Pointing Fingers at Testosterone

Yesterday during the break of one of my classes, my students got quite excited about a story I that appeared on Salon's Broadsheet. It examines the claim that the relative length of one's fingers reveals how one's brain works. According to Rutgers evolutionary anthropologist Helen Fisher, people whose ring fingers are long relative to their index fingers have more "male" cognitive capacities:

Women are "web thinkers" -- they are intuitive data-gatherers and long-term thinkers, she said. Men are "step thinkers" -- they are more analytical, linear and short-term processors. These differences are complementary, according to Fisher, and indicate that a business team balanced with men and women is ideal.

Fisher has made similar arguments about love (and profited from them - she's a consultant for the matchmaking service Chemistry.com). She contends that partners who are too similar will grow bored in the long run, and that the ratio of testosterone to estrogen in a person is one predictor of complementarity versus similarity.

To be honest, I think my students dug the finger-length thing because it was literally a hands-on experiment - or maybe because it was the next best thing to palm-reading. Next class, I should bring a Magic 8 Ball and see if I get the same outburst of enthusiasm. Or maybe a large caliper and see how phrenology goes over.

I'm still trying to sort out what's bunk and what's at least potentially solid science in Fisher's claims. It doesn't help that she started the speech that was reported on (originally by the BBC) by declaring she's "definitely not a feminist." I'm not sure what relevance that has. Does she want to make clear that she's practicing supposedly value-free science, even though she's arguing that businesses need more female managers? Being truly value free would be a heck of a feat for an anthropologist; none of us can avoid bringing own cultural baggage to whatever culture is under study. Does she want us to know that she's a very special kind a scientist, a sexy Queen Bee who made it to the top of her profession without any favors from those ugly old man-haters?

Or does she want to draw attention away from the fact that her conclusions mostly just echo the tired old Mars-Venus stereotypes? She says women are good multitaskers while men have laser-like abilities to focus. Women are empathetic, men analytical. Gosh, I think we've heard this all before.

There seems to be substantial evidence for the notion that fetal exposure to testosterone results in the ring finger being longer than the index finger. The idea that this "digit ratio" indicates roughly how much testosterone was present in the womb seems pretty uncontroversial. However, a twin study found that about genes accounted for about 70 percent of the ratio between ring and index finger, which suggests that prenatal exposure to testosterone may not be the whole reason for long ring fingers. I suppose genes could cause higher testosterone levels in the womb, in which case hormonal influences would still be a mediating factor, even if not the ultimate cause. At any rate, no one claims that the digit ratio is more than a rough mesaure.

What prenatal testosterone exposure means for gender and brain development is less clear, though. A relatively long ring finger has been linked to aggression and fertility in men, and to athletic ability in both men and women. Researchers have correlated SAT scores with finger length, too: higher math SAT scores go with longer ring fingers in both sexes, and higher verbal SATs with longer index fingers in girls. Simon Baron-Cohen (cousin to Sascha of Borat fame) has hypothesized that high levels of prenatal testosterone may be a cause of autism (which he describes as (extreme male brain), and so far his long-term research study seems to be bearing this out.

It's well-nigh impossible to judge how solid the evidence is for any of these conclusions, simply on the basis of media reports. I'm willing to suspend judgment and keep my eyes open for future finger-length evidence.

But I have a more fundamental criticism: Why do all such studies seem so intent on posing these traits as dichotomies? Why don't we acknowledge that someone can be good at both logic and empathy, analysis and synthesis?

I think my own abilities are pretty balanced. (Wow, one whole data point - now that's sound science!) But as one of my students pointed out to me, my ring finger is relatively long - but only on my right hand. So maybe I'm a freak of nature.

If so, I'm in good company. Yet another study found that male scientists tent to have negligible differences in the lengths of their second and fourth fingers. In other words, the guys in some of the most stereotypically male - and male-dominated - professions such as math and physics actually exhibit a more typically feminine pattern, suggesting a balance between estrogen and testosterone.

This doesn't mean testosterone and estrogen are irrelevant. It's just that they don't respect our stereotypes. And that means they're a whole lot more complex and marvelous than most of us recognize.