Hurtling toward a planet without apes.

• Position: Extinction

Great apes, humans' closest relatives, could face extinction within our lifetime, University of Southern California, Los Angeles, biologist Craig Stanford warns in Planet Without Apes. The four species of great apes --chimpanzees, orangutans, bonobos, and gorillas--are being decimated through disease, loss of habitat, regional political instability, and even consumption as bush meat.

Already endangered, our closest evolutionary cousins could disappear within a generation, declares Stanford, codirector of the USC Jane Goodall Research Center and professor of biological sciences. He has studied primates on three continents. His work includes more than 20 years studying chimpanzees in East Africa, with his early years spent working with Goodall, the famed primatologist. "Great apes are our next of kin. They are endlessly fascinating and they inform us about the nature of being human."

Stanford describes the value of building an ape-centered ecotourism industry that employs locals, using tourist dollars to give the apes' neighbors a tangible stake in their conservation. Gorilla-trekking has provided African governments and local people...