Among Orangutans: Red Apes and the Rise of Human Culture
by Carel Van Schaik
photographs by Perry van Duijnhoven
Published by Belknap Press
244 pages, 2004
Reviewed by H. V. Cordry
The orangutan has long been viewed as one of the extras in the drama of evolution. He's an Asian cousin, after all, not part of the main family line. Moreover, orangutans are famously elusive -- hard to find and easy to lose -- and past studies, unlike this one, have found them to be solitary and reclusive; by no means ideal subjects. Primatologists have tended to focus their attention on the other great apes -- gorillas, chimpanzees, bonobos.
Not Karel Van Schaik. Accompanied by Dutch artist and nature photographer Perry van Duijnhoven, Van Schaik discovered in the steamy rainforests of western Sumatra an area with more orangutans per square kilometer (ten-plus) than anywhere else in the world. For years he slogged through slimy muck and fetid pools of reddish-brown water, his head tilted sharply backward and eyes rolled skyward, like a Kansan taking in Fifth Avenue. Never mind the colorful snakes slithering round his ankles. His interest centered exclusively on what was going on in the branchy roof of the rainforest, the canopy, where orangutans spend most of their time.
Another way to find them, Van Schaik tells us, is to listen for "tree-swishing." Orangutans travel more or less as Tarzan does, except that like most movie-goers they've figured out that swinging on a vine doesn't necessarily take you to another vine. So Orangutans climb to the very top of a tree and hang on as they throw their weight in the direction they want to go. When the tree bends to the point at which they are able to grasp the next tree, in the direction they're headed, they climb aboard and let go of the one they used to get there, at which point -- swish! -- it returns to its original position.
Traveling in this manner, as Van Schaik points out, requires some fairly sophisticated calculations. For example: if I bend this treetop in the direction of that tree over there, will it reach? And if it does, will that tree be flexible enough to enable me to reach that next tree?
Pretty bright fellows, to be sure. But even more impressive are their achievements in creating tools for a variety of day-to-day needs. Back-scratchers and artificial penises are only the beginning. Van Schaik also observed the Sumatran orangutans fashioning tools for the collection of food -- one for obtaining honey and termites from tree holes and another for extracting seeds from cemengang fruit.
In both cases the orangutans made the tools before climbing the trees. It was evident, he says, that they reflected subtle differences based on how the orangutans "sized up" the trees before climbing them.
Among other things he noticed that the handles of both tools were routinely left a bit longer than necessary, and were trimmed to the correct length after the orangutans climbed the trees. In other words, they understand that "too long" is correctable without going back to square one; "too short," however, means having to discard the tool and start over.
The cemengang tool, used for prying, is probably their most impressive achievement in tool-making. Early in the season, when the cemengang begins to ripen, the cracks in its thick husks are quite thin, and the tool used to pry them open must be very slender. As the season progresses and the cracks become gradually wider, the orangutans make the tools progressively thicker.
The apes manifested similar sophistication in constructing their beds, which were built on sturdy triangular platforms with canopies to provide shelter from the rain. The beds themselves are made of broken branches as well as live limbs folded back upon themselves, giving the mattress some "inner-spring" bounce.
Tool use is only one aspect of this fascinating book, in which Van Schaik covers every dimension of orangutans' daily lives, as well as the poaching and illegal logging which threaten the red apes' survival. But it is the making of special-purpose tools and the ways in which they are used which demonstrate most clearly high intelligence of the orangutan.
In fact, Van Schaik says, their uses of the tools they make demonstrate a sure grasp of the elementary principles of construction, though of course they rely entirely on breaking and chewing the wood to achieve fits. One can scarcely imagine what they might accomplish with a credit card and access to a Home Depot.
Van Schaik is unabashedly excited about his discoveries and eager to communicate them to a general audience -- which is the purpose of Among Orangutans: Red Apes and the Rise of Human Culture -- as well as explaining why the populations of orangutans and other great apes are declining so alarmingly.
Closeup photographs by Van Duijnhoven provide unprecedented glimpses of the orangutans' day-to-day existence in a friendly but rapidly shrinking habitat. | March 2005
H. V. Cordry is a former professor and veteran journalist, now retired.