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Infighting and Delays: Turns Out Baboons Vote Just Like Congress

This is what baboon democracy looks like.

by Alix Jean-Pharuns
Jun 18 2015, 6:00pm

Majority rule: it's not just for human governments. New research suggests that even among animal species with rigid social hierarchies, group decisions are more advantageous than playing follow the leader. This contradicts research up until now that has maybe overemphasized the role dominant males play in a group.

Working with the Smithsonian Institute, researchers from Princeton University, Oxford, and UC Davis studied the behavior of olive baboons at the Mpala Research Centre in Kenya. Their findings were released today in Science.

Olive baboons are green-grey monkeys native to Equatorial Africa. Nomadic omnivores, they have some one of the widest distributions of any species of monkey, able to forage for food in both low grasslands, and high in forest canopies.

Olive baboons serve as a good case study for animal group behavior. In the wild they form large, complex groups called troops that can include over 100 individuals. Baboon troops also have complicated hierarchies, with males mostly dominant over females, younger adult males mostly dominant over older adult males, and aggressive newcomers mostly dominant over more complacent long-term residents.

One such delay took "an excess of three hours," the study says

Ethologists are still trying to figure out how baboons maintain the cohesion of such large groups. In fact, the 46-member troop this research team followed stayed close together while exploring an area of more than four square miles over the research period.

The research team's findings in Kenya shed some light on how a group structured this way makes decisions. They gathered data by placing specially made tracking collars on 25 baboons, and releasing them back to their troop. The collars pinged back with information on the baboons' location and relative position to each other every second. After 14 days, the scientists had an enormous trove of data to work with, which they inputted into a program they wrote themselves to analyze.

"We had a lot of data to deal with, and it was also quite complex," Ariana Strandburg-Preshkin of Princeton, a lead researcher on the piece, said in an email to Motherboard. "Moreover, these data were substantially different from anything that had been collected before, so they did not fit neatly into any of the standard statistical testing techniques that are commonly used in science."

After analysis that took more than a year, the findings revealed some interesting phenomena. Not only was the most dominant male not more likely to be followed than anyone else, neither rank nor gender strongly correlated to being followed successfully at all.

Furthermore, troop movement wasn't exactly monkey-see-monkey-do. Instead, some pretty advanced group decision-making was at work.

As part of normal foraging behavior, troops move over great distances in search of plentiful food sources. Baboons in a troop could either be "initiators" that would forge on ahead in an attempt to get the group moving, or "anchors," stragglers that would stand pat and pull the group back. When the disagreement on which direction to move in was small, the troop would compromise by splitting the difference and heading in a direction somewhere in the middle. When the disagreement was large, the undecided members wouldn't move until they saw where the majority was headed. After a split decision, even dominant members would capitulate and head back the way the majority was moving rather than split the troop.

The process was undeniably democratic. In fact, in those moments of great disagreement, the baboons were less likely to follow along, with added initiators suggesting new directions. A desire to keep the troop together will cause baboons to delay a decision until a clear majority is reached. One such delay took "an excess of three hours," the study says.

Damien Farine, the co-author of the study, said that this dynamic makes sense for larger groups of animals.

"Actually there are many theoretical models which suggest that shared decision-making, as we observe in this troop, should be preferred in evolutionary terms... decisions made by combining the information of multiple information are typically much more accurate or more likely to be correct than decisions made by single individuals," he said in an email. "Thus, having lots of individuals 'vote' generally yields better decisions. So theory suggests that this is what most groups of animals should use. Of course, there could be exceptions to this, but this requires the fitness of all individuals in the group to be determined by the success of that dominant individual."

Obviously, it would be irresponsible to extrapolate too much from a single study on baboon behavior. But it may suggest that alpha males, or at least their influence, are less important among socially complex animals than previously thought.