Grey wolves (Canis lupus) and dogs (Canis lupus domesticas) are technically the same species but split observably within the last 10,000 - 15,000 years. Within another few thousand years they may be entirely different species. The expected evolutionary mechanism at work here is the evolution and advancement of homo sapiens.
A wolf's diet consists primarily of meat. Their DNA chains contains two sequences for producing amylase, an enzyme used in starch digestion. Dogs have between four to thirty copies of the gene depending on their region. This allows dogs to be approximately 5 times better at processing starch. Similarly, wolves and dogs have the same number of genes to produce maltase, another starch enzyme, but the dog's genes produce a longer version of maltase. These long version is found among herbivorous but not carnivorous mammals like wolves. This again points to the dog's greater ability to process grains (Pennisi, 2013).
The commonly accepted reason for the increase in starch digestion is their association with humans. As mankind became more agrarian and less hunter-gatherer, a greater amount of food refuse was produced. This attracted the more grain-tolerant wolves. Likewise, as dogs were taken into settlements, those dogs with a greater ability to eat what their human masters ate would thrive and breed (Cohn, 1997; Pennisi, 2013).
Social hunting required complex communications and structures among canids. Many of these structures, particularly dominance and alpha-male behaviors, were practiced during childhood in play (Kleiman & Eisenberg, 1973). These social behaviors established which individuals lead hunts, set territory, etc. When humans began domesticating dogs, those who challenged their human masters for dominance, as wolves typically did in their own social structures, would likely be killed and unable to pass on their aggressive traits (Cohn, 1997). However, those who retained more of the “childhood” state of wolves would be allowed to stay and pass their genes on. Thus, domestic dogs show behaviors throughout their lives that match those of young wolves (play behaviors). This may also account for other common features found among dogs. Their licking and begging behaviors are likewise found among young wolves as well as the rounded muzzles and ears. It is thought that those selected for their childlike obedience and submissiveness most likely also had other childlike features (Cohn, 1997).
Cohn, J. (1997). How wild wolves became domestic dogs. Bioscience, 47(11), 725.
Pennisi, Elizabeth. (2013). Diet Shaped Dog Domestication. Science. Retrieved from http://news.sciencemag.org/plants-animals/2013/01/diet-shaped-dog-domestication.Write the first paragraph of your page here.