Cows are more closely related to whales than to pigs, says a genetic study that suggests a new place for whales in the evolutionary family tree.

Prior studies have indicated that whales, along with dolphins and porpoises, are rather closely related to hoofed mammals with an even number of toes. That group includes pigs, hippos, camels, cows, deer, giraffes and sheep.

The previous studies implied that a cow is more closely related to a whale than to a horse.

But even-toed mammals were thought to be more closely related to each other than any of them were to whales. The new study challenges that idea. It says hippos and cud-chewing mammals like cows, sheep and deer are more closely related to whales, dolphins and porpoises than they are to other even-toed mammals like pigs and camels.


The work is presented in the Aug. 14 issue of the journal Nature by scientists from Japan. They reached their conclusions by studying details of genetic material.