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 That is the conclusion of scientists who said on Thursday
they had used modern genetics to unravel canine evolutionary
history, revealing a deep internal split between dogs from
opposite ends of the Eurasian continent.
People and hounds go way back - they were living together at
least 15,000 years ago, or 5,000 years before cows, goats and
pigs arrived - but how, why, when and where the two species got
friendly has been a mystery.
It was widely believed dogs were tamed just once, with some
experts claiming this happened in Europe and others favoring
central Asia or China.
But a new story emerged when researchers used the inner ear bone
from a 4,800-year-old dog unearthed in Ireland to sequence its
full genome, and then compared it to both modern animals and DNA
traces from 59 ancient dogs.
"Our data suggests that dogs were domesticated twice, on both
sides of the Old World," said Laurent Frantz, a geneticist at
the University of Oxford, whose work was published in the
journal Science.
"This suggests that at least two group of humans independently
came to the same conclusion: dogs can be domesticated. It also
suggests that the process of domestication, while mostly rare,
may be replicated more often than we think."
After constructing a family tree for dogs based on the genetic
data, the scientists concluded there were very old domesticated
animals in both the east and west of Eurasia but not in the
middle.
At some point in prehistory, they believe the eastern dogs
dispersed with human migrants and replaced most of the western
ones, so Asian ancestry is now dominant in modern dogs.
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Although it is possible there was only one domestication event in
Asia, followed by early transportation to Europe, the research team
argues the lack of archaeological evidence for dogs in the middle of
the continent makes this very unlikely.
Other scientists not involved in the work believe more samples from
ancient dogs and wolves will be needed to prove the point
conclusively.
WOLF, AFGHAN, YORKIE
What remains unclear is how grey wolves started down the long road
that has ended up with today's kaleidoscope of dog breeds from
Afghan hounds to Yorkshire terriers.
The idea that it began with a hunter-gatherer picking up a wolf pup
and breeding tamer and tamer offspring is probably too simple,
according to Greger Larson, a genetics expert in Oxford's
archaeology department.
"It's likely to have been co-evolution. At first a pack of wolves
got close to humans, then humans got used to the wolves and,
finally, there would have been something more intentional on the
part of people," he said.
(Additional reporting by Will Dunham in Washington Editing by Jeremy
Gaunt)
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