Review of "The Story of the Human Body" by Daniel Lieberman
Daniel Lieberman, The Story of the Human Body: Evolution, Health, and Disease (New York: Pantheon, 2013), 480 pp.
reviewed by Andrew L. Wilson
If an evil super-genius plotted to breed a race of obese, feeble, heart-diseased diabetics, he could hardly do better than to re-create the consumer paradise of twenty-first-century America. From cradle to grave we pass our days largely immobile, gazing at screens and wiggling our fingertips. To fuel this inactivity we devour copious quantities highly processed food, maintaining our metabolisms on ceaseless alert. Our environments are so sanitized of dreaded biological pathogens that our understimulated immune systems attack our own bodies; while in car and home we knowingly inhale a miasma of certified carcinogens against which we have no defense. We bomb the rare infection with such antibiotic force that our indigenous micro-biomes are catastrophically reconfigured, setting off a cascade of ailments only beginning to be understood by science.
It’s not only ballooning overhead that makes caring for America’s health among the most costly line items of any budget, ever: 18% of our GDP from 2009 to 2017, according to the World Bank. Conservatively, seventy percent of this 3.2 trillion dollar annual expense (that’s three times our defense budget, or just shy of $2.3 trillion) goes toward fighting “diseases” that are largely preventable. Yet we still we still hope beyond hope that yet one more device, one more miraculous elixir will save our ruined corpus.
The latest riposte to our pharmacological dystopia seeks to press the body into the mold of anatomical Adam, totemic hunter-gatherer. Out with sugar, grains, milk, and Cybex, preaches the paleolithic gospel, and in with grass-fed beef, foraged veg, and MovNat. The Daniel Diet (frail Christians are hardly immune to novel nostrums) plays the same tune, unearthed from biblical rather than archaeological depths. Are you “sick, tired, depressed, or aging prematurely?” asks the website. Forget those faddish panaceas and join an ancient, Scripture-grounded fast. Away with finest pastries and wines; imbibe instead for ten days running the purest prelapsarian produce! After a couple centuries of repose, Natural Man is back.
The Story of the Human Body, from the pen of Daniel Lieberman, Harvard don of evolutionary biology and paleolithic anthropology as well as curator of human remains at the Peabody Museum, only hints at these digressions. But they’re there nonetheless, lurking behind a scrupulously modest text, tempting the primed reader to draw a thousand latent implications. Lieberman’s breezy style and scientific reserve are rather dwarfed by the grandeur of his theme: the corporeal history of humanity from eight million years ago until today. But we ignore him to the peril of our collective health.
The Story begins in the jungles of Africa, follows proto-humanity out onto the grassy plains, and sees them through the Ice Ages and into the rest of the world. How is it that humans, “athletically pathetic… in many ways,” managed to survive and subdue the earth? A scrawny chimp can out-hoist an NFL lineman, and as for speed, even the dazzlingly fleet Usain Bolt, on his best day, can barely outrun a Jack Russell terrier. Yet here we are, overrunning our planet with seven billion bodies.
Evolutionary biologists since Darwin—primed, no doubt, by an overdose of Enlightenment anthropology—have tended to fixate on brainpower (Linnaeus’s sapiens) and opposable thumbs (Benjamin Franklin’s faber). But these now salient adaptations picked up evolutionary speed millions of years after the hypothesized 6-8 million-year-old Last Common Ancestor. Sustained control of fire, for example, can only be traced back 400,000 years; truly sophisticated tools came much later, and complex language later still.
But there’s one enterprise where hominins (for those not up on the latest Linnaean morphology, this is the correct term, not hominids) excel, and have done so since before the Quaternary (2.8 million years ago). Over long distances, upright apes are among the most accomplished travelers on earth. A whole set of adaptations to feet, pelvis, spine, neck, head, skin, and aerobic metabolism make today’s humans more than four times as efficient as any other ape over any given distance. We are so shockingly good at trekking, in fact, that over marathon distances and greater, well-trained humans can outrun just about any land animal, including a horse. (Over one hundred miles, the human record of less than twelve hours is half the equine equivalent!) This revelation has fueled a flattering fantasy (popularized by Christopher MacDougall’s bestselling Born to Run) that every Joe Sixpack has a Hausa hunter lurking beneath the padding, ready to take down a kudu by chasing it to exhaustion through the African noon.
Inspiring indeed, but only the far end of a grittier story. As continents drift and climates change, picky eaters die (which is why there are fewer pandas and more crows). From reading the dental record alongside geological climatic fingerprints, Lieberman deduces that as central Africa dried up, and abundant fruit with it, hominins extended their territories by thousands of square miles, collecting ever more varied foods—carrion, tubers, grubs, roots, berries. (Studies of contemporary hunter-gatherers reveal diets into the hundreds of different species.) By the time of the last Ice Age, all Italy would have supported a mere 3000 far-ranging humans. Today’s superhuman feats of endurance are the old normal.
Lieberman eventually gets around to the brain, which expanded to unprecedented size in several hominin species (H. Heidelbergensis, H. Denisovan, H. Neanderthalensis). Locating a bewildering array of seasonal fare, tracking skittish game over long distances, as well as passing on this intricate information from generation to generation all favored brainpower. This despite the fact that an inflated cerebrum is a massive caloric hog: the 2.5-lb. organ consumes 20-25% of an adult’s resting energy, 60% of an infant’s! It seems that humanity’s capacity to store fat goes in hand in hand with smarts, for even during long periods of caloric deficit (notably pregnancy and nursing), the greedy brain must be fed non-stop.
We arrive at Homo sapiens some 200,000 years ago; but one giant leap forward was yet to come. Sometime around 50,000 years ago, culture was born. Archaeologists start to find tools and dwellings with heightened complexity: bone needles, fishhooks, flutes, delicate mass-produced flint work. And what is more, these artifacts differ from region to region, indicating separate traditions. Language seems to have emerged, along with religion and art. “People were somehow thinking and behaving differently.” From this point forward, down to today, “the pace and scope of cultural evolution now vastly exceeds the pace and scope of biological evolution.” It’s a point to linger over, especially as we seem all too eager to pound genetic pegs into cultural holes.
Then came agriculture, by far the most momentous of these memes (the cultural equivalent of a gene). Ever since, hunter-gather life has been in slow but inexorable retreat. For species adapted over millions of years to the extreme mobility of nomadic life, diverse diets of wild food, and social networks in the dozens, civilization is a rude shock. Farmers work harder, eat poorer, and are more exposed—by orders of magnitude—to infectious diseases and famines than their Stone Age ancestors. Nothing before or since has had such a profound and rapid effect on the human body, and mostly for the worse. It’s the tale of Paradise Lost.
As individual bodies, yes. But as a species, hardly. The caloric surplus of grain-based diets made for the exponential population growth that continues unabated. Despite limited nutrition, declining stature, flagging fitness, and dwindling lifespans, farmers raise more children to adulthood than nomads: the debilitating trials of farming life accumulate only after the reproductive years have passed. The wrecked peasant’s body lay at its nadir until surprisingly recently: a French girl born in 1789 could expect to live to twenty-eight, starve frequently, and finally die of measles, typhus, or the like—but not before bearing five children. Thomas Hobbes’s sobering judgment on life as “solitary, poor, nasty, brutish, and short” describes humanity not in the state of nature nor in the early Neolithic, as he supposed, but at the dawn of the French Revolution.
Machines, antibiotics, and industrial agriculture have only recently attenuated many of agricultural civilization’s former deficits (the average height of Westerners only surpassed that of cavemen in the late twentieth century!), but to the increasing bewilderment of our prehistoric metabolisms. As bodies balloon and lifespans lengthen, so the short-lived misery of the field is replaced by decades of chronic disease in the city. For every year added to an American’s life since 1990, only ten months of it are “healthy.” Formerly infrequent ailments such as back pain, heart disease, and diabetes are now ubiquitous in the West and infecting the developing world faster than you can say “multinational food conglomerate.” Obesity is epidemic, and it’s no mere matter of body image: it’s a good indicator of the tidal wave of health problems to come. Today’s youth are the first generation expected to live shorter lives than their parents. “We didn’t evolve to be healthy,” as Lieberman reminds us, but to survive long enough to reproduce.
If genomics tipped the epidemiological scales towards nature, Lieberman weighs in heavily for nurture’s role. Set against our hunter-gatherer heritage, today’s nagging ills are exquisite “mismatches” between modern lives and stone-age DNA. Take something as benign as an impacted wisdom tooth—as common now as it is absent in prehistoric skulls. Soft food in youth prompts a reallocation of resources away from wastefully sturdy jawbones towards evolutionarily useful things, like earlier reproduction. Thus programmed, our puny mandibles have no room for the usual array of ivories, creating a pileup of teeth and a fortune for orthodontists. The same goes for our feet, which react to confining shoes by giving us bunions, corns, fallen arches, hammertoes, and plantar faciitis.
As for the rest of our skeletons, bone scans show contemporary humanity to be woefully underbuilt. A recent comparison of paleolithic and modern tibias (a reliable measure of movement-related stress) in The Journal of Human Evolution (2013, 1-8) shows hunter-gatherers’ nearest contemporary kin to be elite college cross country runners, who run up to a hundred miles per week and have done so for many years. Even Roger Federer’s ulna has nothing on your average stone-age aboriginal. If, as Lieberman notes, “hunter-gatherers are essentially professional athletes whose livelihood requires them to be physically active,” it should come as no great surprise that we are ill-adapted to a lifetime of soft cushions.
If our skeletons are perennially understressed, our guts are overtaxed. Remember the variegated, high-fiber, fatty, protein rich, grain-poor diet of the caveman? The only advantage of today’s food is its abundance, but the constant surfeit of sugar and simple starches dopes our metabolism. Frantic to store away the ceaseless windfall, our glands flood the blood with triglycerides and insulin, padding our innards with the gooey excess. The resultant visceral fat is a factory of predictable ills: heart disease, diabetes, and many—perhaps even most—kinds of cancer. Don’t blame bacteria and viruses any longer. In the developed world you’re far more likely to suffer and die from a culturally transmitted disease.
Since “we cannot reengineer our genes, the most effective way to prevent mismatch diseases is to reengineer our environments.” Lieberman is understandably brief if disappointingly modest in his recommendations. Planners, architects, and engineers should favor walking and stairs over cars and elevators. Sugars and refined carbohydrates should be taxed on par with alcohol and tobacco, for their aggregate cost is even more staggering. Transparency about the true toxicity of synthetic chemicals would help, too. Physical education is but a pale shadow of what is truly necessary for long-term health—not to mention sanity in increasingly desk-bound classrooms. Good luck getting these through Congress, though. And anyway, these are but regulatory band-aids for problems so broad as to implicate the very fabric of human society, right down to birthday cake.
It has been fashionable to shame Christianity for its denial of the flesh, but our religion has nothing on the ravages of the remote control. The expulsion of Adam and Eve from Paradise is but the emblematic end of the hunter-gatherer life: “in a rare instance of accord, creationists and evolutionary biologists agree that it has been downhill for humans ever since.” In a premodern world awash in unexplainable illness, Christians pioneered the care of the sick. In a demythologized planet soon to suffer a tsunami of sedentary misery, do we have anything to say about prevention? Perhaps, with Lieberman as a preamble, we ought to spend a bit more theological and political energy thinking about it. We just might salvage our ruined bodies. And our GDP.
Andrew L. Wilson is Production Editor of Lutheran Forum and (soon-to-be) Professor of Church History at Japan Lutheran College and Seminary.
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