Cats - both housecats and outdoor cats, and feral cats to boot - will sometimes make an eerie sound that sounds very much like a human baby crying. It can be quite disconcerting, hearing what sounds like a baby crying outside my window (following by scrabbling and squawking, often).
Why do cats make this sound?
The cats you're hearing are most likely females in heat. The sounds afterwards may be male cats fighting over the female, or possibly the female scrabbling with the male, possibly rejecting him, or after mating.
Sometimes a cat's normal meow by random genetic variation, will sound more like a baby than is typical for a cat, also.
African wildcats, domestic cats’ nearest relative, have a rather scary meow with a wide spectrum, though they don’t use it much around humans anyway. Ditto for other wild felids.
However, there is always some natural variation due to random mutation. Those cats that sounded less scary were more likely to be tolerated by the humans attracting all those yummy mice, which made those cats more likely to survive and produce offspring with that mutation.
This cycle was repeated for thousands of years, and the result is that domestic cats evolved to meow in the narrow frequency band that triggers the same instinctive human reaction that a crying baby does: feed this cute thing now so the noise stops.
However, cats have a pretty limited vocabulary, so the same meow gets reused for many other things, such as wanting to be petted, wanting to go outside, wanting to play, looking for mates, etc.
