On Sun, Jul 17, 2016 at 04:01:56PM +0200, Abu Dhabi wrote:
> By that logic, we now on Earth IRL are all a lovely shade of brown, with no
> particularly distinctive subgroups, given that we've had upwards of 50 000
> years of sharing a common planet since the emergence of *Homo sapiens
> sapiens*.

For almost all of that 50 000 years, transport has been an enormous
barrier.  Contact was impossible between many population groups.  Even
despite that (apart from your sarcastic "lovely shade of brown"), the
populations of Earth's ethnic groups *do* share genetic markers with
by far the largest predictor of similarity in their frequency being a
measure of the ease of travel between them over their history.

Even in the cases of rigidly endogamous cultures, there is ample
evidence of genetic mixing with outsiders over timescales of a few
hundred years, let alone the thousands of years that we're talking
about for Traveller.

> Why do you assume that human mating is some sort of brownian motion
> process that happens entirely randomly, without any guidance from
> the conscious minds humans are equipped with?

I think you have the question completely reversed.  It is not the
absence of individual conscious minds that causes genetic mixing.
Quite the reverse!

It is the ability of individuals to decide to violate any cultural
norms that may prohibit it and have children anyway.  It's the fact
that people and their cultures vary over both time and location.  It's
that sometimes people make mistakes, or deliberately deceive.  It can
come from not everyone knowing everything about every one of their
remote ancestors.  It's that even in the most rigidly endogamous
culture, sometimes there's a woman who doesn't care how many offworld
ancestors her lover had from three hundred years ago.

> Why do you assume that all of Terra is some kind of Coruscant-like
> city planet with no isolated populations?

I don't.  That would be totally superfluous.

> Why do you assume that extraterrestrial immigration was both
> extremely massive and completely unrestricted?

I don't.  That, again, would be totally superfluous.

Why do you keep trying to put words in my mouth?  That makes four
occurrences in one post.  Did you misread what I actually wrote that
many times, or is it just that you would prefer me to have written
something easier to refute?

- Tim