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Join today<\/a><\/p>\n \n Already a member? Scientists say they\u2019ve finally solved a longstanding mystery \u2013 why big dogs<\/a> age faster than little dogs.<\/p>\n It has long been understood that smaller dogs tend to have longer lifespans than larger ones, bucking a wider trend in the animal kingdom<\/a> that often sees bigger creatures living longer. But until now, scientists haven\u2019t known why dogs are different.<\/p>\n However, new research suggests it all comes down to canine DNA<\/a> and a \u201cjumping\u201d gene called LINE1.<\/p>\n LINE1 genes are self-replicating and can copy and insert themselves throughout a dog\u2019s genetic systems.<\/p>\n These genes<\/a> are usually kept in check by a gene activity-regulating process called \u201cDNA methylation.\u201d<\/a> But when methylation is lost, their activity can increase, damaging DNA in the process and speeding aging.<\/p>\n And crucially, larger dogs lose 35 percent more LINE1 gene methylation than smaller dogs, a new analysis<\/a> of 864 dogs enrolled in the multi-year, nationwide Dog Aging Project shows.<\/p>\n \u201cThis is one of the clearest molecular signatures we\u2019ve seen that aligns with the well-known size-lifespan tradeoff in dogs,\u201d Blaise Mariner, an author of the findings and researcher at Arizona State University, explained in a statement<\/a>. <\/p>\n \u201cIt suggests that faster aging in larger dogs may be driven, at least in part, by reduced control over these \u2018jumping genes.\u2019\u201d<\/p>\n Surprisingly, the study also uncovered differences between male and female big dogs revealing that females may experience more LINE1 gene-jumping. <\/p>\n \u201cThis was an unexpected result,\u201d Brianah McCoy, who co-led the work, said. \u201cIt challenges some of our assumptions about how the X chromosome is regulated and highlights the complexity of epigenetic aging.\u201d<\/p>\n Previously, experts had cited faster aging rates<\/a> and shorter lifespans for the difference in the lifespans of man\u2019s larger best friends, but had not understood why this happened.<\/p>\n Recent research<\/a> from the University of Arizona revealed that large dog brains don\u2019t age faster than smaller dog brains, too, indicating the animals died before seeing cognitive decline.<\/p>\n Although more research is needed to determine whether LINE1 activity is a cause or consequence of aging, the researchers hope these findings will help scientists develop methods to extend the lifespan of large dogs \u2013 for their benefit and ours.<\/p>\n \u201cDogs provide an extraordinary model for understanding aging because they show dramatic variation in lifespan within a single species,\u201d senior study author Noah Snyder-Mackler<\/a>, a professor at Arizona State University, said<\/p>\n \u201cOur work suggests that transposable elements may be a fundamental part of the aging process across mammals,\u201d he added. <\/p>\n \u201cIf that\u2019s the case, targeting these elements or the mechanisms that regulate them could be a promising avenue for future therapies to extend the health span in humans.\u201d <\/p>\n
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Researchers say they have uncovered the first compelling molecular explanation of why large dogs live shorter lives (Charlie Leight, Arizona State University)<\/p>\n![\"Noah](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/10\/Low-Res_202610_NoahSnyder-MacklerImages_03.jpeg\")
Noah Snyder-Mackler with his two dogs Homer, center, and Juno (Deanna Dent, Arizona State University)<\/p>\n