Scientists have found in a study that reveals young dogs might be “older” than previously thought, suggesting that a one-year-old puppy is actually about 30 in the human years equivalent.
Researchers at the University of California San Diego’s school of medicine describe how they focused on epigenetic changes to DNA – modifications that don’t change the DNA sequence but can switch genes on or off. The team looked at the way particular molecules, called methyl groups, accumulated in certain areas of the human genome over time and compared them with how they accumulated in similar areas in the dog genome.
The results, which draw on genetic data from about 100 labrador retrievers from puppies to elderly animals, reveal every dog year is not equivalent to seven human years. Instead, dogs show far more rapid accumulation of methyl groups in their genome than humans within their first year or so, suggesting they age at a much faster rate. However, as time passes, the rate of ageing in dogs, compared with humans, slows down. The relationship is described by the formula:
human age = 16 ln(dog_age) + 31
The findings suggest a one-year-old dog would have a “human age” of about 30, while by the age of four they’d be about 54 in “human years”, and by 14 they would be on a par with a human in their mid-70s.