Scientists “Were in Awe” as They Witnessed Longhorn Crazy Ants Perform Uncanny Feats of ‘Swarm’ Intelligence

Scientists studying the cooperative behavior of Longhorn Crazy Ants (Paratrechina longicornis) witnessed individual colony members performing several seemingly impossible feats of swarm intelligence, such as anticipating and clearing potential obstructions for other members transporting food back to the nest.

The team that witnessed the unexpected behavior initially assumed individual Longhorn Crazy Ants were somehow anticipating others’ needs and acting accordingly. However, laboratory experiments confirmed the ants were instead working collectively like neurons in the human brain to perform advanced planning tasks with a level of forethought well beyond any individual ant’s limited brain capacity.

Longhorn Crazy Ants received their name because whenever they discover food, they touch their abdomens to the ground every 0.2 seconds as they run. This staccato stride may appear ‘crazy,’ but the ants are actually depositing small pheromone markers on the ground with each abdomen drop. These chemical signals allow the ants to communicate with the rest of the colony by marking routes to and from food sources.

When studying this behavior in the ant’s natural setting, Dr. Ofer Feinerman, a Weizmann Institute of Science professor, Dr. Ehud Fonio, a Weizmann Institute research fellow, and colleagues witnessed something unexpected. As one team of ants was transporting prey back to the nest, other individual ants appeared to anticipate the team’s path and remove tiny pebbles that could hinder the transport ahead of time. Based on the individual ant’s poppy seed-sized brain, this level of forethought seemed impossible, leaving the scientists scratching their heads.

“When we first saw ants clearing small obstacles ahead of the moving load, we were in awe,” Feinerman said. “It appeared as if these tiny creatures understand the difficulties that lie ahead and try to help their friends in advance.”

Curious how the brains of Longhorn Crazy Ants, which typically contain 250 thousand to 1 million neurons (compared to the 86 billion in a human brain) could accomplish such impressive forethought, the Weizmann Institute-led team decided to replicate the conditions in a laboratory setting. If successful, they hoped to explain how ant colonies appeared to exhibit a form of swarm intelligence beyond the capacity of any individual ant’s brain.

The team began by substituting natural pebbles with plastic beads 1.5 millimeters in diameter, half the typical Longhorn Crazy Ant’s body. Instead of living prey, the team used pellets of cat food, which the ants prefer. After running 83 experiments, the team witnessed several instances of the crazy ant’s ‘supercolony’ displaying this seemingly premeditated obstacle-clearing behavior.

According to the team’s published study, most events involved single ants moving plastic beads located an average of 40mm from the transported food in the colony nest’s direction. The ants typically moved the obstacles up to 50mm from the anticipated path with their mandibles before being dropped. While workloads varied, the team said that one particularly industrious ant cleared a “record-breaking” 64 beads in succession.

Examples of experimental set-up and close-up of collective transport of prey and of obstacle-clearing behavior. Credit: E Fonio, D Mersch, O Feinerman.

One notable exception to the behavior occurred when the food pellet was in crumbs rather than whole. In those instances, individual ants carried the crumbs by themselves and simply walked around any obstacles, rather than the collective efforts needed to transport larger prey.

Perhaps the most unexpected realization came from the mechanics of how the ants were working together to accomplish all aspects of food transport, including the obstacle-clearing behavior. For example, ants that cleared the obstacles didn’t need direct contact with the food beforehand. Instead, their behavior was prompted by ‘forager’ ants who had previously marked the path. Even a single pheromone marker indicating a food source was enough for a worker ant to begin clearing the path back to the nest, one obstacle at a time.

Dr Danielle Mersch, formerly a postdoctoral researcher at the same institute, says that, taken together, these collective behaviors show their initial evaluation was wrong. Instead of any individual ant being smart enough to anticipate the future, the decision to clear a path happened “at the colony level.”

“Each ant follows simple cues – like fresh scent marks left by others – without needing to understand the bigger picture, yet together they create a smart, goal-directed outcome,” Mersch explained.

Dr. Feinerman believes the overriding lesson from their experiments is how individual ants’ brains worked together like a larger collective brain swarm intelligence to accomplish a task beyond the capabilities of one individual. Feinerman likened the situation to that of a human brain, where “from the activity of the relatively simple computational units, namely neurons, some high cognition capabilities miraculously emerge.”

“Humans think ahead by imagining future events in their minds; ants don’t do that,” the professor explained. “But by interacting through chemical signals and shared actions, ant colonies can behave in surprisingly smart ways – achieving tasks that look planned, even though no single ant is doing the planning.”

“We find this to be even more awe-inspiring than our initial guess,” he added.

Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.

I know this is now buried and no one else will come and read this, but this is very cool and I have an Ant “intelligence” story to share with you Badger.

Decades ago the invasive plant “Sahara Mustard” appeared and started to take over the desert southwest. They were popping up everywhere and spreading like wildfire. They were impossible to control.

The way they propagate is they dry out after they mature and then blow around like tumbleweeds. The dried seed pods pop open and spread seeds as they bounce around. Any and every “Disturbed Soil” area was vulnerable for them to grow the next time the temp was correct and they got rain.

The only way to somewhat control them was to pull them or mow them while they were green before they dried out. If you waited until they dried out to deal with them then you were just making the propagation issue even worse in your local area.

Well I got busy one year and was not around to do this weeding on one of my lots like I should have and they grew and dried out. As I was walking through them cussing myself I heard some rustling sounds in the dried Mustard plants. It was perfectly still with zero breeze so it caught my attention right away.

I started to watch a couple of the plants and realized that local Ants had now found out what these new invasive plants were and that they could utilize them as a new source for their operations. As I watched I was blown away with the harvesting operation they had going on.

A collective group was planted in the tops of the dried plants and were cutting off the seed pods causing them to fall to the ground. Then on the ground was another crew that opened the pods. Then another crew collected the seeds and took off transporting the seeds towards their nest.

So they had a three stage operation happening, one crew dropping pods, another opening them, and a third transporting them back to the nest. And there was no wasted movements wandering around, they were on a very efficient and productive mission. One of the most amazing things I have personally seen yet in nature.

Anyhow about three years after introduction to our region and the ants discovering how to utilize these plants they started to disappear and grow less frequently. Now there are almost none in that area because these ants are keeping them abated. Nature had self policed it’s self...

I also observed a similar thing happen with Goathead sticker plants one time forty years ago. We had almost three weeks of steady rain. Because of this long soaking rain a Worm appeared that we had never seen before. Apparently the eggs had been dormant for who knows... Half a century or more maybe.

But it turned out these worms like to eat the center out of the green Goathead seeds. That one worm event had almost completely eradicated the Goathead problem. Where they used to grow like a green carpet on everyone’s bare land after a rain they are now very far and few in between.

The lesson I got from these events is that nature is amazing sometimes and has a way of self regulating it’s self with natural intelligence... So thank you for sharing this cool article. Because of my own experiences I dig this stuff. :)

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