The first people who migrated to the Americas did not bring their dogs with them, suggests a new study that concludes dogs likely first came to the Americas only about 10,000 years ago.
If the new research holds true, then the first successful dog migrations to the Americas post-dated the first human migrations by thousands of years. The findings are published in the Journal of Human Evolution.
"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," project leader Kelsey Witt of the University of Illinois said in a press release. "They can be a powerful tool when you're looking at how human populations have moved around over time."
Dog Burials Found in Egypt: Photos
Witt and her team studied genetic characteristics of 84 sets of ancient dog remains from more than a dozen sites in both North and South America. The study, according to its authors, represents the largest ever analysis of ancient dogs in the Americas.
The data gathered so far on mitochondrial DNA, which is inherited only from mothers, indicates that dogs have a shorter history in the Americas than was previously suspected.
"Dog genetic diversity in the Americas may date back to only about 10,000 years ago," Witt explained.
"This also is about the same time as the oldest dog burial found in the Americas," her colleague Ripan Malhi added. "This may not be a coincidence."
In some samples, the team found significant genetic similarities with American wolves, suggesting that some of the dogs interbred with, or were domesticated anew, from American wolves.
Video: Why Dogs Spin Before They Poop
The study also presents intriguing clues as to what life was like for these earliest American dogs, including how humans valued them.
A site called Janey B. Goode near what is now St. Louis, MO, used to be where the ancient city of Cahokia was located. Cahokia was the largest and first known metropolitan area in North America. It was bustling about 1,000 years ago.
The researchers note that dozens of dogs were ceremonially buried at Janey B. Goode then, suggesting that people there had a special reverence for dogs. While most of the dogs were buried individually, some were placed back-to-back in pairs. The meaning of this remains a mystery for now.
On the downside, at least from a dog's perspective, canine remains were also found with food debris from Cahokia, strongly suggesting that people there consumed dogs for dinner from time to time.
The study also found that there was greater ancient dog diversity in the Americas than previously thought. The researchers, however, found unusually low genetic diversity in some dog populations, suggesting that humans in those regions may have engaged in dog breeding.
There is an important caveat to all of these findings, though.
Prehistoric Dog Found with Mammoth Bone in Mouth
"The region of the mitochondrial genome sequenced may mask the true genetic diversity of indigenous dogs in the Americas, resulting in the younger date for dogs when compared with humans," Malhi admitted.
Prior research suggests that dogs were in Alaska anywhere from 20,000 to 40,000 years ago. Perhaps some people at those much earlier times had dogs with them, but the dogs were not widespread or formally bred.
If a person did not bury a dog's remains, the chances of finding those remains today - if they even survived weathering - would be extremely challenging.
The story of dogs in the Americas is far from being fully unraveled. Witt and others have more studies in the works.
Photo: A dog-wolf hybrid. Credit: Wikimedia Commons