Thoughts in a Haystack

One of the things about natural selection is that it does not involve conscious, deliberate, or active competition. Darwin himself said this, but the message got lost under the influence of another philosopher, Herbert Spencer, who insisted that a better term for Natural Selection was survival of the fittest. This naturally led people to think that "fit" here meant "stronger" or "faster", or even just plain "meaner". But it doesn't. "Fit" in biology means something that seems a little odd at first. It means little more than "has the most grandchildren". An organism is fitter than another if it ends up having more progeny over long periods of time, on average. This means that although I only have two kids of my own, I am fitter than someone who has 12 kids if my kids live to adulthood, raise kids of their own, and so on, and theirs only end up raising a few successful grandchildren.

Evolution isn't nice, but it is an exact bookkeeper.

- John Wilkins, "Misunderstanding Evolution"