I think this is one of the most significant questions that mankind has ever addressed, and yet I very rarely come across any reference to it.
Stephen Jay Gould is probably the scientist best associated with this. His well known metaphor runs as follows:

If you re-ran the tape of evolutionary history, an entirely different set of creatures would emerge. Man would not exist because the multitude of random changes that resulted in us would never be repeated exactly the same way.

Gould is by a long way my favourite science-writer (or was, until Bill Bryson dipped his big toe in the genre), and therefore I was always likely to agree with this view. The concept also appeals to be in that it reinforces our insignificance in the grand scheme of things.
So I was pleasantly surprised when I came across a program dealing with exactly this topic while browsing through the archives of In Our Time; a wonderful series where Melvyn Bragg discusses the big questions of civilisation (subscribe to his newsletter – it’s wonderful reading).

Who were the original proponents of the idea of a grand design? Were they deliberately setting out to find a scientific theory that could sit alongside religious faith? On the other hand, can the concept of contingency – or the randomness of evolution – be compatible with a belief in God?

Visit In Our Time to listen to the program (all quotes and image taken from that page). The discussion takes twenty minutes to get around to this topic, and the jury seems to go against Gould, but it’s good stuff nonetheless.
Take a few minutes to browse through the other programs (it’s not just Science; there’s also History, Culture, Religion and Philosophy) then save this page to your favourites and listen to other programs as you browse next time.

Of course this is much too interesting a question to appear on any Science syllabus.