THE notion that domestication of cattle spread from the Middle East to Europe may not hold up. The first analysis of the ancestry of domestic cattle using DNA on the Y chromosome reveals that Europe may have had home-grown domestication, too.
Studies of cattle origins typically look at mitochondrial DNA, which is only passed on by mothers to their offspring. This work has suggested that all European cattle, Bos taurus, originated in south-west Turkey, where they were domesticated from the aurochs, an extinct type of wild ox. This happened between 8000 and 10,000 years ago, but aurochs survived until the 17th century, when the last one was reportedly shot in Poland.
The problem with using mitochondrial DNA to trace ancestry is that it tells only half the story, says Cecilia Anderung of Uppsala University in Sweden. 鈥淚t won鈥檛 tell us anything about developments on the male side.鈥� She believes that local aurochs might have mated with domestic cattle in Europe, or even been domesticated themselves. But previous studies could have missed that.
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Anderung is part of a research team that analysed the Y chromosomes of 150 modern bulls from across Europe. Classifying the chromosomes according to similarities in their DNA sequence revealed a clear north-south split.
There is some overlap, but the so-called Y1-type is more common in southern Europe, while the Y2-type is more common in the north. If both types were introduced from Turkey, it would be hard to explain this pattern, she says. You would expect them to be mixed at random.
One possible explanation is that there were two separate domestications, one in the Middle East and one in Europe. The team now plans to look at many more DNA samples of modern and early cattle from across Europe and the Middle East.
The case for the local domestication of cattle in Europe is far from firm, says Peter Gravlund of the University of Copenhagen, who is using mitochondrial DNA to research the origins of cattle in Denmark. But looking at Y chromosomes is a useful approach, he says. 鈥淲e do need both sides.鈥�