If you’ve ever gotten the impression that your dog’s calculated age in human-equivalent years seemed a bit off, you’re not alone. A new, more accurate formula for calculating your dog’s age has been published — let’s hope you still have your notes from high school trigonometry class.
The long held formula for calculating dog years is to take a dog’s real age and multiply by seven. This approach is simple enough and roughly accounts for the difference in scale between the lifespans of humans and dogs. As it turns out, though, synchronizing the ages of dogs and humans — including all of the various stages of development — is a bit more complicated than that.
A team of geneticists from the University of California, San Diego, decided to take an alternative approach to comparing the ages of dogs and humans using the process of DNA methylation.
As animals age, our DNA accumulates molecules, known as methyl groups, in a process called DNA methylation. The rate at which methylation occurs is closely linked to our developmental stage and, consequently, our age. Because this process occurs somewhat consistently across species, it offers a benchmark that can be used to determine age equivalence across groups.
The research team compared the methylation profiles of Laborador retrievers ranging in age from 4 weeks to 16 years to those of humans ranging in age from 1 to 103 years old. From the comparison, the research team was able to develop an equation to convert one species’ age to the other. Got your calculators ready? Here it is:
ageh = 16ln(aged) + 31
Got that? Take the natural logarithm of your dog’s age (aged) in actual years, multiply it by 16, then add thirty-one.
This method, while a bit more involved than the classic “multiply by seven” approach, should give you a more accurate sense for how your dog stacks up, developmentally-speaking, to a human.
The research team cautions that this particular equation may be less accurate when comparing humans to dogs breeds other than Laborador retrievers.