Dogs were the only domesticated animals on the first human migrations into the Americas, arriving with hunter gatherers at least 15,000 years ago. New studies of ancient dog DNA fill in what happened after that first crossing.
A 2025 study of 70 complete mitochondrial genomes, from ancient and modern dogs across Central Mexico to Chile and Argentina, found that dogs spread into South America in a slow push that tracked the spread of early farming. The big genetic split between North, Central, and South American dog populations happened roughly 7,000 to 5,000 years ago, right as agriculture and maize moved south. Researchers call it a dual dispersal: dogs and farming, traveling together.
A separate 2026 study of dogs buried at Maya sites in Chiapas, Mexico, adds another layer. Most of those dogs carried chemical signatures that did not match their burial sites, which suggests they were brought in from distant areas and traded between communities. Dogs moved through human networks long before the Spanish arrived.
Colonization changed the canine family tree too. After European contact, lineages from Europe became common across the Americas, and the older Indigenous American lineages became rare. Almost rare. A few modern Chihuahuas still carry a maternal line that traces back to dogs from before Europeans arrived, likely connected to the Techichi of the Toltec era.
What this means for your dog: mostly a reason to look at the small one on your lap with fresh respect. Dogs have been along for every major chapter of the human story, from the first walk into a new continent to the invention of farming. If you have ever wondered whether a dog DNA test is worth it, this is the kind of history those tests are reading. Dogster’s writeup of the study has the full detail.