When confronted aggressively, male rats run to the females, using a “bait-and-switch” tactic to distract the attackers.
A research group led by Joshua Neunuebel from the University of Delaware, in the USA, tracked rat behavior using machine learning to understand how they cope with the aggressive behavior of other rats.
The researchers’ findings, published in the open-access journal PLOS Biology, show that male rats reduce the aggression of encounters by running to a female rat to distract the aggressive male rat.
The researchers recorded the interactions of groups of two male rats and two female rats 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 worsened the conflict.
The researchers found that the male rat that behaved aggressively would frequently run to one of the female rats, and that this reduced aggression.
This may be a “bait-and-switch” tactic, since the aggressive male rat typically followed the other male, but then interacted with the female rat instead of maintaining the aggressive encounter.
Some other tactics, even if they avoided 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 employing this tactic, fights rarely occurred, with the male rats often remaining apart from each other, while the aggressive rat continued to interact with the female.
Although bait-and-switch may be an effective way to reduce conflicts, there may be costs for the victim, such as sacrificing time with the females, and further investigations could assess 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 the many other species with social hierarchies deal with 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 fleeing rapidly, as the aggressor’s focus shifts to her.”
