In the first study of its kind to involve primates, researchers have found that troops of baboons move in a similar way to schools of fish or flocks of birds, with no single animal taking the lead. Despite living in a highly hierarchical society, it seems that baboons take a democratic tack when deciding on which direction to move in.

“Despite their social status, it's not necessarily the biggest alpha males that influence where groups go,” explained Margaret Crofoot, assistant professor at UC Davis, who co-authored the report. “Our observations suggest that many or all group members can have a voice, even in highly stratified societies.”

As described in Science, the team studied a troop of baboons in central Kenya and were able to GPS-track 25 members, gaining detailed second-by-second location data over a period of two weeks. This gave the scientists unprecedented insight into how the primates move at the group level.

Wild olive baboons live in strictly hierarchical groups, with dominant males often displacing subordinate ones. While females will stay within the group in which they’re born, the males will be turfed out when they reach maturity and will have to join another. This means that they then have to work their way up the social ladder from the bottom, competing with each other directly and indirectly for access to females and food.       

You would be forgiven then for thinking that those who are the most dominant – or who have the highest rank – are the ones making the decisions as to where they go. But to the surprise of the researchers, they found that the baboons’ movements fitted almost perfectly with the patterns predicted by theoretical models based on how fish school or birds flocks. For example, if one baboon should decide to move away from the group, it could potentially "drag" another in the same direction. However, should the second member decide not to follow, then the first would return to the troop.

^{Two of the researchers preparing the GPS collars. Credit: Rob Nelson}

“We were really stunned by how well our data fit the predictions of the theoretical model. There has not been a really good test of this before, and never with free-ranging animals in the wild,” Damien Farine, another of the co-authors along with Ariana Strandburg-Peshkin, told IFLScience. “What is surprising about this is that the model was very simple, and made up of lots of identical ‘individuals’ or agents. The fact that we find the same pattern replicated in a socially complex species such as the baboon is fascinating.”

This whole project was only achievable with the incredible resolution now possible with sophisticated, custom-designed GPS devices that take a location point every second, which they managed to fit on 80% of the troop. The resulting 20 million data points then had to be analyzed using newly developed advanced analytical techniques.

Farine believes that this shared decision-making is probably not limited to baboons, but common to any animals that form large groups. This is because it is probably not a very good tactic for a dominant male to control how the rest of the group moves, as it would almost certainly create unnecessary conflict.

“Our next step is to investigate if, and how, certain individuals can have disproportionate influence on the group within this shared decision-making context,” said Farine. “We have some ideas, for example individuals may form alliances with other group members so that when they initiate movement, they can more easily gain the majority.”