Contrary to popular belief, it is not enough to multiply a dog’s age by seven to determine its age in human years. The true ratio changes over time, the American Institutes of Health (NIH) have just affirmed.
- With AFP
All mammals, both humans and dogs, go through the same stages of development: birth, childhood, youth, puberty, adulthood and death. A study published in the journal Cells Systems analyzed the evolution of dog genomes during their lives and generated a new formula for calculating their old age.
The scientists identified chemical marks on the DNA corresponding to these different phases of life. This area of research is called epigenetics. Molecules called methyl groups attach themselves to a part of the DNA, tilting it into a certain position and pushing it into the next phase of its development. “For me it’s like when you look at someone’s face and try to guess their age based on wrinkles, gray hair or other characteristics,” said Trey Ideker of the University of San Diego, who led the study. “These are similar characteristics but at the molecular level,” he adds.
Ideker and his colleagues studied this chemical process of methylation in 104 labrador retrievers, ranging in age from a few weeks to 16 years. It was then compared to the methylation process in humans. The researchers were thus able to generate a complex formula to adequately calculate the human/dog age.
According to the formula, an eight-week-old puppy is about the same age as a nine-month-old human baby, both of which are at the stage of their development where teeth are growing. A Labrador has an average life expectancy of 12 years, which corresponds to 70 years, the human life expectancy. “I like to walk my dog when I run, and I have more empathy for him now that he’s six years old,” says Ideker, his dog having the equivalent of 60 human years according to the formula.
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Elain Ostrander, an NIH scientist and co-author of the study, notes that it was conducted with labradors, but that further research could include breeds of dogs with longer and shorter life expectancies. In particular, the epigenetic clock could help veterinarians in their decisions about diagnosing and treating animals, the team of scientists concludes.