Giving Thanks in a Vacuum
The fact of your own existence is the most astonishing fact you will ever have to face. Don’t you ever get used to it. The universe we live in and the fact of our existence is truly a cause for gratitude. Gratitude for our individual existence and for the process of evolution which from the blind forces of physics produces all that we know and gives it the illusion of design.
Dawkins is speaking of predictability and luck as the two halves of the creative process. Natural selection is the great engine of the predictable half, while blind chance is the other half. If some catastrophe wiped out the mammals today, the surviving vertebrates would evolve into a similar range of ecological types. Humans would have evolved again if the tape of life had been rerun.
But, the predictable engine of natural selection requires luck at certain critical points, the most obviously at the origin of life (self replication coded information that influences the world) is the most obvious case. This first step in the chain of evolution might have been a very lucky step indeed.