SMILING CHIMPANZEE FULL

'All cultures recognize a variety of mouth gestures as indexes of inner emotional states. Somehow we seem to have taken the fright-threat sort of smile and extended it to strangers as a presumably friendly smile. On the other hand, a non-toothy, not-so-broad-but-open-lipped smile is associated with pleasure in human infants.

Among human babies, however, the 'tooth-baring' smile is associated less with friendship than with fright-which, one might argue, is related to the tooth-baring threats of baboons. 'The evolution of smiles is opaque and, as with many evolutionary accounts of social behavior, fraught with just-soism. A broad curriculum across the arts and sciences at both undergraduate and graduate levels is complemented by numerous research centers, as well as facilities and offices around Japan and the world.Anthony Stocks, chairman and professor of anthropology at Idaho State University, responds: Kyoto University is one of Japan and Asia's premier research institutions, founded in 1897 and responsible for producing numerous Nobel laureates and winners of other prestigious international prizes. The paper 'The first smile: spontaneous smiles in newborn Japanese macaques ( Macaca fuscata)' appeared 2nd August, 2016 in Primates, with doi: 10.1007/s1032-7 It may be the case that many mammal infants display spontaneous smiles, in which case smiling would have an older evolutionary origin. 'There are case reports about mice laughing when they get tickled and dogs displaying facial expressions of pleasure. So is smiling special to monkeys and primates? Tomonaga says he won't rule out the possibility. The team interpreted that spontaneous smiles facilitate the development of cheek muscles, enabling humans, chimpanzees, and Japanese monkeys to produce smiles, laughs, and grimaces. On the other hand, this study suggests that spontaneous smiles don't express feelings of pleasure in chimpanzees and Japanese monkeys rather, the smiles are more similar to submissive signals (grimaces) rather than smiles (play faces). Some researchers have argued that infants' spontaneous smiles exist to make parents feel that their children are adorable and to enhance parent-child communication. 'A major difference, though, is that the smiles were much shorter.'

SMILING CHIMPANZEE FULL

There were two significant similarities they both happened between irregular REM sleep, and they show more lop-sided smiles compared to symmetrical, full smiles,' says Kawakami. 'Spontaneous macaque smiles are more like short, lop-sided spasms compared to those of human infants. In total they observed 58 spontaneous smiles from seven macaque infants, all of which showed spontaneous smiles at least once. 'We took this opportunity to empirically examine the behavior.' 'These checkups can take quite long, so the infants tend to nap in between,' says Kawakami. Lead author Fumito Kawakami caught macaque infants smiling when they were receiving routine health checkups. 'Since we see the same behavior 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.'

'About a decade ago we found that chimp infants also display spontaneous smiles,' says study author Masaki Tomonaga. Researchers at Kyoto University's Primate Research Institute show that this not only happens to higher-order primates like humans and chimpanzees, but also in newborn Japanese macaques, which are more distant relatives in the evolutionary tree. These facial expressions - called spontaneous smiles - are considered the evolutionary origin of real smiles and laughter. Kyoto, Japan - When human and chimp infants are dozing, they sometimes show facial movements that resemble smiles. view moreД¬redit: Kyoto University Primate Research Institute

When human and chimpanzee infants are dozing, they sometimes show facial movements that resemble smiles. Video:В The short, lop-sided smiles of baby Japanese macaques.

Smiling chimpanzee