Post History

Charles Darwin more or less spent his whole life proving this theory to be true and it's essentially what _On the Origin of Species_ is all about. So if you are looking for rigorous arguments in published literature, with plenty of examples, this book is surely it.

In order to for his theory of natural selection to be correct, a number of sub-species must have been proven to exist. Supposedly the rich animal life at the Galápagos Islands inspired Darwin with such, as more different species showed a potential for different races and sub-species.

I'm not sure if he made any argument about an infinite amount of sub-species though, because in practice there couldn't have been more than there were individuals. But every individual in the evolution chain, say from bacteria up to human, were probably ever-so-slightly different (and we can prove this with the discovery of DNA).

From a philosophical angle, natural selection could perhaps be applied to a great deal of many other things outside biology. When one thinks of it, it is probably a natural law far broader than just evolution theory.

For example: what is it about a certain radioactive atom in a group of atoms of the same element, that causes it to decay sooner than the others? Are the atoms different from the start (inheritance) or are they differently influenced by their surroundings (environment) etc.

We can apply natural selection to anything constantly in change: civilizations, fashion, technology etc etc.