New research from the University of California, San Diego reveals a more accurate formula for converting dog years to human years. Geneticists and biologists involved in the study believe the seven to one year rule is not accurate because dogs mature much faster than humans. A dog can produce their first litter of puppies before one year of age while a seven year old child is several years away from puberty.

The seven to one rule formula was established in the mid 20th century. Though it is not entirely clear how the seven to one ratio was developed, it may have to do with human life expectancy at that time being about 70 years while dogs lived to about 10 years of age. Hence, the rule was established that every one year of a dog’s life equalled seven human years.

This formula is thought to be far from perfect. In addition to the fact dogs mature at a faster rate than humans, this formula also does not take in to consideration the difference in life spans among the different breeds of dogs. For example, small dogs live longer than large breed dogs. The American Kennel Club’s dog year conversion formula takes into account a dog’s size which makes it more accurate than the one to seven conversion formula.

Researchers from UCSD believe they have determined a more accurate conversion formula using a process called methylation. Methylation is a chemical reaction which occurs in every cell and tissue as a creature ages. The UCSD study was conducted over a 16 year period during which DNA samples collected from 104 Labrador retrievers were compared against DNA collected from 320 humans ranging in age from one year to 103 years.

Researchers looked for similarities between sets of sample DNA. They discovered the DNA profiles evolved similarly throughout the life span of both species. For example, the methylomes of a two year old Lab most closely matched those of a 40 year old human.

The study front loads the first year of a dog’s life more fully than traditional conversion methods. Under the seven times method, a one year old dog is equivalent to a seven year old child. The AKC method converts a one year old dog to a 15 year old teenager. This study converts the age of a one year old dog to 30 human years. Clearly, there are significant discrepancies amongst the three methods.

According to Trey Ideker, the leader of the laboratory at UCSD responsible for the study, this is simply what the data shows. He goes on to say, “This molecular characterization may or may not capture the entire experience of aging. Our curve is based on one particular molecular measurement, albeit the first really quantitative one. But this story is clearly just beginning–the full verdict on dog-human aging is definitely not yet in and likely will not be for some time.”

Source:  Ingraham, Christopher, “Scientists have come up with a better way to convert your dog’s age to human years,” The Washington Post.