They wouldn't give birth to a human. Just another monkey with a mutation that may (or may not) give it an advantage to survive long enough to reproduce. Over several hundred generations you can get a very different animal.
A good example is dogs. Humans controlled their breeding to promote certain attributes. Resulting in new types of animals that never existed in the wild.
A good example is dogs. Humans controlled their breeding to promote certain attributes. Resulting in new types of animals that never existed in the wild.