:: Kinky Mice

Big news from the world of science: apparently the gendered (what scientists call "typically male" or "typically female") sexual behavior of certain adult mammals can be reversed simply by flipping a biological switch.

A study published this week documents the results of experiments on female mice in which "a small sensory organ found in the noses of all terrestrial vertebrates except higher primates" were disabled through surgery or genetic mutation, which.... wait, why am I trying to explain this when I should just be quoting? Here goes:

[The scientists] found that these females, when placed in a cage with a sexually experienced male, would engage in typically male courtship activity: chasing their cage mates, lifting the males' hindquarters with their snouts, and emitting complex ultrasonic vocalizations that are part of the male mouse's mating ritual. Eventually, the female mutants would replicate male sexual behavior by mounting the hapless males and thrusting.

Apparently, the hijinks in the cages escalated until the female mice were impregnated. After giving birth and despite lactating, the female mice persisted in "male" behaviors (it is so tempting to make a series of sexist comments here, but I won't, because that would be wrong. Still, I'm sure you can imagine how the cliche-based joking might proceed).

More science, from scientist-in-charge Catherine Dulac:

"There are two possible interpretations," Dulac says. "Either the vomeronasal organ may be needed to grow a female-specific neural circuit during development, or the mature female mouse brain may require vomeronasal activity to repress male behavior."

To test these two alternatives, Dulac and her colleagues excised vomeronasal organs from the nasal septa of normal adult females. These mice began behaving like males, despite the fact that they - like mutant females in the study - showed testosterone levels, estrogen levels, and estrus cycles indistinguishable from those found in normal females.

"It had previously been thought that entirely different neural circuits, modulated by these hormones, controlled sex-specific behavior," Dulac says. "Remarkably, our work suggests that neuronal circuits underlying male-specific behaviors develop and persist in the female mouse brain, but are repressed by the normal activity of the vomeronasal organ."

"In fact, our research suggests a new model where exactly the same neural circuitry exists in males and females," Dulac says. "In this model, only the vomeronasal pathway itself - which serves as a switch that represses male behavior while promoting female behavior - is dimorphic. While male and female bodies are strikingly different physiologically, it appears the same cannot be said for the brain."

Finally, we are tossed this tantalizing tidbit:

Dulac and colleagues are now studying the behavior of male mice mutant for TRPC2 to determine whether they display femalelike traits.

If humans have an equivalent mechanism to the one described in this study, it might explain why scientists have had such a hard time linking gendered behavior with physiological features of the brain: they're looking for something that isn't there. (In your face, sociobiologists!)

The conventional wisdom that gender identity is naturally tethered to the "either / or" of one's genitalia (and that the fraying of that tether is perverse or "against nature") is increasingly undermined as people feel freer to express a range of unconventional gender identities.

In my mind I keep picturing hordes of Essentialist and Constructionist feminists clashing ala the Spartans and the Persians in the movie 3oo (albeit with less facial hair), but that is because much of my own brain's physiology is stuck in the 1980's.