Gorillas get civilized
Rhitu Chatterjee
Do as I do: A young female gorilla at Zoo Atlanta uses a stick to
probe for food that is out of her reach. Because the behavior was
not seen in other gorilla groups faced with the same dilemma, it
qualifies as culture.
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ST. LOUIS, MISSOURI: Gorillas deserve to join the club of "cultured
apes." That's the conclusion of the first large-scale study of multiple
behaviors in zoo gorillas, reported here yesterday at the annual meeting
of the American Association for the Advancement of Science.
Culture is defined as a range of behaviors learned from others that
varies with the group one belongs to.
For example, chimpanzees belonging to one population in Mahale,
Tanzania, groom each other with one hand while clasping their free hands
together.
Another group in the same region has a slightly different tradition:
grooming partners touch their free wrists.
Yet despite growing evidence for culture in chimpanzees, bonobos, and
orangutans, not much is known about gorilla culture or whether it exists
at all.
The elusive nature of most gorilla species makes it difficult to
gather behavioral data in the wild.
So a team led by primatologist and conservationist Tara Stoinski of
Zoo Atlanta in Georgia decided to monitor the behavior of captive
gorillas in 17 American zoos. Earlier observations by her group had
shown that gorillas could copy their group members.
When one gorilla used sticks to pry apart electric wires around trees
to get at the bark, for example, others in the group followed suit.
But in order for this behavior to be considered culture, other
populations of gorillas would need to react differently.
By asking zoo officials to fill out a survey of their gorillas'
behaviors, Stoinski and colleagues discovered that gorillas in fact do
vary widely in how they deal with the same situations.
For example, while members of some zoo groups regularly used sticks
to retrieve peanut butter or baby food, other groups didn't use tools at
all.
In addition, gorillas in some zoos clapped their hands to invite
others to play, while those in other zoos did not.
That matches the definition of culture, Stoinski concluded. The
findings make the first strong case for the existence of culture in
gorillas, says Andrew Whiten, an evolutionary and developmental
psychologist at the University of St. Andrews in the United Kingdom, who
studies social learning and culture in chimpanzees
He notes that Stoinski's data from captive populations is "more
robust" than his own field data because all zoo environments are fairly
similar, allowing her to control for the complex effects environment may
have on social behavior.
(Science Now) |