Bangkok, Thailand Wah, wow, hoo!
Turns out humans aren t the only primates using songs to warn of
life s dangers and travails.
White-handed gibbons in Thailand s forests have been found to
communicate threats from predators by singing the first time the
behavior has been discovered among non-human primates, researchers
said Wednesday.
While other animals have been shown to use song to attract mates or
signal danger, researchers writing in this month s science journal
PLoS One said their study was the first to show gibbons a slender,
tree-dwelling ape issuing song-like warnings to each other.
This work is a really good indicator that non-human primates are
able to use combinations of calls … to relay new and, in this case,
potentially lifesaving information to one another, said Esther
Clarke, a University of St. Andrews graduate student and co-author of
the study.
This type of referential communication s commonplace in human
language, but has yet to be widely demonstrated in some of our closest
living relatives the apes, she said.
Along with Klaus Zuberbuhler from St. Andrews in Scotland and Ulrich
Reichard of the Max Planck Institute in Germany, Clarke spent 2004 and
2005 at Khao Yai National Park in Thailand observing groups of
gibbons.
Mostly black with a white face, gibbons live in the treetops and are
known for issuing elaborate hooting sounds that echo across the forest
for up to a half mile to advertise pair bonds or attract mates.
To test the primates response to danger, the team conducted a series
of experiments in which they put models of predators snow leopards,
pythons and crested serpent eagles near a group of gibbons and then
made audio recordings of their response.
What they found, Clarke said, is that the gibbons approached the
potential predator and began warbling a series of sounds wahs, wows
and hoos that were picked up by other gibbons, who then repeated
the calls to others.
The sounds made when encountering a predator were more chaotic and
louder than those used to win over a mate, Clarke said.
Gibbons can rearrange their songs to denote different circumstances,
much like we do with words, she said.
Thad Q. Bartlett, a gibbon expert at the University of Texas at San
Antonio, said the findings were interesting and significant.
From a cognitive standpoint, the claim that gibbon calls are digital
is interesting because this is one of the hallmarks of human language,
that is, the ability to rearrange discrete elements to create new
meanings, he said in an e-mail.
Bartlett also said the findings provide further insight into the
behavior of gibbons, contradicting earlier suggestions that their
small social network a male, female and their offspring was
largely a result of the apes facing few threats.
Because large group size is often seen as a response to predator
pressure, researchers have long assumed that gibbons are largely
immune from predators, he said. To my mind, this research further
demonstrates the importance of predator pressure to the evolution of
gibbon social systems.
