More smart critters. Now killer whales.
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More animals join the learning circle
* 27 August 2005
* NewScientist.com news service
* Betsy Mason
KILLER whales and chimpanzees both pass on "traditions" to other members
of their group, according to two separate studies of feeding behaviour.
The findings add to evidence that cultural learning is widespread among
animals.
One study involved killer whales at Marineland in Niagara Falls in
Ontario, Canada. An inventive male devised a brand new way to catch
birds, and passed the strategy on to his tank-mates. The 4-year-old orca
lures gulls into his tank by spitting regurgitated fish onto the water's
surface. He waits below for a gull to grab the fish, then lunges at it
with open jaws. "They are in a way setting a trap," says animal
behaviourist Michael Noonan of Canisius College in Buffalo, New York,
who made the discovery, "They catch three or four gulls this way some
days."
Noonan had never seen the behaviour before, despite three years of
observations for separate experiments. But a few months after the
enterprising male started doing it, Noonan spied the whale's younger
half-brother doing the same thing. Soon the brothers' mothers were
enjoying feathered snacks, as were a 6-month-old calf and an older male.
Noonan presented the research this month at the US Animal Behavior
Society meeting in Snowbird, Utah.
Wild dolphins off the west coast of Australia were the first marine
mammals in which cultural learning was observed. They apparently learn
from group-mates how to use sponges to protect their snouts while
scavenging (New Scientist, 11 June, p 12). But the evidence from killer
whales is much more conclusive because the process was observed from
start to finish.
Some researchers have suggested that many purported examples of cultural
transmission can instead be explained by individuals discovering the
skill on their own rather than following another's lead. But because the
gull-baiting behaviour is so unusual, "it would be hard to argue that it
is individual learning", says ethologist Janet Mann of Georgetown
University in Washington DC, one of the authors of the dolphin sponging
study. Behavioural scientist Andrew Whiten of the University of St
Andrews in the UK agrees, "This is a particularly clear set of
observations."
Whiten and his colleagues have meanwhile shown in a separate study that
when chimpanzees learn a skill from their peers, they tend to stick with
that method even if it isn't the most effective. Whiten's team taught
two female chimps how to get food from a complicated feeder using a
stick to move a barrier. One chimp learned to lift the barrier while the
other was taught an apparently more efficient poking method. The chimps'
group-mates were then allowed to watch their respective experts at work.
The chimps followed the lead of their own expert chimp - the poker's
group preferred to poke and the lifter's group lifted (Nature, DOI:
10.1038/nature04047).
And even when some lifters learned to poke, the majority reverted to the
group's original lifting strategy.
Getting the message
Chimpanzees appear to be capable of communicating using sounds that
refer to specific objects, according to a study of sounds made in
response to different foods. It is the first time this ability has been
demonstrated in chimps.
Primatologist Katie Slocombe of the University of St Andrews, UK,
recorded the grunts made by chimps at nearby Edinburgh Zoo as they
collected food at two feeders. One dispensed bread, considered a
high-quality treat, and the other doled out apples, a much less
sought-after snack.
Slocombe then played back the recordings and watched the reactions of a
6-year-old male named Liberius. The results were striking. After hearing
a bread grunt, Liberius spent far more time searching around the bread
feeder, while an apple grunt would send him hunting under the apple
feeder. Slocombe presented the work at the US Animal Behavior Society
meeting in Snowbird, Utah, this month.
This is the first convincing evidence of "referential communication" in
chimps, says primatologist Amy Pollick of Emory University in Atlanta,
Georgia. Earlier research with a close cousin of the chimpanzee - a male
pygmy chimpanzee, or bonobo, named Kanzi - showed that he made specific
sounds for four different things: bananas, grapes, juice and yes. But
the researchers did not test if the sounds conveyed any meaning to other
bonobos, and the same experiments have never been done in chimpanzees.
Liberius, on the other hand, was able to take cues from apple and bread
grunts made by at least three different chimpanzees.
Slocombe plans to expand her study to include chimps at the Leipzig Zoo
in Germany and hopes to confirm whether the grunts refer to specific
foods or to their relative quality.
Betsy Mason
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http://www.newscientist.com/channel/life/mg18725144.000
--
John Hachmann aa #1782
"Those who can make you believe absurdities can make you commit atrocities"
-Voltaire
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