Dogs are a very common canine mammal , also the highest rate of pet breeding . According to UN statistics, the total number of dogs , about six hundred million , of about two hundred million only .Dog is the earliest human domesticated animals . No one knows who first interaction with the wolves occur at what time . Some scientists believe may be in 5 million years ago , because at least it takes so long time to develop genetic differences wolf now . Man and wolf was distributed in many parts of the Earth's surface , evolution may occur in several different areas . Some scholars believe that the wolf 14,000 years ago , perhaps even in southeastern Asia 16,000 years ago , humans had been domesticated livestock from wild wolves , that dog , used to play , hunt , housekeeping nursing homes . Dog evolution and starch digestion related : Researchers from Uppsala University dogs and wolves by comparing genome reveals many of the wild dog evolution changes for man's best friend in this process . Not surprisingly , these differences have affected many regions of the brain , which may explain differences in temperament In addition, this comparative study also noted that several regional and digestion -related genes including helping break down starch. The researchers said that by finding the humanity , human consumption of leftovers , the dog may have been self- domestication . And genetic studies of fossil Israel during the domestication of the dog determined to be about 10,000 years ago , coincided with the agricultural revolution , when human transition from nomadic hunter to farming and living in the settlements . Some scientists believe that wolves are attracted to these early settlements garbage dump , vegetables and cereals leftovers for food.