December 2004 - Materials Science Institute - University of Oregon

REVIEWS
Orangutan Technology
HOW DID THE GREAT APES GET TO BE SO SMART? BY BARBARA SMUTS
AMONG ORANGUTANS:
RED APES AND THE
RISE OF HUMAN
CULTURE
by Carel van Schaik
Photographs by Perry
van Duijnhoven
Harvard University
Press, 2004 ($29.95)
In this book, Carel van Schaik, a highly
regarded Dutch primatologist now at
Duke University, concludes that “intelligence
is ... socially constructed during
development.” This won’t surprise you—
until you realize that he is referring not to
humans but to orangutans, the large red
apes of south Asia. Van Schaik proposes
that the discovery of orangutan culture
can provide a resolution to a long-standing
puzzle: Why are apes so smart? Perhaps
the complexities of great ape social
relationships selected for large brains. But
orangutans challenge this “social intelligence”
hypothesis: in the wild, they mostly
travel about by themselves, yet they are
at least as smart as chimpanzees.
Van Schaik thinks that social factors
are indeed pivotal in explaining orangutan
intelligence, but not in the way proposed
by the social intelligence hypothesis.
In a beautifully written, compelling
narrative that reads like a detective
story, he weaves together several threads
of evidence to argue that orangutan intelligence
is intimately related to technological
innovations that are passed down
through social learning.
Before hearing about the details of
orangutan culture, we accompany van
Schaik into the fetid, mosquito-ridden
swamp forests of western Sumatra (succinctly
described as human hell—but
orangutan heaven). Through the large
number of outstanding color photographs,
we meet many of the 100 orangutans
his team recognized individually.
They are handsome creatures with long
red hair, expressive faces and round eyes
that gaze out of the photographs with
keen awareness.
Orangutans do something clever that
other great apes don’t do: they use leaves
to make rain hats and leakproof roofs
over their sleeping nests. But until recently,
there was scant evidence of other
kinds of toolmaking. At van Schaik’s site,
tools were common, and he documents in
detail how the orangutans fashion tools
out of twigs. They use some tools to fi sh
for ants or termites, while they skillfully
manipulate others to get at scrumptious
seeds protected by razor-sharp hairs. At
fi rst glance, these tools do not seem to
refl ect advanced cognitive skills, but on
closer inspection van Schaik found that
each tool is carefully crafted to match the
precise needs of a given situation. And
like chimpanzees, orangutans sometimes
make tools for later use, an apparent example
of conscious planning.
How do we know that such feats
represent culture? The argument is
complex, but in brief, orangutans’ use
of tools on the islands of Sumatra and
Borneo varies geographically in ways
that cannot be explained by ecological
or genetic differences between populations.
Instead these differences are best
explained by variation in sociability, as
well as by the locations of geographic
barriers preventing cultural diffusion
between populations.
In most places, intense feeding competition
prevents orangutans from forming
groups, and in these situations, tool
use is rudimentary or absent. But swamp
forests are highly productive, allowing
van Schaik’s orangutans to associate a
lot. As a result, youngsters spend many
hours closely watching tolerant elders
make and use tools. After about seven
years of learning and practice, they, too,
become skillful tool users.
Because we already knew that material
cultures vary among chimpanzee
populations, why is the discovery of
orangutan culture so important? Van
Schaik provides three reasons: First, the
existence of culture in orangutans can
explain why they are so smart—something
the social intelligence hypothesis
ORANGUTAN mother-and-child union is one of
the longest and most intense among mammals.
Many foods eaten by these animals require
some form of processing; youngsters must
learn by observing and copying their elders.
112 SCIENTIFIC AMERICAN DECEMBER 2004
COPYRIGHT 2004 SCIENTIFIC AMERICAN, INC.
COURTESY OF HARVARD UNIVERSITY PRESS