Cooperation Arises Naturally in Successful Ant Societies, Study Shows

"That’s not necessarily what I would have expected."

Every time humans form groups, tensions inevitably arise. Whether they’re part of a workplace or a classroom, individuals must inevitably decide: Should I look out for myself or help my peers? For most animals living in groups, there exists a natural tension between competition and cooperation, much like humans. But as a new paper in Nature suggests, we could learn a thing or two from ant colonies, where spontaneous cooperation appears to be the norm.

In the paper, published Wednesday, an international team of researchers shows that as the size of a group of ants increases, a beneficial division of labor emerges. Remarkably, this organization of labor occurs in groups of as few as six ants, suggesting that, even though competition among individuals might seem to make more sense when a group is very small, cooperation may, in fact, be the more natural behavior.

“One would assume that, at least initially, such individuals should compete over resources, rather than divide tasks and complement each other. But here we show that even small groups of extremely similar individuals can do much better than individuals by themselves, and that division of labor can emerge in a self-organized manner pretty much immediately,” Daniel Kronauer, Ph.D., an associate professor of social evolution at Rockefeller University in New York and one of the authors on the new study, tells Inverse. “That’s not necessarily what I would have expected, and it implies that group living might evolve fairly readily.”

Researchers marked clonal raider ants so that they could be tracked by a computer system that helped analyze their movements.

Ulrich et al

Kronauer and his colleagues based their findings on observations of a unique ant species, the clonal raider ant (Ooceraea biroi). The clonal raider ant doesn’t have queens like other species do. Instead, it reproduces by laying eggs that don’t need to be fertilized. For this reason, the researchers could start with a small number of ants and watch how a community grows and develops.

They did this by putting small groups of ants into petri dishes lined with hardened plaster and watching them for about 40 days. Marking the ants with color codes allowed the scientists to identify how they divided their labor — foraging for food, caring for eggs, disposing of waste, and so on — and where on the dishes that labor took place. When they analyzed the patterns of 112 different colonies, which ranged in size from one to 16 ants of the same age, they found that, even among small groups of extremely similar individuals, a clear division of labor quickly emerged. This pattern only increased as the colony sizes increased, and it made the colonies more stable.

Researchers observed that some ants cared for offspring while others went off to forage. This division of labor emerged naturally.

Ulrich et al

Kronauer points out that while this study provides proof of the principle that small groups of social animals can exhibit an emergent division of their labor, “that doesn’t mean that that’s always going to be the case. The precise dynamics will depend on the characteristics of the species under study, and the environment it is studied in.”

For that reason, even though it’s tempting to draw comparisons between ants and humans, it’s not always appropriate. Humans have individual, thoroughly developed cognitive abilities, while the ant colony exhibits a distributed intelligence, in which each ant makes up a part of the superorganism’s problem-solving abilities.

“What that means is that the fascinating properties we observe at the group-level emerge from local interactions between fairly simple individuals and their environment,” says Kronauer. “No single ant possesses a master plan of what the colony ought to do.” For this reason, it’s more useful to think of ants as cells in an organism, rather than compare them to humans in a society.

Kronauer says the researchers’ next steps will be to run more trials like these, but with a mixture of age ranges and a mixture of genotypes. It’s possible that these more diverse groups will be even better at dividing their labor. And even though humans are so different from ants, it’s hard not to admire their instinct to work together for the benefit of the whole society.

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