WASHINGTON A male chimpanzee may beg for food
from another chimpanzee by gesturing with an extended arm and
Under different circumstances, the same chimpanzee may use
the same gesture to try to coax a female chimpanzee to have
sex. And the same gesture may be used after two males fight as
a signal of reconciliation.
In research published on Monday, scientists seeking clues
to the origins of human language analyzed the way two types of
apes genetically closely related to people -- chimpanzees and
bonobos -- use such hand and limb gestures to communicate.
They found that the apes use such gestures much more
flexibly -- in different contexts with apparently different
meanings -- than they used facial expressions and
vocalizations. The findings, they believe, lend support to the
idea that human language started with such gestures rather than
"We are a naturally gesturing species that may have first
developed language in the gestural domain, and once the brain
parts related to language were well developed, then started
using speech," primatologist Frans de Waal of Emory University
and Yerkes National Primate Research Center in Atlanta said in
a telephone interview.
De Waal conducted the study, published in the Proceedings
of the National Academy of Sciences, with fellow Yerkes
researcher Amy Pollick, who observed and videotaped 13 bonobos
at the San Diego Zoo and 34 chimpanzees at Yerkes.
De Waal and Pollick tallied 31 hand and limb gestures and
18 facial expressions and vocalizations. Both types of apes
used facial and vocal signals in similar and predictable ways.
Screaming was used by both, for example, in fear and pain.
But a particular gesture appeared to communicate wholly
different messages depending on the social context in which it
was used -- for example if food was involved or mating.
"A WIDE RANGE"
"Gestures are used across a wide range of contexts whereas
most facial expressions and vocalizations are very narrowly
used for one particular context," De Waal said.
Although all primates use their voices and facial
expressions to communicate, only people and the great apes --
chimpanzees, bonobos, orangutan and gorillas -- use these types
of gestures as well.
De Waal noted that great apes first appeared about 15 to 20
million years old, meaning such gestures may have been around
"A gesture that occurs in bonobos and chimpanzees as well
as humans likely was present in the last common ancestor,"
Pollick said in a statement. "A good example of a shared
gesture is the open-hand begging gesture, used by both apes and
This last common ancestor may date to about 5 million to 6
million years ago.
The researchers cited differences between the bonobos, the
gentler and more sex-crazed, and chimpanzees, the more violent.
The bonobos employed various gestures more flexibly, combining
them with vocalizations and facial expressions to communicate a
De Waal said there might have been advantages to developing
language from gestures before the spoken word. For example,
silent communication might have been better when hunting for
He added that when the apes gesture, they like to use their
right hands, which is controlled by the left side of the brain
-- the same side where the language control center appears in
the human brain.