The Frontal Cortex

Circumcision and Luck

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.


  1. #1 razib
    December 14, 2006

    Does cutting off the foreskin have any practical benefits besides preventing the spread of HIV?

    there are studies in india that cut men’s partners (women) have lower rates of cervical cancer. they compared muslim and non-muslim men. the thing is that these benefits seem to be a LOT less in modern conditions. e.g., south korea and japan have the same HIV rate, though s.k. is cut & japan isn’t. the USA has a higher HIV rate than most of europe. sweden has the same cervical cancer rate as the USA.

    as for the israelites

    a) circumcision was common in the area. the egyptians and various semitic peoples did it (the european ‘sea peoples’ are noted in the 12th century for their foreskins)

    b) there is some research which suggests that ancient circumcision was far less extreme insofar as a great deal of the foreskin remained. rabbis chided jews who went to classical gymnaseums and stretched their foreskin manually to make it seem intact. the implication being that full removal was not always, or ever, the case in the ancient world.

  2. #2 MiddleO'Nowhere
    December 14, 2006

    I’ve heard the argument that it was easier to keep clean. That makes sense, since the foreskin allows dirt, sweat, etc. to be trapped. With the lack of water to wash one’s self on a regular basis, you could probably see a big difference in rates of infection. I’m mostly refering to infections that are localized to that area, have obvious symptoms, and cause some pain. In those cases, it’d be easy to compare the differences between circumcised and uncircumcised people. Those circumcised guys don’t have some rash after they’ve been wandering in the desert while those uncircumcised guys do.

    I want to say, although I can’t back this up, that modern studies have found no clear winner as long as those who were uncircumcised regularly cleaned underneath the foreskin.

  3. #3 MiddleO'Nowhere
    December 14, 2006

    I thought of this when I first saw mention of it, but haven’t had a chance to read the actual article to see what they say. Is there any preference among people in those areas for circumcised vs. uncircumcised men? For instance, do wealthier (and possibly less likely to be infected) women prefer circumcised men? I assume they controlled for the number of sexual encounters, but did they control for the HIV status of the partners?

  4. #4 razib
    December 14, 2006

    just to be clear. egyptians weren’t semitic. the roman noble publius clodius was circumcized by some arabs he’d insulted to make him ‘look like them.’

  5. #5 Nagu
    December 14, 2006

    Huh, then cut the whole thing off, and one would get even better results.

  6. #6 ivan
    December 14, 2006

    one of the most stupid ideas in the human history.

  7. #7 Torbjörn Larsson
    December 15, 2006

    So from the HIV connection the foreskin immune function really makes a difference. The other study also found statistically significantly no uncircumcised men with chlamydia.

    Amputation of a functional part of the immune system (and sexual mechanic) doesn’t sit well with me, but if one can’t afford condoms I guess it could be a real good idea now. A pity undiscovered chlamydia is so nasty too.

  8. #8 Dukla
    December 20, 2008

    Circumcision also greatly reduces the risk of penile and urinary related diseases and infections (ie urinary tract infections) and would have been particularly effective back in the day when medicine was almost non-existent and hygiene was very poor. In fact circumcision is still suggested by doctors for males who have consistent problems with urinary tract infections and STIs.

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