Against the Grain

There has been an explosion in the availability of grain-free canine diets, not to mention the increasing popularity of meat-based raw diets which accompany the belief that dogs are “natural” meat eaters and little changed from their supposed carnivorous wolf ancestors. Unlike cats, even wolves are not obligate carnivores and eat a varied diet including the grain and grasses in the stomachs of their prey as well as berries.

It bears repeating yet again then, that the domestic dog is not descended from any living wolf but from a mega-fauna wolf that is now extinct. In the initial process of self-domestication, rapidly accelerated when man began to intervene, the dog adapted to new environments and became something utterly unique.

Whole-genome re-sequencing of dogs and wolves has identified 3.8 million genetic variants and 36 genomic regions that are thought to represent targets for selection during dog domestication. Ten of the genes play key roles in starch digestion and fat metabolism which show also that dogs changed as they became domesticated. Mutations in key genes enabled increased starch digestion in dogs relative to wolves, indicating that the early ancestors of modern dogs thrived on an omnivorous diet rich in starch relative to the largely carnivorous diet of wolves. This was a crucial step in
domestication because early dogs probably both scavenged from and lived with man, either way sharing a diet that included starch-based nutrients.

Further evidence that dogs are perfectly well-adapted to eating grain and starch has come from recent research into the Mayan civilisation dating from 1000 BCE to 250 CE. The Pre-classic Period between 1000 BCE and 175 CE provides the earliest direct evidence that live dogs were traded in the Americas as remains of two dogs and one jaguar-type feline, deposited between 400 and 300 BCE, were found to be non-local animals. The remains were recovered from two large pyramids in a central plaza and dated using radiocarbon dating techniques, leading researchers to conclude that that all three animals may have been involved with early ceremonial events at the site. It is thought that the dogs originated from the Guatemalan volcanic highlands and the foothills of central Guatemala and that they were imported via a trade network as gifts or as companions belonging to humans travelling along the route.

Remains of dozens of local dogs proved that they had been eating a diet rich in maize, whilst the two imported dogs showed evidence suggesting that they also consumed less meat than a carnivore. The canines were mostly small and resembled modern Chihuahuas. Butchery marks found previously on ancient dog bones at other Mayan sites suggest that the dogs were raised as a food source and it is possible that maize-fed dogs were a significant protein source for the Mayans before they domesticated turkeys.

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