“We are what we eat” how a change in diet has affected the appearance of domestic dogs

(ORDO NEWS) — Comparing the mandibles of 500 fossil dogs with those of modern wolves, dingoes and domestic dogs, scientists tracked how our loyal four-legged friends changed as their diets changed.

The shape of the lower jaw of mammals is influenced by the jaw muscles attached to it: the stronger they are, the more massive the jaw, and the strength of the muscles, in turn, depends on the diet of the animal.

In addition, the lower jaw is formed by strong dentary bone, which is well preserved in the fossil state – this provides valuable information about the diet of extinct animals and allows for large-scale comparisons of the diet over time.

In a new study published in the journal Proceedings of the Royal Society B: Biological Sciences , an international team of scientists presented the results of studying the shape of the jaws of 525 ancient dog specimens from European archaeological sites.

These specimens, ranging from five to ten thousand years old, have been compared to modern dog breeds, wolves and the Australian dingo dogs.

As it turned out, ancient dogs were distinguished by more massive jaws than modern ones, which was especially expressed in the middle-posterior part of the jaw, where carnassials are located, which play a major role in cutting meat.

Probably, the diet of these animals consisted of more solid and tough food than most modern dogs, and more closely resembled the diet of a wolf or a dingo.

Today’s dogs are omnivores: unlike their carnivorous ancestors, they have multiple copies of the amylase enzyme gene , which allows them to digest starch, a carbohydrate found in plants such as grains.

Probably, the ancestors of today’s dogs acquired this trait when agricultural products began to predominate in the diet of their owners: that is, the animals had to change in order to continue to live next to people.

We are what we eat how a change in diet has affected the appearance of domestic dogs
The general shape of the jaw (left) and the curvature of the jaw under the carnassials (right) in ancient (gold) and modern (grey) dogs

Particularly curious are the results of comparing the jaws of the dingo, a secondarily feral dog that appeared in Australia at least three and a half thousand years ago and until the arrival of European colonists was the only placental predator on the continent.

It would seem that it was worth expecting that the shape of the dingo’s jaw would be similar to the shape of the jaw of ancient European dogs.

However, it turned out to be “transitional” between the wolf and the modern domestic dog. This likely serves as a consequence of both the dingo’s independent existence in Australia for millennia and its diet, which mainly consists of kangaroo and wallaby meat .

Dingoes also have only one copy of the amylase gene and are poorly adapted to eating plant foods: it is possible that this evolutionary line branched off even before the ancestors of modern dogs learned to eat carbohydrate foods effectively.

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