[Poelmo]

Should that group that decided not to breed with people outside their group continue that tradition for many generations, have a small population, have some members that have mutations who successfully breed within the group, it could lead to speciation eventually.

Yes, eventually. But then there'd be clear genetic differences and it would be biologically impossible to interbreed.

[Thunderhawk]

But then there'd be clear genetic differences and it would be biologically impossible to interbreed.

Yes.
A matter of choice (discrimination) could create the kind of seclusion environment does.

JEEEWWWWWWWWWWWWWWSSSSSSSSSSSSSSSSSSSSSS!!!!!!!!

Actually, I'm thinking of weird polygamist cults which effectively have a hand full of male ancestors, and small xenophobic groups (like small Amish splinters, or small cloistered and inbred groups) which allow weird characteristics to become dominant (and back breed) while rejecting outsiders who might normalize the genepool. Even xenophobic Shtetls had a large amount of people internally in addition to migration to/from other xenophobic Shtetls.

[Joe Liberty]

Didnt stop Stalin trying to create a race of super ape men.

True story ...

Suddenly Marvel Comics' Red Ghost and his Super-Apes make perfect sense now.

http://en.wikipedia.org/wiki/Red_Ghost

[Someone5]

Is it possible that given the enormous population of humans on the planet that there may exist 2 humans who physically cannot breed with each other, because they are that different?

Human beings are shockingly similar on a genetic level. There is very little difference from a genetic standpoint. Lots of human beings, but relatively small genetic variation between groups.

Another thought, although even less plausible, is wondering whether there still exist some humans with very ape-like features who might be able to find a chimpanzee to breed with? How would we know? We'd have to test individual people.

Or, you know, use statistics and some logic. Humans wouldn't even be able to breed with our immediate predecessors, let alone a species so far removed as chimpanzees.

[Figlio di Moros]

Both of those are untrue. The notion humans lack diversity is false, the only possible way for us to be genetically similar is to be perfectly adapted to our environment. We each mutate 100 alleles, on average; in other words, 100 new alleles are introduced every time a baby is born. Given the intense selective pressures due to our environments, the idea a bushman, a Malay, and an Irishman are more genetically similar than crocodiles, ostriches, etc. is rather strange.

[Poelmo]

Both of those are untrue. The notion humans lack diversity is false, the only possible way for us to be genetically similar is to be perfectly adapted to our environment. We each mutate 100 alleles, on average; in other words, 100 new alleles are introduced every time a baby is born. Given the intense selective pressures due to our environments, the idea a bushman, a Malay, and an Irishman are more genetically similar than crocodiles, ostriches, etc. is rather strange.

No, humans went through an evolutionary bottleneck. It's true that we have diversified very quickly since then but we are still not diverse compared to most other species (the cheetahs Potemkin mentioned are an exception, they also went through an evolutionary bottleneck and even more recent than humans did). The superficial differences between humans are mostly that, superficial, there are only a few exceptions (like tolerance to lactose).

[Figlio di Moros]

And intelligence, and personality, and genetic diseases, and length of the colon... In fact-

since experts can easily determine race from skeletal features, it appears that those skin-deep differences go all the way to the bone.

The differences between humans are anything but superficial; even the "superficial" differences, such as skin, hair, and eye color, carry significant advantages- and not just in Northern Europe. Note that Amazon and Malays, while darker, are not as dark as Africans, nor is the allele that provides protection from Malaria in SE Asians as health-adverse as the one among Africans.

It's also important to note the incredible amount of diversification among dogs and other domesticated animals; no one would claim the difference between a Chihuahua and a Mastiff are superficial. Yet, they've been domesticated for only 6000 yrs, most breeds are less than two hundred years old, and they're the most diverse species in the world. A bottleneck 100k yrs. ago would not mean a "lack of diversity" for a species w/ a highly variable and constantly changing environment, which selects new alleles at an astonishingly fast pace. Least among these, the genes inherited from Neanderthals by non-Africans.

[Prosthetic Conscience]

I seem to remember reading about a bird that lives, roughly, in sub-Arctic regions around the world. The populations can each successfully breed with those that are close to them but, as you proceed around the world, you end up with so many genetic differences that the offspring of a mating ends up unviable - say between those in Norway and Canada.

Does this ring a bell with anyone else? I don't think I read it in a peer-reviewed paper, so it might have been a misunderstanding, by me or the author. Or complete bollocks.

[Poelmo]

@Figlio di Moros

A lot of scientists who've worked on DNA analysis for years consistently come to the conclusion that humans are unvaried genetically relative to other species. We can be traced back to small numbers of ancestors who lived relatively recently. If you look at DNA profiles instead of bodies humans are incredibly similar compared to most animals, though there are exceptions, usually when the animal is threatened with extinction or was so in the (geologically) recent past.

[Figlio di Moros]

And while I'm not interested in debating scientific fact, the conclusions based upon them need to be drawn, as well as the perception of it. I doubt the fact we're "more genetically similar" means the same thing to many of us- for instance, approx. where do we fall in line w/ other complex species? I know dogs are the most diverse, but I find it odd that, say, crocodiles who are incredibly well adapted to their environments allow for much mutation to be selected. Arguing where we fall in line along the grade (80th percentile? 96th? 52nd?) would be an important point- it's also worth addressing the effects of single allele mutations across the human species. Even if we have relatively similar chromosomes, a few small changes in a handful of alleles can produce drastic phenotypical changes, as well as produce a greater variety than otherwise indicated. Lastly, the vast differences in our environments means that epigenetic variations differ wildly as well, perhaps much more so than among any other animal (personal assumption, to be fair).

This is not to say that you're wrong, but simply that that oft repeated bullet point is highly misleading. To say we're not as genetic diverse as other species is usually read or intended as "we're not genetically diverse", therefore we're genetically similar and race/ethnicity is irrelevant/non-existent. In reality, Tay-Sachs, Sickle cell, and celiacs disease say otherwise, not to mention IQ, personality, and mental health.

[Poelmo]

This is not to say that you're wrong, but simply that that oft repeated bullet point is highly misleading. To say we're not as genetic diverse as other species is usually read or intended as "we're not genetically diverse", therefore we're genetically similar and race/ethnicity is irrelevant/non-existent. In reality, Tay-Sachs, Sickle cell, and celiacs disease say otherwise, not to mention IQ, personality, and mental health.

Since when are IQ, personality and mental health related to race? Ethnicity is really BS for the most part, unless you have practically inbred groups like the orthodox Jews with their Tay-Sachs.

I think humans are predisposed to think animals are not diverse because to us "they all look alike": we don't see the differences between a great white shark from the coast of California and one from the coast of India, but I'm sure the sharks do and to them humans all look alike. That said humans have diversified very rapidly, especially in appearance, because of the diverse climates we migrated to, but we've only had ~70.000 years to do so, that's not enough to become truly diverse on a more fundamental level and the diversifying has ended now, perhaps it will continue once again if humans colonize other solar systems with sub-luminal spaceships, isolating the different populations.

[Rei Murasame]

Despite the fact that humans entered a bottleneck and have less genetic distance between them than most other animals have, it remains a fact that the effective divergence time between geographical population groups that we call 'ethnic groups', are indeed based on the actual real fact of there having been a restricted gene flow between groups at various points in history - in some cases on-and-off - up to and including the present day. This was also coupled with different selective pressures in different environments.

And yet we hear all the time that 'ethnicity is nonsense'. Is that really the case? I would argue that what is being seen is not a destruction of the existence of ethnic groups, but instead, a destruction only of a peculiar colloquial ethnic taxonomy mess that emerged in North America. Some people have confused the two, and this has led them to conclude that it is 'nonsense', even though it clearly isn't.

[Poelmo]

And yet we hear all the time that 'ethnicity is nonsense'. Is that really the case?

Yup, it's an artificial construct. Genetically there's no such thing as "ethnicity", except in rare cases with heavy inbreeding. There's a reason why people use language and culture to identify ethnicity: because you can't reliably see it from appearance or DNA profile.

[Rei Murasame]

I don't believe that you believe that. If there were no way to differentiate ethnicity genetically, it would not be possible to talk about geographic population groups in the first place, because there would be nothing of any significance to see in the results.

So you are making some kind of logical inconsistency here, almost as if you are overreaching in an attempt to counteract something that has not been said. I suspect it's part of an attempt to bend science to the service of a particular ideology, but I wonder which ideology it is?

[mikema63]

Some ethnicities exist in a genetic context, others like Hispanic do not.

There is very little difference between humans genetically speaking and relatively speaking and there isn't any active mechanisms that will cause speciation.

I would consider it extremely unlikely that any human groups will diverge that much unless we start forming colonies using generational ships that creates a relatively unbridgeable divide between human populations.

[Poelmo]

I don't believe that you believe that. If there were no way to differentiate ethnicity genetically, it would not be possible to talk about geographic population groups in the first place, because there would be nothing of any significance to see in the results.

You don't understand: if you start with the premise that two groups of people are different and you start looking for genetic evidence to support your premise then you will always find that some genes are more common in one group than they are in the other. The thing is that that's circular reasoning: I could assert that there is no Japanese ethnicity, that people in the West of Japan are a different ethnicity than those in the East of Japan, I could then look at their genetic profiles and find that indeed some genes occur more often in West-Japanese than in East-Japanese, I could then say West-Japanese are actually two different groups and find some genetic occurence differences as well, then I could say those two groups should be subidivided into two groups each, and so on, down to the family level. Worse, most of the time these genetic differences (usually called haplogroups) are irrelevant to outside appearance, behavior, etc... (especially when they are mitochondrial haplogroups) and a sizeable minority of the ethnicity will belong to a haplogroup that's not the most common/average haplogroup of the ethnicity, which is not really surprising since most ethnicities were invented long before people knew about DNA. Even with the most sophisticated technology available a drop of blood can only tell you there's a 90% probability the owner of the blood is East-Asian, with a 60% probability that he's Japanese. There's even a haplogroup that's the most common group among both the indigenous tribes of Kazachstan and the Maori in New Zealand, while it's much more rare in the lands in between them and there's a haplogroup that's the majority in Ethiopia and a sizeable minority in Germany (and no, that's not because of Ethiopian immigrants in Germany).

[mikema63]

However, determining if someone is of asian, european, or african descent is extreamly accurate.

[Poelmo]

However, determining if someone is of asian, european, or african descent is extreamly accurate.

Yes, but that's by looking at genes that determine appearance which basically tells us that people with different eye colors have different genes that code for eye color... And again that's just the way we choose to group "races", had we chosen hair color instead of skin color to distinguish "races" it would have made no difference for those tests.

[Rei Murasame]

No, I think you are making an assumption here. A computer can find these patterns even if a human is not looking at it. For example structure can do it:

The program structure is a free software package for using multi-locus genotype data to investigate population structure. Its uses include inferring the presence of distinct populations, assigning individuals to populations, studying hybrid zones, identifying migrants and admixed individuals, and estimating population allele frequencies in situations where many individuals are migrants or admixed. It can be applied to most of the commonly-used genetic markers, including SNPS, microsatellites, RFLPs and AFLPs. [...]

Click the link in the quote bar.

[mikema63]

Quite true, except in the sense that race is an adaptation to varying environments.

Certainly nothing I believe to be important, like intelligence, has ever been applied to race. However, despite the obsession with genetics I really think when talking to fascists about ethnicity its best to keep in mind that culture plays a huge role in what they talk about.

Rather than arguing over genetics its easier to insert "culture" when they say race or ethnicity, its not Hispanic ethnicity its Hispanic culture etc.

I tend to like their arguments better that way.

As for frequency of genes in different environments, that's to be expected, different environments create different selective pressures and thus different frequencies. Thus generalizations can be made, even if only with the standard caution that all generalizations must be dealt with.