Busting the myth of ancestral diets

Our dog's ancestors ate a rich, meaty diet with very little grain, therefore our modern dogs should have the same. That's been the argument from many raw and high meat feeding dog owners (and companies) for many years, but for those of us who have never quite accepted the idea or logic, a new study looking at the diet of dogs in Spain living around 3,000 years ago provides strong support, with its conclusion that many early domestic dogs ate almost no meat and were instead fed cereals, such as millet, by their owners.

This study was reported in New Scientist magazine this week and found that that although the low meat diet uncovered may reflect the fact that meat was relatively scarce among human societies at the time, feeding dogs with cereals could have been advantageous. Lead author Silvia Albizuri at the University of Barcelona in Spain, commented that it may have been a way to ensure the dogs had plenty of energy for the strenuous work of herding and guarding livestock.

Dogs were domesticated from wolves in Europe and Asia within the past 40,000 years - wolves are carnivores, getting most of their nutrition from meat. Albizuri and her colleagues studied the remains of 36 dogs from Can Roqueta, an archaeological site near Barcelona. It lies on a plain near the coast and was inhabited from the Stone Age onwards. The dogs lived in the Bronze Age and Iron Age, between 1300 and 550 BC, and had been buried in pits.

The researchers obtained protein from the dogs’ bones and focused on the carbon and nitrogen atoms in the samples, each of which exist in two forms called isotopes. Different foods have varying ratios of carbon and nitrogen isotopes, and this influences the makeup of the protein – so studying the isotopes in the protein gives an indication of what the animals ate.

The dogs’ diets differed considerably: while nine of them ate plenty of meat and 10 were omnivorous, the rest ate mostly plants – and some had isotope ratios that could barely be distinguished from those of the cattle they once guarded.

The finding adds to the evidence that many early domestic dogs ate little meat, says Albizuri. This trend began with the advent of farming. “When human societies began to domesticate plants during the Neolithic period, hunting decreased and the human diet was based mainly on vegetables,” she says. “Dogs began to be fed on plants, mainly cereals.”

This has had effects on domestic dogs today, says Albizuri. Grains are easier to chew than raw meat, so they don’t need their jaw muscles to be as strong as those of wolves. What’s more, their jaw bones have changed shape and their teeth have shrunk. Their digestive systems have also changed. “Dogs have more genes involved in starch metabolism than wolves,” she says.

However, not all dogs have undergone these changes. “Societies that maintained a subsistence system based on hunting and gathering, mainly those located in cold areas, continued to feed their dogs with meat,” says Albizuri. “In today’s dog breeds, there are significant genetic differences related to starch metabolism.”

Fascinating stuff - so, many thanks to New Scientist for sharing this study - and really powerful evidence to support those of us who believe that dogs can thrive on a wide variety of diets, including those with little or no meat.