I think it's been a while since I've seen or heard anyone mention that the world is overpopulated. It is actually the opposite. There is a sharp decline in birth rates in a lot of countries, and many are worried about it.

As far as the resources of the earth are concerned, we are probably overpopulated. The reason countries are worried about birthrates, is because the economy is a pyramid scheme, especially retirement funds and social security. And then there is the issue of who is going to do the actual work that no one wants to do. If those with money are the only ones having kids, their kids aren't going to be garbage collectors.

I completely agree with you about the survival of the fittest and I do think creativity and the ability to think well will be highly valuable for the "fit" to have.