Study: Dogs died out after arrival of Europeans

Scientists unsure why they vanished in North America

NEW YORK — A new study provides fresh evidence that the first dogs of North America all but disappeared after the arrival of Europeans.

The only surviving legacy appears to be a cancer that arose from the cells of a dog that lived more than 8,000 years ago and has since spread to other canines throughout the world, an international team reported Thursday in the journal Science.

Researchers compared the genomes of ancient and modern American dogs. Results confirm that the first domesticated dogs of North America arrived with people from Asia over the same Bering land bridge used much earlier by humans. These dogs thrived for thousands of years but mostly vanished after contact with Europeans. Scientists don’t know why they disappeared.

“I just find it really surprising,” said geneticist Elinor Karlsson from the University of Massachusetts Medical School in Worcester, who did not participate in the study. “There were millions and millions of dogs all over the continent (that) died out after the Europeans arrived. And the fact that we don’t know anything about it is kind of a big hole.”

In an attempt to fill in the historical gaps, researchers sequenced the genetic material of 71 dog remains collected from bones found in Siberia, the U.S. and Mexico.

Researchers could not find any trace of ancient dog DNA in modern-day village dogs from South America or pre-Columbian breeds like the xoloitzcuintli, the Mexican hairless dog. Less than 4 percent of the genome of modern American dogs can be traced back to those that lived before the Europeans came, the study found.