Hunter gatherers may have very egalitarian societies, but evolution says the human love of power and status runs deeper.
When The Spirit Level: Why Equality is Better for Everyone by Richard Wilkinson and Kate Pickett came out in 2009, it chimed well with the post-crash mood. The book claimed that higher levels of inequality were associated with a whole range of poor health issues, including lower life expectancy, increased obesity, and higher murder rates. It seemed that those fat cat bankers hadn’t just wrecked the financial system: they were making us all ill, too.
Subsequently, however, these claims came in for a great deal of criticism, especially from sociologists on the libertarian end of the political spectrum. Whether right or wrong, however, the original book has raised a deeper question, and one that is still wide open. By framing the debate about inequality in a biological context, The Spirit Level harked back to an older philosophical conundrum about human nature. Are we, fundamentally, an egalitarian species or a fiercely competitive one? Or are we perhaps so flexible that we can be equally at home in either kind of society?
Evolutionary biology casts considerable light on this question. Start with the fact that our species has spent more than 90 per cent of its existence living in highly egalitarian bands of hunter-gatherers. There is no room in this nomadic existence for the accumulation of property, and hence no great differences in material possessions. As the American anthropologist Marshall Sahlins observed in his 1968 essay on the ‘original affluent society’:
Of the hunter it is truly said that his wealth is a burden. In his condition of life, goods can become ‘grievously oppressive’ … and the more so the longer they are carried around. Certain food collectors do have canoes and a few have dog sleds, but most must carry themselves all the comforts they possess, and so only possess what they can comfortably carry themselves.
It was only when the first humans started farming, around 10,000 years ago, that it became possible for one person to accumulate many more possessions than another. Farmers are sedentary and can therefore store property in buildings, and stake a claim to land by building walls. Farming is also more efficient than hunting and gathering, so a division of labour can develop. Some grow enough food to support other people who have nothing to do with food production, such as artisans, soldiers, priests and kings. Inevitably, those who do not produce food end up far richer than those who do. Kings skim off the surplus production in the form of taxes and use it to finance armies, palaces and temples. Priests spin yarns about tithing to justify all this robbery in exchange for an income of their own. In just a few thousand years — a blink of an eye in evolutionary terms — humans have gone from living in small egalitarian bands to large-scale sedentary societies with extreme levels of inequality.
It would hardly be surprising then if the sudden appearance of inequality didn’t have deleterious consequences for the human mind and body. Other novelties associated with the advent of farming, such as the constant proximity of domestic animals and higher population density, exposed our ancestors to new threats for which they were unprepared, such as the rise of infectious diseases. Evolutionary psychologists have speculated that our ancestors found the new landscape of social inequality similarly damaging, and that there has not yet been enough time for natural selection to adapt us to it, if it ever will.
According to the social competition hypothesis of depression, humans are exquisitely sensitive to small differences in social status. Such sensitivity was vital when our ancestors lived in smaller bands of hunter-gatherers, where status differences were relatively slight. But in today’s world, where the global elite earn thousands of times more than those at the bottom of the economic heap and have completely different lifestyles, our status detectors go into overdrive. Hence a sensitivity that evolved to help low-status individuals signal obedience would, in today’s world, produce pathological results.
Support for this idea is provided by studies of dominance hierarchies in other primates. Low-ranking vervet monkeys, for example, have serotonin levels that are half those of the alpha males, and low-status yellow baboons have elevated levels of the stress hormone cortisol. Both of these physiological responses are found in depressed people, so perhaps inequality does literally get under our skin. A study of British civil servants found that those in lower-grade jobs showed significantly higher levels of the cortisol-awakening response (the difference between cortisol levels at waking and 30 minutes later, which is thought to be linked to the hippocampus’s preparation to face anticipated stress) than those in higher grades. Contrary to popular belief, then, it seems that those at the top of the pyramid, who tend to have the most decision-making responsibility, have the least stressful lives. One theory is that, the lower one is in the chain of command, the less control one has over one’s daily life. Taking orders, rather than giving them, results in raised heart rate, stress hormones, and blood pressure.
Inequality is not a negative-sum game — in which everybody ends up worse off — but a zero-sum game, in which the poorer health of those at the bottom of the pile is offset by the health gains of those at the top. There is nothing like the sight of a beggar to make one feel rich. It is not enough to succeed, as Gore Vidal said; others must fail.
Evolutionary psychologists have also looked to experimental psychology for evidence that we are naturally averse to inequality. In the ultimatum game, for example, two strangers are paired and given a sum of money. One of them — usually referred to as the ‘proposer’ — has to decide how to divide the money. The proposer might suggest a 50-50 split, or they might offer only 10 per cent and keep the lion’s share. The other player can then either accept or reject this offer. If the responder accepts the offer, each player walks away with the share suggested by the proposer. If the responder rejects the offer, each player walks away with nothing.
According to game theory, a rational proposer should always offer the smallest amount possible, and a rational responder should always accept the proposer’s offer, no matter how small it is. After all, some money is better than none. But this isn’t what people actually do when they play this game. Instead of offering the smallest possible amount, most proposers offer between 40 and 50 per cent of the money. And on the few occasions that proposers offer less than 20 per cent, responders reject about half of those offers, despite the fact that this means both lose.
Such findings have been interpreted as evidence that people naturally dislike inequality and will sacrifice some personal gains to avoid it. However, when the experiment has been carried out with indigenous people with a low degree of market integration, the results are very different. Machiguenga farmers in Peru, for example, offer very little, and accept almost every offer, no matter how derisory. In the cultures least exposed to the influence of capitalism, people behave almost as greedily as game theory suggests they should. This does not bode well for the idea that inequality aversion is part of our DNA.