Ants, Like Humans, Change Priorities When Making Decisions

We have to make decisions every day. What will we eat? When will we sleep? Animals also have to make these decisions as they survive in the wild--sometimes as a group. So how do animals make these choices? Scientists have looked a bit further at group decision-making processes in ants and have discovered that animals can change their strategies based on experience.

"The interesting thing is we can make decisions and ants can make decisions-but ants do it collectively," said Taka Sasaki, one of the researchers, in a news release. "So how different are we from ant colonies?"

In order to find that out, the scientists examined Temnothorax rugatulus ant colonies. They gave these colonies a series of choices between two nests with differing qualities. In one treatment, the entrances of the nests had varied sizes and in the other, the exposure to light was manipulated. Ants prefer both a smaller entrance size and a lower level of light exposure, which means they had to prioritize.

"It's kind of like a human and buying a house," said Stephen Pratt, one of the researchers, in a news release. "There's so many options to consider--the size, the number of rooms, the neighborhood, the price, if there's a pool. The list goes on and on. And for the ants it's similar, since they live in cavities that can be dark or light, big or small. With all of these things, just like with a human house, it's very unlikely to find a home that has everything you want."

After the ants faced the series of choices, they re-prioritized their preferences based on the type of decision they faced. For example, ants that had to choose a nest based on light level prioritized light level over entrance size in the final choice. On the other hand, ants that had to choose a nest based on entrance size ranked light level lower in the later experiment. This means that, like people, ants take the past into account when weighing options. The difference is that ants somehow do this as a colony.

Currently, the scientists are looking into exactly how ants make this collective decision. It could lead to further insight as to how collective decision-making works and differs from individual decision-making. This, in turn, could reveal a bit more about how humans make choices.

The findings are published in the journal Biology Letters.