Okay, feel free to jump in and correct any misconceptions I have on this. Humankind got its start in one area, Africa, then spread and began differentiate and adapt to various climatic surroundings - thus the differences that we call ‘races’ today.
Assuming I’ve got a reader’s-digest handle on this so far, what if some DTBNL (diaster to be named later) wiped the planet free of all human beings except for a small pocket of individuals somewhere where only one race was represented. It doesn’t matter what race the survivors are, so long as they are all of the same race. So now we are back to square one, as it were.
If there were enough individuals to not run afoul of genetic disaster via inbreeding, and if a goodly portion of our modern knowledge still survived (people still wear clothes, build shelters, and grasp the basic concepts of agriculture) would humans diverge into different races again as they moved and settled different parts of the world? Or would our more advanced ways of adapting to our environment mean that the planet would be a single race?
We never did. There’s no such thing as “race,” the way you’re using the term.
But if you’re asking whether there would develop certain general physical attributes linked to geography and climate . . . the only reason that ever happened was because groups of humans were isolated over long periods of time, and natural selection tended to reinforce certain characteristics rather than others. If your hypothetical humans still retain our technology, including transporation, they wouldn’t stay in the same place long enough to establish those characteristics.
I think the dog species would represent this type of evoloution. All dogs have evolved from wolves. It’s said through natural selective breeding that if a wolf was used to catch per say rabbits over time it’s body would change and look similar to a gray hound with the increased lung capacaty, high stretching back legs, lean body etc…
I would think that if the human race started at square one, the only way to create identical races would be for the human to evolve in each enviroment for the same amount of time as past history.
Nope. What we call races today don’t map particularly well onto climatic surroundings, nor do they have any genetic coherence. What we call races today result fom just one factor, and that is people having a desire to group things. It has a poorrelationship to climatic surroundings or adaptation to climate. If it did we wouldn’t find Caucasians living in Ethiopia and Southern India or Australoids living in Tasmania.
Some of the traits that we use to define our arbitrary races may have evolved in response to climatic factors, but that is a far cry from saying that races differentiated in response to climate
Actually it could make a huge difference what ‘race’ the survivors are. Some races, such as American Indians, are genetically very consistent with relatively little diversity. in contrast the ‘Negroid’ race shows a very wide genetic diversity. As a result if you wiped out all but a handful of American Indians you would be eliminating most of the genetic diversity of humanity, which is already low. If you wiped out all but a handful of Negroes you could potentially conserve the vast majority of human genetic diversity.
That’s a tough call, and it really depend son how advanced you think people are going to stay.
When you consider that people were probably already using agriculture when sickle cell or thallasemia evolved, yet those traits still proliferated you can see that basic agricultural technology doesn’t have much effect. Until 150 years ago the only real defence against disease was genetic. As a result those genes that aided survival would be neither more nor less effective than in hunter-gatherer societies. That means that some traits such as dark skin at lower latitudes and lighter skin at high would almost certainly re-evolve.
Having said that we arrive back at my original point, which is that many of the racial traits seem to have little or no inherent survival advantage and are just the result of sexual selection or genetic drift. So we may never get extremely pale skin or ‘slit’ eyes if those things have no survival advantage. In exactly the same environment things could turn out completely differently. That would be even more likely if your survivors were western Europeans or American Indians with relatively low genetic diversity. That would force any racial traits to re-evolve form scratch rather than being selected out of the ancestral African pool, and that way we could get literally anything.
Really? When were human populations ever isolated in ythis manner? Do you have any evidence? Everything I have seen suggests exactly the opposite: that human populations were never isolated for long periods and there has always been constant gene flow between all racial groups.
Said by whom? Wolves are major predators on rabbits and always have been. There is no suggestion of the traits you describe evolving yet.
Just a question - when I read the transplant literature, they always seem to be bemoaning the great genetic diversity of humanity. I’ve even read the word “extreme” somewhere (don’t ask me to cite, I don’t remember which article it was in, probably in JAMA somewhere because I’m not that interested in transplant). But of course they would, since a) they are trying to transplant organs and/or tissues between unrelated humans, which is frustrating, and b) they’re comparing them to balb/c mice.
Anyway, although it’s a slight hijack, why is humanity considered to have a low genetic diversity, and what creatures are considered to have a high genetic diversity?
If I were an anthropologist, perhaps I could say this more elegantly.
We usually think of creationism vs. science as a fundamentalist Christian thing, but this jumps into Native American culture, too. Many NA creation stories have mankind beginning in the Americas. The world’s races are said to have started here and travelled far and wide. As far as archaeology and genetics can tell us now, mankind actually started in Africa, and the question of where the skin color and other differences changed is less clear.
Unlike the fundamentalist Christians, the NA folks are taking the conflict calmly, so far as I know.
Anything more diverse than identical twins will cause rejection issues wrt transplants. The requirements to find a suitable match are extremely strict.
As a reference, chimps are much more diverse genetically than humans. Not only do scientists recognize several races (subspecies) of chimps, you will find more genetic diverstity within one subspecies of chimp than in all of humankind. We seem to have gone thru a series of genetic bottlenecks in recent times (recent on an evolutionary scale). See this cite from a recent GQ thread on this subject.
Thanks, I didn’t know that.
I suppose whether you think humans are “genetically of low variation” or “genetically diverse” depends in part on your standard of comparison… lab animals versus wild chimps.
But now I know about the chimps. And the bottlenecks make perfect sense.
I’m a bit in awe of a guy with 17,000+ posts talking to me.
(This marks the first time that I have said “Riiight” in that tone of voice to a guy with 17,000+ posts)
I’m taking a back seat and watching with great fascination as you and Colibri lob the ball back and forth on the how-many-phalanges-in-the-thumb thread. Can’t wait for **Colibri **to answer.
I’ll defer to **Colibri **on matters biological any day of the week. He’s a real biologist. I’m actually “lobbing the ball” with Darwin’s Finch right now (another real biologist). He knows what he’s talking about. I’m just asking questions.
I’m new here, so please forgive me if I am mistaken, but isn’t this question really better tackled in GD? This is not a question which can be answered conclusively. Heck - even if the event suggested by the OP occured, we’d have nothing more than the results of a single “trial” - the question as posed would remain unanswered. The kind of generalizable answer requested seems likely an impossibility.