TEARS OF THE CHEETAH

The head of the National Institutes of Health’s Laboratory of Genomic Diversity weds gene sleuthing to studies of animals in the wild and combines them with molecular clocks to time evolutionary events, in the process educating readers about what has happened and what can happen to species, including us.

Besides his lab work, O’Brien has also been active in the field studying humpback whales in the Pacific, pandas in China, orangutans in Borneo and Sumatra, and sundry other species, especially cats, worldwide. The slow dwindling of cheetahs in Africa, he tells us, is not caused by human depredation but by the species’ lack of genetic diversity. A catastrophic event in the past probably created a population “bottleneck,” reducing the group to a few incestuous survivors. The result is lowered resistance to infection, lowered fertility, and an increase in harmful genes. The same thing happened, for other reasons, to the Florida panther and to a group of African lions isolated in the Ngorongoro crater, where massive numbers died from a plague of blood-sucking flies. These findings led O’Brien and others to argue for a change in the Endangered Species Act to permit breeding an endangered species with a closely related but healthier subspecies. In other chapters the author explains how genetic analyses were used to show that whales were being illegally harvested in Japan, that pandas are bears, not raccoons, and that human survivors of past great plagues may carry mutations resistant to HIV. O’Brien also explains his crucial evidence at a Canadian murder trial: genetic analysis of a cat hair found on a leather jacket spattered with the victim’s blood and buried in the woods helped convict the wife killer—it matched a blood sample from the family cat.

A rich collection of cautionary tales with considerable relevance—carefully elucidated throughout—to human health and disease.