It is a deeply rooted belief that has no basis, however: by multiplying the age of your dog by seven, you would obtain its age in human years. If it is more or less true towards the end of his life, it is not at all the case during most of his existence. Indeed, the ratio allowing to better match the aging state of the dog and the man evolves over time.
In an exciting study published in the journal Cells Systems (to read in English here), American scientists who analyzed the evolution of the genomes of a hundred labradors gave birth to a new formula, much more complex than a multiplication by seven.
Epigenetics, a little-known science
To understand what we are talking about, it must be borne in mind that all mammals, men and dogs alike, go through the same stages of development: birth, childhood, youth, puberty, adulthood and dead. These stages leave traces visible to the naked eye, wrinkles and white hair for humans, but also chemical traces at the molecular level. Researchers specializing in this discipline, epigenetics, observe this phenomenon called methylation, that is to say the alteration of DNA by molecules called methyl groups.
Trey Ideker of the University of San Diego, and his colleagues, therefore studied this process with precision on 104 retriever labradors of all ages.
By comparing this process with that at work in humans, they were able to observe these differences in ratio at each stage of life, and generate a complex formula to calculate it once and for all.
A puppy 8 weeks to 9 months of human age
According to this formula, an eight-week-old puppy is around the age of a human baby of 46 weeks, that is, nine months, both of which are at the developmental stage when teeth grow. A 10 year old labrador is 60 in human age, and another 12 year old is 70.
It's all very cool, but what is it for? Better care for the animals! The epigenetic clock can indeed help veterinarians in their decisions regarding the diagnosis and treatment of animals.