When confronted aggressively, male rats run to the female rats, using a bait-and-switch tactic to distract the attackers.
A research group led by Joshua Neunuebel at the University of Delaware in the United States tracked rat behavior using machine learning to understand how they cope with the aggressive behavior of other rats.
The findings of the researchers, published in the open-access journal PLOS Biology, show that the male rats reduce aggression during encounters by running to a female rat to distract the aggressive male.
The researchers recorded the interactions of groups of two male rats and two females over five hours. Like many other animals, rats have social hierarchies, and in almost all the groups recorded, one of the males was always significantly more aggressive than the other.
Social interactions can be difficult to study objectively, so the researchers used a machine learning approach to analyze the aggressive interactions and how the rats respond.
In total, they observed more than 3,000 altercations between the male rats, and the machine learning algorithm helped the researchers determine the most likely responses to aggression and whether these actions resolved or escalated the conflict.
The researchers found that the aggressive male often ran toward one of the female rats, and that this reduced aggression.
This may be a bait-and-switch tactic, since the aggressive male typically followed the other male, but then interacted with the female instead of continuing the aggressive encounter.
Some other tactics, even if they prevented aggression for a moment, would later escalate into full fights. However, the researchers found that this was not the case after the bait-and-switch tactic.
After using this tactic, fights rarely occurred, with the male rats often remaining separated from one another, while the aggressive male continued to interact with the female.
Although bait-and-switch may be an effective way to reduce conflicts, there may be costs to the victim, such as sacrificing time with the females, and further investigations could examine whether these tactics are effective in larger groups of rats.
This study also demonstrates how machine-learning tools can be useful for understanding animal behavior, and similar tools could be used to study how many other species with social hierarchies handle aggression.
The authors add: “Using artificial intelligence, we found that male rats move toward nearby females to distract the aggressors and attenuate the conflicts. After an aggressive encounter, the aggressed male briefly engages with a female before quickly fleeing, as the aggressor’s focus shifts to her”.
