For anyone who’s honest, a person has to confess to doing weird things every now and again. Often we don’t even know why we do them. Those who write about our animal cousins after observing them closely offer a storehouse of explanations. Much of our behavior derives from our evolutionary heritage. In Supernormal Stimuli: How Primal Urges Overran Their Evolutionary Purpose Deirdre Barrett presents a most cogent case for why humans take things to the extreme. Everything from sex to overeating to television to our attraction to the young to why we kill each other in conflicts may be explained by the incredible attraction of supernormal stimuli. Beginning with the bird and bee studies of Niko Tinbergen, Barrett explains how we are often simply acting out eons’ old patterns that sometime prove to be destructive when left unchecked. The way to escape from them, she notes, is to become aware of them.

A bird will often favor an exaggeratedly large and crudely patterned egg over her own. Leopards will sometimes attempt to raise baby monkeys after eating their parents, because the babies are so cute. Thousands of citizens will prefer to watch athletes on television while eating unhealthy food rather than exercising themselves. Why? Supernormal stimuli have an immeasurable biological draw, and humans are in no way exempt. Tinbergen, the eventual teacher of Richard Dawkins, saw this as one of the dangers of Christianity. By separating humans radically from animals, religion presents us with false reasoning as to why we act the way we do. Science explains, religion makes up excuses.

The most poignant aspect of Barrett’s fascinating study has to do with war. Territorial animals make frequent displays of force that, in humans, translates to war. There does seem to be a biological basis for the male predilection for aggression. As Barrett notes, “Women throughout history have said—as do contemporary ones in Israel and Palestine—that a group of mothers could sit down and hash out in one afternoon an agreement that has eluded male rulers for years.” If men could lay down their posturing and be willing to let others have a fair share of the goods, life might be more amenable to all. It’s not all bad news, however. Nature endows us with endless curiosity as well. Is that not what brought you to this blog? I hope that curiosity extends to Deirdre Barrett’s Supernormal Stimuli and we will all learn to overcome the baser parts of natural selection.