Excerpt from The Human Age by Diane Ackerman, plus links to reviews, author biography & more

APPS FOR APES

On a blue-sky day at the Toronto zoo, flocks of children squired by teachers and parents mingle excitedly between exhibits. Some kids pull out cell phones and send texts or snap pictures with the easy camaraderie of wired life. Clustered noisily along a large domed habitat that's been designed to look like a multistoried Indonesian forest complete with tree nests and meandering stream, they watch two orangutan moms and young weaving fluently through a maze of thick, flat vines, which in reality are fire hoses. Orangutans are the swivel-hipped aerialists of the ape world, with ankle-length arms built for sky-walking, opposable thumbs and big toes, swervy knees, and bowed ankles. As a result they can twist into almost any angle or pose. In amazement I watch a young female swing smoothly from vine to vine, then grab two with wide-spread hands and feet, flatten her hips, rotate her wrists, and hang still as an orange kite snagged in the treetops.

Even with knuckle-walking far behind us, we sometimes feel the urge to brachiate in that way, hand over hand on a playground's "monkey bars." Yet we're stiff-jointed and feeble by comparison. We may share 97 percent of our genes with orangutans, but they remain the ginger-haired tree-dancers and we the chatterbox ground-dwellers. In the wild, orangutans spend most of their lives aloft, maneuvering with pendulous grace, as they pursue mainly solitary lives, except during childrearing. Moms raise one kid every six to eight years, doting on their young and teaching them the ways of the forest, where edible fruits abound but must be safely judged—and some aren't easy to peel or crack open because the rinds are either tough or spiked like medieval weaponry.

One of the orang moms swoops down to the ground as if on an invisible slide, picks up a stick, and fishes around inside a tree trunk until she snares edibles that she coaxes up and eats. The once-raucous students grow quietly transfixed as they peer at her skillful tool-using, especially the way she downs the morsels like eating peas off a knife.

Beyond the glade, well away from the crowds, I find a long-haired seven-year-old boy staring intently at an iPad and tapping the screen with one finger, which unlooses the pocket-sized roar of a lion followed by the buzzy honk of a flamingo. He glances at me with big brown almond-shaped eyes under a shag of thin auburn hair.

If my mane of black hair, frizzed wide in the heat, amuses him, he doesn't laugh. After holding my gaze for the sheerest moment, he turns back to his way-more-interesting iPad, gripping it with both hands, then with hands and naked feet. Surprisingly clean feet, I must say, and the largest hands I've ever seen on a seven-year-old. My whole hand would fit into his palm.

But that's not unusual for a Sumatran orangutan, and Budi, whose name means "Wise One" in Indonesian, is growing quickly and starting to show signs of puberty: the peach-fuzz beginnings of a mustache and beard, and the billow of what will one day be a majestic double chin that puffs and vibrates when, as a two-hundred pound adult, he gulp-warble-croons his operatic "long call." There's no sign yet of the giant cheek pads between the eyes and ears that will frame his face, acting as a megaphone to shoot his long calls half a mile through dense canopies.

His companion, Matt Berridge, is a tall, slender, forty-something, dark-haired man, holding the iPad near the bars so that Budi can play with it but not drag it off and deconstruct it. The zoo's main orangutan keeper, Matt is the father of two young sons, both iPad devotees. Ape boys will be ape boys, after all.

The Apps for Apes program is sponsored by Orangutan Outreach, an international effort to help wild orangutans, whose bands are dwindling, and improve the lives of those in captivity around the world, by providing mental enrichment and more stimulating habitats. Nourishing the mind is a high priority because these great apes are about as smart as human three- to four-year-olds, and just as inquisitive. Clever tool-users, they wield sticks for many purposes, from batting down fruit to fishing for ants and termites. They fashion leaf gloves to protect their hands while eating thorny fruit or climbing over prickly vines. Day-dwellers, they fold a fresh mattress of leaves in the canopy before sunset each day. They lift leaf parasols overhead to shelter from extreme sun and fold leaf hats and roofs to keep off the rain. For drinking water, in a pinch, they chew and wad up leaves to make a sponge, then dip it into rain-filled plants. Before crossing a stream, they'll measure the water depth with a branch. They build dynamic mental maps of all the food trees in their leaf-cloud canopies.

Excerpted from The Human Age: The World Shaped By Us by Diane Ackerman. Copyright © 2014 by Diane Ackerman. With permission of the publisher, W. W. Norton & Company, Inc. All rights reserved