24 July 2007
A fertile domestication of cats

Cats will always remain mysterious animals--but exactly where they came from is no longer a riddle. A genetic study has shown that the ancestors of all of today's domestic cats prowled the Near East. The work bolsters the notion that cats became useful to humans when agriculture started--which scientists believe happened in the Near East--forcing people to protect grain stores from rodents. "There's been an awful lot of guesswork on how one of the most interesting experiments in natural history took place," says Stephen J. O'Brien, chief of the Laboratory of Genomic Diversity at the National Cancer Institute in Bethesda, Maryland, an author on the study. Based on morphology, scientists already presumed that wildcats--as opposed to other species such as ocelots and pumas--were the progenitors of today's pussycats. The controversy, O'Brien says, concerned where domestication occurred and how many times it might have happened.

Wildcats are a single Old World species. Five subspecies live in Europe, sub-Saharan Africa, China, Central Asia, and the Near East. The researchers collected genetic material from 979 modern-day cats, domestic and wild, from three continents. Their analysis indicates that the common ancestors of all domesticated cats lived in the Near East some 130,000 years ago. They were wildcats living in the Fertile Crescent--the area extending from the Eastern Mediterranean around Turkey and down into Mesopotamia--"exactly the place where humanity settled down to agriculture ten to twelve thousand years ago," says O'Brien. The team found five lineages of mitochondrial DNA (mtDNA) in modern felines. Because of this variation, the researchers believe domestication occurred a half-dozen times or so in the Middle East.

This analysis fits with the oldest archaeological evidence for cat domestication--in 2001, scientists in Cyprus unearthed a cat skeleton that had been buried with a human 9500 years ago (Science, 9 April 2004, p. 189). It also fits with the fact that "domestication of pretty much everything else in the world came from the Fertile Crescent," says Carlos Driscoll of Oxford University, U.K., the first author on the study, which appeared online in Science today. Geneticist Robert Wayne of the University of California, Los Angeles, says, "the data are very convincing." He says it's noteworthy that domestication took place in a relatively limited area, since animals such as pigs, cattle, and horses usually show more complex origins. "This suggests that cats were domesticated for a geographically specific purpose--maintaining rodent free grain stores--unique to the Fertile Crescent," he says. The next puzzle, says O'Brien, is locating the genetic mutations responsible for making cats tame. Finding these "tameness genes" is one of the goals of a cat genome project currently being conducted by a consortium that O'Brien leads.

ScienceNow
July 24, 2007

Original web page at ScienceNow