I'm glad you asked, Pink.
You guys have fallen into Buz's trap where he gets to assail Natural Selection as if it were the only force involved in evolution.
He's right, of course. By itself, natural selection can only reduce the variability of a population to the most advantageous existing traits.
On the other hand, by itself, random mutation can only expand variation in a population randomly, with no regard as to the fitness of traits.
But to say that proves anything is stupid. Obviously, natural selection and random mutation work together to create new, advantagous traits in populations. What Buz is doing is like trying to "prove" that cars can't actually take you anywhere, because a car with no gas doesn't go anywhere, and gas with no car just runs through your fingers.
Duh. Natural selection without random mutation is like a car with no gas. Put them together, and like the car, there's almost no limit to where they can take you.