And let's not forget that during the periods where empires rose and fell, and hence mobility of different races (Romans at least I know were keen to put their mercenaries as far away from their homeland as possible), there would be natural trends in say, Scotland vs Morocco, in people with the same broad lineage of ancestors.
Now that we have a much more globalised race mix process, I wonder is our gene pool getting mixed up even moreso than ever before?
Me, I find that quite exciting. Better germ resistance, for a start. What sort of geniuses can we look forward to as the various genomes in varying states of development get more and more commingled?
Nuclear fusion technology and flying cars by 2100?
 Yes and there will be a downside of weirder genetic conditions that debilitate.
/me scurries off to buy a hat.
"To this day that was the most bullshit caesar salad I have every experienced..." - triggerfinger