• Otávio Santiago

How dogs tracked their humans across the ancient world

DNA from dog remains traces a relationship across time and space.

Sometime toward the end of the last ice age, a gray wolf gingerly approached a human encampment. Those first tentative steps set his species on the path to a dramatic transformation: By at least 15,000 years ago, those wolves had become dogs, and neither they nor their human companions would ever be the same. But just how this relationship evolved over the ensuing millennia has been a mystery. Now, in the most comprehensive comparison yet of ancient dog and human DNA, scientists are starting to fill in some of the blanks, revealing where dogs and humans traveled together—and where they may have parted ways.

"It's a really cool study," says Wolfgang Haak, an archaeogeneticist at the Max Planck Institute for the Science of Human History. "We're finally starting to see how the dog story and the human story match up."

Dogs are one of the biggest enigmas of domestication. Despite decades of study, scientists still haven't figured out when or where they arose, much less how or why it happened. A 2016 study concluded that dogs may have been domesticated twice, once in Asia and once in Europe or the Near East, but critics said there wasn't enough evidence to be sure. A few years later, researchers reported signs of dogs in the Americas as early as 10,000 years ago, yet those canines appear to have vanished without a genetic trace.

Other studies have found evidence of ancient dogs in Siberia and elsewhere, but scientists don't know how they got there or how they're related.

To fill in some of the blanks, two big names in dog and human genetics teamed up: Greger Larson, an evolutionary biologist at the University of Oxford, and Pontus Skoglund, a paleogenomicist at the Francis Crick Institute. Larsen, Skoglund, and colleagues sifted through more than 2000 sets of ancient dog remains dating back nearly 11,000 years from Europe, Siberia, and the Near East. In the process, they added 27 ancient dog genomes to the five already on record. They then compared those with the genomes of 17 humans living in the same places and times as the dogs.

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