The Digestive Difference Between Wolves & Dogs - And Why It Matters
Scientists have verified genetic differences between wolves and dogs directly related to the process of human domestication. A 2013 scientific study “conducted whole-genome resequencing of dogs and wolves to identify 3.8 million genetic variants used to identify 36 genomic regions that probably represent targets for selection during domestication. Nineteen of these regions contain genes important to brain function, eight of which belong to nervous system development pathways and potentially underlie behavioral changes central to dog domestication. Ten genes with key roles in starch digestion and fat metabolism also show signs of selection”.
These ten digestive changes were not selected consciously by our ancestors but happened naturally as wolves and early dogs began to survive in part and later in whole on waste dumps (middens) near human habitations. To understand our modern dog’s digestion (in relation to wolves) it is important to know what these middens contained in part or in whole, across almost all cultures.
Middens contained bones, both raw and cooked, discarded vegetation matter but first and foremost - human feces. Canine domestication began before humans turned to agriculture, so dogs sadly went from sharing the “kill” to eating partially digested plant and some meat matter in the form of feces. Scientist James Bultler studying the diet of modern free-ranging dogs in Zimbabwe found that fifty-six percent of 1,000 dog droppings they studied contained human feces. Butler found that this human poop contained twice as much protein as the local “dog food” which was a porridge. In fact, he concluded human feces were “comparable to the upper range of energy content for mammal tissue, vegetable and fruit.”
So, how did poop-eating turn wolves into dogs?
By the development in dogs of more copies of starch-digesting genes and a more adaptable gut microbiome, allowing them to thrive on human feces and human provided diet. Wolves have remained strictly carnivorous with stronger stomach acids necessary for a diet exclusively raw meat and bone. Stories of wolves eating large amounts of plant matter are simply not true except in cases of extreme emergency or an insignificant amount of seasonal berry eating.
Wolves have highly acidic stomachs (pH 1 – 2) compared to dogs, making them better at digesting raw meat, bones and killing bacteria. Dogs, on the other hand, have significantly more copies of a gene leading to higher amylase production resulting in far better starch digestion. Dog gut bacteria have adapted to a varied diet heavy in starches by having more specific bacteria involved in carbohydrate breakdown.
As an aside, for those creationists who state that science never produces “missing links” in the evolutionary processes (they do) one study done on a Bronze Age archaeological site in Solarno, Italy has produced interesting results.
The microbiome structure of the Solarlo dogs of 3,500 years ago revealed continuity with that of modern dogs, but it also shared some features with the wild wolf microbiome, as a kind of transitional state between them. These findings suggest that Neolithic dogs could have responded to the transition to a starch-rich diet by expanding microbial functionality.
Bottom line, science says dogs are fivefold better than wolves at digesting starch, the chief nutrient in agricultural grains such as wheat and rice. Do dogs need to eat diets composed of all or a high percentage of meat to thrive? Is corn a “horrible” food for dogs? The answer is no. And this explains why some dogs do very well on “low quality” dog foods such as “Old Roy” or “Kibbles & Bits”. Unlike wolves, they literally can do just fine eating “shit”.
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