Recently, the neuroscience journal Cerebrum examined a “sexy” topic that’s currently a hot one among researchers—distinctions between male and female brains. The article was accompanied by an illustration depicting the concerns of a female mind (perfume, flowers, music) and that of a male (computers, science, math).
“This should have been from 40 years ago,” Natalie Angier ’78 declared, as she showed the illustration—which was actually from the journal’s spring 2014 issue—to a packed auditorium at The Diana Center on September 29. In the artwork, she said, “sex differences devolve into something cartoonish.” A New York Times science writer and Pulitzer Prize winner, Angier served as moderator for a panel, “Sexes, Genders, and Brains: Four Scientists, Four Perspectives,” which explored the growing scientific field that focuses on gender differences in brains. Panelists urged caution in reaching conclusions too quickly, and the danger of simplifying complex findings.
Four scholars addressed the subject during the evening presentation, one of several events held to celebrate the College’s 125th anniversary. The first two speakers were involved in the early studies on sex differences: Art Arnold, a professor in UCLA’s department of integrative biology and physiology; and Rae Silver, a psychology professor at Barnard and Columbia, and also a professor of pathology and cell biology at Columbia University Medical Center. Their presentations were followed by talks by two younger academics, who approached the topic with informed skepticism, touching on the flaws in scientific studies supporting innate sex differences: Rebecca Jordan-Young, Tow Associate Professor and chair of women’s, gender, and sexuality studies at Barnard; and Daphna Joel, professor, School of Psychological Sciences and Sagol School of Neuroscience, Tel Aviv University.
Arnold has been researching the origins of sex differences in animals since the mid-1970s. One of his early experiments explored how hormones—both in adults and in prenatal development—influence gender. When he excised the testes of a zebra finch, the bird still sang the male mating song, but less often. “The brain structure did not change much,” says Arnold. When he treated female babies with male hormones, however, he noticed permanent changes. The female sang the “male song.”
But Arnold said his thinking evolved in the mid-1990s, when he encountered a very unusual zebra finch. A gynandromorph, the finch had traits of both sexes. Its right side featured a testis and the the tell-tale male patch of orange plumage. Its left side included an ovary and the plainer plumage of a female. Yet it sang only the male song. “It doesn’t take a whole lot of thinking to realize that the sex is not determined only by hormones, or by a message sent from the gonads to the brain, but by the brain itself,” said Arnold. “It has an inherent code.”
Like Arnold, Silver’s interest in the topic of gendered traits was first piqued almost 40 years ago. Then a new parent, she marveled at the way doves, often monogamous, attend to their eggs. The father typically begins caring for the eggs only after seeing the mother in the nest. The male stays in the nest from 10 a.m. to 4 p.m.; the female incubates the eggs for the rest of the day and night. Each parent takes a shift.
“How do they know whose turn it is?” asks Silver. “The answer is in their gonadal (ovarian and testicular) secretions. If the male is paired with another male and given ovarian hormones, he will care for the eggs and young at a female-typical time of day; a female given testicular hormones will take a shift during the male’s time.”
Jordan-Young noted that many academics are “not so happy with the explicit focus on documenting differences instead of also focusing on similarities.” The latter emphasis doesn’t always provide the meaningful results, she said. As an example, Jordan-Young pointed to a study that showed vast differences in the arterial elasticity between men and women, differences which became almost negligible when controlled for height. “The most important thing for the cardiologist to know is how tall [the] patient is,” added Jordan-Young.
The final panelist, Daphna Joel, discussed how her research indicates “masculinity and femininity cannot describe individuals but can describe traits.” She spoke about what she terms a “mosaic model,” in which individuals she studied typically possessed a range of masculine and feminine traits. She added that these traits themselves vary a lot depending on class, ethnicity, age, as well as on other factors, and that the characteristics also can change; they may be expressed differently depending on environment.
Joel noted that in an unpublished study by the National Longitudinal Study of Adult to Adolescent Health base (ADD), of 5,000 American adolescents, 97 percent of them had both female characteristics (such as depression, self-control) and male characteristics (such as impulsive, violent). “We think that people come in two forms,” said Joel. “We need to start celebrating human variability.”
