A common retort when people start taking about the risks of nanotechology (manipulating matter on the atomic scale) is saying something to the effect of:

Look at it this way – we have self-replicating nano-bots right now – they are called bacteria. Have they turned the world into gray goo in runaway exponential growth? Are we going to be able to make more efficient nano-bots than mother nature has done in the last 4 billion years?

The answer, of course, is yes. Here was the response to that Slashdot post, which was, unlike the parent, not modded up as “Insightful”:

We can build machines that fly faster and higher than any bird, that can travel over land and water faster than any animal, that can see and hear better than any living thing, that can survive higher and lower temperatures than any living thing, etc.

Yes, I think it could happen.

Your argument is stupid. Evolution is not about an intelligent attempt to create the best thing possible, it is about a random attempt to create something that will survive better then the things around it. There is a difference.