No kidding -- apes can laugh, too.
Humans and apes learned to laugh from a shared ancestor who gave both species the ability to crack up at a joke, a new study shows.
Researchers tickled three human babies and 21 apes, comparing the laughing sounds both made and creating a map of how the sounds related to one another.
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Both responded similarly to the tickling, though the apes' laughter was slightly deeper than the responses of the human babies.
The distinct traits the apes and humans shared indicated an ancestral link between the two, the scientists from the University of Portsmouth in England reported in the study, published online Thursday in the journal Current Biology.
The study gives strong evidence that laughter developed in the two species as an evolutionary trait, Frans de Waal of the Yerkes National Primate Research Center at Emory University said of the report.