Young babies giggle like chimps, say researchers
Humans start out in life laughing in the same way as their ape ancestors, a study has found.
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, rather than a sudden, 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 showed that the youngest babies often laughed both while breathing out and in.
But laughter from older babies was mainly produced on the exhale.
The researchers are looking to see if there is a link with what triggers laughter, which also changes with age.
Like non-human primates, infants and younger babies laugh when they are tickled or engaged in other forms of physical play.
As humans get older, laughter also begins to arise from social interactions.
Dr Sauter added: “I’d be interested in seeing whether our findings apply to other vocalisations than laughter.
“Ultimately, the research could offer insight into vocal production of children with developmental disorders.
“If we know what normally developing babies sound like, it could be interesting to study infants at risk to see whether there are very early signs of atypical development in their non-verbal vocalisations of emotion.”
The findings were presented at the annual meeting of the Acoustical Society of America in Victoria, Canada.
