That there are small variations and that they can be amplified is obvious, and humans have used them in selective breeding since forever. But it's not obvious t

That there are small variations and that they can be amplified is obvious, and humans have used them in selective breeding since forever. But it's not obvious that you can take it far enough that you can create new species. Or that you can end up with very different creatures like humans and birds just by selecting for long enough.