Dog DNA and wolf ancestors

Humans created dogs from wolves and dog genome-wide SNP and haplotype studies on dog domestication show from DNA that dogs originated about 40,000 years ago from different races of gray wolves, namely the Middle Eastern wolf, the Chinese wolf, the North American wolf and the European wolf.

I highly recommend this TV show Man created Dog and Dog's Decoded a facinating show:

"Among the questions the episode explores are why dogs bark, when their predecessors, wolves, didn’t, and whether it’s a behavior that evolved so they could communicate with humans; why a hormone that humans release at birth to bond mother to baby is also released when humans interact with dogs, bonding us not just emotionally, but biologically; what makes dogs able to understand social cues, like pointing, that other animals cannot; and what clues dog DNA might hold to understanding the genetic causes of certain diseases."