In the book “The Beak of the Finch”, one species of bird was believed to have evolved from another (I think a small beaked bird gave rise to a species with a larger beak, better able to handle a certain hard seed). Both species coexist, and the numbers of the different birds fluctuates back and forth. They can interbreed, yielding a range of offspring with varying beak size.
Why does the possibility of two different human species on Earth at the same time disprove “evolution”?
It doesn’t “disprove evolution”, and that’s NOT what they’re saying. They’re saying it disproves a certain theory within evolution - that of man’s descent.
But generally you’re correct; I don’t know why 2 species coexisting means that 1 could not possibly have originated from the other.