As everybody knows by now, having a circumcised penis cuts a man’s risk of contacting AIDS from heterosexual sex by half. Those ancient Israelites were some astute scientists:
Uncircumcised men are thought to be more susceptible because the underside of the foreskin is rich in Langerhans cells, sentinel cells of the immune system, which attach easily to the human immunodeficiency virus, which causes AIDS. The foreskin also often suffers small tears during intercourse.
So here’s my question: was this just blind luck on the part of Abraham and his offspring? Does cutting off the foreskin have any practical benefits besides preventing the spread of HIV? This isn’t as silly a query as it might seem. After all, scholars have come up with all sorts of nifty explanations for other religious rituals and taboos. For example, some argue that Jews who keep kosher abstain from shellfish and pork because those food products tend to carry deadly diseases, especially when you’re lost in the desert. In other words, the obscure laws of Leviticus actually had some sort of adaptive value way back when. (Take that Richard Dawkins!) This doesn’t mean that Moses understood the germ theory of disease. It just implies that some sort of cultural evolution was taking place, and that this ancient tribe realized that certain rituals kept you from getting trichinosis.
But I’m not aware of circumcision having any adaptive value apart from reducing the risk of HIV infection. (Other studies tend to support this view.) Given that AIDS wasn’t a big problem for the ancient Israelites, this leaves us with two tantalizing possibilities: either God really is prophetic and he created a ritual that would reap benefits a few thousand years hence, or the authors of the Old Testament just got lucky.
Update: There’s a third possibility: the Israelites were trying to reduce the risk of cervical cancer. See Razib’s astute comment below. He also makes the important point that circumcision was common among other semitic peoples as well.
My own hunch is that the authors of the bible were just looking for some way to connect God to a ritual of human fertility. They looked around, saw this extra flap of skin on the penis, and decided that removing it would be a nice way of thanking God for giving Abraham and Sarah a baby boy named Isaac. Having read the Old Testament for the first time in college, I was struck by its prurient obsession with sex. God is very adamant that he controls our fertility, and so it’s only natural that he would want to denote this by marking our bodies.