Dog DNA clock study links faster biological aging to death risk in nearly 900 dogs

Why do big dogs die younger? A new study suggests a possible clue in the chemistry of their DNA. Picture a Great Dane and a Chihuahua on the same walk. Great Danes and mastiffs rarely live more than a decade, while Chihuahuas can live twice as long, and scientists haven't been sure why. Researchers studied nearly 900 dogs from about 120 breeds in the Dog Aging Project, using owner surveys and blood samples. They built an epigenetic clock, which estimates biological age from methyl tags on DNA rather than from birthday. The clock predicted a dog's age to within about a year. Dogs whose clock ran ahead of their actual age had a higher risk of dying in the next two years. That's a link, not proof that the clock causes anything. Big dogs' clocks ran a little faster per year of life, and males aged faster than females, even when neutered young. In bigger dogs, methyl tags on transposable elements, or jumping genes, were being lost. When that happens, the elements may become too active, damage other genes and feed inflammation. The study suggests they may play a role, but it doesn't prove it. Immune cells also appeared to grow more alike with age, a pattern the researchers call a loss of cell identity. Why big dogs age this way is still open. A trade-off between rapid growth and immune investment is one idea, but it remains a hypothesis. The clock explains only part of the differences between dogs, so the team plans better clocks as the Dog Aging Project follows more dogs for longer. Dogs share our homes and catch some of our diseases, so what shapes their aging may teach us something about ours. In this video: • Bigger dogs' DNA clocks ran a little faster per year of life, and males aged faster than females. • In bigger dogs, methyl tags on jumping genes were being lost, a pattern linked to size, not proven to shorten lives. • The DNA clock predicted age to within about a year and tracked risk of death, but it shows correlation, not cause. • Why big dogs age faster is still a hypothesis, and the clock explains only part of the variation between dogs. Which surprises you more, the jumping genes or the immune cell clue? Tell me below, and subscribe to Science News for more curious science. Subscribe: https://www.youtube.com/@ScienceNews_ Sources: https://www.livescience.com/animals/dogs/big-dogs-age-faster-at-an-epigenetic-level-new-study-finds https://www.nature.com/articles/d41586-026-03199-5 https://www.eurekalert.org/news-releases/1146434 Visual credits: Zocha_K via Getty Images) · www.livescience.com · Editorial source excerpt Jacob King/PA Images/Alamy · www.nature.com · Editorial source excerpt #DogScience #Epigenetics #ScienceNews