Rats Smile With Their Ears, Study Reveals

First Posted: Dec 17, 2016 03:06 AM EST

Some animals like dogs show they are happy by wagging their tails. Meanwhile, rats show an unusual way on how to be happy and it could be seen through their ears, according to a new study.

The study was printed in PLOS One. It was led by a team of researchers at the University of Bern in Switzerland. The researchers discovered that rodents display their happiness by relaxing their ears and then they would flush pink.

In the previous studies, they indicated that rats like to be tickled on their bellies. With this, the scientists use tickling to determine how rats show their happiness.

In the new study, the team chose 15 male Lister hooded lab rats. They subjected them into types of environmental experiences and labeled them as either positive and negative. The positive experiences have tickling sessions and the negative would make the rats subjected to random blasts of white noise. The team also used microphones to record the vocalizations by rats and observations of their physical features such as changes to faces were made.

The results showed that rats with tickling sessions vocalized more and their ears became droopier and pinker. On the other hand, they did not display visible reaction during the negative experiences. The team said that the lowered ears of rats were in a more relaxed state. The reason for having pinker ears when they are happy was not clear. They indicated that it might be a sign of happiness or just an increased blood flow because of the physical exertion they made when they were being tickled and happy, according to

Rats are also referred to as long-tailed rodents and of medium size. They belong to a superfamily Muroidea. They are also known as mice by their size. The most noticeable rats are the black rat and the brown rat. They are known as the Old-World rats or true rats and originally come from Asia.

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