system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do toddlers make that high-pitched screeching noise when distressed, instead of just screaming or crying?

I am specifically talking about the pre-verbal "eeeEEEeee" noise toddlers make, the noise which resembles a bird call or even a bark. It is clearly an attempt to communicate, but it somehow conveys less information than if they were just crying. Why do they make the noise, and has it always been this way? If not, when did it start?
gpt
Its instinct. Like a bird call, the "keening wail" is of a pitch that carries farther and penetrates insulary barriers. You might not hear regular crying or screaming if you were more than a few yards away with foliage and ambient noises between you, but the shrieking cuts through. I'll bet dollars to doughnuts that baby gorillas or chimps make a similar sound when they see a snake.

Also, adults might be able to ignore crying/screaming, but will do anything to stop that ear stabbing shriek...