Tuesday 22 December 2015

DNA Reveals Dogs Have Been Human Companions For Over 30,000 Years



“The domestic dog represents one of the most beautiful genetic sculptures shaped by nature and man.”
Dog lovers, do you agree?
This sentence comes from a fascinating study published this week in the journal Cell Research, in which scientists from China, Canada, Finland, Singapore, Sweden, and the U.S. set out to trace the origin and evolution of the domestic dog.
Scientists have believed for a while in a two-stage process; in the first stage, primitive dogs emerged from their wild ancestors, grey wolves. The idea was that the wolves began to hang around humans, perhaps because they found food nearby. Then, as they stayed with people, they became tamer, and started performing tasks like hunting and guarding. It was over a very long time (read thousands of years) that the wolves became the first dogs. In the second stage, these primitive dogs were further selected into many different dog breeds.
That’s the general idea, but the exact details of how this happened have remained in dispute.
This group of scientists (proving that we can all get along, at least in the scientific community) set out to unearth more specific details about how the domesticated dog evolved. To do this, they used the whole genome sequences, or complete sets of DNA, from 58 canids: 12 grey wolves, 27 primitive dogs from Asia and Africa, and a collection of 19 diverse breeds from across the world.
grey-wolf
Photo Credit: Thinkstock
They found that dogs from south-east Asia have a much higher genetic diversity than all other populations of dogs, and relate most directly to grey wolves, and from this they deduced that domestic dogs originated in south-east Asia around 33,000 years ago, beginning with the grey wolf, seen above.
After evolving for several thousand years in east Asia, a subgroup of dogs radiated out of southern East Asia about 15,000 years ago to the Middle East, Africa as well as Europe. One of these out-of-Asia lineages then migrated back to northern China and made a series of admixtures with endemic east Asian lineages,” the scientists write.
Our study, for the first time, reveals the extraordinary journey that the domestic dog has travelled on this planet during the past 33,000 years.
In other words, for all you dog lovers out there, here’s the family tree of your pooch: about 33,000 years ago, his distant ancestor, the grey wolf, first made friends with a human. Jumping forward, about 15,000 years ago, a small group of domesticated dogs, descended from grey wolves, left home and headed for the Middle East and Africa. They made it to Europe about 10,000 years ago. And when humans first came to the Americas, they are thought to have brought dogs with them.
With the added twist that it’s possible some of the dogs trotted all the way back to China, and began interbreeding there.
terrier-with-toy
Photo Credit: Thinkstock
And that’s how the grey wolf is connected to this cute little terrier.
How did these researchers make these findings?
The Guardian explains: “Because each genome is a text copied (with regular misspellings, or mutations) through the generations, and every genome is related to every other genome, any comparison begins to tell a story of family connections and separations long ago. The more ‘texts’ that can be compared, the more certain the story they start to tell.”
So we still don’t know all the fascinating details, like whether your dog’s ancestors went out scavenging with hunter-gatherers, or exactly what persuaded him to hang out with the humans, but we do know a lot more about the geography of his ancestry.
Now I wonder if those first domesticated dogs had learned how to bark?

Read more: http://www.care2.com/causes/dna-reveals-dogs-have-been-human-companions-for-over-30000-years.html#ixzz3v54Hl0M2

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