Scientists have discovered that mice try to bring unconscious mice back to consciousness by licking and biting their faces. (Photo by Richard Drury/Getty Images)
Researchers have found that mice can provide first aid if they find another mouse that has lost consciousness.
They try to bring their friends back to life by licking their faces or even touching their mouths or tongues, according to a study published Feb. 21 in the journal Science.
The scientists noted that mice that spent more time with a needy individual showed more active behavior, including mouthing, biting and licking, which contributed to a faster recovery.
“The most striking finding in this study is the presence of instinctive emergency responses in animals that allow them to resuscitate unconscious and even recently deceased partners. This study provides the first documented evidence of resuscitation-like behavior in naive, untrained mice,” lead author Wenjian Sun, a postdoctoral fellow at the University of Southern California, told Live Science in an email.
Sun noted that helping other animals that are injured or sick has been observed in a variety of species, including dolphins, elephants and non-human primates.
“These behaviors often include touching, licking, prodding, and in some cases more intense physical actions such as hitting. However, the specific behaviors such as biting and tongue-thrusting observed in this study have not been described previously,” Sun added.
In the paper, the researchers describe how dozens of mice responded after being introduced to another mouse in a state of need. These states included stress and unconsciousness in the other mouse.
Mice spent more time in physical contact with another mouse if it was unconscious than if it was conscious, and the intensity of grooming increased over time if the other was unconscious. On average, mice spent 47% of the 13-minute test interacting with the unconscious partner.
As the test progressed, grooming became more intense, from sniffing and licking to nipping at the mouth and tongue of the other mouse, with more aggressive behavior seen in pairs of mice that knew each other better. More than 50% of the mice ended up tugging at the tongues of their unconscious mates.
The mice could also determine that their mate was unconscious without relying on visual cues, initiating grooming behavior even in the dark.
More grooming behavior was correlated with better recovery in the unconscious mice, with a faster return to consciousness later. When their companion regained consciousness, the first-aid mouse stopped performing grooming behavior.
“It appears that the animal is able to recognize the unconscious state of its partner, with the absence of a response initiating the behavior and the restoration of the response stopping the behavior,” Sun explained.
While these results suggest that mice have an instinct to help others, just like humans, the researchers cannot pinpoint exactly why they act this way.
“We do not rule out the possibility that the animal is simply driven by instinctive impulses to perform these actions – an instinct that may have developed over time during evolution – rather than acting with the conscious intention of bringing its partner back to life,” Sun said.
In another study, also published Feb. 21 in Science, other scientists at the University of California, Los Angeles, discuss the neural mechanisms that underlie this behavior. They found that courtship is likely driven by the release of oxytocin — a hormone that plays a key role in social bonding, sex, and reproduction — in areas of the brain called the amygdala and hypothalamus.
“Deactivating the neurons responsible for oxytocin, or blocking its receptors, disrupted behavior,
Sourse: www.livescience.com
