Here is the third and last “unanswered question about evolutionary biology” that I discussed in a short BBC Focus essay. (#1 is here and #2 here). I’m putting this up because the second and third questions appear only in the print version.
How much of our behavior reflects our evolutionary past? What does it mean to be human? Part of the answer involves knowing which of our behaviors were instilled in our ancestors by natural selection. This is the purview of the popular field of “evolutionary psychology.”
Unfortunately, its popularity—as measured in books and articles that give Darwinian explanations for everything from homosexuality to music—is not a sign of scientific rigor. It turns out to be hugely difficult to determine what portion of our modern behavior was adaptive in our ancestors. For one thing, our culture is far more elaborate than that of any other animal, being transmitted instantly from individual to individual through emulation. Is men’s preference for young, curvy women a function of past evolution in favor of choosing mates with marked reproductive potential, or is it simply a function of what we see on the covers of magazines? These debates are important. How much of gender difference in academic performance, for example is due to genetic evolution versus cultural differences between males and females? It’s hard to tell because it’s unethical and unpalatable (not to mention impossible) to settle the issue by raising children in completely gender-neutral environments. And since many of our behaviors evolved thousands or millions of years ago under unknown conditions, we’re often forced into speculative historical reconstructions, cynically known as “just-so stories.”
Some of our behavior is clearly due to natural selection. Eating, sleeping, and copulating all promote our survival and reproduction. The greater choosiness of females than males in finding mates, predicted by evolutionary theory and seen in most animals, is also borne out by psychological tests. We favor kin over non-kin, an evolutionary prediction met in many animals. And the human penchant for sweets and fats, now a maladaptive taste, was probably a valuable asset to our fuel-starved ancestors on the savanna.
But when you read evolutionary explanations about why gentlemen prefer blondes, or why so much of the world is religious, always ask yourself two questions. First, could these traits be culturally influenced and not genetic? More important, what is the evidence for whether these behaviors were favored in our ancestors by natural selection? My own standard for judging whether our behaviors represent evolutionary adaptations is this: employ the same rigorous scrutiny used by biologists when deciding whether studies of behavior in nonhuman species should be published in scientific journals. By those lights, much of “pop” evolutionary psychology doesn’t pass muster.