Dogs may have been domesticated
not once, as widely believed, but twice, once in Europe and once in
Central Asia or China, a major study said Thursday.
Scientists have debated where domestic dogs come from for a very
long time. Some argued that humans first domesticated wolves in
Europe, while others claimed this happened in Central Asia or
China.
All these claims, according to the new study published in the
U.S. journal Science, may be right.
The study, supported by funding from the European Research
Council and Britain’s Natural Environment Research Council, said
that man’s best friend may have emerged independently from two
separate, possibly now extinct, wolf populations that lived on
opposite sides of the Eurasian continent.
The team, led by the University of Oxford and including French
researchers based in Lyon and at the National Museum of Natural
History in Paris, made the conclusion after reconstructing the
evolutionary history of dogs.
They first sequenced the genome of a 4,800-year-old medium-sized
dog from bone excavated at the Neolithic Passage Tomb of Newgrange,
Ireland.
Then, they obtained mitochondrial DNA from 59 ancient dogs
living between 14,000 to 3,000 years ago and compared them with the
genetic signatures of more than 2,500 previously studied modern
dogs.
Their analyses revealed a genetic separation between modern dog
populations currently living in East Asia and Europe, one they said
occurred several thousand years after the first known appearance of
dogs in Europe.
The new genetic evidence also showed a population decline in
Europe that appeared to have mostly replaced the earliest domestic
dog population there, which supported the evidence that there was a
later arrival of dogs from elsewhere.
Lastly, a review of the archaeological record showed that early
dogs appeared in both the East and West more than 12,000 years ago,
but in Central Asia no earlier than 8,000 years ago.
Combined, these new findings led the researchers to believe that
dogs were first domesticated from geographically separated wolf
populations on opposite sides of the Eurasian continent.
At some point after their domestication, the eastern dogs
dispersed with migrating humans into Europe where they mixed with
and mostly replaced the earliest European dogs.
Most dogs today are a mixture of both Eastern and Western dogs
— one reason why previous genetic studies have been difficult to
interpret, they said.
The international project is currently analyzing thousands of
ancient dogs and wolves to test this new perspective, and to
establish the timing and location of the origins of our oldest
pet.
“Animal domestication is a rare thing and a lot of evidence is
required to overturn the assumption that it happened just once in
any species,” senior author Greger Larson, professor of the Oxford
University, said in a statement.
“Our ancient DNA evidence, combined with the archaeological
record of early dogs, suggests that we need to reconsider the
number of times dogs were domesticated independently,” he said.
“Maybe the reason there hasn’t yet been a consensus about where
dogs were domesticated is because everyone has been a little bit
right,” he added. Enditem
