Daniel Lieberman Quotes on the Evolution of Human Physical Activity

Learn from and inspire yourself with these insightful Daniel Lieberman Quotes.

Dr. Daniel E. Lieberman is a Professor in the Department of Human Evolutionary Biology at Harvard University. He writes about himself:

“I study and teach how and why the human body looks and functions the way it does. I have long been fascinated by the evolution of the human head but my main focus is currently on the evolution of human physical activity.

I am especially interested in how evolutionary approaches to activities such as walking and running, as well as changes to our body’s environments (such as wearing shoes and being physically inactive) can help better prevent and treat musculoskeletal diseases.  

To address these problems, I integrate experimental biomechanics and physiology in both the laboratory and the field with analyses of the human fossil record.”

I have been a fan of Daniel Lieberman quotes and his work for a while and I believe that his book “The Story of the Human Body” should be essential reading for every human in order to understand where we come from and why we are the way we are.

The following are all Daniel Lieberman quotes that demonstrate his ideas about the development of the human body, health, physical fitness, diet, habits, disease and living methods, all understood within an evolutionary context.

At the Outdoor Fitness Society, we always strive to give you the best tools to be the healthiest, happiest, fittest and most functional human you can be, and Daniel Lieberman’s work is a valuable asset in regards to those areas of life.

Woman diving into lake
Enjoy your body Jana Sabeth

They will help you to understand and improve yourself, based on your own biological makeup, conditioning and natural impulses. They will show you why you crave sugar, salt, starch and fatty foods, why most diets fail and why you are evolved to be an incredible athlete.

They will show you why it is an innate instinct to cooperate and help other humans, why people get fat and how certain structures in society are not set up in alignment with your natural evolutionary tendencies and wishes.

They will also show how this biological mismatch and disharmony can cause many ailments and diseases.


Knowledge is power, so armed with his information you can make better (or reinforce already positive) choices about what foods you put in your body, how to live in accordance with what you are hardwired to do and how to optimise your movement, athleticism and health in general.

Whether you love ultrarunning over frozen Icelandic landscapes or slow walks in the peaceful Finnish countryside; maxing out your clean and jerk in the Box or daily yoga, these quotes will give you a deeper understanding of your own body and what it is designed to do.

Enjoy these Daniel Lieberman quotes.


Learn more from these Daniel Lieberman quotes on fitness, health and movement.

“Like it or not, we are slightly fat, furless, bipedal primates who crave sugar, salt, fat, and starch, but we are still adapted to eating a diverse diet of fibrous fruits and vegetables, nuts, seeds, tubers, and lean meat. We enjoy rest and relaxation, but our bodies are still those of endurance athletes evolved to walk many miles a day and often run, as well as dig, climb and carry.”

“Men and women aged forty-five to seventy-nine who are physically active, eat plenty of fruits and vegetables, do not smoke, and consume alcohol moderately have on average one-fourth the risk of death during a given year than people with unhealthy habits.”

“Muscle imbalances caused by hours of sitting in chairs have also been hypothesized to contribute to one of the most common health problems on the planet: lower back pain. Depending on where you live and what you do, your chances of getting lower back pain are between 60 and 90 percent.”

“The general trend is that people who frequently carry heavy loads and do other “back-breaking” work get fewer back injuries than those who sit in chairs for hours bent over a machine.”

“Another relevant factor is money. In the United States and many other countries, health care is partly a for-profit industry. Consequently, there is a strong incentive to invest in or promote treatments such as antacids and orthotics that alleviate the symptoms of diseases and that people have to buy frequently and for many years.

Another way to make lots of money is to favor costly procedures like surgery instead of less expensive preventive treatments like physical therapy.”

“Further, although it makes sense for doctors and public health officials to categorize diseases based on whether they are caused by infections, malnutrition, tumors, and so on, an evolutionary perspective suggests that we should also look at the extent to which diseases are caused by evolutionary mismatches between the environmental conditions (including diet, physical activity, sleep, and other factors) for which we evolved and the environmental conditions that we now experience.”

Daniel Lieberman quotes on human activity
Be present Jakob Kriz

“In fact, several studies have shown that losing weight and exercising vigorously can sometimes actually reverse the disease (diabetes), at least during its early stages.

One extreme study placed eleven diabetics on a grueling ultra-low-calorie diet of just 600 calories per day for eight weeks. Six hundred calories is an extreme diet that would challenge most people (it’s about two tuna fish sandwiches a day).

After two months, however, these seriously food-deprived diabetics had lost an average of 13 kilograms (27 pounds), mostly visceral fat, their pancreases doubled how much insulin they could produce, and they recovered nearly normal levels of insulin sensitivity. Vigorous physical activity also has potent reversal effects by causing your body to produce hormones (glucagon, cortisol, and others) that cause your liver, muscle, and fat cells to release energy.

These hormones temporarily block the action of insulin while you exercise, and then they increase the sensitivity of these cells to insulin for up to sixteen hours following each bout of exercise.”

Daniel Lieberman quotes on human evolution.
Stay in touch with you body Alberto Bigoni

“Walking long distances is fundamental to being a hunter-gatherer, but people sometimes have to run. One powerful motivation is to sprint to a tree or some other refuge when being chased by a predator.

Although you only have to run faster than the next fellow when a lion chases you, bipedal humans are comparatively slow. The world’s fastest humans can run at 37 kilometers (23 miles) per hour for about ten to twenty seconds, whereas an average lion can run at least twice as fast for approximately four minutes. Like us, early Homo must have been pathetic sprinters whose terrified dashes were too often ineffective.

However, there is plentiful evidence that by the time of Homo erectus our ancestors had evolved exceptional abilities to run long distances at moderate speeds in hot conditions.

The adaptations underlying these abilities helped transform the human body in crucial ways and explain why humans, even amateur athletes, are among the best long-distance runners in the mammalian world. Today, humans run long distances to stay fit, commute, or just have fun, but the struggle to get meat underlies the origins of endurance running.

To appreciate this inference, try to imagine what it was like for the first humans to hunt or scavenge 2 million years ago. Most carnivores kill using a combination of speed and strength.

Large predators, such as lions and leopards, either chase or pounce on their prey and then dispatch it with lethal force. These dangerous carnivores can run as fast as 70 kilometers (43 miles) per hour, and they have terrifying natural weapons: daggerlike fangs, razor-sharp claws, and heavy paws to help them maim and kill.”

“…the solution to this problem is an ancient method of hunting based on endurance running known as persistence hunting. Persistence hunting takes advantage of two basic characteristics of human running.

First, humans can run long distances at speeds that require quadrupeds to switch from a trot to a gallop. Second, running humans cool by sweating, but four-legged animals cool by panting, which they cannot do while galloping.

Therefore, even though zebras and wildebeest can gallop much faster than any sprinting human, we can hunt and kill these swifter creatures by forcing them to gallop in the heat for a long period of time, eventually causing them to overheat and collapse. This is just what persistence hunters do.”

“Your guts also have about 100 million nerves, more than the number of nerves in your spinal cord or your entire peripheral nervous system.”


These Daniel Lieberman quotes on diet and nutrition will help you understand what you are meant to eat as an evolving Homo Sapien.

“Fructose, which is often paired with glucose, is naturally present in fruit and honey, as well as table sugar (sucrose, which is 50 percent fructose). Assuming your baker used plenty of sugar, your cake probably has a fair amount of fructose.

Unlike glucose, which can be metabolized (essentially burned) by cells throughout the body, fructose is almost entirely metabolized by the liver.

The liver, however, can burn only so much fructose at once, so it converts any excess fructose into fat, which again is either stored in the liver or dumped into the bloodstream…both of these fates cause problems.”

“These visceral (belly) fat cells behave differently than fat elsewhere in the body in two important ways. First, they are several times more sensitive to hormones and thus tend to be more metabolically active, which means they are capable of storing and releasing fat more rapidly than fat cells in other parts of the body.

Second, when visceral cells release fatty acids (something fat cells do all the time), they dump the molecules almost straight into the liver, where the fat accumulates and eventually impairs the liver’s ability to regulate the release of glucose into the blood.

An excess of belly fat (a paunch) is therefore a much greater risk factor for metabolic disease than a high BMI.”

Blueberries on a bush
Eat healthy Tomas Williams

“If fructose sounds dangerous, it can be, but only in fast and large doses. For most of human evolution the only big, rapidly digestible source of fructose that our ancestors could acquire was honey.”

“We therefore have irrefutable evidence that hominins started to consume meat by at least 2.6 million years ago. How much meat they ate is conjecture, but meat constitutes approximately one-third of the diet among hunter-gatherers in the tropics (more fish and meat are consumed in temperate habitats).

In addition, hunter-gatherers must have craved meat back then as much as chimps and humans still do today, and for good reason.

Eating an antelope steak yields five times more energy than an equal mass of carrots, as well as essential proteins and fats. Other animal organs such as the liver, heart, marrow, and brain also provide vital nutrients, especially fat, but also salt, zinc, iron, and more.

Meat is a rich food source. Meat has been an important component of the human diet ever since early Homo, but being a part-time carnivore is time-consuming, chancy, dangerous, and difficult for hunter-gatherers today, and it must have been even more challenging and risky at the dawn of the Paleolithic, long before projectile weapons were invented.”

“There is nearly universal consensus that we should prohibit selling and serving alcohol to minors because wine, beer, and spirits can be addictive and, when used to excess, ruinous for their health. Is excess sugar any different?”

“These natural tendencies then make us vulnerable to manufacturers and marketers who easily exploit our basic urges to eat too much, eat the wrong foods, and exercise too little. Because these unhealthy behaviors are deep instincts they are very difficult to overcome.

The bottom line is that knowledge is power, but not enough. Most of us need information and skills, but we also require motivation and reinforcement to overcome basic urges in order to make healthier choices in environments replete with plentiful food and labor-saving devices.”

“Before World War I, the average American consumed about 15 grams of fructose (half an ounce) a day, mostly from eating fruits and vegetables that surrender the fructose slowly; the average American today consumes 55 grams (almost 2 ounces) per day, much of it from soda and processed foods made with table sugar.

All in all, the chief reason why more people are getting fatter, especially in our bellies, is that processed foods are supplying them with too many calories, many from sugar—both glucose and fructose—in doses that are both too high and too rapid for the digestive systems we inherited.”

“Another set of mismatch diseases that can be caused by farming diets are nutrient deficiencies. Many of the molecules that make grains like rice and wheat nutritious, healthful, and sustaining are the oils, vitamins, and minerals present in the outer bran and germ layers that surround the mostly starchy central part of the seed. Unfortunately, these nutrient-rich parts of the plant also spoil rapidly.

Since farmers must store staple foods for months or years, they eventually figured out how to refine cereals by removing the outer layers, transforming rice or wheat from “brown” into “white.”

These technologies were not available to the earliest farmers, but once refining became common the process removed a large percentage of the plant’s nutritional value. For instance, a cup of brown and white rice have nearly the same caloric content, but the brown rice has three to six times as much B vitamins, plus other minerals and nutrients such as vitamin E, magnesium, potassium, and phosphorus.”


Learn more about these Daniel Lieberman quotes on evolution.

“We didn’t evolve to be healthy, but instead we were selected to have as many offspring as possible under diverse, challenging conditions. As a consequence, we never evolved to make rational choices about what to eat or how to exercise in conditions of abundance and comfort.”

“Our body’s evolutionary journey is also far from over.

Natural selection didn’t stop when farming started but instead has continued and continues to adapt populations to changing diets, germs, and environments. Yet the rate and power of cultural evolution has vastly outpaced the rate and power of natural selection, and the bodies we inherited are still adapted to a significant extent to the various and diverse environmental conditions in which we evolved over millions of years.

Daniel Lieberman Quotes on the environment
Embrace your surroundings Jakub Kriz

The end product of all that evolution is that we are big-brained, moderately fat bipeds who reproduce relatively rapidly but take a long time to mature.”

“The fundamental answer to why so many humans are now getting sick from previously rare illnesses is that many of the body’s features were adapted in environments from which we evolved, but have become maladapted in the modern environments we have now created.

This idea, known as the mismatch hypothesis, is the core of the new emerging field of evolutionary medicine, which applies evolutionary biology to health and disease.”

“An evolutionary perspective predicts that most diets and fitness programs will fail, as they do, because we still don’t know how to counter once-adaptive primal instincts to eat donuts and take the elevator.”

“Our recent divergence from a small population explains another important fact, one that every human ought to know: we are a genetically homogenous species.”

“According to one calculation, everyone alive today descends from a population of fewer than 14,000 breeding individuals from sub-Saharan Africa, and the initial population that gave rise to all non-Africans was probably fewer than 3,000 people.”

“The Good News: Taller, Longer-Lived, and Healthier Bodies…The last 150 years have profoundly transformed how we eat, work, travel, fight disease, keep clean, and even sleep. It is as if the human species had a total makeover: our daily lives would be barely comprehensible to our ancestors from just a few generations ago, but we are essentially identical genetically, anatomically, and physiologically.

The change has been so rapid that too little time has elapsed for more than a modicum of natural selection to have occurred.”

“We are still evolving. Right now, however, the most potent form of evolution is not biological evolution of the sort described by Darwin, but cultural evolution, in which we develop and pass on new ideas and behaviors to our children, friends, and others.

Some of these novel behaviors, especially the foods we eat and the activities we do (or don’t do), make us sick.”


Learn more from these Daniel Lieberman quotes about farmers and hunter gatherers.

Field of wheat
Martin Noren

“Farming is often viewed as an old-fashioned way of life, but from an evolutionary perspective, it is a recent, unique, and comparatively bizarre way to live.”

“More than six hundred generations ago, everybody everywhere was a hunter-gatherer. Until relatively recently—the blink of an eye in evolutionary time—your ancestors lived in small bands of fewer than fifty people.

They moved regularly from one camp to the next, and they survived by foraging for plants as well as hunting and fishing. Even after agriculture was invented starting about 10,000 years ago, most farmers still lived in small villages, labored daily to produce enough food for themselves, and never imagined an existence now common in modern life.”

“How did farming change how much physical activity we do and how we use our bodies to do the work? Although hunting and gathering is not easy, nonfarming populations like the Bushmen or the Hadza generally work only five to six hours a day.

Contrast this with a typical subsistence farmer’s life. For any given crop, a farmer has to clear a field (perhaps by burning vegetation, clearing brush, removing rocks), prepare the soil by digging or plowing and perhaps fertilizing, sow the seeds, and then weed and protect the growing plants from animals such as birds and rodents. If all goes well and nature provides enough rain, then comes harvesting, threshing, winnowing, drying, and finally storing the seeds.

As if that were not enough, farmers also have to tend animals, process and cook large batches of foods (for example by curing meat and making cheese), make clothing, build and repair homes and barns, and defend their land and stored harvests. Farming involves endless physical toil, sometimes from dawn to dusk.”

“One very simple way to compare the workloads of farmers, hunter-gatherers, and modern postindustrial people is to measure physical activity levels (PALs). A PAL score measures the number of calories spent per day (total energy expenditure) divided by the minimum number of calories necessary for the body to function (the basal metabolic rate, BMR).

In practical terms, a PAL is the ratio of how much energy one spends relative to how much one would need to sleep all day at a comfortable temperature of about 25 degrees Celsius (78 degrees Fahrenheit). Your PAL is probably about 1.6 if you are a sedentary office worker, but it could be as a low as 1.2 if you spent the day in a hospital on bed rest, and it could be 2.5 or higher if you were training for a marathon or the Tour de France.

Various studies have found that PAL scores for subsistence farmers from Africa, Asia, and South America average 2.1 for males and 1.9 for females (range: 1.6 to 2.4), which is just slightly higher than PAL scores for most hunter-gatherers, which average 1.9 for males and 1.8 for females (range: 1.6 to 2.2).

Fishing nets
Tools of the trade Jakob Kriz

These averages don’t reflect the considerable variation—daily, seasonal, and annual—within and between groups, but they underscore that most subsistence farmers work as hard if not a little harder than hunter-gatherers and that both ways of life require what people today would consider a moderate workload.”

“Hunter-gatherers who survive childhood typically live to be old: their most common age of death is between sixty-eight and seventy-two, and most become grandparents or even great-grandparents.

They most likely die from gastrointestinal or respiratory infections, diseases such as malaria or tuberculosis, or from violence and accidents. Health surveys also indicate that most of the noninfectious diseases that kill or disable older people in developed nations are rare or unknown among middle-aged and elderly hunter-gatherers.

These admittedly limited studies have found that hunter-gatherers rarely if ever get type 2 diabetes, coronary heart disease, hypertension, osteoporosis, breast cancer, asthma, and liver disease.

They also don’t appear to suffer much from gout, myopia, cavities, hearing loss, collapsed arches, and other common ailments. To be sure, hunter-gatherers don’t live in perpetually perfect health, especially since tobacco and alcohol have become increasingly available to them, but the evidence suggests that they are healthy compared to many older Americans today despite never having received any medical care.

In short, if you were to compare contemporary health data from people around the world with equivalent data from hunter-gatherers, you would not conclude that rising rates of common mismatch diseases such as heart disease and type 2 diabetes are straightforward, inevitable by-products of economic progress and increased longevity.”

“Of all the advantages of farming, the most fundamental and consequential is that more calories allow people to have bigger families, leading to population growth. But larger populations and their effects on human settlement patterns also fostered new kinds of infectious diseases.

Without a doubt, these diseases have been and remain the most devastating of the evolutionary mismatches caused by the Agricultural Revolution.”

“Group cooperation has probably been fundamental to the hunter-gatherer way of life for more than 2 million years.”

“Hunter-gatherer mothers rely on one another to help watch children, and males share meat extensively not just with their families but also with other men. When a hunter kills something large, like a several-hundred-pound antelope, he distributes meat to everyone in camp.

This sort of sharing isn’t just an effort to be nice and to avoid waste; it’s a vital strategy to reduce the risk of hunger, because the chances of a hunter killing a large animal on any given day are small. By sharing meat on the days he hunts successfully, a hunter increases his chances of getting meat from fellow hunters on the days he comes home empty-handed.

Men also sometimes hunt in groups to increase their probability of hunting success and to help one another carry home the bounty. Not surprisingly, hunter-gatherers are highly egalitarian and they place great stock in reciprocity, helping assure everyone a more regular supply of resources.”

Daniel Lieberman’s work demonstrates the importance of staying active and fit for life, eating well and understanding why you feel what you feel, and crave what you crave.

From hiking to kayaking, walking your dog to running ultramarathons, do what you love and stay fit and active so that you can enjoy the natural world as a functional, informed human.

If you enjoyed these Daniel Lieberman quotes then try these workout quotes, Walden quotes or quotes about the wild places of the world.

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