Over the course of time, environmental factors have played a huge role in the evolution of a species. In this case, living on a farm has caused man's best friend to evolve in such a way that starches are more easily digested than before. Because farming was so common in the past, both humans and dogs had to adapt to a diet with more starch.
Three years ago, evolutionary geneticist, Erik Axelsson, and a few colleagues discovered that dogs have anywhere between four to thirty copies of the gene that digests starch. This gene is called Amy 2B. Wolves only have 2 copies of this gene, showing that dogs have evolved to have as much as 15 times more copies of the gene than a wolf would. Morgane Ollivier, a paleogeneticist, worked with Axelsson to uncover when the genetic change seemed to occur.
DNA was extracted from the bones and teeth of 13 wolf and dog samples. Four out of the thirteen samples had more than 8 copies of the Amy 2B. These samples were from sites 5,000-7,000 years old. With the copies of these genes increasing in dogs, it allowed them to survive on human leftovers instead of a diet composed of only meat. This was an advantage for dogs in terms of survival when migrating with humans. The copies of this starch gene also increased in humans around the same time it did in dogs. Scientists predict that evolution of metabolism and several other processes could be similar between man and dog.
It's very interesting to see that dogs have evolved to digest starch much more efficiently than before. Adapting to the environment they were put in not only impacted survival rates, but they were also able to stay with the humans during any type of travel/migration.