Credit: M. WESSELS

Curr. Biol. 10.1016/j.cub.2009.05.028 (2009)

A study of recordings made while researchers tickled infant humans and juveniles of several species of ape shows that the relationship between different species' laughter closely matches an independent family tree derived from genetic differences.

Biologists have debated whether human laughter, which sounds distinct from that of apes, consists of true innovations, or simply continues evolutionary pathways pioneered by ape-like ancestors. Marina Davila Ross of the University of Portsmouth, UK, and her colleagues conclude from their analysis of the recordings that tickle-induced laughter has a common evolutionary origin in apes and humans. They add that the analysis could have implications for the evolution of human speech.