Talking apes? That's a laugh, say scientists
By Roger Highfield, Science Editor
SCIENTISTS have solved the mystery of why apes cannot be taught to speak -
by tickling them.
A team at the University of Maryland Baltimore County found that their
grunt-like chuckling shared rhythmic characteristics with that of humans,
thought to have evolved from laboured breathing during play.
But the study, which also involved 51 human volunteers, revealed a
different link between the breathing and laughter patterns of man and
apes.
Prof Robert Provine and Dr Kim Bard studied - and tickled - seven
chimpanzees from the Yerkes Regional Primate Centre.
They found that human laughter was composed of stereotyped, vowel-like,
notes - ha, ho, he - lasting about one-fifteenth of a second and made only
while breathing out. Chimps made only one "laugh note" per inhalation or
exhalation.
The difference could be appreciated by placing a hand on the abdomen while
laughing, or imitating the pants of a chimp. Laughter produced a steady
contraction of the diaphragm, while panting produced pulsations.
Prof Provine believes that this different laughing mechanism accounts for
why chimpanzees cannot produce human-like speech, which involves
modulating sounds during only exhalation.