Several months ago, I blogged about a new theory on why men love breasts. New theories pop up all the time, so it’s no surprise that there are new theories on male body parts, too. A recent issue of Archives of Sexual Behavior features an alternative explanation for the shape of the human penis.

As described in BLONDES, the prevailing theory on why the human penis has a distinctive head and corona (rounded projecting border) is that it can scoop out semen deposited in the vagina by a woman’s previous lovers, thus averting a pregnancy. This means the last lover, not the first, gets the head-start.

Not likely, says Dr. Edwin Bowman, in his letter to the editor.

Instead of scooping out other men’s semen, writes Bowman, the penile head and corona scoop out vaginal secretions. After collected, these fluids are then absorbed by the foreskin. The mucous membrane of the foreskin, it turns out, is like a sponge for the stuff.

Why would evolution select for men to absorb vaginal secretions?

Just as semen has “mind control properties,” so do vaginal fluids. When ovulating and most likely to conceive, these secretions contain neurohormones such as pitocin and vasopressin. The latter in particular has been associated with bonding and is thought to trigger protective behavior among males for their partners. Vasopressin, after all, is thought of as a male “love drug.” Flooded with bonding hormones, a guy may be more likely to stick around if he impregnates his partner.

Knowing this, will more men use condoms?