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A new study led by Dr. Aurélie Manin from the School of Archaeology at the University of Oxford has traced the incredible journey of humankind's best friend across the Americas, showing how dogs slowly spread southward alongside early farming societies—mirroring the rhythms of human migration, agriculture and cultural change.

An international team of scientists sequenced 70 complete mitochondrial genomes from archaeological and modern dogs, collected from Central Mexico to Central Chile and Argentina, revealing that all pre-contact dogs in Central and South America descended from a single maternal lineage that diverged from North American dogs after humans first arrived on the continent.

The study, "Ancient dog mitogenomes support the dual dispersal of dogs and agriculture into South America," is in the journal Proceedings of the Royal Society B: Biological Sciences.

Rather than dispersing rapidly, dogs followed a slower path—what scientists call "isolation by distance"—gradually adapting to new environments as they moved with people through the Americas between 7,000 and 5,000 years ago, in step with the spread of maize cultivation by early farming communities.

While the arrival of Europeans introduced new dog lineages that largely replaced indigenous ones, the team found that some modern Chihuahuas still carry maternal DNA from their pre-contact Mesoamerican ancestors. These rare genetic echoes highlight an enduring legacy of the first American dogs, and the deep roots of this iconic breed.

Lead author Dr. Manin said, "This study reinforces the important role of early agrarian societies in the spread of dogs worldwide. In the Americas, we show that their spread was slow enough to allow the dogs to structure genetically between north, central and south America. It is rather uncommon for domestic animals and it opens new research avenues on the relationship that existed between dogs and these early agrarian societies."

The study adds a new chapter to the long, shared history of dogs and humans—one shaped by movement, survival, and enduring companionship across continents.