Ants’ collective intelligence exceeds that of humans

There are only two animals capable of transporting an object so large that it can only be moved by cooperating: humans and ants. And not every species in the Formicidae family is capable of such a feat. Just 1% are able to work in teams to move a T-shaped object through two narrow doorways placed close together. The experiment is a standard of computer science and artificial intelligence, but a group of entomologists utilized it to compare the cognitive abilities of insects and people, both individually and in teams. Under equal conditions, ants perform better than us in collective intelligence.

The longhorn crazy ant (Paratrechina longicornis) is among the 1% of the Formicidae species who can use their strength and body to solve this kind of puzzle. They get their name from their erratic, seemingly insane movements — they rarely traverse in straight lines. But from those wild moves emerges a collective intelligence. As they do on an individual level, when in groups, the ants will sense, integrate and respond to their environment. Ofer Feinerman’s lab at the Weizmann Institute of Science in Israel has studied them for years. Recently, its researchers designed a challenging experiment for the bugs in which they had to get a piece of wood in the shape of a “T” out of a room, through a small door which led to a second, narrower room leading to an even smaller door, finally ending up in a third room in the direction of their nest. To see who could accomplish the task more quickly between insects and humans, the team made five T’s of varying sizes and constructed a human-sized version of the same door-room sequence. They conducted a series of tests with single ants and people (using smaller T’s), then groups of six to nine, then large teams of up to 25 people and 80 ants.

Their results, which were published in the Proceedings of the National Academy of Sciences journal, demonstrate how the collective intelligence of ants takes hold, but also, how humans have trouble making decisions when they are in large groups. It’s obvious that involving more individuals allows a group to carry more weighty T’s. But the project also shows how the sum of individuals’ intelligence is not equal to that of the collective. The insects that tried to get out the small T’s failed many more times than when several got together, and large groups had even higher rates of success, thanks to a kind of emergent memory.

“An ant that carries a load on its own doesn’t remember the way it moved for very long: it changes constantly, especially if it hits a wall,” Feinerman, the study’s lead author, says in an email. “The group of ants can remember the direction in which they were headed for a few seconds ago and persist in walking in that direction, even if an edge of the load they are carrying hits a wall,” adds the entomologist. This fits into what they call emergent intelligence, “a memory that the group of ants has, but the individual ant does not.” The crazy ants’ ability may have an evolutionary basis. “This is a species of ants that tend to give up at the slightest conflict. In this context, this means that, if a neighboring colony of another species also arrives looking for food, they will chase the crazy ants away,” Feinerman explains. The only chance the crazy ants have of getting food is to cooperate to get it to their nest as quickly as possible. “Therefore, they become amazing problem-solvers when it comes to transporting large loads in complex environments,” says the Israeli scientist.

The comparison between these special ants and humans led to various results. On an individual level, ant versus human, man always bested the bug. In groups, both small and large, the homo sapiens were more efficient than the ants at moving the T. But there was one variation of the experiment in which ants beat humans: during the large group test in which they were not permitted to speak or make gestures. To make sure they followed directions, researchers made subjects wear masks and very dark sunglasses in an attempt to equalize the communication capacity of the two species. The edges of the T carried by humans were equipped with force sensors in order to measure the intensity and direction of the participants’ movements. This was the only way they had to communicate their intentions. The result was that, in the majority of the groups’ attempts, the ants were more efficient.

“People in a non-communicative group (i.e., with a communication scheme similar to that of ants) start to behave a bit more like them and, in so doing, their performance levels decrease,” says Feinerman. The experiment has led to a better understanding of the cognitive abilities of the crazy ants as a group, but also those of humans. “An individual person and an individual ant are, of course, very different. The person transforms the maze in his mind into a graph, which is an extreme dimensional reduction. Instead of exploring the whole complex maze, only a handful of nodes are explored,” says the entomologist. He adds, “To solve the puzzle, people need to try to figure out which node is connected to which other nodes and slowly discover the links between unconnected nodes until they find their way through the maze.”

When people discover a link between nodes, they use long-term memory to remember that action and not repeat it later. A single ant is very different. Unable to reproduce the puzzle in its brain, it lifts the load and tries to move it in all directions. Feinerman recalls that in this, they surpass most other species, which will commonly pick up the T and pull it toward the nest using the straightest and shortest path, even if the object cannot fit, without ever trying anything different. But when many ants get together, “they acquire some human-like characteristics,” says the entomologist.

In their conclusions, the authors share two primary findings. “Our results exemplify how simple minds can easily take advantage of scalability, while more complex minds need ample communication to cooperate efficiently.”

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