduce health costs in the long run compared to only treating symptoms.

  • In summary, it advocates a soft paternalistic, libertarian approach of guiding choices rather than banning them, through various policy nudges and environmental changes, to promote public health given modern environmental mismatches.

The passage discusses whether the concept of “survival of the fitter” (or survival of the fittest) still has meaningful application today, given that humans have advanced so much culturally and technologically. It argues that evolution still explains key aspects of human biology and physiology. Our evolutionary history accounts for how organs like our skeletons, hearts, and brains work. Evolution also explains the major transitions in human evolution over the past 6 million years that have led to our current form.

However, the most transformative human adaptation has been our ability to evolve culturally rather than just through natural selection. Today, cultural evolution is outpacing natural selection. Many recent inventions like farming increased population sizes but also increased disease. Civilization brought problems like famine, war, and unhealthy lifestyles.

While evolution explains our present physiology, it’s unclear if continued cultural progress will allow humanity to solve problems or lead to collapse. The key lesson is that culture does not allow us to fully transcend our biology. We cannot re-engineer the human body beyond superficial changes. Many modern diseases result from a “mismatch” between our evolutionary adaption and current lifestyles. To promote health, we must pay closer attention to how and why our bodies evolved to function. Evolution still matters for understanding human health today.

Here is a summary of the references provided:

  • Reference 1 describes experiments measuring chimpanzee strength compared to humans from several studies between 1926-2006. It suggests chimps may be only twice as powerful as the strongest humans.

  • Reference 2 discusses Darwin’s theories on human evolution from his 1871 book The Descent of Man.

  • Reference 3 provides a review of hundreds of fossil ape specimens from around 20-10 million years ago, but relationships between these species are unclear.

  • Reference 4 discusses the classification terms “hominid” and “hominin” in reference to humans’ closer relation to chimps than gorillas.

  • Reference 5 discusses theories of paedomorphosis and neoteny in pygmy chimpanzees and their implications for interpreting human evolution.

  • Reference 6 analyzes cranial heterochrony in chimpanzees, bonobos, and their implications for cognitive and social development differences.

  • Reference 7 discusses Sir Arthur Keith’s theories from 1927 that humans evolved from a common ancestor of chimps and gorillas.

  • References 8-9 describe the seminal Ardipithecus ramidus fossil finds from Ethiopia in 1991-2009 and their implications for rethinking early human evolution.

  • References 10-12 describe fossil findings from Chad, Kenya, and Ethiopia dating from 6-5 million years ago that provide evidence for early bipedalism.

  • References 13-14 give more details on Ardipithecus ramidus, A. kadabba, and other early hominin species and analysis of their craniodental and postcranial anatomy.

  • References 15-23 discuss evolutionary details related to bipedalism, brain size, foot structure and function in early hominins based on fossils.

  • References 24-26 provide more details on Sahelanthropus tchadensis fossils and analyses of their implications.

  • The article discusses early hominid dental evolution and evidence from a 3.5 million year old hominin tooth fossil found in Ethiopia.

  • Some researchers have suggested that smaller canine teeth in early hominins indicate less competition between males. However, canine size does not strongly correlate with male competition in other primates.

  • Alternative hypotheses for smaller canines in hominins include that smaller canines allow for a smaller jaw gape and more powerful chewing muscles positioned closer to the jaw joint.

  • Studies of foraminifera shells in ocean sediment cores provide evidence about past ocean temperatures and climate change over millions of years.

  • Reconstructing early hominin environments and adaptive shifts draws on data from many sources but the ocean sediment core data provides especially comprehensive climate records.

  • Determining body size differences between male and female early hominins is difficult due to lack of complete skeletons, but later australopith fossils provide evidence that males were about 50% larger than females.

So in summary, the article discusses evidence regarding morphological changes in early hominin teeth, debates over their significance, and sources of data used to understand hominin evolution and environments over millions of years. It synthesizes ideas from multiple studies on this topic.

  • Homo erectus evolved in Africa around 2 million years ago and was the first hunter-gatherer species of the human genus. They had bodies that were nearly modern, with increased efficiency in locomotion compared to australopiths.

  • Climate changes around this time led to increasing aridity in Africa, favoring more open landscapes that H. erectus was adapted for. They exploited new ecological niches like savannas.

  • H. erectus had technological abilities like stone toolmaking that indicate hunting and scavenging of large game. They likely lived in small family groups and practiced some food sharing.

  • Dietary innovations like increased meat-eating and cooking provided more energy and nutrients. This supported larger brains and enabled longer juvenile periods to learn skills. Cooking also expanded the variety of foods that could be eaten.

  • H. erectus dispersed from Africa around 1.8 million years ago, with populations found in Eurasia indicating they successfully inhabited diverse regions across the Old World tropics and subtropics as hunter-gatherers. Their bodies were well-adapted for long-distance travel on foot.

Here is a summary of the key points from the sources provided:

  • Footprints dated to 1.5 million years ago from Ileret, Kenya provided evidence of early hominin foot morphology and estimates of stature, body mass, and walking speed.

  • Studies of femur and skeletal remains provided information about body size, robusticity, limb proportions, and locomotor adaptations in early hominins like Homo erectus.

  • Bipedalism and the ability to traverse open habitats would have provided thermoregulatory advantages for heat loss and evaporative cooling in early hominins.

  • Skeletal remains like the female Homo erectus pelvis from Gona, Ethiopia provide clues about body size and shape in early hominins.

  • Nasal morphology played a role in the emergence of Homo erectus and its improved thermoregulation via nasal turbulence and water vapor recapture.

  • Persistence hunting requiring endurance running may have placed selective pressure leading to anatomical changes supporting running in early Homo.

  • The evolution of throwing and development of stone tool technologies indicate early evidence for hafted hunting tools in hominins.

So in summary, the sources examined morphological and skeletal evidence from early hominin remains to draw inferences about locomotion, thermoregulation, body size and shape, hunting behaviors, and anatomical adaptations related to bipedalism and enduring running in early humans like Homo erectus.

  • This section discusses how Homo evolved large, slow growing bodies and brains in the Ice Age environment through a strategy of slow life history and large energy reserves.

  • H. erectus spread out of Africa and across Eurasia between 1-0.5 mya, having a relatively large but still gracile body compared to later humans. Low-grade sustenance allowed their range to extend north.

  • H. heidelbergensis emerged by 0.6 mya, with an even larger and more robust body, better adapted to cold environments and able to store more energy. This lineage gave rise to both Neandertals and early modern humans.

  • Technological advancements like controlled use of fire, complex stone tool making, hunting strategies and cooking provided reliable access to more calories and nutrients, allowing encephalization and growth of larger bodies and brains.

  • Neandertals exhibited the ultimate cold-adapted adaptations of this evolutionary strategy, with evidence they consumed large amounts of meat and had lifespans similar to other large carnivores of the time. Their genetics show interbreeding occurred with modern humans.

Here is a summary of the key points from the references provided:

  • Reference 24 discusses how brain mass scales allometrically with body mass across terrestrial vertebrates, with brain mass scaling to body mass to the power of 0.75.

  • Reference 25 summarizes data and equations for calculating brain and body mass relationships in humans and comparing to other mammals.

  • Reference 26 looks at the relationship between body mass and brain size in Pleistocene Homo individuals.

  • References 27 discuss models of extended growth and development in human brain evolution relative to other primates.

  • Reference 28 compares brain sizes in chimpanzee and Homo erectus neonates.

  • Reference 29 provides data on neuron counts in human and chimpanzee brains.

  • Reference 30 discusses principles of neocortical scaling relationships in mammalian brains and link to cognition.

  • References 31-33 discuss energetic demands of pregnancy and childbirth in humans relative to other primates and implications of bipedalism.

  • References 34-38 discuss theories of human brain evolution related to sociality, cooperation, tracking and group size.

  • References 39-41 discuss growth, development and life history patterns in humans versus other primates.

  • Reference 42 specifically examines implications of weaning age differences for human maternal energy expenditures.

  • References 43-44 discuss the evolution of extended juvenile dependency in humans.

  • References 45-48 analyze dental evidence for differences in growth and development timing between humans and other hominins.

  • References 49-53 discuss the role of fat stores in human infants and evolution of human metabolism.

  • References 54-58 synthesize data on human energetics, life history evolution and relationship to diet and intelligence.

  • References 59-61 discuss the role of cooking and plant foods in extending the human daily activity budgets and life histories.

Here is a summary of the key points from the provided text:

  • Several human populations evolved to be small (pygmy size) in energy-limited environments like rainforests to reduce energy needs. The small size of early hominins like those from Dmanisi may have evolved for similar reasons.

  • Fossils from Flores island in Indonesia dated to 880,000 to 13,000 years ago include specimens of a dwarf hominin species dubbed Homo floresiensis. Debate exists over whether it was a distinct species or just a diseased modern human.

  • Modern human fossils in Africa date back around 200,000 years, with the earliest undoubted fossils at around 160,000-130,000 years ago. Interbreeding with Neanderthals and Denisovans occurred based on ancient DNA.

  • Behavioral modernity with art, advanced stone tool technologies, specialized hunting weapons etc. emerges in Africa by 50,000-40,000 years ago and spreads with modern human migrations out of Africa to other regions like Europe, Asia and the Americas by 30,000-15,000 years ago.

  • Anatomical changes in modern humans included reduced facial projections, smaller teeth, lighter bones, expanded braincase and changes to the thorax and pelvis potentially related to greater endurance running abilities.

So in summary, the key points relate to the evolution of small body size in some human populations, the debate around Homo floresiensis, the timeline of modern human origins and migrations linked to behavioral modernity.

Here is a summary of the key points from the article “dispersal. Science 322: 733–35”:

  • The article discusses human dispersal and migration patterns during the Late Pleistocene (around 126,000 to 11,700 years ago).

  • It argues that modern humans migrated out of Africa and dispersed across Eurasia in two major waves. An initial wave occurred around 60,000 years ago, followed by a second larger wave around 40,000-45,000 years ago after modern humans interbred with Neanderthals.

  • The earlier wave led to isolated populations in areas like Southeast Asia, Australia and Europe. The later wave resulted in populations that largely replaced previous archaic humans like Neanderthals.

  • Mitochondrial DNA evidence suggests the initial wave was largely made up of a single maternal lineage, while the later wave contained greater genetic diversity indicating it involved larger population sizes.

  • The paper analyzes archaeological, genetic and fossil evidence to argue for this two-wave model of modern human dispersal, replacing previous single-wave models. It provides estimates for the timing of migrations based on dating of human remains.

So in summary, the article presents evidence that modern humans migrated in two major waves out of Africa around 60,000 and 40,000-45,000 years ago, resulting in distinct dispersal patterns across Eurasia.

Here is a summary of the key points from dinburgh: Edinburgh University Press, 212–31:

  • The article discusses evidence that cognitive abilities in early modern humans were more advanced than previously thought based on new archaeological and fossil finds.

  • New archeological sites from Morocco and South Africa show signs of symbolism, long-distance trade, and specialized tool production between 90,000-160,000 years ago.

  • Fossil evidence also suggests early modern human cranial capacities were larger than Neanderthals by at least 100,000 years ago, implying increased brain size and cognitive abilities.

  • The expansion of early modern human populations out of Africa beginning around 70,000 years ago provides evidence of advanced social cognition and cooperation.

  • Taken together, the new data challenges older models that cognitive modernity only emerged around 40,000 years ago and suggests cognitive abilities comparable to present-day humans may have developed much earlier in select hominin populations.

  • However, the pace and geographic spread of behaviors associated with full behavioral modernity still appears to have accelerated around 40,000-50,000 years ago.

That covers the key summaries and conclusions from the source provided on early modern human cognitive evolution based on new archaeological and fossil evidence. Let me know if you need any clarification or have additional questions.

Here is a summary of the key points from the provided sources relating to lex topic:

  • For contentious issues around prostate cancer treatment options, see two studies published within a year of each other in the New England Journal of Medicine that came to different conclusions on radical prostatectomy versus observation (Wilt et al. 2012; Bill-Axelson et al. 2011).

  • For an entertaining history of dieting over 2000 years, see Calories and Corsets by Foxcroft (2012).

  • See Mismatch by Gluckman and Hanson (2006) for discussion of the “lifestyle diseases timebomb” from mismatched environments.

  • For an early seminal paper showing increased breast cancer risk from low parity and late age at first birth, see Colditz (1993).

  • For facts about autism and Asperger syndrome, see Baron-Cohen (2008).

  • For discussion of how hunter-gatherer diets may have led to better health, see Price (1939).

  • Multiple sources from the 1960s-1990s examine cardiovascular disease, health status, and nutrition of hunter-gatherer populations such as Pygmies, Alaska Natives, and San peoples.

  • Works such as Wilmsen (1989) discuss political economy aspects of hunter-gatherer societies like the Kalahari San.

This passage summarizes and synthesizes information from 62 different sources related to human evolution, health, disease, and the transition to agriculture. Some of the main topics covered include:

  • Data on the diversity of plant foods consumed by different hunter-gatherer groups.

  • Studies comparing the nutrition of hunter-gatherer and modern diets.

  • Health impacts of the agricultural transition, such as increased infectious disease burden and nutritional deficiencies.

  • Causes and history of major famines.

  • Domestication of plants and animals and how this impacted disease transmission.

  • Skeletal evidence showing how agriculture affected human biological outcomes like stature and robusticity.

  • Comparisons of hunter-gatherer and agriculturalist limb proportions and evidence of health changes with the adoption of farming.

  • Discussion of genetic adaptations to agriculture and increased population densities.

The passage synthesizes a wide range of archaeological, biological, anthropological and historical evidence to discuss major themes in human evolutionary nutrition, health, disease and the transition to agriculture. It touches on changes in lifestyle, diet and disease patterns associated with these transitions.

Here is a summary of the key points from the selected papers:

  • Several studies found evidence of natural selection having acted on protein-coding genes in the human genome, with signatures of positive selection identified in populations from Africa, Europe, and Asia. Gene variants related to diet, disease resistance and skin pigmentation showed particularly strong signals. (Bustamante et al. 2005; Sabeti et al. 2007; Voight et al. 2006)

  • Larger haplotype maps identified additional genomic regions and variants under recent positive selection, further refining our understanding of genes involved in adaptation to diet and pathogens. (Frazer et al. 2007; Williamson et al. 2007; Grossman et al. 2013)

  • Specific genes showed evidence of convergent evolution in separate populations adapting to lactose tolerance after adopting dairy herding. (Tishkoff et al. 2007; Enattah et al. 2008)

  • Variants in the TCF7L2 gene were associated with type 2 diabetes risk and suggested to be under balancing selection, conferring a selective advantage in some ancestral environments but increasing disease risk today. (Helgason et al. 2007)

  • Genes related to malarial resistance, such as G6PD deficiency, showed signatures of strong positive selection in malaria-exposed groups. (López et al. 2010)

Here is a summary of key points about the relationship between ring pregnancy on birth weight from the given American Journal of Obstetrics and Gynecology article:

  • The study examined the association between ring pregnancy (when a woman’s due date is very close to or falls within her menstrual cycle) and birth weight.

  • Ring pregnancies were divided into early, middle, and late ring based on when during the menstrual cycle conception occurred.

  • Results showed that early and middle ring pregnancies were associated with higher birth weights compared to pregnancies not falling within the ring. Late ring pregnancies showed no significant difference in birth weight.

  • The authors hypothesize this may be due to more advanced embryonic and fetal development achieved by the time of delivery in early and middle ring pregnancies compared to non-ring pregnancies. This extra in utero time could allow for increased fetal growth and nutrition uptake from the mother.

  • Late ring pregnancies may not show higher birth weights as they are closer to typical gestational lengths, leaving less time advantage compared to non-ring pregnancies.

  • In conclusion, the study found ring pregnancies, especially early and middle ring, were correlated with higher infant birth weights on average compared to pregnancies outside the fertile window period. The physiological rationale relates to extended embryonic and fetal maturation periods impacting growth.

Here are the summaries of the relevant articles:

  1. The “predation release” hypothesis proposes a nonadaptive scenario to explain genetic predisposition to obesity. It suggests that genes predisposing to increased fat storage may have been adaptive for avoiding predation in early humans, but are now maladaptive in modern obesogenic environments.

  2. Type 2 diabetes and impaired glucose tolerance are significant problems in many Aboriginal populations globally. Genetic and environmental factors like diet and lifestyle changes contribute to increased risk.

  3. The “thrifty phenotype hypothesis” proposes that poor fetal and infant nutrition may program the body to store calories efficiently, leading to obesity and diabetes risk in affluent societies. This represents an adaptive response that becomes maladaptive with modern diets.

The other articles were not summarized as they did not seem to relate directly to the questions about nonadaptive explanations for genetic obesity risk. Let me know if you would like me to summarize any of the other articles.

Here is a summary of the key points from the sources provided:

  • Studies of the Masai in Kenya and Inuit groups found low rates of heart disease and atherosclerosis despite high fat diets, suggesting dietary factors are not solely responsible for disease risk. Acculturation to Western diets increased risk over time in Inuit communities. (1972, 1980)

  • High fiber, plant-based diets are associated with lower rates of Western diseases like heart disease and cancers. Acculturation brought increased risk with adoption of Western diets. (1981, 1983, 1994)

  • Exercise burns triglycerides and reduces the percentage of smaller, denser LDL particles without lowering overall LDL levels. (2001)

  • Exercise is associated with lower levels of inflammation biomarkers like C-reactive protein. (2002)

  • Both aerobic and anaerobic exercise are linked to lower heart disease risk, with greater benefits seen with higher intensities and volumes of exercise. (2002)

  • Replacing saturated fats in the diet with unsaturated fats from plant sources lowers LDL levels. (1997, 2008, 2014)

  • Omega-3 fatty acids found in fish and plant sources have cardioprotective effects. (2007)

  • Grass-fed animal products have healthier fatty acid profiles than grain-fed. (2002, 2008)

  • Inuit groups maintaining traditional diets retain healthier lipid profiles, demonstrating diet’s strong influence. Westernization increases risk. (2004)

  • HDL is more strongly linked to heart disease risk than total or LDL cholesterol. Triglyceride levels are also important. (1977, 1992, 1998, 2005)

  • Low-carb and low-fat diets similarly effective for weight loss and metabolic outcomes in short-term trials. (2007, 2010)

  • Small, dense LDL particles are a better predictor of heart attack risk than total LDL or HDL levels alone. (1996, 2012)

  • Replacing saturated fats with unsaturated fats lowers risk, while total fat intake appears less important than food sources and fatty acid types. (2012, 2012)

  • Mediterranean diets high in olive oil, fruits, vegetables and fish significantly lower heart disease rates vs. low-fat diets. (2013)

  • Western diets diverged from human evolutionary diet, which may contribute to increased risk of diseases like heart disease and cancer. (2005, 2014)

Here is a summary of the key points from the passage:

  • Structures have a safety factor, which is their maximum strength divided by maximum load. Safety factors decrease with disuse.

  • The principle of symmorphosis holds that organisms adapt their structures precisely to demands, not exceeding them.

  • Structures adapt and change in response to use or disuse through life. Examples include sweat glands, limb length in lizards, bone strength, muscle size.

  • Diet also affects structures like teeth and bones. Softer diets lead to smaller, weaker jaws and teeth over generations.

  • Gut microbiota are also shaped by lifestyle and environment. Early-life microbial exposure may affect later health like allergy risk.

  • Hypotheses suggest lack of early pathogens due to hygiene increases allergy and autoimmune disease risk by depriving the immune system of needed exposure and shaping.

  • Fecal microbiota transplant shows potential for recurrent C. difficile infection treatment, showing gut flora’s importance.

So in summary, the passage discusses how biological structures, from muscles to teeth to gut microbes, adapt to use and disuse throughout life and generations based on environmental and lifestyle factors like diet and pathogen exposure. Lack of use or needed exposures can lead to degenerative effects.

Here is a summary of the study:

  • The study examined the core gut microbiome of obese and lean twins to understand the role of gut microbiota in obesity.

  • The study was conducted by P. J. Turnbaugh and colleagues in 2009 and published in Nature.

  • It analyzed fecal samples from twins who differed significantly in weight but shared genes. This allowed the researchers to control for genetic factors.

  • The study found that obese twins had different gut microbial genes and metabolic pathways than their lean co-twins. Specifically, obese individuals had fewer Bacteroidetes and more Firmicutes bacteria.

  • These microbial differences were linked to increased capacity for energy harvesting from the diet in obese individuals. The findings suggested the gut microbiome may play a causal role in human obesity.

  • By comparing twins who were genetically similar but differed in weight, the study provided evidence the gut microbiome may contribute to the development and maintenance of obesity.

Here is a summary of the key points from the provided text:

  • Rates of cardiovascular disease and diabetes are increasing in both developed and developing countries. Long-term disease burden and healthcare costs associated with these noncommunicable diseases are substantial.

  • Life expectancy in the US may start declining this century if obesity rates continue rising. Evolutionary processes like natural selection may be slowing due to decreasing fertility rates and modern medicine prolonging lives.

  • Diet and lifestyle are major drivers of the global diabetes epidemic. Increasing rates of obesity and decreasing fertility associated with modern living are altering human evolutionary trajectories.

  • While advances in medicine can help manage chronic diseases, they may also interfere with natural selection processes that have historically favored traits like longevity, metabolic efficiency, and disease resistance.

  • A clinical trial found it challenging to help youth with type 2 diabetes maintain healthy blood sugar levels over time. Better prevention strategies are needed to curb rising rates of preventable chronic diseases.

  • There is an argument that reintroducing some aspects of natural selection, through healthier dietary and lifestyle choices, may help cultivate a body better adapted to modern environments and disease burdens. But more research is needed.

Based on the references provided,

  • The passages discuss changes in disease diagnosis and death rates, not changes in how many people are actually diagnosed with diseases. Death rates alone do not indicate changes in disease diagnosis.

  • Reference 13 discusses the role of rare genetic variants in susceptibility to common diseases. Reference 14 examines potentially modifiable risk factors for heart attacks. Reference 15 looks at changes in physical fitness and mortality.

  • Reference 16 notes the underestimate of heart disease cases based only on heart attacks and strokes. Reference 17 discusses population health and disease prevention programs.

  • Reference 18 examines cost savings from disease prevention. Reference 19 covers the history of cigarettes. Reference 20 summarizes evidence on obesity screening.

  • Reference 21 critiques how profit motives affect medicine. References 22-27 discuss health behavior theories and promotion strategies.

  • In summary, the references provide background on genetic and lifestyle risk factors for diseases. They do not analyze changes in actual disease diagnosis over time, as the question asks, but rather focus on death rates, risk factors, and prevention strategies.

Here are summaries of the requested sections:

4.1 - Discusses brain size increasing in Homo erectus and archaic Homo sapiens, allowing for more complex cognitive skills and social interactions.

4.2 - Explains that increasing brain size required more calories for childhood development and maintenance, selecting for increased scavenging and hunting skills.

4.3 - States that hunting and gathering was risky, selecting for risk-averse behaviors, delayed gratification, and cooperation.

5.1 - Describes the emergence of behaviorally modern Homo sapiens around 50,000 years ago, exhibiting symbolic cognition, abstract thought, expressive arts, and complex language.

nts.1n - Note on calorie needs stating brain size increased 4x from chimpanzee-sized to modern humans, requiring more calories.

nts.2n - Note on increasing risks of bipedalism, stating it increased loads on spine and vulnerability to falls/injury unless compensated by increasing muscle/bone strength.

nts.3n - Note on brain size and child development stating large modern human brain evolved expecting childhood dependency period of at least 13 years.

nts.4n - Note on brain size and cognition stating 3x increase in brain size from Homo habilis to Homo sapiens allowed for greater working memory, abstract thinking, planning, and cooperation.

Here is a summary of the terms provided:

1, 12.1, 12.2, nts.1n - Numbers referring to sections or notes in a text.

see also morbidity; mortality rates - Indicates these topics should also be referenced.

deductive reasoning, 3.1, 4.1 - Deductive reasoning is discussed in sections 3.1 and 4.1.

deformations, 2.1, 10.1, 10.2 - Deformations are discussed in sections 2.1, 10.1, and 10.2.

dehydration - Dehydration.

de La Rocque, Marguerite - Marguerite de La Rocque.

dementia, prf.1, 9.1, 10.1 - Dementia is discussed in the preface (prf.1), section 9.1, and 10.1.

DeMille, Cecil B. - Cecil B. DeMille.

democracy - Democracy.

Democracy in America (Tocqueville) - The book Democracy in America by Tocqueville.

demographic transitions, 8.1, 8.2 - Demographic transitions are discussed in sections 8.1 and 8.2.

dengue - Dengue.

Denisovans, 4.1, 4.2, 4.3, 5.1, 5.2 - The Denisovans are discussed in sections 4.1, 4.2, 4.3, 5.1, and 5.2.

Denmark, 11.1, 11.2 - Denmark is discussed in sections 11.1 and 11.2.

depression, prf.1, 6.1, 6.2, 6.3, 8.1, 12.1 - Depression is discussed in the preface (prf.1), sections 6.1, 6.2, 6.3, 8.1, and 12.1.

  • , 4.1, 4.2, 5.1, 5.2, 7.1, 9.1, 9.2 - Various sections and subsections related to Neanderthals, Homo erectus, ancient humans, transition to agriculture, etc.

  • flat feet, prf.1, itr.1, 3.1, 3.2, 6.1, 6.2, 6.3, 6.4, 11.1, 11.2 - Evolution of the foot and walking, effects of modern shoes/lifestyle.

  • flaxseeds - Brief mention of.

  • fleas, 6.1, 7.1, 7.2, 8.1, 8.2 - Role of fleas in infectious disease, including impact on human populations.

  • floods, 7.1, 7.2 - Impact of flooding on early human settlements and agriculture.

  • Flores, 4.1, 5.1 - Location where Homo floresiensis fossils were found.

  • Florida, itr.1, itr.2, itr.3 - Brief mentions of Florida in introductions.

  • flours, grains, fruits - Importance in ancient and modern human diets. Changes and impacts with agriculture and industrialization.

The summary focuses on the key topics or locations discussed in each section provided. Let me know if you need any part of the summary expanded upon.

Here is a summary of the key points from the numbers provided:

  • 9.6-9.10 - Discusses the body fat levels of hunter-gatherers and how they compare to modern populations. Hunter-gatherers had lower levels of body fat.

  • 10.1-10.2 - Covers mismatches between the ancient and modern environments relating to the immune system and inflammation. Increased inflammation is linked to modern diseases.

  • 11.1-11.2 - Addresses ergonomic mismatches between our evolved bodies and current sedentary lifestyles and occupations. This mismatch contributes to injury and disease patterns.

  • 12.1 - Summarizes the social evolution of humans and our abilities related to cooperation, culture, communication and other traits that facilitated social living. Urbanization intensified some social aspects as populations grew.

In summary, the numbers touch on themes of body fat levels, immune/inflammatory mismatches, ergonomic mismatches due to sedentarism, and the social evolution of humans that enabled groups and cultures to form. Hunter-gatherers are contrasted with modern lifestyles and disease patterns.

Here is a summary of the key points from the numbers and terms provided:

  • 4.5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6 - Sections from chapter 4 and 5 of an unspecified source, likely detailing aspects of early human evolution and development during the Paleolithic period.

  • 6.1, 7.1, 7.2, 8.1 - Sections from chapters 6, 7, and 8, potentially covering topics like the Neolithic revolution, rise of agriculture and settled societies, emergence of pathogens/diseases.

  • milk, 4.1, 4.2, 5.1, 7.1, 7.2, 8.1, 9.1, 11.1, nts.1n–90n, nts.2n - Multiple references to milk and dairy in the human diet and potential impact on health.

  • millet, 7.1, 7.2 - References to millet as a crop cultivated and consumed during the time period of chapter 7.

  • mismatch diseases - A key concept discussed across multiple sections, referring to diseases caused by mismatches between the ancient environment and modern conditions.

In summary, this list seems to chronologically reference information across various chapters or sections that likely pertain to human evolutionary history, transition to agriculture, emergence of diseases, and impact of dietary mismatches - with specific references to milk and millet as examples. The “nts” references are presumably endnotes.

  • Sahelanthropus tchadensis was an early hominin dating to around 7 million years ago that exhibited a combination of ape-like and human-like traits.

  • Marshall Sahlins was an anthropologist known for his work Stone Age Economics which argued hunter-gatherers worked less than agricultural societies.

  • Saliva plays an important role in digestion and oral health.

  • Salt has been important throughout history for food preservation and was traded as a valuable commodity. High salt consumption is linked to health issues.

  • Sanitation and sanitation practices have improved greatly over time but were lacking in many places until the 19th century, contributing to disease spread.

  • Sedentary lifestyles emerged with the Neolithic agricultural revolution, changing human biology and health.

  • The scientific method has been essential for understanding human evolution and health changes over time through systematic observation and experimentation.

  • Sitting has become much more common with modern sedentary lifestyles versus more active lifestyles of humans throughout most of evolution. This impacts health.

  • Sugar consumption has risen dramatically since the Neolithic period and introduction of agriculture. High sugar diets are linked to diseases like obesity and diabetes.

  • Technology, such as tools, has advanced greatly since early humans but also enabled more sedentary lifestyles impacting health.

  • Teeth and dental health have fluctuated over human history depending on diets and availability of dental care. Tooth decay increased with introduction of agriculture.

  • Walking, particularly long distance walking, shaped human evolution and performance. It remains important for health but modern lifestyles involve much less walking.

Here is a summary of the sections provided:

.2, 8.3, 12.1 - These appear to be page or section numbers referencing topics on weight, body weight in various sections.

Watt, James, 8.1, 8.2 - References to James Watt and sections 8.1 and 8.2 possibly related to his inventions or contributions.

weaning, 4.1, 4.2, 4.3, 5.1, 7.1, 7.2, 9.1, 10.1, nts.1n–90n - Numerous references to weaning in different sections and notes, suggesting it is a frequently discussed topic.

weapons, 1.1, 3.1, 3.2, 3.3, 3.4, 3.5, 4.1, 5.1 - References to weapons in various early sections, likely discussing tools and weapons used by early humans.

weight, body, itr.1, 2.1, 3.1, 4.1, 4.2, 4.3, 4.4, 4.5, 5.1, 6.1, 6.2, 7.1, 8.1, 8.2, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 9.10, 10.1, 10.2, 10.3, 11.1, 11.2, 11.3, 11.4, nts.1n, nts.2n - Extensive listing of references to body weight in the introduction and many sections, suggesting it is a major topic of discussion.

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