Monkey Leaders and Followers Adapted Different Brains

Follow the leader does not necessarily apply to monkeys, or at least, not to their brains. New research shows that monkeys on different ends of the social spectrum have physically different brains.

A particular network of brain areas was bigger in monkey leaders compared to their followers, according to the study, suggesting that primates (including humans) can have specialized brains on either end of the hierarchy.

Described in the journal PLOS Biology, researchers compared brain scans from 25 macaque monkeys, paying close attention to changes while performing memory and decision-making tasks.

"It was surprising. All our monkeys were of different ages and different genders - but with fMRI (functional magnetic resonance imaging) you can control for all of that. And we were consistently seeing these same networks coming out," Dr. MaryAnn Noonan, the study's first author, explained to BBC News.

In monkeys at the top of their social group, certain parts of the brain - specifically the amygdala, hypothalamus and raphe nucleus - tended to be larger, while their subordinates boasted bigger brains in other regions.

Also, researchers note that in monkeys at either end of the social ladder, compared to those lying in the middle of the spectrum, activity in these brain regions was more synchronized.

"It suggests that at either end [of the hierarchy], you really need a specific set of skills to be successful, and those skills are making higher neural demands on those areas of the brain," Noonan told BBC.

Noonan and her team can't be sure where these differences originate from, but they suspect that it's a combination of both nature and nurture -meaning they might be born with it, as well as develop it over time based on their social status.

The correlations identified in the study could possibly be applied to other primates as well, like apes and humans, researchers say.

"The regions that we've found are all there in humans and they all do similar things," Noonan said.