Recent research published in the journal Science revealed that mice demonstrate altruistic behaviors by assisting unconscious companions, similar to how bystanders help a collapsed person. Two research teams, one led by Wenjian Sun from the University of Southern California and another by Fangmiao Sun from the University of California in Los Angeles, systematically tested these behaviors under laboratory conditions, providing evidence for their helpfulness.
The mice were observed engaging in behaviors resembling first aid measures. When familiar mice became unconscious, helper mice immediately sprang into action, first sniffing and then licking the unconscious mouse's fur, particularly focusing on the face and throat area. In more than half of the trials, the caring mice pulled the unconscious mouse's tongue out of its mouth to enlarge the airways and did not stop nibbling until they had pulled and tugged on the tongue.
"These behaviors remind us how humans are taught to clear the airways of an unconscious individual during cardiopulmonary resuscitation," wrote the research team. In some experiments, if a foreign object such as a plastic ball was placed in the mouth of the motionless mouse, the helping mouse usually removed it before attending to the tongue. In 80 percent of cases, the helping mice successfully removed the object, according to New Scientist.
The actions of the helper mice had an impact on the recovery of their unconscious companions. The anesthetized or sedated mice that were cared for by helper mice recovered faster than those without such assistance, waking up and starting to walk again more quickly. Once the anesthetized or immobilized mice had recovered, the helper mice stopped their care, demonstrating that they helped only as long as necessary.
The role of oxytocin, often referred to as the cuddle or bonding hormone, was found to be crucial in the helping behavior. Li Zhang and his colleagues at the University of Southern California discovered that the behaviors were driven by oxytocin-releasing neurons in the amygdala and hypothalamus regions of the brain, according to New Scientist. When the release of oxytocin was blocked, the helping mice reduced their reanimating actions to a minimum, even if they were cage mates.
"They start with sniffing, and then grooming, and then with a very intensive or physical interaction," said Li Zhang. "They really open the mouth of this animal and pull out its tongue,” he added.
The researchers suggest that helping motionless group members is widespread among social animals. Reports have circulated for some time that certain species, such as elephants, dolphins, and chimpanzees, assist their fellows in distress. For example, dolphins have been observed attempting to push a distressed pod mate to the surface so it can breathe. Zhang and his colleagues think the behavior in mice is innate rather than learned, observing that all the tested animals were just two to three months old and hadn't seen this behavior or anesthetized cage mates before.
While the motivation behind the helper mice's actions is difficult to identify, the authors emphasize that curiosity and the desire for social interaction likely played no role. The sex of the mice and the helpers had little influence on the helping behavior. The findings suggest the complexity of social behaviors in animals and indicate that caring for motionless group members is likely an innate social behavior that is widespread among many species.
"It is generally difficult to interpret animal behavior, and caution is advised in attributing intentionalities to sequences of behaviors as cause-effect," noted the researchers.
The article was written with the assistance of a news analysis system.