As the saying goes, man and dog are best friends. But new research shows that, in the Americas at least, Homo sapiens sapiens and Canis lupus familiaris have only been best buds for about 10,000 years. That’s several thousand years after the first humans migrated from the land bridge connecting Siberia and North America.
Ancient Sites, New Knowledge
A new study, led by researchers at the University of Illinois, examined the genetics of the remains from 84 ancient dogs at more than a dozen sites throughout North and South America. It represents the largest analysis ever done of how dogs lived in ancient times in the New World.
“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 Kelsey Witt, a graduate student who co-led the study.
Witt says the close-knit association humans have with dogs makes canines a promising subject for the study of ancient human behaviour including how humans migrated across the globe.
Being Pals With Humans Has An Advantage
Unlike their wild wolf ancestors, dogs who lived thousands of years ago benefitted greatly from chumming around with humans. They gained access to steady food sources and benefitted from the security of living in human settlements. They also gained the opportunity to travel the world, spreading to locations they otherwise may never have encountered on their own.
In order to analyze how dogs came to live in North America, the researchers looked at mitochondrial DNA from dozens of ancient dog remains at several sites in Canada and the U.S. One of these sites is the ancient city of Cahokia, which is near present-day St. Louis. Cahokia is the largest and most ancient metropolitan settlement in North America, active from 1,000 to 700 years ago. Some of the dogs analyzed were buried in back-to-back pairs, indicating they had special significance to their masters.
New Genetic Signatures
When researchers analyzed the dog DNA from these ancient sites they discovered new genetic signatures indicating there was greater dog diversity in North America in ancient times than was previously thought. At other sites they discovered very low levels of genetic diversity in their samples. This indicates ancient humans at these locations may have engaged in dog breeding. But the big surprise was how (relatively) young the samples are, indicating dogs may only have arrived in North America about 10,000 years ago. This is much more recent than was previously thought. So next time you’re out playing fetch with your best four-legged bud, remember that the bond you share goes back thousands of years.
