Smile dates back to 30 million years 0%/100% 132

Smile dates back to 30 million years

Written by Aravind   |   Posted: 08/09/2016 12:35 PM IST

According to a new study, the origin of smiles goes back at least 30 million years. The study states that when human and chimp infants are dozing, they sometimes show facial movements that resemble smiles.

“About a decade ago we found that chimp infants also display spontaneous smiles,” said Masaki Tomonaga from Kyoto University in Japan. “Since we see the same behaviour in more distant relatives, we can infer that the origin of smiles goes back at least 30 million years, when old world monkeys and our direct ancestors diverged.”

“These checkups can take quite long, so the infants tend to nap in between. We took this opportunity to empirically examine the behaviour,” Fumito Kawakami from Kyoto University said. Researchers observed 58 spontaneous smiles from seven macaque infants, all of which showed spontaneous smiles at least once.

“Spontaneous macaque smiles are more like short, lop-sided spasms compared to those of human infants. There were two significant similarities, they both happened between irregular Rapid Eye Movement (REM) sleep and they show more lop-sided smiles compared to symmetrical, full smiles,” said Kawakami. “A major difference, though, is that the smiles were much shorter,” he said.

Researchers interpreted that the spontaneous smiles facilitates the development of cheek muscles, which enables humans, chimpanzees, and Japanese monkeys to produce smiles, laughs and grimaces.

By Premji

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Tags : origin of smiles  Masaki Tomonaga  Kyoto University  Japan  Rapid Eye Movement  

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