New finding: Mice don't laugh with their mouth but with their ears

How do we know when a rat is having fun? The answer lies in its ears. A new study shows that, similar to how people laugh to express satisfaction, rats will relax their ears, which will then flush.

In the past, there have been many studies examining the behavior of rats when sad or anxious, mainly because they are the most experimental organisms, and they want to know when they are affected pole. For example, mice that are worried, will separate from the herd and do not communicate, or will not try to escape when being lifted up by the tail. Scientists have even invented a "mouse grimace scale (rat grimace scale)" to assess how painful the mouse is suffering through facial expressions.

But not much research has been done to identify positive emotions in mice.

A happy mouse laughs with his ears.(Photo: PLOS ONE).

Researchers have recently discovered that when tickled, rats seem to show pleasure, even though they produce sounds - even though the frequency is too high for reception. of human ears - in the same way as when we laugh. Based on this, the researchers decided to use abdominal abduction to see how the facial expressions changed when they were happy.

Scientists are experimenting with rats.(Photo: Internet).

The 15 subjects were teased by the research team, then photographed on the face to see if there were any significant changes. They found that the mice actually "laughed" with their ears. When the mice are happy, their ears hang down and relax, reddened at the same time. When they are unhappy, for example, when they are attacked by white noise, their ears will prick forward.

Left: The mouse is happy, when their ears hang down, relax, slightly pink.Right: Mice are unhappy, when their ears prick forward.(Photo: Internet)

There is still no clear mechanism behind this phenomenon. Their ears are drooping probably due to the relaxation mechanism in the mouse , but the change in the ear area is quite difficult to explain. They turn pink because of the increase in blood flow to their ears, but it is unclear why they are having fun, or because of increased physical activity when their stomachs are tickled.

How they feel when they laugh and drop their ears, this is even more confusing, because we cannot ask you directly to gnaw this hairy. But scientists can look at the results of brain scans, and it is because their brains have similar structures and mechanisms that are similar to us, including similar chemicals and functions, so no it's too far away to think that they feel the same to us.