Social convention of 1884, when FDR was photographed at age 2 1/2, dictated that boys wore dresses until age 6 or 7, also the time of their first haircut. Franklin’s outfit was considered gender-neutral.

But nowadays people just have to know the sex of a baby or young child at first glance, says Jo B. Paoletti, a historian at the University of Maryland and author of Pink and Blue: Telling the Girls From the Boys in America. (…)

For centuries, children wore dainty white dresses up to age 6. (…) The march toward gender-specific clothes was neither linear nor rapid. Pink and blue arrived, along with other pastels, as colors for babies in the mid-19th century, yet the two colors were not promoted as gender signifiers until just before World War I—and even then, it took time for popular culture to sort things out.

{ Smithsonian Magazine | Continue reading }

If beautiful people have more daughters, and if physical attractiveness is heritable, then it follows that, over time, women become physically more attractive than men. This indeed appears to be the case.

The logic of the generalized Trivers-Willard hypothesis (gTWH) suggests that physically more attractive parents are more likely to have daughters than physically less attractive parents. (…)

Earlier studies indeed show that women are on average physically more attractive than men both in Japan and in the United States. Analysis of the NCDS data now replicates the sex difference in physical attractiveness in the United Kingdom.

{ PsychologyToday | Continue reading }

In recent years several studies have suggested that women’s voices change at different times over the menstrual cycle, with the tone rising as ovulation approaches.

Now a study conducted by researchers at the West Texas A&M University in which women’s voices were subjected to computerized acoustical analysis contradicts those findings.

After assessing 175 samples provided by 35 study participants at various points throughout the menstrual cycles, the researchers say that changes in hormonal status have no significant impact on eight distinct voice parameters.

{ EurekAlert | Continue reading }

photo { Zev Jonas }

My own research into gender differences stems from my interest in the neurodevelopmental condition of autism. (…)

What we know is that girls, on average, make more eye contact than boys from at least 12 months of age and that, on average, language develops faster in girls than in boys, measured at 18 and 24 months of age. The question is: “Why?” Given that reduced eye contact and delayed language are two of the signs of classic autism in preschoolers, it seems necessary to consider whether autism is an extreme form of the typical male pattern of development.

{ NewStateman | Continue reading }

photo { Bill Owens }

Q: You’ve devoted your career to studying hormonal effects on the brain, including sex differences. What surprises you most about how male and female brains differ?

McEwen: There are fundamental sex differences between males and females that go well beyond reproduction. The more people look, the more differ­ences are found in both the structure and function of cells throughout the brain. It’s just mind-boggling when you see the complexities. There is recent data suggesting that glial cells from male and female neonates respond differently to estrogen, as if there’s already been some programming that keeps the male glial cells from responding to estrogen the same way as the female cells. We have evidence, as do others, that the hippocampus, a memory-related organ unrelated to reproduction, responds differently to estrogens. The female responds to estrogen by forming new synaptic connections in the hippocampus, while the male does not. But if you block the actions of testosterone in the male at birth, then the male will respond to estrogens to induce these synapses. There are many other examples. The differences include cerebellum, the autonomic nervous system, cerebral cortex, and hypothalamus. The more we look, the more sex differences we discover.

Q: Has science done enough to take into account sex differences in basic and clinical research?

McEwen: Science has not done enough to take into account sex differences in either basic or clinical research. It’s very clear, for example, that psychotropic medications and many other drugs work differently in males and females. Some of it is related to sex differ­ences in how the liver clears drugs from the body, but almost any drug that affects the brain is going to work somewhat differently in the male and female, depending on the gender first and secondly on the hormonal status. The NIH now has an office of Women’s Health Research and there are a number of private and university-sponsored programs in women’s health research. This has revitalized the study of sex differences, meaning, in large part, the study of whole animals and how they differ behaviorally and physiologically. You can’t just assume that what works in the male is going to work the same way in the female.

{ Sex Differences in the Brain, Inetrview with Bruce McEwen | The DANA Foundation | Continue reading }

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