# Calculate the age of the dog: How the conversion to human years works

• A common rule of thumb for dog owners is that one dog year is equal to seven human years.
• New research shows, however, that the simple relationship of one to seven years is wrong, as puppies age much faster than young children.
• In old age, on the other hand, the relationship is reversed: dogs grow old more slowly than humans.

On average, dogs live up to twelve years. Man’s life expectancy, on the other hand, is at least five times as long.

This difference forms, among other things, the basis for the general rule of thumb that a dog year is equal to seven human years.

But according to a new study published in the American journal Cell, this relationship of one to seven years is unsustainable. The reason for the statement is new genetic evidence that has shown that puppies and young animals age much faster than older dogs.

This means that you have probably miscalculated your dog’s age to human years.

According to the researchers, the age of a six-year-old dog is comparable to about 60 human years. “I like taking my dogs for walks and am a little more understanding with my six-year-old now,” Trey Ideker, co-author of the new study, said in a press release. “The age of a one-year-old dog is surprising – it’s the same as a 30-year-old human.”

To find a better formula for comparing the ages of humans and dogs, Ideker’s team looked at chemical markers in the DNA of 104 Labradors, ranging in age from just a few weeks to 16 years.

## An eight-week-old puppy is equivalent to a nine-month-old baby

An animal’s DNA does not change during its lifetime, but its chemical markers – called methyl groups – do. Over the years, methyl groups accumulate in DNA, turning certain genes on and off.

After studying how these methyl groups accumulate over time in different parts of the Labrador genome, the researchers compared the results with changes in methyl groups in humans.

Ideker’s team found that dogs accumulate more methyl groups than humans in the first year of life. The age of an eight-week-old puppy is therefore the same as for a nine-month-old baby.

Over the years, the rate at which the methyl groups in the DNA increase in dogs is slower and better suited to humans. This suggests that dogs age more slowly as they get older.

In the end, a dog year cannot be equated with seven human years. In fact, if you want to calculate your dog’s human age, you will need a calculator.

The formula used by the researchers is: human age = 16 x ln (dog age) + 31. So the dog’s human age is obtained by multiplying 16 by the logarithm of the dog’s age and adding 31 to the result.

In essence, as each year a dog ages, the corresponding increase in human years becomes smaller and smaller. Based on this formula, the age of a six-year-old Labrador equals 60 human years. However, a 12-year-old laboratory would correspond to 70 human-years old.

“If we understand aging based on the age of our cells, this new study is really useful in reconciling human and canine aging,” Lucy Asher, an animal behavioral researcher who was not involved in the study, told the British newspaper The Guardian.

In the future, Ideker would like to repeat the study of other dog breeds that have a different life expectancy.

## Comparing the age of humans and dogs is a challenge

The new study showed that methyl groups accumulated on some of the same genes during the aging process in both dogs and humans. The reason for this, according to the authors of the study, is that dogs share the living environment with their owner and enjoy almost the same standard of health care.

After all, age conversion does not apply to hormones and behaviors in humans and dogs.

“While a 30-year-old human may have cells the same age as a one-year-old dog, many dogs are immature at this point and exhibit behavioral and hormonal conditions similar to puberty,” Asher told The Guardian.

This is probably why your one-year-old dog does not act after his human age of 30, but instead prefers to hunt sticks and squirrels with childish zeal.

“Dog development is not just a condensed version of human development, which is why it is difficult to find a clear correlation between a dog’s age and a human’s age,” Asher added.