There’s no denying that newborns are adorable. Their small hands, their chubby cheeks, and their tiny yawns are just too cute for words. You melt every time you see your baby because how could you not?

If you’re a new mama you’ve probably even asked yourself, “How could my little one get any cuter?” It turns out the answer is: With age. New research shows that babies reach peak cuteness around 6 months old.

According to a new study published in Evolution and Human Behavior, adults tend to find babies who are six months old to have the most appealing faces.

Specifically, researchers showed participants images of 18 children taken shortly after birth, at 3 months old and at 6 months old, and discovered that adults rated 6-month-old infants highest across all facial cues: cuteness, happiness, health and self-resemblance.

Researchers were surprised by the results, though. As lead author Prarthana Franklin, a graduate student at Brock University, notes, it’s commonly thought that the younger babies are, the cuter they are perceived to be.

Ethologist Konrad Lorenz theorized in the 1940s that a baby’s cuteness draws out an adult’s nurturing and caretaking side, which would guarantee infant survival. In turn, that would mean newborns should be seen as being “the cutest of all” because they are most in need of care and protection, but the new findings challenge this, the researchers say.

“We wondered, why would there be this specific peak?,” explains Tony Volk, Child and Youth Studies associate professor at Brock University, “But then, we read the medical literature, which was almost universal in that six month olds are better at surviving illness than younger babies.”

The reason parents don’t perceive newborns as the cutest has an evolutionary basis. Volk says it might be a leftover from back when babies often didn’t make it to six months.

“A delay in attachment makes those early losses easier to cope with,” he explains, adding that the findings could explain why some parents today find it takes longer than they expected to bond with their infants.

“We want to let parents know that if they’re not instantly grabbed by this baby as much as they thought they might be, then that’s normal. The bonding will build and grow over time,” Volk continues.

According to Volk, how our babies express themselves and whether or not we see ourselves reflected in them also factor into how we might bond with a newborn versus a baby a few weeks older. He says it can take up to a month for infants to develop the ability to smile out of happiness, which adults often find endearing. That’s also when dads tend to notice how much their baby looks like them—something that has been proven to increase father-baby bonds.

Learning that parents perceive 6-month-olds as the cutest is good for another reason, too, say the researchers. If parents are aware of this bias we can work to strengthen parent-child bonds earlier in infancy, through things like infant massage and skin-to-skin contact.

And although cuteness may scientifically peak around six months, many mamas never stop wondering if our kids can get any cuter, because, somehow, they do it every day.

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