Baboons Stay Together by Making Compromises As a Group

Biological Strategy

Baboons

Sam Stier

Image: David Mark / Pixabay / Free non-commercial use

Coordinate by Self-Organization

To create and maintain a healthy community of individuals and ecosystems requires that living systems coordinate their activities. Coordination doesn’t necessarily mean that there’s a leader orchestrating what happens. In nature, coordination is usually achieved through self-organization. In a flock of geese flying in a V-formation, for example, there’s no lead goose controlling where all of the others fly. The flock uses this formation because each goose gains energy from air vortices created by the goose in front of it. The lead goose doesn’t gain that benefit, so when it tires, it moves back and another goose takes the front position.

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Mammals

Class Mammalia (“breast”): Bats, cats, whales, horses, humans

Mammals make up less than 1% of all animals on earth, but they include some of the most well-known species. We know first-hand some of the characteristics that make mammals unique, like having hair, being able to sweat, and producing milk through mammary glands. Another critical shared feature is a set of highly-specialized teeth. Unlike sharks or alligators, for example, whose teeth are generally all the same size and shape, mammals have differently shaped teeth in different areas of the jaws to target specific foods or foraging strategies.

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Baboons stay together through distributed decision-making and compromise

Olive baboon troops travel together in large groups as they forage for food, and they tend to follow one another as they move across the land. The troops consist of dominant males and females that make many of the troop’s decisions. Sometimes one baboon will be interested in fruit in one area, while another baboon may be interested in eating some leaves in another area. Because they must always stay together, how do baboons decide as a group which baboon to follow? Interestingly, these dominant individuals don’t determine the direction the troop forages in. Instead, the troop’s direction is shaped moment to moment by a set of simple rules.

If two leading baboons are heading in different directions, a follower baboon has to make a choice. Does it follow one of the leaders, or go in its own direction? It turns out that it depends on how far apart the two leading baboons are. Imagine there is an angle created between the two leading baboons and the follower. The leading baboons are the two points at the ends of the lines that make up the angle, and the follower is the vertex, or point where the two lines intersect. If the angle created between the three baboons is greater than 90 degrees, the follower baboon follows one of the leaders. If the angle is less than 90 degrees, the follower baboon moves in between the two baboons so that it splits the difference between them.

Hence, the movement of baboons through their environment is a continuous compromise. The group may not go where any one individual would choose, but each individual can shape, and be shaped by, the group’s direction. Most importantly, this system of internalized decision-making rules keeps the group’s many individuals together.

Image: BombX / CC BY SA - Creative Commons Attribution + ShareAlike

Olive baboon troop

Image: Babouin / CC BY - Creative Commons Attribution alone

Olive baboon foraging

Last Updated May 14, 2020

References

“In events with two initiators, followers consistently choose one direction or the other when the angle between the initiators’ directions is greater than approximately 90°, but they compromise when the angle falls below this threshold…” (Strandburg-Peshkin et al. 2015: 1360)

Journal article

Shared decision-making drives collective movement in wild baboons.

Science | Strandburg-Peshkin, A., Farine, D.R., Couzin, I.D. and Crofoot, M.C.

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