Dogs May Look Like They're Aging Faster Than Cats, but That's Not Actually the Case! 21 Shares Dogs are man's best friend. More so than cats, they aim to please, they mimic human behavior and they love to hang out with their owners. They're so similar to their pet parents that they even age similarly to humans, according to a study by researchers at the National Institutes of Health. "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," said Elaine Ostrander, National Institutes of Health distinguished investigator and co-author of the paper, in a release.