Dogs have been following humans for thousands of years.
Archaeological and genetic data has revealed that dogs accompanied humans when they were migrating to the Americas from East Asia, according to a study published Monday in the Proceedings of the National Academy of Sciences.
Dogs were likely domesticated over 23,000 years ago in Siberia, said lead study author and archaeologist Angela Perri, a research fellow at Durham University's department of archaeology in the United Kingdom. Her team analyzed the genetic makeup of ancient dog remains to estimate when the domestication from wolves to dogs happened.
Archaeological evidence showed that the humans migrated over 15,000 years ago from Northeast Asia across the Bering Land Bridge, a piece of land that connected modern-day Russia to Alaska. The land crossing no longer exists due to rising sea levels.
Perri studied the lineage of American dogs outside the Arctic, which come from a different genetic ancestor than Arctic dogs, and traced it back to ancient Siberian dogs. This lineage has shown that humans brought their dogs with them when they migrated to the Americas, according to the study.
Many people have dogs as pets today and some wonder, "What is this animal and how did it go from a wild predator to curled up next to my bed?" Perri noted.
While there is no definitive answer on why dogs became domesticated, the freezing climactic conditions during this time likely brought wolves and humans closer together for survival, she said.
"Wolves likely learned that scavenging from humans regularly was an easy free meal, while humans allowed this to happen so long as wolves were not aggressive or threatening," Perri said.
The dogs could have also helped humans transport items faster, she said. There is also evidence in the Pacific Northwest of humans using furry creatures as emergency sources of food and fur.
The study is a fascinating example of how canine and human DNA and archaeology can be used to find out more about our past, said Jeffrey Kidd, associate professor of human genetics at the University of Michigan Medical School, who was not involved in the study.
Modern dogs are similar to domesticated dogs from 15,000 years ago, he said, but today there are different furs and colors as a result of breeding.
Kidd is not surprised that humans brought their dogs with them when they migrated to the Americas because of how intertwined dogs are in our society.
"If you and your entire community was going on a journey across the land, wouldn't you bring along your dog?" Kidd said.
The earliest confirmed dog bones were found in Germany over 100 years ago and are about 15,000 years old, Perri said, so her next project is to search for older dog bones in Siberia to aid in her research. She's hoping to gather more evidence to discover how dogs became man's best friend.