> Oddly, tameness has also long been associated with traits such as a shorter face, a smaller head, floppy ears and white patches on fur—a pattern that Charles Darwin noted in the 1800s.

Hmm, so evolutionary pressure of existing around humans makes animals cuter.

I wonder why we find these features endearing?

I believe the main biological lever is retaining juvenile features as adults, physically as well as mentally (like with dogs). What we see as cute is an honest signal that they are more child-like: less aggressive, more trusting and pro-social.

My guess: possibly co-evolution. The article subsequently describes the genetics behind things becoming cute - which would have been completely benign to our ancestors (the core of your question). However, those of our ancestors who completed domestication of these animals (by random chance) would have enjoyed more protection from predators, rodents, etc. Those of our ancestors who attempted to domesticate things without the mutations might have had bad companions at best, and would have been predated at worst. This would have provided evolutionary pressure to adopt animals that were showing early signs of domestication. What we call "cute" is merely "likely to cooperate with us."

Since humans associate cuteness with large eyes and small body size, nocturnal / twilight animals, like raccoons, sugar gliders, cats, squirrels, etc have a larger chance to be domesticated as pets.

Daytime, larger animals (e.g. sheep, goats, or even rabbits) have a larger chance to be domesticated as food.

> I wonder why we find these features endearing

It's a side effect, evolution made sure we take care of our offspring.

I would bet on Paedomorphism, because we find babies and puppies cute.

Animal Auditions: Cute vs. Food - Denis Leary

https://youtu.be/IZBAtd9rty8

Perhaps a combination of adaptableness, small size, prodigious reproduction, and cuteness saved some species from being wiped out whereas other species didn't fare so well once humans arrived and transformed their territory. Adapt to urban encroachment or face extinction.

I thought it's because adrenalin and melatonin are produced in the same brain region, or something like that.

I've heard that the same process of domestication towards "cuteness" has been outlined in human evolution too.

Larger head-size relative to the body, larger eyes, smaller jaws and noses, longer limbs, etc.

Interesting parallels across species towards less aggression, greater pro-social behavior, more physical traits that shout "trust me, I'm harmless."

Almost like pro-social, intelligent team co-operation is a huge advantage compared to solo predatory behavior.