Thursday, October 29, 2020

New ancient genomes reveal a complex common history of dogs and humans

Newly sequenced whole genomes of ancient dogs reveal a complicated genetic legacy that reflects a long, shared history with humans spanning more than 11,000 years into the past. "The dog is the oldest domesticated animal and has a very long relationship with humans. Therefore, understanding the history of dogs teaches us not just about their history, but also about our history," says lead author, Anders Bergström, in an accompanying video. 

While the antiquity of the inextricable bond between dogs and humans is well recognized, its origin - where and when it began - remains shrouded in history. To date, few whole dog and whole wolf genomes have been available for analysis. As a result, very little is known about the population history of prehistoric dogs and how it relates to humans. Here, Bergström and colleagues greatly expand upon the number of ancient dog genomes and present 27 new whole-genome sequences up to 11,000 years old, from across Eurasia. Analyzing these new data alongside other ancient and modern dog genomes, the authors found that all dogs share a common ancestry distinct from present-day wolves, with limited gene flow from wolves since domestication but substantial dog-to-wolf gene flow. 

While the precise timing and location of domestication remain elusive, the results indicate that at least five major dog lineages had already diversified and spread worldwide by 11,000 years ago, suggesting a considerable genetic history during the Paleolithic. Bergström et al. also compared the ancient dog genomes with commensurable ancient human genome-wide data, revealing aspects of dog population history that likely reflect their migration alongside human groups, as well as instances where population histories do not align. 

Together, the findings underscore dogs' complex common history with humans. Pavios Pavlidis and Mehmet Somel discuss the study further in a related Perspective. Of note to reporters focused on trends, this study builds on recent related work published at Science. In 2016, for example, a study by L.A. Frantz and colleagues revealed a deep split between dogs from Western Eurasia and East Asia. In 2018, a study by M. Ni Leathhlobhair showed the first dogs of North America arrived alongside humans and were not domesticated from North American wolves, but rather, from an ancient breed of Siberian sled dog.

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