Spring 2013 saw another round of misguided right-wing attacks on basic scientific research in the U.S. Congress, a political tactic that purports to demonstrate the wastefulness of the federal government by showing off the price tag (often small in terms of scientific research budgets) for obscure research that can be described in ways that make it sound goofy or idiotic. This time around, it peaked my interest a good bit more, because it brought national media attention to one of my favorite bits of biological research: Patricia Brennan’s work on duck genitalia. (Brennan wrote a wonderful defense of her research for Slate. Even the Union of Concerned Scientists weighed in.)
Why do I love this research so much? The biology is interesting, yes (more on that in a minute), but also, as a philosopher of science with a long-standing interest in feminist science studies, I see it as following the exact structure of some of the classic cases from that literature. That is, Brennan’s work exemplifies the pattern of research of women entering a field of research dominated by men, revolutionizing and improving the methods and theories in that field. It is thus similar to the earlier cases of primatology as described by Donna Haraway—where scientists hadn’t paid much attention to the behavior if female primates and ended up with theories where their roles were entirely passive—and reproductive cell biology as described by (inter alia) Emily Martin—where the “Prince Charming/Sleeping Beauty” theory of sperm/egg fertilization was a going idea, I kid you not.
To get the basics, let’s start with this “True Facts” video by Ze Frank:
The duck penis had been studied prior to Brennan’s work, and the main evolutionary explanation for its odd structure was “sperm competition” between males (Brennan et al 2007). One of the things Brennan discovered was that while there had been work on duck penises (technically “phallus”, as it functions pretty differently from the mammalian penis), there hadn’t been any serious anatomical work on duck vaginas. As she puts it, “Obviously you can’t have something like that without some place to put it in. You need a garage to park the car.”
In Brennan’s 2007 PLOS One article, Brennan and collaborators “examined vaginal and phallus anatomy in a sample of 16 waterfowl species, collected during the reproductive season” and “found great variation among species in vaginal morphology.” The main findings were (a) that duck vaginas had structures including clockwise spirals (opposite the male’s counter-clockwise spiraling penis) and dead-end pouches that make it more difficult for the male to inseminate the female and (b) that the length of the phallus and the elaborateness of the vagina co-varied between species. This led her to suggest two new evolutionary explanations in terms of intersexual selection: (1) it allows the females to choose mates of higher quality, or (2) it is an “arms race between the sexes” for control of reproduction. These explanations have the added benefit of explaining another known fact: that while “forced copulation” is common amongst ducks, it very rarely results in the female becoming impregnated, as compared to copulating with the a chosen mate. (Ducks pair with a single mate each mating season, but males often force themselves on females paired with someone else.) Presumably the female is able to contract or relax her vaginal tract to make it harder or easier for the male.
Because the claims about the mechanics of duck mating in the original article were largely speculative, Brennan followed up in a 2009 Proceedings of the Royal Society article to study the duck penis in action, using a variety of glass tubes to simulate different duck vagina setups (and bringing the phrase “female genital novelties” into the world of science abstracts). This work supports the view that the duck’s “vaginal complexity” works to prevent insemination via forced copulation. As several commentators pointed out at the time, the Republicans should actually love the research on duck genitals, as it shows that when it comes to forced copulation, “the female [duck’s] body has ways to try to shut that whole thing down.”
Brennan’s work also produced some frankly fantastic slow-motion videos:
Carl Zimmer has written several articles about this research. In 2007, he quoted one of Brennan’s collaborators, Kevin McCracken, as remarking on the relationship between Brennan’s gender and her discoveries: “Maybe it’s the male bias we all have… It’s just been out there, waiting to be discovered.” As Peggy Kolm puts it at the Women in Science: Past, Present, and Future blog, “What else have male scientists missed?” This is precisely the sort of story of androcentric blinders that is familiar from those older cases from the feminist science studies literature. More recently, many have argued that there are significant epistemic benefits to diversity, including Helen Longino and Carla Fehr (who just visited the Center for Values in Medicine, Science, and Technology at UT Dallas).
There’s a small wrinkle in this story. Recent research has shown that research on animal genitalia and genital evolution exhibits a significant male bias, and female genitals are significantly understudied. (Favorite headline: “Genitalia Gap: Biologists Prefer the Penis – But Why?”.) But this research shows that this male bias is roughly equally distributed between men and women researchers. As Ed Yong puts it, “The gender of the scientists themselves isn’t a factor.” This matches the research on implicit biases, which shows that implicit gender biases and stereotypes are held by both men and women. And some argue that it really is more difficult to study female genitalia (a body cavity rather than a protruding tube), though the authors of the cited study argue that this cannot be the only major factor.
Even your humble author is susceptible to this sort of bias. Through the past few years, when I talk about this case with colleagues and students, I tend to talk about “duck penis research” and “the duck penis case” rather than talk more inclusively about “duck genitalia” etc.
So why was Patricia Brennan drawn to correct the inattention to female duck genitalia that led her to discover better evolutionary explanations for duck penis, vagina, and reproductive behavior? What, besides her gender, did she bring to the table? Greater consciousness of gender issues? Feminist values? The vehicular metaphor of cars and garages?