Are left and right a feature (or bug) of evolution?
Perhaps the main reason that scientists don’t think these psychological and attentional differences simply reflect learned behaviors—or the influence of cultural assumptions—is the genetic research. As Hibbing et al. explain, the evidence suggests that around 40 percent of the variation in political beliefs is ultimately rooted in DNA. The studies that form the basis for this conclusion use a simple but powerful paradigm: they examine the differences between pairs of monozygotic (“identical”) twins and pairs of dizygotic (“fraternal”) twins when it comes to political views. Again and again, the identical twins, who share 100 percent of their DNA, also share much more of their politics.
In other words, politics runs in families and is passed on to offspring. Hibbing and his coauthors suspect that what is ultimately being inherited is a set of core dispositions about how societies should resolve recurring problems: how to distribute resources (should we be individualistic or collectivist?); how to deal with outsiders and out-groups (are they threatening or enticing?); how to structure power relationships (should we be hierarchical or egalitarian?); and so on. These are, of course, problems that all human societies have had to grapple with; they are ancient. And inheriting a core disposition on how to resolve them would naturally predispose one to a variety of specific issue stances in a given political context.
All of which brings us to the really big question. It is difficult to believe that systematic psychological and biological differences between those who opt for the left and the right in different countries—differences that are likely reflected in the genetic code—arose purely by chance. And yet, providing an evolutionary explanation for what we see is fraught with peril: to put it bluntly, we weren’t there. We didn’t see it happen.
Moreover, in evolution, some things happen for an explicitly Darwinian “reason”—traits become more prevalent or fixed in populations because they advanced organisms’ chances of survival and reproduction in a particular environment—while others happen more accidentally. Some complex social traits may emerge, for instance, because they are a fortuitous by-product of other, more fundamental traits laid down by Darwinian evolution.
A good example of such a trait may be religion. It’s pretty clear that evolution laid down a series of attributes that predispose us toward religiosity, such as “agency detection,” which refers to the human tendency to detect minds and intentions everywhere around us in the environment, even when they aren’t necessarily there. The evolutionary reason for such a trait seems obvious: after all, better to be safe than sorry when you’re out in the woods and hear a noise. But start thinking that there are intentions behind the wind blowing, or the hunt failing, and you are well on your way to constructing gods. And indeed, religion seems to be a cross-cultural human universal. But does that mean that evolution selected for religion itself, or just for simpler precursors like agency detection?
You see the difficulty. In this context, Hibbing and his colleagues consider a variety of potential explanations for the stubborn fact that there is large, politically relevant psychological and biological diversity among members of the human species, and ultimately settle on a tentative combination of two ideas. First, they assert, conservatism is probably more basic and fundamental, because it is more suited to a world in which life is “nasty, brutish, and short.” Being defensive, risk aversive, hierarchical, and tribal makes sense when the threats around you are very real and immediate. As many of these threats have relaxed in modern times, however, this may have unleashed more variability among the human species, simply because now we can afford it. Under this scenario, liberals are the Johnny-come-latelys to the politico-evolutionary pageant; the Enlightenment itself is less than 300 years old, less than an eyeblink in evolutionary time. “Liberalism may thus be viewed as an evolutionary luxury afforded by negative stimuli becoming less prevalent and deadly,” write Hibbing et al.
However, Hibbing and his colleagues also consider a more controversial “group selection” scenario, in which evolution built some measure of variability in our political typologies because sometimes, diversity is strength (for the group, anyway, if not for the individual). The trouble is, it is still fairly novel for evolutionary explanations to focus on the reproductive fitness of a group of individuals, rather than on the fitness of a single individual or even that individual’s DNA. Nonetheless, it’s easy to see why a group of early humans comprised of both conservative and liberal psychologies might have fared better than a more homogenous group. Such a society would have forces in it that want to hunker down and defend, but also forces that push it to explore and change. This would surely make for better adaptation to more diverse environments. It just might enhance the group’s chance of survival.
Yet it would be going much too far to suggest that Hibbing et al. have a strong or highly developed theory for why biopolitical diversity exists among humans. Avi Tuschman does, though. “Political orientations are natural dispositions that have been molded by evolutionary forces,” he asserts. If he’s right, a dramatic new window opens on who we are and why we behave as we do.
One of the most stunning revelations of recent genetic anthropology is the finding that Homo sapiens, our ancestors, occasionally bred with Homo neanderthalensis in Europe or the Middle East some 40,000 to 50,000 years ago. These encounters may have been quite rare: just one offspring produced every thirty years, according to one estimate. But it was enough to shape who humans are today. Recent genetic analyses suggest that some modern humans have a small but measurable percentage of Neanderthal DNA in our genomes—particularly those of us living in Europe and Asia.
The more you think about it, the more mind-boggling it is that this cross-species mating actually occurred. Imagine how strange it must have been, as a member of Homo sapiens, to encounter another being so closely related to us (much more closely than chimpanzees), and yet still so different. J. R. R. Tolkien buffs can probably visualize it the best, because it would indeed have been something like humans encountering dwarves. Neanderthals were shorter and stronger, with outjutting brows. There is some evidence suggesting that they had high-pitched voices and red hair.
Knowing how prevalent racism and xenophobia are today among members of the same human species, we can assume that many of our ancestors would have behaved even worse toward Neanderthals. And yet some Homo sapiens bred with them, produced offspring with them, and (presumably) cared for those offspring. Which ones were the lovers, not the haters?
The answer, hints Tuschman in Our Political Nature, is that it may have been the liberals. For one core of the apparently universal left-right difference, he argues, is that the two groups pursue different reproductive strategies, different ways of ensuring offspring and fitness in the next generation.
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