New research suggests dogs first came to the Americas only about 10,000 years ago, which would have been thousands of years after humans first showed up.
In the largest analysis of ancient dogs in the Americas researchers looked at the genetic characteristics of 84 individual dogs from over a dozen sites across the region, the University of Illinois at Urbana-Champaign reported. Studying the 11,000 to 16,000 year-old relationship between dogs and humans could help researchers gain insight into ancient human behavior, including their migration patterns.
"Dogs are one of the earliest organisms to have migrated with humans to every continent, and I think that says a lot about the relationship dogs have had with humans," said University of Illinois graduate student Kelsey Witt. "They can be a powerful tool when you're looking at how human populations have moved around over time."
Past studies of ancient dogs in the Americas focused on the dogs' mitochondrial DNA because it is easier to obtain from remains, but this is only inherited from the mother. This new study also looked at mitochondrial DNA, but included a much larger sample of dogs than has ever been analyzed.
The research allowed the team to identify four never-before-seen genetic signatures suggesting ancient dogs in the Americas were more diverse than we thought they were. They also found unusually low genetic diversity in some dog population, which may be signs of dog breeding thousands of years ago.
Some of the samples were found to be genetically similar to American wolves, which indicates a cross-breeding between domestic dogs and wolves.
"Dog genetic diversity in the Americas may date back to only about 10,000 years ago," Witt said.
"This also is about the same time as the oldest dog burial found in the Americas," anthropology professor Ripan Malhi added. "This may not be a coincidence."
In the future the researchers plan to continue their studies, possibly even sequencing the e full mitochondrial genomes of 20 ancient dogs.
The findings were published in a recent edition of the Journal of Human Evolution.
