People and dogs have been living together for hundreds of years. When did dogs and people become friends? Where did dogs come from?
A group of scientists tried to answer these questions. They just finished a study about the history of dogs. In the study, they looked at the DNA of dogs all over the world and found that dogs, like human, shared DNA with their family members. The scientists put together a big family tree for dogs. It went all the way back to the animal's beginning.
In this way, scientists learned about the history of dogs. The first dogs lived in Asia. They were born about 33,000 years ago. At first, there were only about 6, 400 of them. Their parents were wolves.
The new study answers many questions. It raises some, too. For example, what caused wolves in Asia to become dogs all those years ago?
One idea is that their DNA slowly changed and the wolves became dogs in the end. As time goes by, dogs became "man's best friends". Or it could happen the other way around. It was possible that some wolves started living with people before they became dogs. Living with people led to many changes to these wolves. It changed their DNA, So their offspring（后代）became dogs. In other words, it was possible that wolves were our friends before they became dogs.
By studying DNA, scientists now have a much better understanding of the history of dogs. ____ How exactly dogs came to be our friends is still unclear.
