45 years of selective breeding he got what he aimed for: a population of tame foxes, less fearful of humans and more interested in playing with them. But Belyaev also got much more than he aimed for: these tame foxes had floppier ears, curlier tails, smaller brains, higher serotonin levels, and much sharper social skills than their wild relatives. These tame foxes acquired the same package that virtually all other domesticated mammals had acquired: some desired and desirable traits and some surprises.
Belyaev’s study shows that even under highly controlled laboratory conditions, artificial selection leaves a trail of unanticipated consequences, traits that come along for the ride. This link between desired and unanticipated features arises because the genes that create these features are like coupled oscillators: changes in the expression of one gene directly link to changes in the expression of others. At the level of the traits — the gene’s expressions — some have no impact on survival or reproduction, while others may increase or decrease these aspects of fitness. We can illustrate this point by looking at an example from dog breeders.
Several hundred years ago, dog breeders used artificial selection to create snub-nosed breeds such as the pug, bull dog, and boxer. The idea was to satisfy our aesthetics for diminutive noses, and reduce the size of the dog’s classically large protuberance. Over the course of several generations of picking the smallest-nosed members of the litter, pugs, bull dogs, and boxers emerged. But they also emerged with an unanticipated and maladaptive health problem: all of these breeds have a harder time breathing and staying cool than full-nosed or snouty dogs. No breeder would select for respiratory problems or an inability to stay cool. These traits emerged as costly byproducts of selection for a diminutive nose, and more abstractly, as a byproduct of our aesthetics. As in Tsien’s experiments on memory enhanced mice, when we tamper with nature, we can cause great harm.
Research on the evolution of religion provides my second example of how to think about adaptations and byproducts. The different types of religion are like the different dog breeds: distinctive in many ways, but with a large number of shared traits in common. Most religions have a set of rules for group membership and expulsion, ritual practices, and beliefs in the supernatural. These commonalities suggest to some scholars that religion evolved to solve a particular problem, one that all humans confront. That problem is large scale cooperation among unrelated strangers, a topic I pick up in greater detail further on in this chapter. Other species cooperate, usually with a small number of individuals, mostly close kin. As the size of potential cooperators grows, and genetic relatedness among individuals within the group shrinks — adding more unfamiliar strangers to the mix — the potential risks of cooperating with a cheater increases. Religion, and its core features, evolved to diminish this risk and increase the odds of developing a society of stable cooperators. Viewed from this perspective, religion is an adaptation — in the evolved for sense.
For those scholars who favor the idea of religion as adaptation, supporting evidence comes from
Hauser Chapter 1. Nature’s secrets 24
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