Cultured 'man of forest' in peril

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http://www.japantimes.co.jp/cgi-bin/getarticle.pl5?fe20030109rh.htm

 

NATURAL SELECTIONS

 

Cultured 'man of forest' in peril

 

By ROWAN HOOPER

 

Culture, from a biological point of view, is behavior

that is passed on through social contact. But what are

the origins of culture? And what is it about humans

that has allowed us to develop such rich and diverse

cultures?

 

Our relatives might hold the answers.

 

Chimpanzees, our closest relatives, show a wide range

of cultural behaviors, from tool use to signaling.

That indicates that culture arose at least 7 million

years ago, the point at which ancestors of chimps and

humans diverged.

 

But work published in Science last week on a great ape

unique to Asia suggests that primate culture has far

older origins.

 

There are two closely related species of great ape in

Asia, Pongo pygmaeus, the orangutan, and Homo sapiens,

us. Carel van Schaik at Duke University in Durham,

N.C., and a group of international scientists, have

shown that wild orangutans exhibit true cultural

traits. This pushes back the origin of culture to when

the ancestors of chimps and orangutans diverged,

around 14 million years ago.

 

Orangutans are only found on the islands of Sumatra

and Borneo, where human activity (particularly the

spread of palm oil tree plantations, but also illegal

logging and gold mining) has resulted in their

populations plummeting by 50 percent over the last 10

years. Eighty percent of orangutan habitat has

disappeared in the last 20 years.

 

And despite decades of research, we have only just

found that orangutans have culture.

 

The discovery comes not a moment too soon: the World

Bank estimates that mechanized logging in the

Kalimantan forest, Indonesian Borneo, will result in

its total loss by 2010.

 

In Sumatra, orangutans are disappearing at a rate of

1,000 per year; in Borneo the rate is very likely

higher.

 

The most optimistic predictions give the orangutans 10

years before they go extinct.

 

" Some people have asked us 'Haven't you learned enough

by studying these animals for some 30 years?' " said

van Schaik.

 

" And it is obvious from these findings that we

haven't. Some of the areas included in this study have

already been lost to illegal logging. And even if

somehow you could restore the forest and the animals,

just as with human cultures, once a culture is gone,

it's gone. "

 

In earlier work, van Schaik found that groups of

orangutans in Sumatra use sticks to pry out fat-rich

seeds from a fruit called neesia, thereby avoiding the

stinging hairs that surround the seeds.

 

Significantly, such tool use was present only among

certain groups, even when the habitat appeared to be

the same. For example, orangutans on one side of a

river used tools on the fruit, while those on the

other, blocked by the river from social contact with

the other group, did not. The observation suggested to

van Schaik, a professor of biological anthropology and

anatomy, that orangutan behaviors might be culturally

transmitted.

 

To explore the possibility, van Schaik held a workshop

where orangutan researchers from around the world,

including primatologist Akira Suzuki of Kyoto

University, also the author of the Science paper, met

and pooled their data.

 

" It was an open-ended exercise, in which we looked at

each other's videos and other data from our own

observation sites, " said van Schaik. " We looked for

behaviors that were different among the different

groups.

 

" While we were by no means certain that we would come

up with any evidence for cultural variability, we

ultimately identified 24 behaviors that likely

represent cultural variants. Frankly, we were all

rather giddy at the end, when we realized what had

come out of our data. "

 

Newly identified orangutan cultural behaviors include

making a spluttering " raspberry " or " kiss-squeak "

sound; using leaves as protective gloves or napkins;

and using sticks to poke into tree holes to obtain

insects or to extract seeds from fruit.

 

Orangutans also have " snag-riding, " the apparent

equivalent of a sport. The animals ride falling dead

trees, grabbing hold of other vegetation before the

tree hits the ground. And if that sounds like fun,

what about this: sticks are also used by both sexes as

" autoerotic tools " for sexual stimulation.

 

The researchers were worried that the behaviors they

identified might be nothing more than the animals'

adaptation to varying habitats, without social

transmission. In other words, that they wouldn't

demonstrate true culture.

 

" However, we saw that habitat did not have a

significant impact on similarity of these behaviors, "

said van Schaik. " And our confidence that we were

seeing cultural transmission was increased by analyses

showing that proximate sites showed more behavioral

similarity than distant sites. This finding strongly

suggested that we were observing a process of

innovation and cultural diffusion. Also, we found the

biggest behavioral repertoires within sites that

showed the most social contact, thus giving the

animals the greatest opportunity to learn from one

another, " he said.

 

The findings shed light on the evolution of culture in

humans.

 

" All these findings suggest that the first ancestral

man-apes must have had a pretty solid evolutionary

cultural foundation on which to build, " said van

Schaik.

 

Van Schaik and his colleagues distinguish four kinds

of culture -- labels, signals, skills and symbols --

of which all great apes show the first three. Human

culture shows far more sophisticated development of

all four. However, observations of chimpanzees and

orangutans have revealed hints of symbol use, and

further study might reveal clearer evidence of

symbols, said van Schaik.

 

Van Schaik's work is supported by that of a Japanese

Ph.D student, Noko Kuze, who is based at the Tokyo

Institute of Technology, but is currently working on

orangutan behavior in the rain forest reserve at

Sepilok in Malaysian Borneo. At Sepilok, orangutans

that have been orphaned are rehabilitated and released

into the reserve. Kuze's field work suggests possible

cultural behaviors.

 

" Rehabilitant orangutans can learn how and what they

can eat in the forest without any assistance from

humans, " Kuze told me when I met her in September last

year. " Maybe they learn that from predecessors in the

forest. " Predecessors are young and adult orangutans

who have been released before.

 

Kuze also emphasized the precarious nature of the

orangutan's existence. " The most important thing we

must do is conserve their natural habitat. At the same

time, we need more research on the ecology of wild

orangutans. Because now we don't have enough

information about their ecology for conservation, " she

said.

 

And if we don't act immediately, the orangutan (Malay

for " man of the forest " ) will be replaced by its

relative, the plundering brute, the man of the city.

 

Orangutans can be seen in the wild at the Borneo Rain

Forest Lodge in Danum Valley, Sabah, Malaysia. For

more information check www.borneorainforestlodge.com

 

Information on Sepilok Orangutan Rehabilitation Center

can be found at www.sabah-travel.com

 

Rowan Hooper welcomes comments at rowan.hooper

 

The Japan Times: Jan. 9, 2003

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