14,000 years ago: dogs were first domesticated
The results of the DNA analysis first performed on a boxer dog called Tasha in 2005 and afterwards, on hundreds of dogs, indicate that they all diverged from the gray wolf (Canis lupis) in Eurasia, approximately 40 to 14 thousand years ago.
Recent studies suggest that domestication started in China, in a region called Asia South of Yangtze River (ASY).
One possible theory is that wolfs and humans established a relation of mutual benefit: the tamest, least aggressive wolfs would approach human settlements in search of food and find it, warning the settlers when strangers approached by barking.
Dogs became the first species to be domesticated by humans. But humans did much more than that; they started making artificial selection. They would select for different traits, breeding all sorts of dog types that would meet all kinds of needs.
It is surprising to see the huge differences there are among a gray wolf, a Chihuahua, and an Irish wolfhound. However, all these dogs, along with all existing breeds, are genetically more similar to each other than humans and bonobos.