Who is fittest?

I got this quote from
http://economistsview.typepad.com/economistsview/2009/01/darwin-and-the.html#comments

The commenter attributed it to Charles Darwin, but other commenters disagreed that Darwin had said it. Regardless, if you are talking about long-term survival, it is true.

“It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is the most adaptable to change.”