New-born babies laugh like chimps, says study
New-born babies laugh in a similar way to their non-human primate ancestors, scientists have learned.
Like chimpanzees, they both exhale and inhale as they gurgle happily.
In contrast, adults, and older offspring, generally only laugh with an out-going breath.
Psychologists made the discovery after studying videos of 44 infants and children aged between three months and 18 months at play.
Lead researcher Dr Disa Sauter, from the University of Amsterdam in the Netherlands, said: "Adult humans sometimes laugh on the inhale, but the proportion is markedly different from that of infants' and chimps' laughs.
"Our results so far suggest that this is a gradual shift."
The recordings were analysed by 102 psychology students who assessed the extent to which the babies were laughing on the exhale and on the inhale. The findings were presented at the annual meeting of the Acoustical Society of America in Canada.