Being in a baboon troop is pretty much just like "Mean Girls"—everyone prefers to spend time with those who are just like them in temperament as well as background.

The observation was made after six years of study in Namibia's Tsaobis Nature Park, an arduous process of slowly tracking two large troops of baboons (Papio ursinus) from dawn until dusk to observe their interactions, with the results now published in the Royal Society Open Science.

"Within these big troop networks over time social preferences are generally dictated by age, rank, personality and so on," said Dr. Alecia Carter from the University of Cambridge's Department of Zoology and first author of the study. "This happens in humans all the time; we hang out with people who have the same income, religion, education etc. Essentially, it's the same in baboons."

For the study, Carter placed items that would be unfamiliar to the baboons near paths they use and measured how long they spent investigating these novelties, and whether they ate them. She found that it is the juveniles that are the most important “information generators,” learning what is safe and tastes good. She used this to rate each member of the troop for boldness.

While it is always amusing to discover how like us animals can be, Carter's observations were part of a quest for something deeper. As she says on her blog, “Animals can get information in two ways: either by sampling their environment themselves, i.e. personal information, or by watching other individuals, i.e. social information. I investigate whether, how and why individuals differ in their preferences for using personal and social information.” A preference for associating with those of similar age or personality seems to work against this, making it hard for young baboons to learn from older ones, or for the cautious to take advantage of lessons learned by the brave.

"Our analysis is the first to suggest that bolder and shyer baboons are more likely to associate with others that share this personality trait," said senior author Dr. Guy Cowlishaw of the Zoological Society of London. "Previous studies in other animals—from chimps to guppies—suggests that time spent in the company of those with similar personalities could promote cooperation among individuals.”

As to why baboons cluster by personality, the researchers are not sure. Cowlishaw says boldness “could be a heritable trait, and the patterns we're seeing reflect family associations,” but this remains uncertain.

They also found that the baboons prefer to spend time with members of the opposite sex, with females spending a lot of time grooming males. Associations such as grooming can help keep the troop bonded and aid in learning. However, there is also a dark motivation.

"Chacma baboon males will often commit infanticide, killing the babies of rivals,” says Carter. Bonding with males can be a way to get them to protect a female's offspring. Another technique is for the females to be “as promiscuous as possible to confuse the paternal identity.”