Since the time of Darwin we understand much better why living creatures are adapted to their environment. It is not that their environment was made to be suitable to them but that they grew to be suitable to it, and that is the basis of adaptation. There is no evidence of design about it.
When you come to look into this argument from design, it is a most astonishing thing that people can believe that this world, with all the things that are in it, with all its defects, should be the best that omnipotence and omniscience have been able to produce in millions of years. I really cannot believe it. Do you think that, if you were granted omnipotence and omniscience and millions of years in which to perfect your world, you could produce nothing better than the Ku Klux Klan or the Fascists?
From his article Why I Am Not A Christian.