[burnished]

Quibble: I'm not sure its true, though it is entertaining, reasonable, and appears to fit the facts.

The cuteness one is good too. I wonder if this sort of thing emerged slowly or quickly? Like, is cooperation just generally selected for and animal cuteness has been developing for a long time, or did it appear swiftly somewhere and provide some huge benefit? Or something else entirely?

[IshKebab]

I reckon both must have evolved along with the increase in head size. Most animals have babies that have developed enough so that they are reasonably independent. They can at least walk!

But humans have really big heads so they have to give birth really early before the baby is capable of walking, so screaming for help and being super cute is their only option.