Unconscious behavioral changes from birth-control chemicals
Interesting report by Brandon Keim at Wired:
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.
Men’s responses may also be scrambled. In one infamous study, men gave more money to strippers when they approached ovulation, and very little money if they were on the pill.
Such studies are compelling, but ambiguous. Does preference for certain immune-system profiles, as identified from sweat-soaked T-shirts, translate to real-world behavior? The results appear mixed. Do men really smell something, or did women dance differently? It’s hard to tell. And mate choice is just one of the animal kingdom’s many roles for scent…
