One of the hottest fads in social science is “evolutionary psychology,” also known as “evolutionary ethics.” The story line is that by considering how we came to be, we will learn more about how we are. According to this view, Darwinism reveals the universal, persistent features of human nature.
Why it should do so is very strange, because Darwinism is not a predictive theory. For instance, it does not proceed by saying, “According to our models, we should expect human males to be more interested in sexual variety than human females; let’s find out whether this is true.” Rather, it proceeds by saying, “Human males seem to be more interested in sexual variety than human females; let’s cook up some scenarios about how this might have come to pass.” In other words, the theory discovers nothing. It depends entirely on what we know (or think we know) already, and proceeds from there to a purely conjectural evolutionary history.
These conjectures are made to order. You can “explain” fidelity, and you can “explain” infidelity. You can “explain” monogamy, and you can “explain” polygamy. Best of all (for those who devise them), none of your explanations can be disconfirmed, because all of the data about what actually happened are lost in the mists of prehistory. In the truest sense of the word, they are myths -- but with one difference, which is this: The dominant myths of most cultures encourage adherence to cultural norms. By contrast, the myths of evolutionary ethicists encourage cynicism about them.