Well Traveled: Gene split arose early in domesticated goats
Present-day domestic goats may look humble, but they harbor more genetic diversity than any other livestock species. In fact, analyses of goats’ mitochondrial DNA have shown that these animals evolved through five distinct maternal lines that spread from the Near East and central Asia across Europe.
A new study indicates that goats representing the earliest two of the five genetic lines inhabited the same location in southwestern Europe by about 7,000 years ago, only 3,000 years after the initial domestication of the animals in the Near East.
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This ancient genetic diversity in a region far from the goat strains’ origins reflects the long-distance transport of goats from the Near East by European pioneers soon after the origins of animal domestication, farming, and village life, say geneticist Pierre Taberlet of Joseph Fourier University in Grenoble, France, and his colleagues in the Oct. 17 Proceedings of the National Academy of Sciences.
Today’s other three genetic lines arose later in parts of central Asia, Taberlet’s group proposes.
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The scientists analyzed mitochondrial DNA retrieved from 19 goat bones found at an ancient farming site in southern France. Other researchers had excavated these fossils about 20 years ago in soil that contained the remains of more than 5,000 animals, including pigs, cattle, and sheep.
New radiocarbon measurements of five goat bones placed them at between 7,300 and 6,900 years old.
By extracting and analyzing genetic material from several goat bones, two independent laboratories confirmed that the sequences that Taberlet’s group examined were uncontaminated, ancient DNA.
Comparisons of the ancient goat mitochondrial DNA with sequences of modern goat DNA revealed that the two Near Eastern lineages had inhabited the prehistoric French site at the same time.
Taberlet and his colleagues suspect that early farmers transported each line of goats into Europe along a separate westward route, one inland and the other running along the Mediterranean Sea.
A preference for moving goats long distances in ancient times makes sense (SN: 5/12/01, p. 294: Available to subscribers at Domesticated goats show unique gene mix). Goats are the hardiest livestock species. They’re easy to transport by land or boat, and they willingly follow people.
The new data convincingly show the domestication of two ancient goat lineages at the same time somewhere in the Fertile Crescent region, remarks archaeobiologist Melinda A. Zeder of the Smithsonian Institution’s National Museum of Natural History in Washington, D.C.
Genetic studies of modern domestic sheep have revealed a pattern similar to that of goats, with three to four ancient lineages, Zeder notes. “This suggests that both sheep and goats moved together, as they do today, in mixed herds as they diffused out of the Near East,” she says.