Scientists believe in an evolutionary reason behind cuteness.
Cute babies are healthy babies and cute babies get more
attention from mom. Let's say someone has a set of fraternal
twins; whoever has the most symmetrical face, the biggest eyes,
and the nicest smile is going to get more attention. Same with
animals. Endangered species that are considered cute have a
better chance of surviving than more homely species simply
because more people will care (Leonard 2007). In order to
understand why cats are so cute, it's important to explain what
makes a baby anything so appealing in the first place. In terms
of evolution, there are certain subtle characteristics about a
person that indicate just how healthy it is. It's not that
there's some checklist or anything, it's simply that the bigger
a human baby's eyes or the smaller it's mouth, the more healthy
it is (healthy meaning fewer genetic mutations). Symmetry is
also a big factor; it plays a role in not just how we react to
babies, but how we find mates attractiv