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NIH Researchers Reframe Dog-to-Human Aging Comparisons

An owner walks a puppy.

One of the most common misconceptions is that 1 human year equals 7 dog years in terms of aging.

One of the most common misconceptions is that 1 human year equals 7 dog years in terms of aging. However, this equivalency is misleading and has been consistently dismissed by veterinarians. A recent study, published in Cell Systems, lays out a new framework for comparing dog-to-human aging.

In one such comparison, the researchers found the first 8 weeks of a dog’s life is comparable to the first 9 months of human infancy, but the ratio changes over time. The research used epigenetics, a process by which modifications occur in the genome, as a biological marker to study the aging process. By comparing when and what epigenetic changes mark certain developmental periods in humans and dogs, researchers hope to gain specific insight into human aging as well.    

Researchers performed a comprehensive analysis and quantitatively compared the progression of aging between two mammals, dogs and humans. Scientists at NHGRI and collaborators at the University of California, San Diego, UC Davis and the University of Pittsburgh School of Medicine carried out the research. 

All mammals experience the same overarching developmental timeline: birth, infancy, youth, puberty, adulthood and death. But researchers have long sought specific biological events that govern when such life stages take place. One means to study such a progression involves epigenetics—gene expression changes caused by factors other than the DNA sequence itself. Recent findings have shown that epigenetic changes are linked to specific stages of aging and that these are shared among species. 

“Dogs experience the same biological hallmarks of aging as humans, but do so in a compressed period, around 10 to 15 years on average, versus over 70 years in humans. This makes dogs invaluable for studying the genetics of aging across mammals, including humans,” said Dr. Elaine Ostrander, NIH distinguished investigator and co-author of the paper.  

The group acknowledges that the dog-to-human years formula that they developed is largely based on data from Labrador retrievers alone. Hence, future studies with other dog breeds will be required to test the formula’s generalizability. Because dog breeds have different life spans, the formula may be different among breeds.

The NIH Record

The NIH Record, founded in 1949, is the biweekly newsletter for employees of the National Institutes of Health.

Published 25 times each year, it comes out on payday Fridays.

Associate Editor: Carla Garnett
Carla.Garnett@nih.gov

Staff Writers:

Eric Bock
Eric.Bock@nih.gov

Dana Talesnik
Dana.Talesnik@nih.gov

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