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bbcnews |  Monkeys at the top and bottom of the social pecking order have physically different brains, research has found.

A particular network of brain areas was bigger in dominant animals, while other regions were bigger in subordinates.

The study suggests that primate brains, including ours, can be specialised for life at either end of the hierarchy.

The differences might reflect inherited tendencies toward leading or following, or the brain adapting to an animal's role in life - or a little of both.

Neuroscientists made the discovery, which appears in the journal Plos Biology, by comparing brain scans from 25 macaque monkeys that were already "on file" as part of ongoing research at the University of Oxford.

"We were also looking at learning and memory and decision-making, and the changes that are going on in your brain when you're doing those things," explained Dr MaryAnn Noonan, the study's first author. 

The decision to look at the animals' social status produced an unexpectedly clear result, Dr Noonan said. 

"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."

The monkeys live in groups of up to five, so the team identified their social status by watching their behaviour, then compared it to different aspects of the brain data.

In monkeys at the top of their social group, three particular bits of the brain tended to be larger (specifically the amygdala, the hypothalamus and the raphe nucleus). In subordinate monkeys, the tendency was for a different cluster of regions to be bigger (all within the striatum).