Laughing apes.

The AP is laughing it up over sensitive research into what makes apes laugh:

To investigate that, Marina Davila Ross of the University of Portsmouth in England and colleagues carried out a detailed analysis of the sounds evoked by tickling three human babies and 21 orangutans, gorillas, chimps and bonobos.

After measuring 11 traits in the sound from each species, they mapped out how these sounds appeared to be related to each other. The result looked like a family tree. Significantly, that tree matched the way the species themselves are related, the scientists reported online Thursday in the journal Current Biology.

You can read the article summary here, including the phrase: “the current work examined the acoustics of tickle-induced vocalizations.”