[Sethomas]

I'm not qualified to argue genetic biology

I noticed.

First of all, it seems like you have a backwards understanding of what we mean by "bloodlines" and "race". A bloodline simply refers to a population that for whatever reason has for the most part had isolated reproduction, id est, its members tend to breed only amongst themselves. A bloodline could be established within a few decades, or through what is known as a "genetic bottleneck", it could be established in a single generation.

In biological terms "race" refers to the level of genetic diversity among members of the same species who can all produce viable, fertile offspring with any of the others. There is a huge amount of diversity in human phenotypes, sure, but at the genetic level we're all almost exactly the same. When biologists took a serious look at race in comparison to all other organisms, it became quite apparent that humans are quite surprisingly homogeneous. Sure, a Bantu looks a hell of a lot different than an Inuit, but the difference is insignificant than say comparing an irish wolfhound to a chihuahua. Humans simply lack the genetic diversity of other organisms that leads to a cogent understanding of "race".

Bloodlines, however, do exist. Chemical underpinnings of human populations varies extremely from region to region. They also vary greatly by what common convention holds erroneously to be "race", such as from Black to Hebrew to Korean to Aryan. This can reflect regional evolutionary factors, such as malanin distribution or sickle-cells in blacks, or increased lung capacity in the Inca, or short body stature in the Inuits, et cetera blah blah. At dinner tonight my sister was talking about how when she was studying the liver in med school, she was tought that Asians produce a certain enzyme in lesser quantities than the world norm and consequently have a lower alcohol threshold. I don't see any immediate evolutionary benefit to that, but hey, it seems to be true.

So you can't ask how long it takes for a "race" to be established, because humans have only been around for 100,000 or so years, and have only moved out of Africa for about the past 40 millennia. There is no genetic race because we genetic bloodlines have had neither the time nor the impetus to diversify away from the norm. For example, there's a common belief that the more chromosomes a species has, the more "evolved" it is. Humans have only a few dozen, coming from mammals who evolved less than 100 million years ago. Ferns, I believe, have several hundred chromosomes, reflecting the fact that they have been around since probably before the Triassic.

So, yeah. No race, just bloodlines.