I didn't mention fear of heights, just different states to which the brain reacts with vertigo/dizziness. I agree that it seems like a learned behaviour; and as many of us also know it can be unlearned to some degree.
That's an interesting point about the 4-legged mammals with better balance.
Were you thinking safety warning as in the brain signalling to to the muscles to reduce movement?
Why do humans (and other mammals) get nauseated from dizziness or vertigo?
I can see the evolutionary advantage of nausea from food poisoning, but I can't see the direct "link" between vertigo and vomit.
I found something on verywell.com...