Stein was scripted and had the advantage that Dawkins was not expecting an adversarial interview due to having been intentionally misled about the nature of it.
Considering that Dawkins wrote a book called The God Delusion, you would think he would already have a pat answer to a simple question like that. I mean, his whole premise is that God does not exist, and he has certainly given thought to how that very first living cell came to be. I mean, that’s his whole schtick — disproving God.
I have to admit that he was not nearly as intimidating as I expected, having never seen or heard him before.