San José (AFP)

A jawbone discovered more than 30 years ago could be the key to proving that dogs populated Central America 12,000 years ago.

And if there was a dog, it was bound to have a master, which would change current knowledge, according to Costa Rican and Mexican researchers.

Because if there is evidence of human migration in Mexico, Chile or Argentina at that time, no trace has yet been formalized in Central America.

It is among other bone remains, notably those of a species of Equus (giant horse) and of a glyptodon (large armadillo), that this jaw was unearthed in the early 1990s in a site dating back to from the Upper Pleistocene (12,000-10,000 BC), discovered twelve years earlier in Nacaomé, Costa Rica.

But the jawbone was then labeled as that of a coyote ... before fading into oblivion.

"It seemed very strange to us that there was a coyote in the Pleistocene. And when we examined these bone remains, we began to glimpse characteristics that could be those of a dog," explains Costa Rican researcher Guillermo Vargas. .

Also examining the images of the jaw, Mexican biologist and zooarchaeologist Raul Valadez Azua, of the Anthropological Research Institute of the National Autonomous University of Mexico, also asserts that he may well be the "best friend. of man ".

"It could be the oldest dog in the Americas," enthuses Mr. Vargas.

The oldest dog fossil in the Americas was discovered in Alaska and dated to 10,000 years ago.

Above all, "this discovery of the dog would be the first human proof in Costa Rica of a much older period and confirms the theory of human migrations until the settlement of the continent", he underlines.

According to this theory of the settlement of the American continent, humans migrated from Asia through the Bering Strait, located between Siberia and Alaska, when sea levels fell during the last great ice age.

For now, the jawbone is kept by the National Museum of Costa Rica and researchers have received an offer from the University of Oxford to carry out studies on mitochondrial DNA and carbon 14.

Costa Rican researcher Guillermo Vargas works on documents identifying a dog's jaw, September 21, 2021 in San José Ezequiel BECERRA AFP

These would make it possible to obtain more genetic information and to determine more precisely the age of the fossil.

The museum also wants the results to be validated by a specialist publication.

- Change of teeth -

Mr. Vargas, his compatriot Natalia Rodriguez and the Nicaraguan Myrna Baez, with the support of the Mexican Raul Valadez Azua, have been studying for six years the relationship between pre-Hispanic cultures and dogs, within the framework of the "Xulo" project, which means " dog "in the native language of the archaeological zone of Gran Nicoya.

"We have done a lot of research on the history of canines because they are traces of human presence" and when the dog becomes domestic "the jaw changes, the teeth are less sharp, less intended to tear bones and meat" , explains Vargas.

When "the dog eats the surplus of human food, its dentition is not so decisive for its subsistence".

And the found jaw "reflects this difference" he adds.

Undated photo released on October 11, 2021 by Proyecto Xulo of a dog jawbone proving dogs populated Central America 12,000 years ago - Proyecto Xulo / AFP

“The first domesticated dogs entered the continent about 15,000 years ago, following the migration of Asians through the Bering Strait. And there have never been dogs without humans. They moved from north to north. south as part of groups of hunters and gatherers, "Valadez told AFP by phone from Mexico.

"The dog-man pairing is inseparable. There are no dogs without humans (...). Sometimes, we do not explore in depth what such a discovery can mean, but it can piece together history. of Man ", he emphasizes.

"This shows us that there were companies which could have dogs for fun, which had a surplus of food. They were not attack dogs like, for example, those which the Spaniards brought back during their second trip (to America) which were intended to kill, ”says Mr. Valadez.

© 2021 AFP