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UC Davis research reveals decision-making behavior of wild baboons

Millions of data points were collected for a study of wild baboon behavior. The study, which included UC Davis researchers, was published in Science.
Millions of data points were collected for a study of wild baboon behavior. The study, which included UC Davis researchers, was published in Science.

When it comes to making directional choices, baboons are not always playing a game of follow-the-leader.

Researchers from UC Davis recently participated in a field study that revealed that baboons often make decisions about day-to-day movement based on consensus. The study, published Thursday in Science magazine, suggests that even in hierarchical societies where a dominant individual does exist, a democratic process often prevails.

Baboons typically live in troops of up to 100 individuals but tend to move through the day as a unified group, leaving researchers wondering whether a single individual is dictating movement or if shared decision-making ever comes into play.

In the past, researchers have been limited to less-complex species when they wanted to simultaneously monitor individual behavior. In species such as birds, fish or insects, each individual can often be assumed to have an identical relationship with every other member of the group.

Baboons, on the other hand, live in societies where no relationship between two members is exactly the same.

To investigate how one individual baboon moves relative to a second individual baboon within a troop, the collaborative study used highly advanced GPS tracking devices at the Mpala Research Center in Kenya. The trackers monitored 26 wild olive baboons during daylight hours over approximately 14 days of movement, collecting a data point on each baboon every second and generating almost 20 million total data points over the course of the study.

From the large data set, movements between two individual baboons were extracted and then classified as either a “pull” or “anchor” scenario. If a baboon, acting as the initiator, travels in one direction, a second baboon has the choice to either follow and be pulled in a similar direction, or to not move and act as an anchor, in which case the initiator will return to the original location.

Even though in the past it had been assumed that decisions were driven by dominance, the researchers “realized that it doesn’t make sense that a single individual would have all the say,” according to joint first author Damien Farine, a postdoctoral fellow at UC Davis, the Smithsonian Tropical Research Institute and the University of Oxford.

Farine told The Bee “that decision-making and leadership in animal groups is fascinating.”

If two initiators or two subgroups of similar size begin to travel in opposing directions, other baboons will choose to pursue one chosen path over the other if the angle between the two directions is approximately greater than 90 degrees. If however, the difference is less than 90 degrees, the baboons will compromise and instead move in a path somewhere along the middle. When two subgroups of baboons that are significantly different in number want to move along divergent paths, often the followers will choose the path that the majority of baboons have selected.

Analysis of the data revealed that dominant males did not have a higher success rate than any other baboon in initiating movement throughout the day, and successful initiation of movement was even independent of the sex of the initiator.

Margaret C. Crofoot, an associate professor at UC Davis and a research associate at the Smithsonian Tropical Research Institute, also participated in the study.

In addition to Farine and Crofoot, the study involved researchers affiliated with Princeton University, the Smithsonian Tropical Research Institute, University of Oxford, the Max Planck Institute for Ornithology and the University of Konstanz.

Katie L. Strong: (916) 321-1101, @katielstrong

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