by Ed Ayres

About the author: Ed Ayres is the editor of World Watch, a bimonthly environmental magazine published by the Worldwatch Institute.

It may come as a shock to many to find that our closest genetic relatives on the planet—the primates—are diminishing in numbers at an alarming rate. If we were to draw a graph tracking the evolution of primates over the past four million years, this decline would appear, in the last 1-percent of the time-line, as a free-fall.

Primates are by no means the only category of life going into free-fall. Mammals in general are in decline; birds are in decline; amphibians are in decline; freshwater fish are in decline; and now we find that reptiles are in decline too. And, in numbers of species, all of these categories together...