Why are there still monkeys?

One of the most annoying creationist canards is to ask "if we evolved from monkeys, why are there still monkeys?" John Wilkins of Evolving Thoughts has taken the time to answer this question in much more detail than anyone could possibly want. The quick answer, by the way, is:

Now, back to the "why are there still monkeys?" part of the question: on the older view of evolution that was the common idea of evolution for a century prior to Darwin (both the evolution of organisms, or languages, and of social institutions), if a lineage had evolved, it moved "up" the ladder as a whole. On the Darwinian view, only one part of a species evolves into the next (and there's no "next step" - a species evolves into whatever suits the local conditions of the population it evolves from; it may be bigger brained or smaller brained, or for that matter bigger or smaller). The rest of the species remains. So we end up with an increase in the diversity of life, which is, I think, the single most important point Darwin ever made. Monkeys remain because we are monkeys, and so are chimps, orangs, and all those other primates. All of them remain because they evolved by the multiplication of taxa.

(Hat tip: Carl Zimmer).