A new genetic analysis shows that many modern dog breeds carry measurable wolf DNA added after wolves were first domesticated about 20,000 years ago.

The study, led by researchers at the American Museum of Natural History, examined 2,693 modern dogs and found detectable wolf ancestry in a wide range of breeds, from tiny companion dogs to deliberately bred wolfdogs. This extensive analysis encompassed nearly 3000 individual canines, shedding light on the diverse genetic tapestry that shapes our modern pets.

The team identified clear differences in the amount of wolf ancestry between breeds. At one extreme, the chihuahua showed about 0.2% wolf ancestry. At the other end, intentionally bred wolf–dog types such as the Saarloos wolfdog and the Czechoslovakian wolfdog carried between 23% and 40% wolf ancestry. Other examples included the Anglo-French tricolor hound, with roughly 4.7% to 5.7% wolf DNA, and the Shiloh shepherd, at 2.7%. The Tamaskan, noted for its wolf-like appearance, was also listed among breeds with notable wolf connections. Some behaviors seen in these breeds, notably howling and certain personality traits, can be traced back to their wolf ancestry, further emphasizing the impact of genetics on dog behavior.

“Prior to this study, the leading science seemed to suggest that in order for a dog to be a dog, there can’t be very much wolf DNA present, if any. But we found if you look very closely in modern dog genomes, wolf is there,” said Audrey Lin, lead author and a researcher at the American Museum of Natural History.

Co-author Logan Kistler of the National Museum of Natural History put the finding in plain terms: “Dogs are our buddies, but apparently wolves have been a big part of shaping them into the companions we know and love today.” His remark underscores the study’s conclusion that interbreeding with wolves continued after the initial domestication of dogs. Interestingly, breeds that retain closer genetic ties to their wolf ancestors tend to exhibit more wolf-like behaviors, showcasing the lasting influence of this ancient relationship.

Researchers highlighted how wolf-derived genes are not merely historical footprints. Wolf genes appear in places in the dog genome linked to traits that help animals adapt to different environments, and the study noted that some dogs carry substantial amounts of wolf ancestry. Those genetic contributions, the authors say, likely helped dogs solve challenges associated with living alongside humans across a variety of landscapes. In fact, dogs have inherited vital traits such as olfactory abilities and body size, further proving the enduring connection between dogs and their wild relatives.

The findings were made public in late November 2025, with the study announced on November 23 and published on November 24. The research team placed breed-level results alongside the broader pattern of post-domestication gene flow, showing that wolf ancestry is distributed unevenly but broadly across modern dog populations.

The analysis and its conclusions are described in coverage of the study, including reporting by ScienceDaily, which summarizes the research findings and their implications for how dog genomes tolerate wolf DNA. Additional context about which breeds carry detectable wolf ancestry and how those figures were estimated is available in summaries such as those published by LiveScience.

Lead author Audrey Lin emphasized that modern pet dogs can appear distant from wolves in behavior and appearance, yet genetic traces persist. “Modern dogs, especially pet dogs, can seem so removed from wolves, which are often demonized. But there are some characteristics that may have come from wolves that we greatly value in dogs today and that we choose to keep in their lineage,” she said. This highlights that while dogs may have evolved significantly since their domestication, their genetic heritage remains a core component of their identity.

By outlining where wolf ancestry concentrates in the dog family tree, the researchers aim to clarify how hybridization shaped traits such as body size, scent-related genes and behavioral tendencies. The study’s dataset and breed comparisons provide a map of that variation without implying that wolf ancestry transforms the basic status of an animal as a dog.

The research team noted the long timescale involved: dogs were first domesticated from wolves about 20,000 years ago, and the study documents that interbreeding between wolves and dogs continued for millennia afterward, contributing genetic material that persists in many breeds today. Additionally, the majority of modern dog breeds have been analyzed for their wolf DNA content, providing insight into the complex genetic history of these beloved companions.

The study was conducted by scientists at the American Museum of Natural History with collaboration from the National Museum of Natural History and released to the public in late November 2025.

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Original reporting: view the original article.