Evolution and Our Inner Conflict

Are human beings intrinsically good but corruptible by the forces of evil, or the reverse, innately sinful yet redeemable by the forces of good? Are we built to pledge our lives to a group, even to the risk of death, or the opposite, built to place ourselves and our families above all else? Scientific evidence, a good part of it accumulated into the past twenty years, suggests that we are all of these things simultaneously. Each of us is inherently complicated. We are all genetic chimeras, at once saints and sinners—not because humanity has failed to reach some foreordained religious or ideological ideal—but because of the way our species originated across millions of years of biological evolution.

Don’t get me wrong. I am not implying that we are driven by instinct in the manner of animals. Yet in order to understand the human condition, it is necessary to accept that we do have instincts, and will be wise to take into account our very distant ancestors—as far back and in as fine a detail as possible. History is not enough to reach this level of understanding. It stops at the dawn of literacy, where it turns the rest of the story over to the detective work of archaeology; in still deeper time the quest becomes paleontology. For the real human story, history makes no sense without prehistory, and prehistory makes no sense without biology.

Within biology itself, the key to the mystery is the force that lifted pre-human social behavior to the human level. The leading candidate in my judgment is multilevel selection, by which hereditary social behavior improves the competitive ability not of just individuals within groups but among groups as a whole. Its consequences can be plainly seen in the caste systems of ants, termites, and other social insects. Between-group selection in addition to between-individual selection is not a new idea. Charles Darwin correctly deduced its role, first in the insects and then in human beings—respectively in The Origin of the Species and the Descent of Man.

The reader should be warned that the revival of multilevel selection as the principal force of social evolution remains a hotly contested idea. Its opponents believe the principal force to be kin selection: when individuals favor kin (other than offspring), the evolution of altruistic behavior is favored. The loss suffered by the genes of the altruist are compensated by genes in the recipient made identical by common descent of the altruist and recipient. If the altruism thus created is strong enough it can lead to advanced social behavior. This seems plausible, but in 2010 two mathematical biologists, Martin Nowak and Corina Tarnita, and I demonstrated that the mathematical foundations of the kin selection theory are unsound, and that examples from nature thought to support kin selection theory are better explained as products of multilevel selection.

A strong reaction from supporters of kin selection not surprisingly ensued, and soon afterward more than 130 famously signed on to protest our replacement of kin selection by multilevel selection, and most emphatically the key role given group selection. But neither then nor up to the present time, have our mathematical and empirical arguments been refuted or even seriously challenged. The number of supporters of the new approach has grown, to the extent that a similarly long list of signatories could be obtained. But such exercises are futile: science is not advanced by polling. If it were, we would still be releasing phlogiston to burn logs and navigating the sky with geocentric maps.

So, admitting bias, I am convinced after years of research on the subject that multilevel selection, with a powerful role of group-to-group competition, has forged advanced social behavior—including that of humans, as I documented in my recent book The Social Conquest of Earth. In fact, it seems clear that so deeply ingrained are the evolutionary products of group selected behaviors, so completely a part of the human condition, that we are prone to regard them as fixtures of nature, like air and water. They are instead idiosyncratic and diagnostic traits...