Ancient DNA Traces Dog Migration Across the Americas
A 2025 genetics study reveals dogs moved into South America alongside the spread of agriculture thousands of years ago, with their ancient lineage
Dogs were living across South America long before the 16th-century arrival of Spanish conquistadors like Hernán Cortés. A 2025 study of ancient canine genetics analyzed 70 complete mitochondrial genomes to map their prehistoric journey.
Genetic and archaeological evidence shows dogs were the only domesticated animals accompanying human migrations into North America at least 15,000 to 16,000 years ago. These early hunter-gatherer communities had complex relationships with their dogs. Roles varied. At Hinds Cave in Texas, researchers found evidence of dog consumption dating back about 9,260 years. Dogs were not merely a food source, however. Their functions shifted over time and between cultures, gradually encompassing guardianship, herding, and companionship.
Tracing Maternal Lineages Through DNA
The 2025 research focused on mitochondrial DNA, which is passed from mother to offspring. By comparing 70 genomes from ancient and modern dogs across Central and South America, scientists identified a key pattern. Dogs from Central and South America belonged to a specific maternal lineage that had split from North American dogs long after the initial continental entry.
The populations grew more distinct as geographic distance increased, a pattern known as isolation by distance. This genetic signature indicates dogs did not migrate south independently. They were transported by people.
The Link Between Dogs and Early Farming
The major genetic divergence among North, Central, and South American dog populations is estimated to have occurred roughly 7,000 to 5,000 years ago. This timeframe coincides with the spread of agriculture and maize into South America. The researchers describe a dual dispersal. As human communities established new settlements and expanded farming, their dogs traveled with them.
Further evidence of long-distance canine movement comes from a separate 2026 paper. Researchers studying ancient dogs from Maya sites in Chiapas, Mexico, found chemical signatures indicating most dogs were imported from distant areas and moved between communities.
European Colonization and Genetic Replacement
For millennia, dogs lived alongside Indigenous American communities. European colonization dramatically altered this landscape. The ancient DNA study found new dog lineages appearing in South America after European contact. These lineages, likely originating from European dogs, eventually became far more common. The Indigenous American A2b mitochondrial lineage and its associated nuclear ancestry are now extremely rare.
The Chihuahua's Ancient Ancestry
A trace of this ancient history persists in a familiar breed. Some modern Chihuahuas carry a maternal lineage connected to dogs that lived in Mesoamerica before European arrival. This does not mean the modern Chihuahua is a direct prehistoric survivor. The breed, believed to have origins as the 'Techichi' in the Toltec civilization around the 10th century, was shaped by selective breeding. The genetic evidence simply indicates that some Chihuahuas retain a maternal link to that older Mesoamerican lineage. A small piece of ancient canine history endures in these tiny dogs today.
