The cheetah, a virtual running machine, is a model of aerodynamic engineering. Its skull is small and lightweight and its limbs are long and slender, not unlike a greyhound's. Its heart, vascular system, lungs and adrenal glands are all enlarged, enhancing the animal's ability to accelerate and navigate during a high-speed chase.

These various adaptations have made the cheetah a particularly effective hunter on the flat, open savannas of central and southern Africa, where it has a higher rate of successful kills than even the lion. After stalking its prey the cheetah launches a high-speed chase (often clocked at up to 70 miles per hour), pushes over or trips its winded victim and swiftly kills the prey by strangulation in its strong feline jaws. . . .

How is one to explain the cheetah's march to extinction? Our investigations of the past five years suggest that the species has somehow lost its genetic variation. As a result of intensive inbreeding generations ago, each cheetah appears to be nearly identical with every other cheetah. Ever since Charles Darwin wrote "On the Origin of Species" a century ago it has been evident that genetic uniformity would hamper the ability of a species to adapt to such ecological perturbations as temperature shifts, drought, glaciation or the ascendance of new viruses or bacteria. . . .

When a species has little genetic variety, its ranks are unlikely to contain many members whose genetically determined traits are well suited to withstand ecological change; the species competes poorly for survival under changed conditions and may die out.