New research published May 28 in Evolutionary Psychology found that male and female artists had significantly higher prenatal testosterone levels than male and female non-artists — a finding that has implications in the debate over the evolution of the arts.
Italian researcher Danae Crocchiola wrote in her study that the underrepresentation of women in the arts could be “due to historical and cultural constraints.” However, this could also have a “hormonal-based explanation,” namely differences in prenatal testosterone levels.
“The levels of hormone exposure in utero seem to determine a wide range of physiological and psychological conditions,” she noted.
Exposure to testosterone in the uterus has been linked to lasting changes in brain structure. Researchers cannot directly measure prenatal testosterone levels in adults. But the difference between the length of the index finger to the ring finger has been found to be an indicator of prenatal testosterone. This ratio is known as 2D:4D — or second digit to fourth digit.
“A lower ratio between the second and fourth finger reflects embryonic exposure to high testosterone levels, and a higher ratio is the result of the exposure to a low testosterone prenatal environment,” Crocchiola explained.
For her study, Crocchiola recruited 25 male and 25 female visual artists, along with another 25 men and 25 women who were not artists. All of the participants had their hands photographed and completed the Bem Sex Role Inventory questionnaire, a survey designed to measure masculinity and femininity.
Crocchiola found the average 2D:4D ratios were significantly different between artists and non-artists. She didn’t, however, find any significant differences between the average digit ratios of male and female artists. She also didn’t find a correlation between artistic ability and masculinity.
“As the results demonstrate, our sample of visual artists had lower 2D:4D ratios compared to controls. However, decreasing 2D:4D ratio was not associated with increasing artistic ability, without relevant sex difference, and no significant relation between visual art works sold and lower 2D:4D ratio was recorded,” Crocchiola wrote.
Crocchiola believes her study provides evidence that artistic ability is an evolutionary adaptation rather than simply a side effect of humans’ increased brain size.
“According to one school of thought, the ability to produce and appreciate art is a co-opted trait that, at the beginning, had a different primary adaptive function,” Crocchiola explained. “From a different perspective, art is considered to be a trait originally selected for in the domain of natural environment-driven competition (i.e., a character able to enhance reproductive success chances).”
In the latter perspective, “cultural displays and, more specifically, art may signal a direct benefit to the female’s offspring by advertising the male’s good genes,” she wrote. “If artistic behaviors are linked to prenatal testosterone, as the present study suggests, this strengthens the hypothesis of interdependence between art, cultural displays in general, and sexual selection.”