Scientists explain why small dogs live longer than large ones. This is also true for humans

A new study has shown that the lifespan of dogs depends on 'jumping genes' — LINE1 sequences. In large breeds, protective methylation marks disappear 35% faster per year than in small breeds, accelerating aging. The discovery may shed light on the mechanisms of human aging.

A major new study conducted as part of the Dog Aging Project has proposed a molecular explanation for a long-known phenomenon: large dog breeds live shorter lives than small ones. Scientists analyzed data from 864 dogs and studied DNA methylation — chemical marks that regulate gene activity. Special attention was paid to LINE1 sequences, so-called 'jumping genes,' which can copy themselves and move around the genome, damaging DNA. It was found that in large breeds, protective marks disappear about 35% faster per year than in small breeds. This is one of the clearest molecular patterns explaining the link between a dog's size and its lifespan. Researchers believe that large dogs age faster because their bodies are less able to control the activity of 'jumping genes.' Dr. Noah Snyder-Mackler from Arizona State University notes that dogs are a unique model for studying aging because their lifespans vary greatly even within the same species. The results may also be important for humans: if the effect on 'jumping genes' is confirmed, it could become a promising direction for developing life-extension methods.