Birth Control Messes With Monkey Business

[n2doc]

By Brandon Keim July 28, 2010

The powerful hormones in birth-control drugs change how lemurs smell, radically altering the subtle chemical cues that guide their attraction and communication.

Research on a 2-foot-tall primate shouldn’t be extrapolated directly to humans, but the findings resonate with studies in people, which have come largely from behavioral observations and are just beginning to quantify the chemistry.

“I’m not telling people not to take birth control. But what we found in lemurs needs to be studied in humans,” said Christine Drea, a Duke University reproductive biologist.

Hormone contraceptives work by tricking bodies into thinking they’re pregnant, thus preventing the release of eggs. However, these hormones are powerful. Possible side effects include sexual and romantic dysfunction. And researchers studying the broader effects of contraceptives have noticed an apparent interference with women’s taste in men.


When asked to rate the attractiveness of male odors, women are generally more attracted to men whose scents signify an immune system quite different from their own. Such a preference ostensibly leads to children with the most versatile disease defenses possible. That preference seems lessened when women take hormone contraceptives, possibly because women’s noses can’t properly calibrate if their own scent has been changed.



Read More http://www.wired.com/wiredscience/2010/07/contraceptive-scents/

[Xithras]

1. The MHC gene research is interesting.

In a nutshell: Ovulating women have shown, in multiple studies, to show a preference for men with MHC genes that are very different from their own. As the article mentioned, differing MHC genes are beneficial for children because the genetic diversity strengthens their immune system.

Women who are pregnant have a shift in the MHC "settings", instead prefering to be around people with MHC's similar to their own. It's thought that this might be a truly ancient human behavioral trait...females go out to find the best mate, but then retreat to the safety and security of their relatives while pregnant and vulnerable.

The pill apparently triggers this MHC switch, and has been cited as a causal factor for at least a small portion of the modern divorce rate. A woman dates and marries a man while on the pill, and then stops taking it to have children. If his MHC is incompatible with hers, she may rapidly find herself losing interest in her chosen mate.

Isn't human biology grand?

Back when this came out, a few researchers actually suggested that women on the pill and considering marriage would be wise to get off the pill and switch to an IUD or other birth control for at least six months. The suggestion was widely ignored and quickly forgotten, but the idea does have some merit.