How Ants Hold Grudges

Did you know ants can actually learn from experience? It’s true! A group of scientists recently discovered this fascinating behavior. They ran a series of experiments to see how ants respond to past encounters with other ants—and the results were eye-opening.

Here’s what they found: if an ant had a bad experience with a particularly aggressive ant from another nest, it would remember it. Later, when it came across ants from that same nest, it would react more aggressively.

On the flip side, if the ant’s earlier interactions were with passive, non-threatening ants, it would behave more calmly the next time it met ants from that nest. Basically, ants hold grudges—or, at least, they remember who gave them a hard time!

So how do ants even tell each other apart? It’s all about smell. Each nest has its own unique scent, and ants use this to identify who’s “us” and who’s “them.” Scientists already knew that ants are especially aggressive toward their closest neighbors—biting, spraying acid, the whole deal. But why do nearby nests get all the hostility? Turns out, it’s because ants recognize the smell of attackers and become more combative when they encounter that familiar scent again.

The experiments were pretty interesting. In the first phase, the scientists exposed groups of ants to different experiences. Some met aggressive ants from a specific nest (let’s call it Nest A), while others met aggressive ants from Nest B or just interacted with their own nestmates. After a few days, when these ants faced off with competitors from Nest A, the ones with prior experience of aggression from that nest were significantly more aggressive.

To dig deeper, the scientists tweaked the experiment. This time, they introduced both aggressive and passive ants by making some of them passive (cutting off their antennae—ouch!). Ants that only met passive rivals weren’t as aggressive later on.

One of the researchers summed it up perfectly: “We often think of insects as mindless robots, but this study shows ants can learn and even hold grudges!” The team is now exploring whether ants’ sense of smell adapts based on these experiences. Pretty cool, right?