Daniel Lieberman

“The Story of the Human Body: Evolution, Health, and Disease” is the type of popular science book that is so fascinating and well written that it can truly be described as intellectual entertainment…candy for the inquiring brain. In so many ways, this book was a delight. I knew I would be attracted to the topic; that is why I got the book, but I did not intend to read everything cover-to-cover. I already had a great deal of academic background on the subject of human evolution and show more mismatched diseases, so my intent was just to read those parts that were new to me. However, the truth is that once I began reading, I couldn’t stop; I found the book so stimulating and fascinating that I read it straight through, every word, in a little less then three days.

Personally, I’m going to tuck the name of author Daniel E. Lieberman into a special corner of my memory where I keep a growing list of select scholars who possess the uncommon ability of being able to communicate their academic disciplines to the general public through unusually clear and engaging prose. Lieberman may not (yet) be as famous, but his name will join others on that list like Vilayanur Ramachandran (neurology), Stephen Jay Gould (evolution), Edward O. Wilson (biology), Richard Feynman (physics), Frans De Waal (zoology), Jane Goodall (zoology), Dian Fossey (zoology), Oliver Sachs (neurology), Stephen Picker (cognitive science), Jared Diamond (interdisciplinary), Kay Redfield Jamison (psychiatry), and a few more.

Lieberman gave his book a perfect title; it is “The Story of the Human Body.” That is what makes it compelling and engaging. It is a story…and that story is about us. It explains how we came to be in the situation we are in today.

In particular, this story focuses on dysevolution, a form of cultural evolution where humans pass on behaviors and environments that promote mismatched diseases. Mismatch diseases are those diseases that exist because the biology of our human body has not had time to adapt to how most of us live in the modern world. According to the author, hypothesized noninfectious mismatch diseases include: acid reflux, acne, Alzheimer’s, anxiety, apnea, asthma, athlete’s foot, ADHD, bunions, certain cancers, carpal tunnel syndrome, cavities, chronic fatigue syndrome, cirrhosis, chronic constipation, coronary heart disease, Crohn’s disease, depression, diabetes (type 2), eating disorders, emphysema, endometriosis, fatty liver syndrome, fibromyalgia, flat feet, glaucoma, gout, hammer toes, hemorrhoids, hypertension, impacted wisdom teeth, chronic insomnia, irritable bowel syndrome, lactose intolerance, lower back pain, malocclusion, metabolic syndrome, multiple sclerosis, myopia, obsessive-compulsive disorder, osteoporosis, preeclampsia, rickets, scurvy, and stomach ulcers.

The author only touches briefly on most of these diseases, but a few of them are discussed in detail. Those that are discussed in detail provide clear examples of the rationale behind the science of mismatched diseases. For those that he did not cover, there are often valuable leads for further study in the bibliography.

I could write more summarizing the content of this book, but I think it is perhaps more fitting if I end this review with a quote from the author. The quote occurs toward the very end of the book. It’s a quick summary, plus it aptly shows how well and engagingly the author writes.

“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, often run, as well as dig, climb, and carry. We love many comforts, but we are not well adapted to spend our days indoors in chairs, wearing supportive shoes, staring at books or screens for hours on end. As a result, billions of people suffer from diseases of affluence, novelty and disuse that used to be rare or unknown. We then treat the symptoms of these diseases because it is easier, more profitable, and more urgent than treating their causes, many of which we don’t understand anyway. In doing so, we perpetuate a pernicious feedback loop—dysevolution—between culture and biology.”

If this review piqued your interest, I’m sure you will be one of those who will enjoy reading this remarkable and captivating book. show less

Exercise is one of those topics, along with diet, that generates a lot of confusion. And while there is no shortage of advice to be found online, it is rarely based on our best science or on our understanding of the intricacies of human physiology, evolution, and anthropology.

In Exercised, Harvard professor of evolutionary biology Daniel Lieberman explains that to truly understand exercise science, you must first understand something about human evolution and anthropology and how the body show more evolved to handle exercise. As Lieberman wrote, “nothing about the biology of exercise makes sense except in the light of evolution, and nothing about exercise as a behavior makes sense except in the light of anthropology.”

Using this evolutionary/anthropological framework, Lieberman sets out to explain how the body works when at rest (sitting and sleeping), when active (walking, running, lifting, fighting, dancing), and what this means for establishing effective exercise habits in the modern world. Far from being a self-help book or a simple guide to developing an exercise routine, Exercised helps you to understand why exercise is good for you and the science behind when, how, and what types of exercises you should be pursuing, dispelling several myths about exercise along the way.

The first—and most fundamental—myth is that we evolved to exercise. The truth is the opposite, and there are good evolutionary reasons for why most people wish to avoid it. (Note that by “exercise” Lieberman means voluntary physical activity pursued for no other purpose than to promote health and fitness.)

The first thing to understand is that humans spent most of their 200,000-year evolutionary history as hunter-gatherers, with the invention of agriculture occurring only around 10,000 years ago and the modern industrial revolution beginning only about 200 years ago. The key to understanding our relationship to exercise, therefore, is found in the study of these hunter-gatherer groups.

As Lieberman explains, modern hunter-gatherer tribes (including the Hadza) are puzzled by any mention of exercise, or voluntary activity with no purpose other than the promotion of health. Because hunter-gatherers spend hours each day sourcing food, they tend to spend the remainder of the day conserving energy.

You find the same behavior in apes, our closest evolutionary cousins, and in all other animals. Energy is expended on obtaining food, survival, and reproduction, with periods of rest in between. Since every calorie expended in nature counts, it would make no sense to expend needless energy on any activity that does not enhance reproductive fitness.

What’s unique about modern post-industrial humans is that we’ve flipped this logic on its head. Because most of our jobs are now sedentary and we’re surrounded by labor-saving devices, we have to engage in physical activity for no other purpose. This is both unprecedented in the animal kingdom and in most of our own evolutionary past. There is little wonder, then, that most people lack the motivation to work out.

That’s the bad news. The good news is that it would take less exercise than you might think for the modern sedentary Westerner to match the energy expenditure levels of a hunter-gatherer. This is because your resting metabolic rate (RMR) (the daily energy required to sustain your body at rest) represents about two-thirds of your energy requirements. If you’re an average adult male that weighs 180 pounds, your RMR is about 1,700 calories, while your total daily energy expenditure (DEE) is approximately 2,700 calories.

The upshot is that, since both you and a hunter-gather expend most of your energy at rest—and because hunter-gatherers are also sedentary when not sourcing food—“it would take you just an hour or two of walking per day to be as physically active as a hunter-gatherer,” as Lieberman writes. This both eliminates the stigma associated with not wanting to exercise and demonstrates that it doesn’t take all that much effort to get the appropriate amount of exercise—even for those with sedentary lifestyles.

Having outlined our evolutionary aversion to exercise, Lieberman proceeds to explain the physiology and biomechanics of a host of physical activities, dedicating each chapter to one activity or function (walking, running, weight training, etc.). Each chapter provides insightful and fascinating information, but the focus on debunking myths often feels forced and tedious.

Lieberman decides to open each chapter with a myth, but the reader is left wondering just how prevalent these “myths” really are. Myth #6, for example, is the belief that we evolved to be extremely strong, but you might wonder how common this belief really is. Lieberman’s tendency to present all of his ideas as profoundly opposite of conventional wisdom gets tiresome fast.

Here’s another example: “Myth” #8, which is the belief that you can’t lose weight by walking, seems to be largely true and not a myth at all. As Leiberman himself writes:

“It bears repeating that if I power walk five miles, I’ll expend roughly 250 extra calories, as many calories as I’ll acquire from snacking on the granola bar in my backpack.”

If walking five miles equals the calorie content of a granola bar—and walking those five miles makes you hungrier and more likely to eat that granola bar—then that tells me that it is significantly easier to lose weight through diet than exercise, and that it is unlikely that walking is going to result in substantial weight loss over a reasonable amount of time. While there are several benefits associated with walking, weight loss is unlikely to be one of them (without the appropriate diet).

Yes, you can lose weight by walking, but it would be (1) very slow, (2) very time-consuming and inefficient, and (3) impossible without resisting the urge to consume more calories after expending the extra energy. So when you hear that you can’t lose weight by walking, while that statement is not entirely true, I wouldn’t call it a myth either. And this is my biggest problem with the presentation overall; it encourages black-and-white thinking even when the reader probably wasn’t thinking in those terms to begin with. To be fair, Lieberman does present the full complexity of the issues, but I felt that the focus on dispelling myths in every chapter was forced and unnecessary.

In the final part of the book, Lieberman again reminds us that we did not evolve to exercise. Our ancestors engaged in physical activity out of necessity (survival and reproduction) or pleasure (games, dancing, etc.), but never for the purpose of promoting health and fitness. We are therefore evolutionarily programmed to avoid wasting energy on unnecessary activities.

At the same time, Lieberman also reminds us that because most of our lives are now relatively sedentary, we do require exercise to stay healthy, as study after study demonstrates the various mental, physical, anti-aging, and disease-prevention benefits of exercise. As recommended by several health agencies, a good rule of thumb for adults is a minimum of 150 minutes per week (30 minutes a day for five days) of moderate aerobic exercise with two supplemental sessions involving weights.

So how can we get ourselves to exercise more? According to Lieberman, because exercise is optional, and, for most people, unpleasant, we should adopt strategies that make exercise either mandatory or more fun. Lieberman recommends things like listening to music or podcasts while working out, working out with friends, exercising outdoors, instituting variety into our routines, rewarding ourselves, and various suggestions for making exercise mandatory through commitments to friends or organizations (physical activity has always had a strong social component for humans).

His most profound recommendation—one that has the potential for the largest impact on society—is expanded mandatory physical education in K-12 and college education. As Liberman wrote:

“In one study, 85 percent of students who exercised regularly in college continued to exercise later in life, but 81 percent of those who were physically inactive in college remained sedentary as older adults.”

Compare this with the fact that most universities have dropped their physical education/activity requirements altogether. In fact, it is estimated that only a quarter of college students get baseline levels of regular exercise despite high levels of depression and anxiety, and despite the fact that studies suggest that exercise can treat depression and anxiety as well as or better than medication or therapy.

Additionally, only 11 percent of elementary school districts have physical activity breaks during the school day, and that number drops to 2 percent for high schools. By encouraging inactivity, we are training our kids to establish habits of inactivity that last the rest of their lives—all to prioritize standardized testing and academics (even when exercise has been shown to improve cognition and memory).

According to the CDC, only 23 percent of all US adults get the recommended 150 minutes per week of exercise. For children ages 6 to 17, less than 24 percent get the recommended 60 minutes of physical activity every day. Not only is this unhealthy in the short term, it sets up lifelong habits of inactivity that increase the risk of developing various diseases including heart disease, diabetes, stroke, and more (some of the leading causes of death in the US). I’d say it’s about time we start reassessing our priorities. show less

[W]hat makes Homo sapiens special and why we are the only human species alive is that we evolved a few slight changes in our hardware that helped ignite a software revolution that is still ongoing at an escalating pace.

Lieberman, a professor of human evolutionary biology at Harvard, develops this apt metaphor by examining the key physical transitions that separated us from apes and then the intellectual transitions that separated us from all other hominins. Life only gets better and better show more for us over millions of years as we become bipeds whose increased mobility allows foraging further distances for food, those better diets then leading to bigger brains and the strategic thinking necessary for hunting, tool-making, and eventually language and social cooperation.

Only better and better ... until a couple of cultural transitions have mixed results: the agricultural revolution’s huge increase of food supply and caloric density (but: sometimes famine) and population growth (but: sometimes infectious outbreaks from living densely with animals/people); the industrial revolution’s relief of brutal physical labor (but: creation of obesity and "under-use" diseases). He asks, “Has civilization led the human body astray?” and answers, in a definite affirmative, via an exploration of the mis-matches between the body we've evolved and the environment we've cultured that are responsible for the bulk of today’s healthcare spending, disabilities, and deaths.

This book is a detailed scientific exploration of how we evolved to live and how we actually do live now, connecting the dots to show why we're in epidemics of infectious disease; heart disease; autoimmune disease; obesity; type 2 diabetes; cancer; osteoporosis; and dozens more. I’m very familiar with the current situation but the evolutionary backstory here was fascinating -- logically developed, conversationally presented, extensively (and entertainingly) endnoted, and completely accessible to the non-scientist reader. Highly recommended ... and even motivating toward a healthier lifestyle.

(Review based on an advance reading copy provided by the publisher.) show less

This excellent book far exceeded my expectations, and indeed, wasn't at all about what I thought it would be about from the title. The author, a professor of evolutionary biology at Harvard, seeks to acquaint us with the evolutionary imperatives that make our current health habits non-adaptive. In particular, he argues that many of the chronic illnesses besetting 21st Century humans can and should be avoided.

He explains: "The fundamental answer to why so many humans are getting sick from show more previously rare illnesses is that many of the body’s features that were adaptive in environments for which we evolved have become maladaptive in the modern environment we have now created.”

One example is how our bodies were developed to store fat before the age of easy food, grocery stores, refrigerators, freezers, and hot fudge sundaes. We still have that adaptation in our bodies, but now we access and store way too much fat, leading to problems like heart disease, obesity, and Type II Diabetes. This mismatch between the way our bodies evolved and our current sedentary and overindulgent lifestyles forms the basis of the emerging field of evolutionary medicine, which applies the insights gleaned from studying evolution to biology and health. The author explains the origin and nature of the problem in detail in this book.

He tells you so many interesting facts about the human body: who knew that the semicircular canals of the inner ear function like data-emitting gyroscopes: not only sensing how fast the head pitches, rolls, and yaws when one runs, but then triggering reflexes that cause the eye and neck muscles to counter these movements. Or who knew that the Achilles tendon, only four inches long, stores and releases almost 35% of the mechanical energy generated by the body during running!

Discussion: This book can fill you with anxiety or even cause you to hyperventilate (speaking for myself, at any rate) as the author details the many ways in which we modern humans hurt our bodies. In fact, I listened to it in the car, which totally ruined my grocery store shopping trips. How could I buy cookies and ice cream when I could hear the author in my mind excoriating me? I can tell you definitively that he would not be in favor of the technique employed by the rich people in The Hunger Games, who ate all they wanted and then threw up so they could eat more. Rather, he would suggest we consider adhering to a regimen of a healthy diet and moderate exercise. (Gasp!) And I could picture him nodding his head sadly at the brilliant section in Julianna Baggott's book Fuse, in which the hero, Bradwell, bemoans the fact that the world was dying of "...the corn-fed grief, the unbearable weight of pie fillings…"

Evaluation: I found this book terrifically interesting. Every chapter provided me with new facts and insights, and new internal pressure to take better care of myself. I listened to this book on audio, and the narrator, Sean Runnette, was excellent. I recommend buying this for people you love, and insisting they read it. show less