Puppies: Always adorable! But if you're susceptible to adoption or the inability to stop bestowing boops and num-nums, beware. Science has determined the precise age when pups reach peak cuteness.

A new study found there's an "optimal age" for puppy cuteness to humans, which is between 6 to 8 weeks of age. There's a biological explanation: About then, the mother starts wrapping up her job of nursing the pups, and they have to start finding new homes.

"Just as their mother is getting sick of them and is going to kick them out of the den and they’re going to have to make their own way in life, at that age, that is exactly when they are most attractive to human beings,” said lead study author Clive Wynne, a professor of psychology and director of Arizona State University’s Canine Science Collaboratory.

This may give researchers further clues about how dogs evolved from wild wolves to domesticated companions. In the wild, baby wolves stay with their parents for two years, while they're taught how to hunt prey. But feral dogs often never meet their fathers and are left by their mothers around two months of age.


"This attraction of humans to dog pups at that phase of life may have given early dogs, and may continue to give today’s free-living dogs, a competitive advantage by being adopted and cared for by humans,” the researchers wrote in the May 3 issue of the journal Anthrozoös.

In the study, 51 participants were shown 39 black-and-white pictures of puppies at different life stages and asked to rate their cuteness from "very attractive" to "not at all attractive." There were three breeds pictured: the Jack Russell, the cane corso and the white shepherd. The pups were rated least attractive at birth, peaked before 10 weeks and declined before leveling off. The peak cuteness ratings by breed were 6.3 weeks (cane corso), 7.7 weeks (Jack Russell) and 8.3 weeks (white shepherd).

Wynne acknowledges that puppy videos might produce different results — to say nothing of breeds singing, skateboarding or giving high-fives — and might do a follow-up study.

"But it’s an interesting new hint toward how people make a difference in the lives of dogs — and make being a dog possible," he told the "Washington Post." "How is it possible to be a dog? Part of the reason is that people are really attracted to you at that age when human intervention can be most helpful."

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