Many of our current problems stem from the fact that our brains were 'designed' for life in the stone age

How is it possible that humans in America and elsewhere in the rich world can have so much stuff, and yet be so unhappy? How is it that we can have hot running water, comfortable and rugged shoes, central heating and A/C, vaccines and treatments for so many dreadful ailments, and so forth, and yet still be so miserable so much of the time? My friend Hannah asks the question more poetically, with help from Allen Ginsberg.

Before we can ever answer that question, we need to understand something about the timescale of human evolution. I always imagined a gradual progression from monkeys living in trees, to hairy hominids hunting and gathering with stone knives, to hairless humans in Mesopotamia inventing agriculture. But after doing some reading up, it turns out that the stone knives era was extremely long, and the agricultural part has been surprisingly short. There have been anatomically modern humans for a million years at least, but only for the past forty thousand has there been anything resembling vigorous technological change. Jared Diamond calls that turning point the 'great leap forward' - after a million years of flint knives, all of a sudden, human artifacts start to include bone flutes, sculptures of the female form, paintings of wildebeest, needles, fishhooks, and so on. Agriculture and domestication of animals are only ten or twenty thousand years old, reading and writing half that, and I think it's safe to assert that the external circumstances of your typical homo sapiens have changed more in the past thousand years than in the previous hundred thousand combined.

Everybody assumes that this evolutionarily sudden turn of events has been a good thing for humanity. Sure, the modern world has its problems, but would anyone really rather be a caveman? If you take very recent history and project it backwards, it's not an unreasonable conclusion. The present certainly seems preferable to a hundred years ago, which looks a lot more appealing than two or three or four hundred years ago. But we have to remind ourselves that anatomically modern people lived for hundreds of thousands of years as hunter-gatherers in essentially ape-like conditions, and we are all still born designed for those conditions. Evolution progresses, in the sense that today is different from the past, but it doesn't progress towards anything in particular. It's more like an arms race, with gradual changes brought on by continually changing environmental factors, including the progress of the arms race itself.

Humans don't live in a vacuum. A host of microbes, insects, birds, mammals, plants, birds and fish live intimately among us, and we coexist with countless more. Evolution has favored us more than the dodo or the dolphins, not to mention dinosaurs and trilobites. But evolution also favors the cockroach, HIV, E Coli, rats, tobacco, opium poppies and antibiotic-resistant bacteria. If you believe the meme people, and I do, then group behaviors like Christianity and free-market capitalism are evolving independently of humanity, and not necessarily with our best interests at heart.

Jared Diamond argues that hunter-gatherers like our remote ancestors have it better than farmers and their high-tech descendents in a lot of basic ways. From an opinion piece he wrote entitled The Worst Mistake Ever Made:

Are twentieth century hunter-gatherers really worse off than farmers? Scattered throughout the world, several dozen groups of so-called primitive people, like the Kalahari bushmen, continue to support themselves that way. It turns out that these people have plenty of leisure time, sleep a good deal, and work less hard than their farming neighbors. For instance, the average time devoted each week to obtaining food is only twelve to nineteen hours for one group of Bushmen, and fourteen hours or less for the Hadza nomads of Tanzania. One Bushman, when asked why he hadn’t emulated neighboring tribes by adopting agriculture, replied, "Why should we, when there are so many mongongo nuts in the world?"

Here are some excerpts from a highly recommended book, Why We Get Sick: The New Science of Darwinian Medicine by Drs Randolph M Nesse and George C Williams:

While natural selection has been changing us in many small ways in the last ten thousand years, this is but a moment on the scale of evolutionary time...We are specifically adapted to Stone Age conditions. These conditions ended a few thousand years ago, but evolution has not had time since then to adapt us to a world of dense populations, modern socioeconomic conditions, low levels of physical activity, and the many other novel aspects of modern environments. Even more specifically, we seem to be adapted to the ecological and socioeconomic conditions experienced by tribal societies living in the semiarid habitat characteristic of sub-Saharan Africa.

Imagine what it must have been like in that idyllic era. You were born into a nomadic band of forty to a hundred people. Whatever its size, it was a stable social group. You grew up in the care of various close relatives. Even if your local band consisted of a hundred or more people, many of them were distant cousins. You knew them all and knew their genetic and marital connections to yourself. Some you loved deeply and they loved you in return. If there were those you did not love, at least you knew what to expect from them, and you knew what everyone expected from you. If you occasionally saw strangers, it was probably at a trading site, and you knew what to expect of them too. In a sparsely peopled world the necessities of life - plant and animal foods uncontaminated by pesticides - were there for the taking. You breathed the pure air and drank the pure water of a preindustrial Eden.

Having asked you to imagine an idyllic past, we now urge that you be more realistic...The unpleasant fact is that our hunter-gatherer ancestors lived with enormous difficulty and hardship... Death always balanced reproduction, even though people reproduced at something approaching the maximum feasible rate.

Infant mortality and death in childbirth were commonplace, not to mention starvation, injury and accident, conflict with other bands, wild animal encounters, water- and insect-borne parasites, etc. As for the menu back then, remember Tom Hanks trying to get the coconut open in Cast Away?

The mainstay foods in the Stone Age would seem to us inedible or too demanding of time and effort. We would find most of the game strong-tasting and extremely tough. Most of us have little appreciation of the tedious skinning and butchering it takes to turn a wild animal into a serving of meat. Many wild fruits, even when fully ripe, are sour to our tastes, and other plant products are bitter or have strong odors...Most natural human foods require a far greater labor of preparation and chewing than the foods we eat now. Domesticated animals and plants have been artificially selected to be tender, nontoxic and easily processed.

People did a lot less hunting and a lot more gathering than fictional accounts would have us believe. Hunting makes for much more exciting fiction than gathering. Archery wasn't invented until very late in the game, and dogs didn't become common in human societies until fifteen thousand years ago. Most meat and hides probably came from scavenging.

In addition to xenophobic conflict with other groups, social strife within groups, famines, and toxic diets, there were many other environmental stresses. Our ability to tolerate the atmospheric pollution of modern cities may owe much to our many thousands of years of exposure to smoke toxins from woods and other fuels. Atmospheric pollution was different [in the Stone Age] but it was substantial and real. We would find the odors of a Stone Age settlement most unpleasant...The average Stone Ager lived in a dump and moved away when conditions got really bad.

Children grew up, and adults lived out their lives, in the constant awareness, and sooner or later the personal experience, of woeful illness, painful injury, physical handicaps, debilitation, and death. There were no antibiotics, tetanus shots, or anesthetics, no plaster casts, corrective lenses, or prosthetic devices, no sterile surgery or false teeth. Our remote ancestors had few cavities, but they had many other dental problems... Abrasive plant products can wear molars down to gum level, as seen in some fossil skulls and even some contemporary groups.

Lest it seem that our account of the EEA [Era of Evolutionary Adaptedness] is merely a selection of items for a catalog of horrors, we should emphasize that we are discussing our fully human ancestors, with a fully human capacity for pleasure as well as pain and a fully human intellect. The bonds of kinship and friendship could be strong and a source of great pleasure and security. In seasons of plenty there would be abundant time for play: games, music and dancing, storytelling and poetry recitals, intellectual and theological disputes, and the creation of ornamental artwork... And our ancestors also had the ability to look on the bright side in times of adversity and to find reasons for laughter. Mark Twain's hero Sir Boss in A Connecticut Yankee In King Arthur's Court lamented having to listen, at a sixth-century campfire, to the same jokes he had already found tiresome in the nineteenth. We suspect that if he had gone back to the Stone Age he would have groaned at many of the same jokes.

For everyone alive today and for the far future, there's going to be a tension between our instinctive, nonconscious responses programmed in to anticipate the African savannah a million years ago and the facts of the world as it is now. I think a lot of our present woes arise from this tension. It's true that your brain is highly flexible and shapeable, but our neural plasticity has its limitations. Jared Diamond observes that guys in Papua New Guinea whose parents lived in essentially Stone Age conditions are fully functioning airline pilots, lawyers, etc, but I would bet you that these New Guineans have much more complex and troubled inner lives than their great-grandparents did. Flexible the human brain may be, but reprogramming of the emotions is no small matter, and fundamental design changes to these intricate body systems are a long ways off.

Doctors Nesse and Williams call the conflicts between our evolved physiology and our present environment 'diseases of civilization.' The obvious examples are obesity and clogged arteries, but there are many others. If you expect the human lifespan to be seventy or eighty, then aging seems to present us with a bewildering variety of medical afflictions. But if you expect a human lifespan to be around half that, as it usually was during the Stone Age, then there would be no reason to expect your body to continue working after age fifty. Alzheimer's and prostate cancer wouldn't have prevented our distant ancestors from living long enough to raise a few babies into physical adulthood, so from the perspective of the selfish gene, there's no compelling reason to eliminate them. Medical science has extended the human lifespan dramatically, but it hasn't been nearly so successful at extending the youthful part of life.

In the modern world, we have the infectious diseases on the run, but the gravest diseases of modern civilization are mental and emotional. Humans literally depend on our social groups for basic survival, as do other large-brained social predators from penguins to whales to wolves to chimpanzees. A modern American's social and family life is radically unlike the one we're expecting at birth. Growing up, I saw my mom every day, but never during working hours. After age five, I only saw my dad on Wednesdays and every other weekend. I saw my grandparents every few weeks on average; I saw my aunts and uncles and cousins every few months. I received a lot of high-quality caretaking from hired professionals like nannies and teachers, along with an enormous amount of educational enrichment, and I have the best stepfather in history, but these relationships are evolutionarily novel and thus uncertain, harder to trust. Meanwhile, I live in a city with nine million other humans, nearly all of whom are perfect strangers. I have plenty of friends, and a wonderful marriage, but my relationships with other people have been fraught for most of my life, and my social rootlessness continues to be a major hardship for me. I'm not alone here. How else can we explain the Trench Coat Mafia?

With the amount of profound emotional upheaval we're constantly experiencing, it's no wonder that we're having some major problems forming and maintaining attachments, and it's no wonder that depression and its many cousins are at epidemic levels. It's no wonder that Americans commit so many homicides, and that we self-medicate so carelessly with alcohol, painkillers, crystal meth, nitrous oxide, etc. Another major problem facing us today is how to figure out how to map each individual's forty-to-one hundred-member tribal circle into big complex modern societies. It's no wonder that the suicide rate in the extremely wealthy and well-ordered Scandinavian countries and Japan is so far off the charts. From Nesse and Williams:

Natural selection clearly favors being kind to close relatives because of their shared genes. It also favors being known to keep one's promises and not cheating members of one's local group or habitual trading partners in other groups. There was, however, never any individual advantage from altruism beyond these local associations. Global human rights is a new idea never favored by evolution during the Stone Age. When Plato urged that one ought to be considerate of all Greeks, not merely all Athenians, it was a controversial idea. Today, humanistic sentiments still face formidable opposition from parochialism and bigotry... As Michigan biologist Richard Alexander so neatly put it, today's central ethical problem is 'within-group amity serving between-group enmity.'

Another thing to remember is that the human body and the mind it contains wasn't 'designed' at all. The brain evolved via an extremely long series of happenstances. When we bemoan our frailty and mortality, we implicitly imagine that there's some perfectible and immortal ideal for a human body. A friend of mine professes to being so terrified by the idea of her own death that she refuses to even think about it. Instead, she clings to a fervent belief that medical science will, in her natural lifetime, advance to the point where she'll never have to die at all. If I were her, I wouldn't hold my breath. More Nesse and Williams:

Despite their exquisite design, our bodies have crude flaws. Despite our multiple defenses, we have a thousand vulnerabilities. Despite their capabilities for rapid and precise repairs, our bodies inevitably deteriorate and eventually fail. Before Darwin, physicians could only wonder at the incongruity of it all, perhaps with the hope that our bodies are part of an unfathomable divine plan, or with the suspicion that they are some cosmic prank. Ever since Darwin, the incongruity has often mistakenly been attributed to the supposed weakness or capriciousness of natural selection. In the light of modern Darwinism, however, the incongruity unfolds into a sharply blocked tapestry with a place for each of several distinct causes of disease.

Why isn't the body more reliable? Why is there disease at all? As we have seen, the reasons are remarkably few. First, there are genes that make us vulnerable to disease. Some - though fewer than has been thought - are defectives continually arising from new mutations but kept scarce by natural selection. Other genes cannot be eliminated because they cause no disadvantages until it is too late in life for them to affect fitness. Most deleterious genetic effects, however, are actively maintained by selection because they have unappreciated benefits that outweigh their costs. Some of these are maintained because of heterozygote advantage [having different sets of genes inherited from each parent]; some are selected because they increase their own frequency, despite creating a disadvantage for the individual who bears them; some are genetic quirks that have adverse effects only when they interact with a novel environmental factor.

Second, disease results from exposure to novel factors that were not present in the environment in which we evolved. Given enough time, the body can adapt to almost anything, but the ten thousand years since the beginnings of civilization are not nearly enough time, and we suffer accordingly. Infectious agents evolve so fast that our defenses are always a step behind. Third, design results from design compromises, such as upright posture with its associated back problems. Fourth, we are not the only species with adaptations produced and maintained by natural selection, which works just as hard for pathogens trying to eat us and the organisms we want to eat. In conflicts with these organisms, as in baseball, you can't win 'em all. Finally, disease results from unfortunate historical legacies. If the organism had been designed with the possibility of fresh starts and major changes, there would be better ways of preventing many diseases. Alas, every successive generation of the human body must function well, with no chance to go back and start afresh.

The human body turns out to be both fragile and robust. Like all products of organic evolution, it is a bundle of compromises, each of which offers an advantage, but often at the price of susceptibility to disease. These susceptibilities cannot be eliminated by any duration of natural selection, for it is the very power of natural selection that created them.

We mistakenly imagine emotion to be a spiritual thing, or at the very least confined solely to the brain. But every emotional response you have is a body-wide happening, affecting your blood vessels, muscles, viscera, blood chemistry, pulse, respiration, and so on. Emotions often originate outside the brain - consider how a full stomach brightens your entire outlook, and how an upset or empty stomach darkens it. We humans imagine emotions to be magical or mystical happenings because they make themselves known to our consciousness only after they're already in progress. Our consciousness is capable of limited control of our feelings, ie our mental reactions to our emotional responses, but the responses themselves are well below the level of conscious accessibility, down there in the brain stem where we regulate our pulse and respiration rates. Emotions and the feelings they provoke in the brain are difficult to verbalize, store and analyze consciously, since consciousness is itself comprised largely of the interaction between those same emotions and feelings. This is not to say that we can't remember and recall such states - music does an excellent job of preserving and transmitting emotion - but our society priveleges verbal thinking, and America's collective emotional intelligence is appallingly low.

Our emotions were valuable survival stratagies in the environment in which they adapted. Humans are born intrinsically affectionate towards members of their tribe and inclined to be suspicious or hostile towards other tribes, the same way that chimpanzees and wolves and penguins and whales are, and for the same reasons. But things have been changing for us humans really fast lately, and our emotional toolkit will be slow to keep up. That puts the burden on us to understand our own evolutionary history and to design better strategies for reconciling it with the realities of the modern world. Between-group enmity is a universal human reflex that needs to be recognized, validated and managed as best we can, since we can never hope to completely remove it from ourselves.

How do we escape the bind we're in, between the relentlessly accelerating pace of our cultural evolution and population growth and the glacial slowness of our bodies' adaptation? As my shrink is fond of saying, the only way out is through. For me, that means increased present-moment body-centered awareness, with an eye towards eventual Buddhist acceptance. Darwin Saves!

© ethan hein 2007 | back to memebase | back to top