If the strong governments made possible by agriculture essentially "tamed" people, one might expect members of groups with shallow or nonexistent agricultural experience to be less submissive, on average, than members of longtime agricultural cultures. One possible indicator of tameness is the ease with which people can be enslaved, and our reading of history suggests that some peoples with little or no evolutionary exposure to agriculture "would not endure the yoke," as was said of Indians captured by the Puritans in the Pequot War of 1636. In the same vein, the typical Bushman, a classic hunter-gatherer, has been described as "the anarchist of South Africa."
BOURGEOIS VIRTUES
Agriculture itself, and the particular form it took in state societies, must have selected for personalities that can only be called bourgeois, characterized by the traits that make a man successfulrather than interesting. One such trait was the ability to defer gratification for long periods of time. This was a practical requirement for farmers, since they had to save a portion of their crop for seed and some of their domesticated animals for breeding stock.
This wasn't easy. Food was often shortest just before sowing, and those early farmers had to abstain from eating the seed grain when they and their families were hungriest. This is something that classic hunter-gatherers just didn't do: There was no way for them to store food effectively, so they either consumed it on the spot or shared it with others. Foragers had no tradition of self-denial and no inclination to deny themselves. They weren't very good at self-denial back in the early Neolithic period, and they aren't very good at it even today: Efforts to teach Bushmen to become herders frequently fail when they eat all their goats. People can learn new traditions, but genetic differences must make this kind of self-denial easier for some people than it is for others. It takes a certain type of personality—with traits including patience, self-control, and the ability to look to long-term benefits instead of short-term satisfaction—and natural selection must have gradually made such personalities more common among peoples that farmed for a long time.
Agriculture also led to the birth of property. Among hunter- gatherers, there hadn't really been any. Although tribes sometimes claimed hunting grounds, there was no individual ownership of land. The mobile way of life that hunter-gatherers pursued kept them from accumulating much property other than some personal tools and weapons. Farmers, being sedentary, could accumulate domesticated animals, land, and other forms of property. This became more practical and more important as states appeared and limited local violence. Law and order allowed for population gains that increased the scarcity and value of land. In some cases, governments made property safer and more secure.
Farmers could thus accumulate resources that increased their fitness and that of their descendants—if they decided to do so, and if the state didn't take too much. But those choices didn't come easily. Hunter-gatherers routinely shared resources, partly in order to cement relations with other members of the tribe, partly because there often wasn't anything else to do with those resources. Try eating a whole giraffe before the meat goes bad. Even with the wife and kids helping, it can't be done. The effective cost of sharing that meat is zero. Foragers aren't selfish.
Farmers, in contrast, have to be selfish. At minimum, they can't afford to give away seed grain or breeding stock—not if they want to stay farmers. More than that, farmers could gain increased fitness by being miserly, at least in comparison to foragers.
And once there was property, laziness must have decreased. There were many ways in which hard work could produce enduring assets that could increase an individual's fitness or that of his children and relatives. Farmers could save to buy more land or livestock. They could build long-lasting improvements like buildings or irrigation works. This was not really possible for hunter-gatherers—there was no way for them to accumulate wealth. If they had full stomachs and their tools and weapons were in good shape, hunter-gatherers didn't work. They hung out: They talked, gossiped, and sang. They were lazy, and they should have been: Being lazy made biological sense. They could usually obtain enough food fairly easily, since constant localviolence kept human numbers below the land's carrying capacity. When law and order let human density increase, farmers eventually had to work harder and harder just to survive. Here again, selection must have favored those odd people who like to work, even when there was enough to eat.
Ultimately, this meant that both sexes had to work hard. In fact, for most people, that became the only way to produce enough to feed and raise a family. That pattern is not universal. In situations where resources are abundant, men sometimes do little work. Men working hard to feed their families—"high paternal investment," we call it—is common among contemporary hunter-gatherers and may well have been a standard feature of the ancestors of all modern humans. Women bring in most of the calories in such societies (from plant foods), at least in warm climates, but the meat contributed by male hunters is a vital source of protein and other essential nutrients.
However, the grueling labor required of peasants in well- governed states—inevitable when local violence no longer keeps the population well below carrying capacity—takes this to another level entirely. Since a hardworking husband was essential, in some cultures the practice of dowry arose, so that a farmer with assets could buy his daughter a productive husband—making dowries yet another way of using property to increase fitness.
Given a stable government and reasonably low taxes, self- denying individuals could make wealth generate more wealth. In many early civilizations, the real interest rate was around 10 percent per year, a rate high enough that anyone who managed to put some money aside as savings would, after a few decades, be able to kick back and relax a bit. At that point menwere too old to truly enjoy that income, but it could still increase their children's fitness, and so selection may have favored that kind of behavior. As "time preference" declined (that is, as propensity toward delay of gratification increased), interest rates eventually fell as more and more people saved rather than spending any spare money.
Agriculture in Malthusian conditions must have also favored individuals who were metabolically efficient and could produce the maximum work for a given amount of food. Among hunter-gatherers the selective pressures were different—in their way of life, bursts of strength in war or hunting were relatively more important. We see differences in the gene alpha-actinin-3 (ACTN3) that may reflect this. The gene has two forms—one that produces a protein that is active in fast-twitch muscles, and one that produces no protein at all. The intact version of the gene increases muscle power and is noticeably more common among world-class sprinters than in the rest of the population; the other version of the gene increases aerobic efficiency and endurance. Gene-engineered mice with the endurance version of ACTN3 can run 33 percent farther than standard lab mice before exhaustion sets in.24 Both forms of ACTN3 are found in all populations, but the endurance form appears to have become more common since the advent of agriculture in Europe. We suspect that it made peasant farmers more productive.
At first, all these pro-agricultural behaviors must have run against the grain: It's unlikely that humans were comfortable doing things that had never made sense in the past. But over time, alleles that induced this kind of ant-like behavior must have increased in frequency, until eventually, after millennia, selfish, hardworking, self-denying people were far more commonthan they had been among hunter-gatherers. Acting like ants rather than grasshoppers didn't improve the average standard of living over the long haul, since the world was Malthusian, but farmers who worked harder than average and saved more than their neighbors would have had higher-than-average fitness. Eventually there must have been many people with personality types that hadn't existed at all among our forager ancestors.
MONEY AND MARKETS
In Narrow Roads of Gene Land, theoretical biologist William Hamilton wrote, "It seems to me that there are some aspects of innate intelligence that civilization steadily promotes. Mercantile operations, f
or example, are an inseparable part of Old World civilizations and need complex models in the minds of their operators, just as military ventures do. The main difference is more emphasis on prudence and less on daring. It is probable that civilization has given steady selection for the intelligence needed for this mercantile kind of preparatory modeling."25
Agriculture would have selected for traits that enable people to engage successfully in trade: A farmer able to sell his wheat at a higher price than the other wheat farmers or to make more advantageous trades would have been more successful and better able to support a large family. And so salesmen, businessmen, and financiers were born.
If this theory is correct, we would not expect populations that have never experienced such pressures, or that have only experienced them for limited periods and to a limited degree, to be very successful in such activities today. Groups that becameagriculturalists relatively recently, or not at all, are slow to master important new social and technical developments. This is the case for the Amerindians, and it underlies a current wave of discontent with liberal economic policies in South America.
Along the same line, the well-known middleman minorities, such as Armenians, Jews, Lebanese, Parsees, Indians in East Africa, and Chinese in Southeast Asia, are all descended from long-established agricultural populations. Evidently, a long history of getting and spending does not lay waste your power.
MODERN TIMES
The kind of gradual, directional biological change we've outlined should have generated historical trends. These trends wouldn't necessarily have been monotonic, but over time, to the extent that the underlying biological changes favored certain kinds of societies and organizations, those kinds of societies and organizations would have become more common. Ultimately, some populations may have changed enough to allow some social patterns to prevail that couldn't have worked at all in long- ago societies. More exactly, those patterns could only exist in populations that had been reshaped over millennia by the selective pressures associated with hierarchical agricultural societies.
The fact that there is undoubtedly a lot of overlap between the psychologies of different populations does not mean that the same social patterns and the same kinds of organizations are always possible. The distribution of personality traits also matters.
For example, a high-trust society can largely avoid some costs—in modern terms, they could leave their doors unlocked and wouldn't worry much about corruption. All else equal,they'd be more effective in war than societies with less trust among their own members, since they wouldn't suspect betrayal at every setback. A different society, one in which 20 percent of the population practiced cheater strategies, would have to spend a lot of resources on punishment and prevention. Certain activities that required a high degree of mutual trust might be effectively impossible.
So a population in which no personality was truly alien (one in which everyone resembled some character in Shakespeare, for example) might generate a qualitatively different civilization because the mix of personality types differed from ours. A society that had many more Hamlets than ours might never accomplish anything at all.
We have two ways of looking for social patterns favored by recent natural selection. The most obvious is to look for patterns whose frequency changed over time. In the strongest examples, such patterns would be rare or unknown until some point in history, possibly quite recently. This can be difficult to do, though, because in many cases we simply do not have much information about ancient civilizations. For example, we doubt that the Indus civilization had a bicameral legislature, an independent judiciary, and a written constitution—but since we can't read their script, how can anyone know? The other way is to exchange time for space: to look at contemporary peoples that have never lived as peasants, or have done so for a considerably shorter period of time than Europeans, East Asians, and Middle Easterners, then check to see what social patterns and institutions (if any) do not flourish in those populations. Although this method can be more controversial than looking at the earliest civilizations, it does have one advantage in that recent history is at least well documented.
The relative ease with which old agricultural civilizations (many of them, anyhow) have managed to adopt complex new technologies and forms of social organization, compared to populations that have had less experience with agriculture and dense hierarchical societies, suggests that gradual biological changes in cognition and personality played a key role in the birth of the industrial and scientific revolutions.
Jared Diamond observed in Guns, Germs, and Steel that "the nations rising to new power are still ones that were incorporated thousands of years ago into the old centers of dominance based on food production, or that have been repopulated by people from those centers. . . . Prospects for world dominance of sub- Saharan Africans, Aboriginal Australians, and Native Americans remain dim. The hand of history's course at 8000 BC lies heavily on us."26 But what kind of experience are we talking about? Diamond asserts that such differences were entirely cultural, that is to say, learned—but if this were so, populations that missed out on these experiences could in principle catch up rapidly. After all, culture is learned anew every generation, so presumably new technologies and new forms of social organization that had proved successful in other countries could be adopted over two or three generations, just as most farmers in many countries have become city dwellers over a few generations. Yet economists have shown that the age of the transition to agriculture appears to have a strong influence on a country's economic development in recent decades, even after controlling for many other factors.27 It's hard to see how this could be due to cultural effects. Even if a nation could learn from experiences their ancestors had back in the Bronze Age and benefit from them (which sounds unlikely), why can't everyone else learn those same lessons? Why would those experiences confera relative advantage? On the other hand, genetic changes that accommodated people to a dense hierarchical society could easily have developed over those millennia, and genetic information can't easily be transferred—yet.
If the root causes of these differences are biological changes affecting cognitive and personality traits, changes that are the product of natural selection acting over millennia, conventional solutions to the problem of slow modernization among peoples with shallow experience of farming are highly problematic. And yet, methods based on an understanding of underlying biological causes might be very effective. It's entirely possible that such methods would turn those prospects of world dominance around, which would certainly liven things up.
The new social patterns we find most intriguing are those that have led to greatly increased rates of innovation in the past few centuries—usually called the scientific and industrial revolution. Some argue that gradual genetic changes could not be responsible for such rapid social changes. We don't call them revolutions without reason. We believe, however, that these arguments are mistaken. Consider an example in which an allele affecting behavior had a frequency of 20 percent and a 6 percent selective advantage in a European population in 1500—we know that there are many sweeping alleles with a selective advantage in that range. Over the next 300 years, the frequency of that allele would have doubled, and going from 20 percent to 40 percent could be a significant change, enough to give European society in 1800 some new capability or tendency.
Such a favored allele takes about a millennium to increase by a factor of ten. When its frequency is 1 in 100,000, 1 in 10,000, or even 1 in 1,000, that allele has no social impact: Butwhen the frequency changes from 1 percent to 10 percent, the allele starts to make itself felt. When it increases from 10 percent to 50 percent in less than a millennium, its impact could be dramatic.
Modest biological changes might also trigger dramatic social changes by crossing some threshold, just as a tiny increase in temperature can turn ice into water. Such changes (ice into water, water into steam, graphite into diamond) are called phase transitions. There may be analogous social transitions. Picture an army i
n the middle of a battle, one that's not going very well. Soldiers are beginning to run away—first a few, then more. Those who are still fighting suspect that their chance of victory is rapidly decreasing as more and more of their comrades leave, and as the odds grow worse, more and more soldiers flee. This accelerates until the army completely disintegrates, with every soldier trying to save himself. A small change in the battle situation has transformed a highly organized, functional army into a mob. Depending on the mix of personality types in that army, such disintegration could range from unlikely to virtually inevitable, and the difference between those mixes might not be all that large. Cultural factors could influence the probability of that kind of social transition, but so could biological influences on personality.
It is also likely that some significant activities had effective thresholds, such that only individuals with atypical traits could perform them. It's easy to imagine a boulder so heavy that only a few of the strongest men could lift it, but then it's also easy to imagine a puzzle so difficult that only a few people could solve it, or a song with notes so high that only a few people could sing it. In such situations, outliers are important.
Many traits are distributed approximately in a bell curve, or "normal distribution." This is the shape that describes most of us being middling, a few of us being a bit different from average, and a tiny number of us being quite a lot different from average. The average height among men in the United States, for example, is about 5 feet 9 inches, while the standard deviation (the typical difference between two U.S. men chosen at random) is about 3 inches. This means that about two-thirds of men are between 5 feet 6 inches and 6 feet tall, with about a sixth over 6 feet. As we go further from the norm, we find fewer and fewer individuals: About 1 in 50 are over 6 feet 3 inches, while one in 770 are over 6 feet 6 inches. The fraction above a threshold falls off more and more rapidly as we increase the threshold. Now consider another, shorter population—let's say that the average height of men in this population is 5 feet 6 inches, one standard deviation below the average height of American men. There is substantial overlap between the two populations, but the difference in the frequency of Eastwoods becomes very large: Men taller than 6 feet 6 inches will be more than forty times rarer in the shorter group than in the U.S. sample.
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