Listening Script Vocabulary
(Section 4: You will hear a talk on the topic of domestic dogs. First, you will have some time to look at questions 34 to 40 [20 seconds]. Listen carefully and answer questions 34 to 40.)
Good morning, zoology students, and welcome to this lecture on the domestic dog. Today, we're going to look at a new study that compares DNA from dozens of dogs and wolves, including 18 ancient fossils. The results of the study provide the clearest picture yet of where, when and how wild predators came to be man's best friend.
Domestic dogs evolved from a group of wolves that came into contact with European hunter-gatherers between 18,800 and 32,100 years ago, and may have since died out. The new study follows two earlier studies that looked at the genetic signatures of domestication in dogs, and came to differing conclusions about canine origins. One group suggested that dogs were domesticated around 10,000 years ago during the Agricultural Revolution, when wolves started scavenging human scrap heaps. The other concluded that wolves and dogs split 32,000 years ago, somewhere in East Asia.
Both studies compared the genes of a wide variety of living dogs and wolves, but modern samples can be deceptive. Dogs and wolves diverged so recently that many of their genes have not had time to separate into distinct lineages. They have also repeatedly inter-bred with each other, further confusing their genealogies.
To deal with these problems, a team of scientists examined the DNA from 18 fossilised canids. They compared these ancient sequences of DNA to those from 49 modern wolves and 77 modern dogs, and built a family tree that charts their relationships.
The tree conclusively pinpointed Europe as the major centre of dog domestication. It identified four families of modern dogs, which are almost closely related to ancient European canids rather than wolves from China or the Middle East. This suggests that the population of wolves in Europe that gave rise to modern dogs may have become extinct, which is plausible given how humans have wiped out wolves over the centuries.
According to this new family tree, the largest group of domestic dogs last shared a common ancestor 18,800 years ago, and collectively, they last shared a common ancestor with a wolf around 32,100 years ago. They must have been domesticated at some point during this window.
These dates fit with fossil evidence. The oldest dog fossils come from Western Europe and Siberia, and are thought to be at least 15,000 years old. By contrast, those from the Middle East and East Asia are believed to be 13,000 years old, at most. However, the analysis does not include any ancient DNA from the Middle East or China. Who knows what would be found if ancient canid samples from East Asia or elsewhere were used?
In short, this is not the final word on canine origins. It would be a mistake for scientists to jump and say that dogs were domesticated in Europe and not anywhere else. We know pigs were domesticated independently in China and Turkey, so there's no thinking that dog domestication had to happen in just one place.