Working out how old your dog is in ‘human years’ is simple, many of us believe: you just take the animal’s age and multiply by seven.
But it’s not quite as simple as that, scientists from the University of California have discovered - and the idea that you simply multiply by seven is ‘a myth’.
For a start, some breeds live far longer than others, with large breeds such as mastiffs living for just 6-7 years and chihuahuas lasting up to 18 years.
But a team led by Tina Wang set out to compare DNA methylation, a measurable ‘biological clock’ based on molecules added to DNA over time, Science Alert reports.
Wang and her team compared dog data to ‘methylation profiles’ from 320 humans aged between one and 103 years - plus 133 mice.
The researchers wrote, ‘Using targeted sequencing, we characterise the methylomes of 104 Labrador retrievers spanning a 16 year age range, achieving >150X coverage within mammalian syntenic blocks
‘Comparison with human methylomes reveals a nonlinear relationship which translates dog to human years, aligns the timing of major physiological milestones between the two species, and extends to mice.’
In other words, there is a relationship, but it’s complicated.
To get the age of your dog, find the natural logarithm of its age (here’s a calculator) then multiply by 16 and add 31.
The researchers say it works well for young dogs, but less well for the period between adolescence and middle age, as dogs reach puberty far faster than humans.