Why did early human ancestors keep dog's ancestors?

Ah, so according to what you read, it is the wolves who came to join us on their own free will rather than we "adapted" them in the first place. Interesting.

I have seen on TV where some people got close to the wolves at Yellow Stone. Those wolves were actually imported Canadian wolves. Since the American wolves were all wiped out clean many years ago by the European settlers.
In the show, it seems the wild wolves are extremely friendly to the approaching people. The pack leader even played with this one guy with repeat physical contact. I couldn't believe my eyes. Most stories I heard about wolves were quite the opposite. They were seem as dangerous animals.

It got me quite confused on whether the wild wolves are dangerous or friendly to humans.