Often referred to as man’s best friend, we humans tend to build very close bonds with dogs. We also tend to humanise certain aspects of their lives, like their personalities, their emotions and even their age. Many people refer to one dog year being equal to seven human year but it turns out it is not as simple as a little multiplication. So how exactly do dogs age and do you really know how old your dog is?
Dogs, like other mammals, pass through similar phases as they age… juvenile, pubescent and adult stages of life. They also show many physicals signs of aging in the same way we humans do; they tend to go grey as they get older and their joints stiffen up. However studies have found that the overall aging process in dogs is very different to that in humans, and simply multiplying a dog’s age by seven doesn’t add up.
Any dog owner could probably debunk the seven years to one dog year myth. Most dog reach sexual maturity well before the age of one, which definitely does not compare to human development. So what number should we use?
Nobody is quite sure where the seven to one year age ratio originated. It appears it began as a nine to one ratio, according to an inscription etched into the floor of Westminter Abbey, recording the life span of a number of animals, including dogs and humans. Over the years the nine turned into a seven, then in 1953 a French scientist mapped out different life-stage markers shared by humans and dogs. This study established that dogs age at different rates from puberty to adulthood.
The study suggested that dogs do not age at the same rate as we humans do. For some parts of their life, particularly the first year, they age really
quickly, up to 15 to 20 times faster than humans. The study suggested that this slows down to a rate of just five times the human aging rate, for the second year of the dog’s life and by the time the dog reaches old age, their aging rate is on a par to ours.
To investigate the aging process further, a recent research team took a closer look at the DNA of more than 100 dogs. In particular, the study focused on a process called methylation, whereby methyl groups are added to particular regions of DNA. This happens in humans as well as dogs. These methyl groups act like little tags and their abundance and location can be mapped to processes like aging.
Based on this new study, the first year of a dog’s life is more like 30 years to us humans. The research led to a very specific formula for a dog’s age, this one isn’t just a simple multiplication, you’ll need a calculator. The new formula for a dog’s age in human years is 16 ln * (dog’s age) + 31 (*where ln refers to the natural log of a number).
The study that has created this formula looked at only one breed of dog, Labradors retrievers. Maybe with extended research (more dogs and breeds) the mathematics of just how old a dog is, will expand too. So, while you can’t teach an old dog new tricks, maybe you can teach an old person a new equation.