The science of sex: Debating mice, libido and gender bias

By Shannan Palma | Nov. 5, 2014

Is the science of sex biased? Two Emory graduate students asked that question of a recent study on mice and libido, and found the answer in this case to be yes.

Mallory Bowers, a sixth year Ph.D. student in neuroscience, and Natalie Turrin, a fifth year Ph.D. student in women's, gender, and sexuality studies, co-led a lively discussion of a study published recently in the Journal of Neuroscience titled, "Pain Reduces Sexual Motivation in Female But Not Male Mice."

Their presentation was the latest installment of the series "Neuroscience, Ethics and the News," a thrice-a-semester salon-style gathering at the Center for Ethics, open to people from across the university to explore the ethics of various neuroscience studies and how they are reported in the media.

"Many of us identify with our cognitive lives and even simply our brains," says Karen Rommelfanger, director of the Neuroethics Program and assistant professor in the Department of Neurology. "Perhaps for this reason, neuroscience has a particular allure to the general public and neuroscience findings…are seen as particularly compelling or convincing and often challenge our conceptions of self, agency and responsible human behaviors."

During the Oct. 15 event, Bowers gave an in-depth explanation of the questions, methods and results presented in the mice libido study. Researchers had conducted two experiments measuring the impact of inflammatory pain on sexual behavior for male and female mice.

Based on indications that the female mice exhibited less sexual interest than the males did when both were subjected to pain, the authors concluded that "the well known context sensitivity of the human female libido can be explained by evolutionary rather than sociocultural factors." Salon participants questioned the assumptions behind the researchers' questions and the absolutism in their claims.

Aspects of the study that came under particular scrutiny included the potential influence of extreme size and age differences in the mice — male mice had to weigh more than 45g and be between 10-25 weeks in age, female mice had to weigh less than 25g and be between 7-15 weeks in age.

Scientists in the group also questioned the use of male mounting behavior as a measure of female sexual receptivity, rather than employment of a more direct measure such as female lordosis, in which the female arches her back to indicate receptivity to mating. Others asked if mounting behavior is always indicative of sexual desire, or if it is ever associated with dominance behavior.

"Not tonight, dear, I've got a headache"

The second portion of the presentation, led by Turrin, focused on media coverage and cultural ramifications of the study. The Daily Mail reported the study findings with the headline, "Not tonight dear, I've got a headache: Women ARE more likely to go off sex when they are in pain."

Immediately following the headline are three bullet points: "Males are still interested in sex even when they are in severe pain; even just mild pain can significantly reduce females' libido; this could be nature's way of preventing women conceiving when ill."

The fact that it's a mouse study isn't mentioned until more than halfway through the story. The article goes on to state, "Canadian researcher Jeffrey Mogil said it has long been known that women's sexual desire is more 'context dependent,' or affected by factors such as self-confidence and relationship fears, than male libido."

Media coverage of scientific studies can often be problematic, with editors leaving out scientists' careful framing of limits and scope in favor of headline-grabbing claims, Turrin says.

In this case, however, the abstract itself makes absolutist claims, and Mogil, one of the authors, has gone on record numerous times about the study's applicability to humans, according to Bowers.

Science News quotes Mogil: "These data suggest very strongly that [differences between men and women's sexual behavior have] nothing to do with culture … It has everything to do with biology."

Bowers was troubled by the either-or thinking assumed in such claims. Must biology or culture alone influence sexual behavior? Several audience members shared her concern.  

The cross-species relevance also came into question. Is sexual behavior in mice close enough to human sexual behavior that the two are even comparable? Turrin asked the group to consider what assumptions about male and female sexuality, masculinity and femininity underlie the "not tonight" aphorism referenced in the study and by the media.

One audience member noted the extent to which the research questions and findings assumed and protected male virility – "It's not that you're not desirable; pain really does impact her libido." Others noted that for some women, refusing sex without a "valid reason" could make them a target of intimate partner violence.

The next "Neuroethics and Neuroscience in the News" discussion is set for Dec. 10, when Patricia Bauer facilitates a discussion on "Is eyewitness testimony from children reliable?"