Number 40, Spring 2003

Study finds Mexico dogs predate Europeans

Researchers looking into the origins of pre-Columbian dogs hadn't expected to discover them crossing the Bering Straits along with humans thousands of years ago.

Most modern European dogs originate from a small group of Eurasian gray wolves that began associating with humans at least 15,000 years ago, scientists believe. It stood to reason that a similar domestication process took place in the Americas.

Pictographs, sculpture and pottery show a small hairless dog living in the Americas thousands of years before Columbus arrived.

So when scientists began analyzing the DNA of ancient dogs, they made sure to include samples from Alaskan wolves.

A UCLA team led by Drs. Robert K. Wayne and Jennifer Leonard and supported by a UC MEXUS grant, analyzed 37 dog DNA samples taken from archaeological digs in Mexico, Peru and Bolivia, that predated the arrival of Europeans to the new world. They also studied 11 specimens dug from the Alaskan permafrost more ancient than European explorers’ discovering of the state.

The results showed the DNA of dog-remains preserved from archeological digs resembled those of the Eurasian dogs.

"This implies that humans who colonized America 12,000 to 14,000 years ago brought multiple lineages of domesticated dogs with them," says Leonard.

Most dogs found in the Americas today are related to modern European dogs. When Europeans arrived on the heels of Columbus, they brought their own dogs and shunned native ones.

Xoloitzcuintle, the Mexican hairless, is one of a few breeds believed to resemble the ancient American dogs. Native people used its antece-dents for food, sacrifice, companionship, hunting and protection, and possibly for medicinal and curative purposes. Aztecs believed their dog would guide them to the next world, Mictlán.

The six investigators had been working independently on the origins of ancient dogs worldwide, but a series of associations brought them together.

In 1997, Mexican biozoologist Raúl Valadez Azúa invited Carles Vilà, to an event related to the study of Mexican hairless dogs. The two men saw in their areas of expertise the potential for collaboration. Valadez had spent more than 12 years building a collection of pre-Columbian dog remains. Vilà, a postdoctoral fellow in Robert Wayne's Genetics Lab at UCLA, had just published a paper in Science on the origins of dogs.

The two men sent samples to Wayne's lab where Leonard completed DNA analysis. Investigators conferred online to analyze the results.

Vilà and Leonard met two Peruvian zooarcheologists during a trip to Peru. They then started sampling dogs from South America as well.

Results of their joint research were published in Science 2002 298: 1613-1616: “Old World Origin of New World Dogs,” Jennifer A. Leonard, Robert K. Wayne, Jane Wheeler, Raul Valadez, Sonia Guillen, and Carles Vilà.