Exercised Quotes

“Among other theories, bipedalism is thought to have evolved as an adaptation for carrying food, foraging upright, saving energy, making and using tools, keeping cool, seeing over tall grasses, swimming, and showing off genitalia. These hypotheses range from sensible to dubious, but all of them require knowing what we evolved from: our last common ancestor with chimpanzees. Did this “missing link” knuckle walk like a chimpanzee by resting its weight on the middle digits of its fingers? Did it swing in trees like a gibbon? Or did it climb cautiously above branches on all fours like a monkey?”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Whether you walk on two or four legs, the dominant function of a leg is to be a pendulum. This is illustrated in figure 19, but if a picture is worth a thousand words, then action is worth even more, so take a few steps around the room and focus on what your right leg is doing. Notice when it isn’t on the ground, it swings forward like the pendulum on a grandfather clock with its center of rotation at the hip. This “swing phase” of a stride is primarily powered by your hip muscles. Your leg’s pendular action flips, however, at the end of the swing phase when your foot collides with the ground. At this instant, your leg becomes an upside-down pendulum whose center of rotation is the ankle. In essence, your leg becomes a stilt during this “stance phase” of the stride. The stilt-like behavior of legs during stance is key to understanding how you use energy when you walk. During the first half of the stance phase, muscles vault your body up and over that leg, elevating your center of mass about two inches (five centimeters). That upward lift expends calories but stores potential energy, just as if you were to raise this book. Then during the second half of stance, your body converts that potential energy to kinetic energy by falling downward and forward, as if you were to drop the book. Eventually, your swing leg collides with the ground, halting your body’s fall and starting a new cycle. Walking thus costs calories to raise the body’s center of mass in the first half of stance, then redirect it upward and forward from one step to the next, and to swing the arms and legs.8 While at least one foot is on the ground at all times during a normal walk, the key energetic principle that moves you forward is using your legs like pendulums to exchange potential and kinetic energy. Quadrupeds like dogs and chimpanzees use their four legs in just the same way.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“As with war, suppressing reactive aggression and following rules are fundamental to most sports. Indeed, sports might have evolved as a way to teach impulse control along with skills useful for hunting and controlled proactive fighting. What is more unsportsmanlike than punching an opponent who scores a goal or, even worse, punching a teammate who scores instead of you? Professional tennis players aren’t even allowed to say rude things on court. Surely other hominins including Neanderthals engaged in play, but I hypothesize that sports evolved when humans became self-domesticated. As noted above, it is primarily among domesticated species that adults play, and among the many reasons humans in every culture play sports, one is to teach cooperation and learn to restrain reactive aggression. Regardless of whether you are trying to beat your opponent to a pulp in a cage or impress the judges of a synchronized swimming competition, to be a “good sport” you have to play by the rules, control your temper, and get along with others. Sports also foster habits like discipline and courage that are crucial for proactive aggression such as warfare. Perhaps the Battle of Waterloo really was won on the playing fields of Eton.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Sports, even those as extreme as Calcio Storico Fiorentino, evolved from play. Almost all mammal infants play to develop the skills and physical capacities needed to hunt or fight as adults.68 Additional benefits of play include helping youngsters to learn or change their place in social hierarchies, to forge cooperative bonds, and to defuse tensions.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“I have little fear walking up to a pig on a farm or my neighbor’s dog, but I wouldn’t dream of approaching a wild boar or a wolf in the same way. Over generations of breeding, farmers have reduced the aggressiveness of these and other animals by selecting for lower levels of testosterone and higher levels of serotonin.36 Correspondingly, many domesticated species have smaller faces. Intriguingly, some wild species also evolved reduced aggression, less territoriality, and more tolerance on their own through another kind of selection known as self-domestication. The best example are bonobos. Bonobos are the rarer, less well-known cousins of chimpanzees that live only in remote forests south of the Congo River in Africa. But unlike male chimpanzees and gorillas, male bonobos rarely engage in regular, ruthless, reactive violence. Whereas male chimpanzees frequently and fiercely attack each other to achieve dominance and regularly beat up females, male bonobos seldom fight.37 Bonobos also engage in much less proactive violence. Experts hypothesize that bonobos self-domesticated because females were able to form alliances that selected for cooperative, unaggressive males with lower levels of androgens and higher levels of serotonin.38 Tellingly, like humans, bonobos also have smaller browridges and smaller faces than chimpanzees.39 Many scientists are testing the idea that humans also self-domesticated.40 If so, I’d speculate this process involved two stages. The first reduction occurred early in the genus Homo through selection for increased cooperation with the origins of hunting and gathering. The second reduction might have occurred within our own species, Homo sapiens, as females selected for less reactively aggressive males.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Aside from evidence for proactive violence among contemporary hunter-gatherers, two thorny facts don’t entirely square with the view that we stopped fighting ever since we became hunter-gatherers. The first fact is muscle. The average adult man today is 12 to 15 percent heavier than the average adult woman, but women have much higher percentages of body fat masking underlying differences in muscle mass. Whole-body scans show that males average 61 percent more muscle mass then females, with most of that difference in the upper body.30 Men’s extra brawn, moreover, is added during puberty, when testosterone levels shoot up, accelerating muscle growth in the arms, shoulders, and neck.31 In this regard, human men resemble male kangaroos, whose upper bodies also enlarge during adolescence to help them fight.32 Enhanced upper-body muscularity in male humans might also have been selected for hunting, but we cannot rule out aggression. The second fact is literally staring us in the face. Consider the faces of assorted males in the genus Homo lined up for you in figure 16. Note that until about 100,000 years ago, even in some of the earliest Homo sapiens, males tend to have massive, heavily built faces and menacingly large browridges. The earliest H. sapiens males have smaller, less robust faces than Neanderthals and other non-modern humans, but truly lightly built, “feminized” faces don’t appear until less than 100,000 years ago.33 It is intriguing to hypothesize that these big faces reflect higher levels of testosterone during adolescence. In males today, elevated testosterone contributes to not only higher libidos, more impulsivity, and more reactive aggression but also bigger browridges and larger faces.34 Another molecule that possibly affects facial masculinization is the neurotransmitter serotonin, which reduces aggression; less masculinized faces are associated with higher levels of serotonin.35”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Dart initially echoed Darwin’s theory that bipedalism freed the hands of early hominins to make and use hunting tools, which in turn selected for big brains, hence better hunting abilities. Then, in a famous 1953 paper, clearly influenced by his war experiences, Dart proposed that the first humans were not just hunters but also murderous predators.18 Dart’s words are so astonishing, you have to read them: The loathsome cruelty of mankind to man forms one of his inescapable characteristics and differentiative features; and it is explicable only in terms of his carnivorous, and cannibalistic origin. The blood-bespattered, slaughter-gutted archives of human history from the earliest Egyptian and Sumerian records to the most recent atrocities of the Second World War accord with early universal cannibalism, with animal and human sacrificial practices of their substitutes in formalized religions and with the world-wide scalping, head-hunting, body-mutilating and necrophilic practices of mankind in proclaiming this common bloodlust differentiator, this predaceous habit, this mark of Cain that separates man dietetically from his anthropoidal relatives and allies him rather with the deadliest of Carnivora. Dart’s killer-ape hypothesis, as it came to be known, was popularized by the journalist Robert Ardrey in a best-selling book, African Genesis, that found a ready audience in a generation disillusioned by two world wars, the Cold War, the Korean and Vietnam Wars, political assassinations, and widespread political unrest.19 The killer-ape hypothesis left an indelible stamp on popular culture including movies like Planet of the Apes, 2001: A Space Odyssey, and A Clockwork Orange. But the Rousseauians weren’t dead yet. Reanalyses of bones in the limestone pits from which fossils like the Taung Baby came showed they were killed by leopards, not early humans.20 Further studies revealed these early hominins were mostly vegetarians. And as a reaction to decades of bellicosity, many scientists in the 1970s embraced evidence for humans’ nicer side, especially gathering, food sharing, and women’s roles. The most widely discussed and audacious hypothesis, proposed by Owen Lovejoy, was that the first hominins were selected to become bipeds to be more cooperative and less aggressive.21 According to Lovejoy, early hominin females favored males who were better at walking upright and thus better able to carry food with which to provision them. To entice these tottering males to keep coming back with food, females encouraged exclusive long-term monogamous relationships by concealing their menstrual cycles and having permanently large breasts (female chimps advertise when they ovulate with eye-catching swellings, and their breasts shrink when they are not nursing). Put crudely, females selected for cooperative males by exchanging sex for food. If so, then selection against reactive aggression and frequent fighting is as old as the hominin lineage.22”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“One long-standing idea, which traces back to Darwin, is that the human lineage long ago became fundamentally less brutish and violent than apes. Unlike Rousseau, Darwin was no romantic, but he had a benevolent view of human nature. In his 1871 masterpiece, The Descent of Man, he reasoned (somewhat long-windedly) that reduced aggression was a key driving force early in human evolution: In regard to bodily size or strength…we cannot say whether man has become larger and stronger, or smaller and weaker, in comparison with his progenitors. We should, however, bear in mind that an animal possessing great size, strength, and ferocity, and which, like the gorilla, could defend itself from all enemies, would probably, though not necessarily, have failed to become social; and this would most effectually have checked the acquirement by man of his higher mental qualities, such as sympathy and the love of his fellow-creatures…. The slight corporeal strength of man, his little speed, his want of natural weapons, &c., are more than counterbalanced, firstly by his intellectual powers, through which he has, whilst still remaining in a barbarous state, formed for himself weapons, tools, &c., and secondly by his social qualities which lead him to give aid to his fellow-men and to receive it in return.17”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Yet nonreactive adult humans can excel at purposeful, planned forms of hostility. This kind of proactive aggression is characterized by predetermined goals, premeditated plans of action, attention to the target, and lack of emotional arousal. Chimpanzees sometimes engage in proactive aggression, but humans have taken planned, intentional forms of fighting to new heights such as ambushing, kidnapping, premeditated homicide, and, of course, war. Arguably, hunting and combative sports like boxing are also forms of proactive aggression. And, importantly, hunting and other forms of planned aggression are utterly different psychologically from reactive aggression. Violent criminals, ruthless dictators, torturers, and other proactive aggressors can simultaneously be loving spouses and parents, reliable friends, and patriotic fellow citizens who remain utterly calm and pleasant in situations that would send a chimpanzee or a toddler into a rage. They also don’t need to be as physically powerful.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“How, then, do we reconcile our extraordinary capacities for cooperation and conflict avoidance (Rousseau) with our capacities for aggression (Hobbes)? A persuasive resolution to this age-old debate was proposed by Richard Wrangham, who points out that we wrongly conflate two profoundly different kinds of aggression: proactive and reactive.10 According to Wrangham, humans differ from other animals, especially our ape cousins, in having exceedingly low levels of reactive aggression but much higher levels of proactive aggression. We correspond to Rousseau in terms of reactive aggression and to Hobbes in terms of proactive aggression. To illustrate this difference, imagine I just now rudely snatched this book from your hands. You might shout indignantly and try to grab it back, but it is unlikely you will attack me. Your brain would immediately inhibit any major act of reactive aggression. If you were a chimpanzee, however, you’d probably respond to my theft with instantaneous, uninhibited violence. Unless I were the dominant male in the troop, without pausing to think, you’d give me a thumping and retrieve your book. One widely reported case of this sort of reactive aggression that is only too common among chimpanzees involved an adult chimp named Travis who had spent his entire life peacefully as part of Sandra and Jerome Herold’s family. Then, in February 2009, at the age of fifteen, he flew off the handle after one of Sandra’s friends, Charla, picked up one of his favorite toys. Travis’s immediate and savage attack left Charla with no hands and without much of her face including her nose, eyes, and lips.11”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“As detailed comprehensively by Steven Pinker, our species has become exponentially less violent only very recently thanks to social and cultural constraints, many fostered by the Enlightenment.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Pinker, S. (2011), The Better Angels of Our Nature: Why Violence Has Declined (New York: Penguin).”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Beaudart, C., et al. (2017), Nutrition and physical activity in the prevention and treatment of sarcopenia: Systematic review, Osteoporosis International 28:1817–33; Lozano-Montoya, I. (2017), Nonpharmacological interventions to treat physical frailty and sarcopenia in older patients: A systematic overview—the SENATOR Project ONTOP Series, Clinical Interventions in Aging 12:721–40. 55. Fiatarone, M. A., et al. (1990), High-intensity strength training in nonagenarians: Effects on skeletal muscle, Journal of the American Medical Association 263:3029–34. 56. Donges, C. E., and Duffield, R. (2012), Effects of resistance or aerobic exercise training on total and regional body composition in sedentary overweight middle-aged adults, Applied Physiology, Nutrition, and Metabolism 37:499–509; Mann, S., Beedie, C., and Jimenez, A. (2014), Differential effects of aerobic exercise, resistance training, and combined exercise modalities on cholesterol and the lipid profile: Review, synthesis, and recommendations, Sports Medicine 44:211–21. 57. Phillips, S. M., et al. (1997), Mixed muscle protein synthesis and breakdown after resistance exercise in humans, American Journal of Physiology 273:E99–E107; McBride, J. M. (2016), Biomechanics of resistance exercise, in Haff and Triplett, Essentials of Strength Training and Conditioning, 19–42.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“One study even demonstrated marked improvements in strength among eighty-seven- to ninety-six-year-old men and women following eight weeks of resistance training.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“My friend and colleague Professor Jenny Hoffman likes to run preposterously long distances. In one race, she ran 142 miles in twenty-four hours. I’d rather pluck my toenails out one by one than try such a feat, but she claims it’s fun and doable by settling into a slow pace and refueling regularly with ginger snaps (which, I note, can be enjoyed without running for twenty-four hours nonstop).”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Being upright has another disadvantage: when running, we lost the use of our spines as stride-extending springs. Watch a slow-motion video of a greyhound or a cheetah galloping. When it lands on its back legs, its hind paws land below the shoulders as its long, flexible spine curves like a powerful bow, storing elastic energy. Then as the animal’s hind limbs push off, the spine rapidly unbends, releasing elastic energy to help catapult it into the air and increase its stride length.11 Our short, little upright spines do nothing to help us run faster, but instead struggle to keep our inherently tippy upper bodies stable while also dampening the shock wave that travels from the foot up to the head every time we hit the ground.12”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“The world’s fastest humans, then, are no match for much of the animal world. Consider also that we have been comparing the speediest humans alive—exceptional athletes who have trained for years with the help of coaches and others for the sole purpose of sprinting prescribed distances on tracks as fast as possible—with average, untrained mammals.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“In addition, as we age, we sleep less and wake up more easily, and while many of us sleep through the night, others sometimes wake up for as much as an hour or two before going back to sleep. Debate over the normality of these varying patterns was triggered by the anthropologist Carol Worthman and the historian Roger Ekirch.33 These scholars argued that it was normal prior to the Industrial Revolution for people to wake up for an hour or so in the middle of the night before going back to sleep. In between “first sleep” and “second sleep,” people talk, work, have sex, or pray. By implication, electric lights and other industrial inventions might have altered our sleep patterns. However, sensor-based studies of nonindustrial populations reveal a more complex picture. Whereas most foragers in Tanzania, Botswana, and Bolivia sleep through the night, subsistence farmers in Madagascar often divide their sleep into first and second segments.34”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Last, and perhaps most important, prolonged sitting can kindle chronic inflammation by allowing muscles to remain persistently inactive. In addition to moving our bodies, muscles function as glands, synthesizing and releasing dozens of messenger proteins (termed myokines) with important roles. Among other jobs, myokines influence metabolism, circulation, and bones, and—you guessed it—they also help control inflammation. In fact, when researchers first started to study myokines, they were astonished to discover that muscles regulate inflammation during bouts of moderate to intense physical activity similarly to the way the immune system mounts an inflammatory response to an infection or a wound.40 Without going into too many details, we have learned that the body first initiates a proactive inflammatory response to moderate- or high-intensity physical activity to prevent or repair damage caused by the physiological stress of exercise and subsequently activates a second, larger anti-inflammatory response to return us to a non-inflamed state.41 Because the anti-inflammatory effects of physical activity are almost always larger and longer than the pro-inflammatory effects, and muscles make up about a third of the body, active muscles have potent anti-inflammatory effects. Even modest levels of physical activity dampen levels of chronic inflammation, including in obese people.42”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Long hours of commuting, a demanding desk job, being sick or disabled, or otherwise being confined to a chair can be stressful situations that elevate the hormone cortisol. This much-misunderstood hormone doesn’t cause stress but instead is produced when we are stressed, and it evolved to help us cope with threatening situations by making energy available. Cortisol shunts sugar and fats into the bloodstream, it makes us crave sugar-rich and fat-rich foods, and it directs us to store organ fat rather than subcutaneous fat. Short bursts of cortisol are natural and normal, but chronic low levels of cortisol are damaging because they promote obesity and chronic inflammation. Consequently, long hours of stressful sitting while commuting or a high-pressure office job can be a double whammy.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Instead of blazing acutely in one spot for a few days or weeks, as when we fight a cold, inflammation can smolder imperceptibly in many parts of the body for months or years. In a way, chronic, low-grade inflammation is like having a never-ending cold so mild you never notice its existence. But the inflammation is nonetheless there, and mounting evidence indicates that this slow burn steadily and surreptitiously damages tissues in our arteries, muscles, liver, brain, and other organs.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Technically, “inflammation” describes how the immune system first reacts after it detects a harmful pathogen, something noxious, or a damaged tissue. In most cases, inflammation is rapid and vigorous. Whether the offenders are viruses, bacteria, or sunburns, the immune system quickly launches an armada of cells into battle. These cells discharge a barrage of compounds that cause blood vessels to dilate and become more permeable to white blood cells that swoop in to destroy any invaders. This extra blood flow brings critically needed immune cells and fluids, but the swelling compresses nerves and causes the four cardinal symptoms of inflammation (which literally means “to set on fire”): redness, heat, swelling, and pain. Later, if necessary, the immune system activates additional lines of defense by making antibodies that target and then kill specific pathogens.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“By convention, your heart rate during sedentary activities is between its resting level and 40 percent of maximum; light activities such as cooking and slow walking boost your heart rate to between 40 and 54 percent of maximum; moderate activities like rapid walking, yoga, and working in the garden speed your heart rate to 55 to 69 percent of maximum; vigorous activities such as running, jumping jacks, and climbing a mountain demand heart rates of 70 percent or higher.27 Large samples of Americans asked to wear heart rate monitors indicate that a typical adult engages in about five and a half hours of light activity, just twenty minutes of moderate activity, and less than one minute of vigorous activity.28 In contrast, a typical Hadza adult spends nearly four hours doing light activities, two hours doing moderate-intensity activities, and twenty minutes doing vigorous activities.29 Altogether, twenty-first-century Americans elevate their heart rates to moderate levels between half and one-tenth as much as nonindustrial people.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“In Europe, it was not until the late sixteenth century that chairs with supportive backs started to become common among the growing middle and upper classes who could afford furniture.17 Then, during the Industrial Revolution, a German manufacturer, Michael Thonet, figured out how to mass manufacture bentwood chairs with backrests that were light, strong, beautiful, comfortable, and affordable to the needy masses.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“To be sure, the muscular effort isn’t great: squatting and standing use about the same degree of muscle activity.14 But over long periods of time those muscles require and develop endurance. My colleagues Eric Castillo, Robert Ojiambo, and Paul Okutoyi and I found that rural teenagers in Kenya who rarely sit in chairs with backrests have 21 to 41 percent stronger backs than teenagers from the city who regularly sit in the sorts of chairs you and I usually use.15”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Because I rarely squat, my calves were too tight to allow me to keep my feet flat on the ground, and my foot muscles started to ache, as did my calves and quads.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Because squatting creates tiny smoothed regions on ankle bones known as squatting facets, we can see that humans for millions of years, including Homo erectus and Neanderthals, regularly squatted.12 Squatting facets also indicate that many Europeans squatted habitually until furniture and stoves became common after the Middle Ages.13”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Despite Ogden Nash’s observation that “people who work sitting down get paid more than people who work standing up,” a growing chorus of exercists who nag us to exercise condemn sitting as a modern scourge.1 One prominent physician has declared that chairs are “out to get us, harm us, kill us” and that “sitting is the new smoking.”2 According to him, the average American sits for an unacceptable thirteen hours a day, and “for every hour we sit, two hours of our lives walk away—lost forever.” This admonition is obviously hyperbole, but other well-publicized studies estimate that sitting more than three hours a day is responsible for nearly 4 percent of deaths worldwide and that every hour of sitting is as harmful as the benefit from twenty minutes of exercise.3 By some estimates, replacing an hour or two of daily sitting with light activities like walking can lower death rates by 20 to 40 percent.4 As a result, standing desks are all the rage, and many people now wear sensors or use their phones to keep track of and limit their sitting time. We have become exercised about sitting.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Whether we take the stairs, jog, or go to the gym, we need to override ancient, powerful instincts to avoid unnecessary physical activity, and it should hardly be surprising that most of us—hunter-gatherers included—naturally avoid exercise.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

“Of course, this logic applies to all animals. Whether you are a human, ape, dog, or jellyfish, natural selection will select against activities that waste energy at a cost to reproductive success. In this regard, all animals should be as lazy as possible. However, the evidence suggests that humans are more averse to needless physical activity than many other species because we evolved an unusually expensive way of increasing our reproductive success from an unusually low-energy-budget ancestor. When your expenses are high, every penny saved is valuable.”
― Daniel E. Lieberman, Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding