Beauty is famously in the eye of the beholder; but it’s also in the beholder’s brain, and may work differently in the brains of men and women.

In men, images they consider to be beautiful appear to activate brain regions responsible for locating objects in absolute terms — x- and y-coordinates on a grid. Images considered beautiful by women do the same, but they also activate regions associated with relative location: above and behind, over and under. The difference could be the result of evolutionary pressures on our hunter-gatherer ancestors.

The findings, published Monday in the Proceedings of the National Academy of Sciences, are preliminary and based on a small number of people, but intriguing nonetheless.

“This the first study about neural activation in aesthetic tasks to include sex as a variable,” said study co-author Camilo Cela-Conde, an evolutionary anthropologist at Spain’s Universitat de les Illes Balears.

Earlier studies on sex-based cognitive differences have found that men seem to have a heightened sense of absolute location. Women, by contrast, are quicker to process relative values.

How these brain systems became tied to the perception of beauty, widely considered a defining human trait, is an evolutionary mystery. According to Cela-Conde, aesthetics may simply be a byproduct of other cognitive tasks.

Differences in cognitive tasks, however, may be less mysterious: For much of human history, men and women had different jobs. Their brains may thus have developed in subtly different ways.

“In current hunter-gatherer groups, men are in charge of hunting; meanwhile women collect,” said Cela-Conde. “If this is a scheme that can be extended to ancestors’ behavior, then we can think about a selective pressure to increase the capacity of spatial orientation in men, and the capacity to identify edible plants and tubers in women.”

In the study, 10 men and 10 women looked at images of modern and classic paintings, as well as photographs of landscapes, artifacts and urban scenes. The researchers recorded their reactions with a magnetoencephalograph, which monitors real-time neural activity by measuring magnetic fields generated by electrical currents in the brain.

The subjects varied as to what they considered beautiful, but brain patterns were consistent: coordinate-processing activation in both men and women, and category-processing in only women.

These differences do not seem to translate into differences in the actual experience of beauty. In earlier research, said Cela-Conde, both men and women describe beauty as being “original, interesting and pleasant.”

However, as the differences were expressed only in response to images the subjects found to be beautiful, they do not seem to reflect a general sex-based difference in perception.

As the brain regions involved are far more developed in humans than chimpanzees — our closest living relative — Cela-Conde’s team suspects that the differences are rooted in early hominid divisions between men and women.

Another possible explanation is language-based: Coordinate-reading brain systems are less activated by linguistic communication than categorical systems.

The differences observed in the study would then originate in another sex-based difference, albeit an arguable one: Women are especially talkative.

Brandon Keim