Quote Originally Posted by oskar View Post
No population evolves to be less fit. A gene's fitness is defined by it's ability to result in reproduction. The gene that reproduces is the most fit. So if somehow a brownish mono-race would evolve. It would be because it's the most fit one. By definition.
There is more to fitness than the state of having been naturally selected and ability to breed in that context. Ability to be selected for new environments and to breed in them is also fitness. A species can breed such that it is the most fit for its current environment while losing ability to adapt to a new environment.

You don't lose genetic diversity by interbreeding races.
What I'm referring to is more along the lines of fixation and along the lines of how Frequency-dependent selection is the hypothesis that as alleles become more common, they become more vulnerable. The resultant product of a species that breeds randomly is different ability to adapt to new environments. It's like comparing how a diverse collection of corn may have in it subsets that are more able to resist a new pathogen, yet if you bred all corn together long enough, that same pathogen would more likely wipe out more/all corn.

The full sets are still available to be used in the next generation.
Are they available to use for every subsequent generation? Do they appear at an unchanged rate?


Ong is correct in pointing out that even in your hypothetical where you would remove all types of selection pressures that go into the production of a new human being, instead you just randomly shuffle sperm and eggs around (why you would do that is a different matter) - even then, the individuals would revert back to their racial differences you see today within a couple of generations once returned to the usual selection mechanism.
You see exactly that happening with stray dogs once left to their own devices will return to wolf like behaviors and features in a very short time even after thousands of years of artificial selection.
I get this. It's because in the real world there is environment differentiation. The hypothetical was in response to an idea that didn't include environment differentiation.


BTW I am not, have never been, and do not consume material by race elitists or xenophobes. The idea I expressed I got from the best mathematician I know of. Sadly I can't find the reference again because everything gets buried on Twitter.