Dogs' Ability to Digest Human Food Key to Domestication

A research team from Sweden has discovered that dogs' ability to easily digest starch helped them evolve into the domesticated, human-friendly animals they are today. According to the study, which was published on Wednesday in the journal Nature, dogs evolved from wolves after finding new food sources in refuse outside of human settlements.

The Washington Post reported that similar diet evolution occurred to humans when they left the forest and began to farm and eat diets rich in grains. Erik Axelsson, a geneticist at Uppsala University, told the Washington Post, "I think it is a striking case of co-evolution. The fact that we shared a similar environment in the last 10,000 years caused a similar adaptation. And the big change in the environment was the development of agriculture."

The new study revealed that dogs have the ability to break down starch into sugar and then transfer those sugars from their guts into their bloodstream, the Los Angeles Times reported. In order to better understand this, researchers compared dog and wolf DNA and found several different starch and sugar-processing genes among the two.

Lead author Axelsson and his team examined DNA from 12 gray wolves and DNA from 60 domestic dogs from several different breeds. According to the LA Times, the researchers sequenced the DNA to look for differences and found 36 places in the genome (containing 122 genes) that appeared crucial in the evolution of dogs.

The LA Times reported that the Swedish scientists discovered 10 genes that were involved in starch or fat metabolism. Three of those genes carried instructions for making a protein needed to digest starch.

The first gene makes alpha amylase to break down starch into sugar maltose and carbohydrate strands. The second gene makes an enzyme to turn maltose into glucose, the LA Times reported. The last gene allows the glucose to move from the gut to the bloodstream. All three were more prevalent among dogs.

"It is such a strong signal that it makes us convinced that being able to digest starch efficiently was crucial to dogs. it must have been something that determined whether you were a successful dog or not," Axelsson told the Washington Post.

The research team also discovered 19 genome regions that contained nervous system genes considerably different between wolves and dogs, the Washington Post reported. However, further research must be done in this area.