Race and Evolution

Factual Questions
1

Hi guys, I suppose this one will be easy to answer. Who knows, though?

I suppose the most accepted theory for the origin of human beings was the “out of Africa” theory. I don’t know enough about it, but I think that’s right. I was curious though, what would the original homo sapiens look like? Would he be really dark, like the current inhabitants?

Secondly, how long did it take for such differences to occur? I could understand lighter-skinned folks adapting by developing more melanin, but not the other way around. What harm would being black do in the far north? Furthermore, how long did all of this take?

You always see some of the pictures of early man with a somewhat caucasian look. I kind of doubt this if we evolved from the hottest places on the planet.

Finally would this be considered part of the evolutionary process? I mean, it’s kind of hard for me to grasp, because it seems like an obvious adaptation to the environment, but yet we are all the same genetically. We are all one species regardless of race. I suppose you could say that dogs are similar in their diversity (even more so really) but we also consider them to be the same species.

Anyone wanna fill me in?

2

Almost certainly, yes. Regular overexposure to strong sun can apparently reduce folate levels in the body, leading to a higher rate of birth defects.

Weaker ultraviolet light in the far north, means more difficulty in producing essential vitamin D.

Yes, it’s natural selection at work. Being one species does not prevent us from having variable phenotypes. Dogs are a reasonable example of the same thing, with the caveat of course of their variability being the result of deliberate breeding programs.

I’ll have to try to look up the timeline guestimates and get back to you on that, if someone doesn’t beat me to it first.

  • Tamerlane
3

That part I can answer: it would cause vitamin D deficiency. Same thing as working in an office all day would do to all of us nowadays, if we didn’t have so many foods with vitamin supplements.

Our bodies synthesize vitamin D from sunlight shining on our skin. High melanin content decreases the efficiency of this process; but in tropical environments, the large number of hours of sunlight more than compensates, and the benefits outweigh that disadvantage. During a northern winter, though, a dark-skinned person would likely suffer serious effects from the short days, back before the days of pasteurized homogenized vitamin-D fortified milk.

4

Yes, that is correct.

We don’t know, but they probably had dark skin and curly hair. Some scientists hypothesize that they looked like the [url=]Bushmen of Southern African, who seem to have features found in a variety of races. They have medium-dark skin, for instance, and high cheekbones as well as epicanthic folds on their eyes.

Probably at least 10,000 years. Darker skin protects against skin cancer, but lighter skin aids in the production of vitamin D from sunlight. The truth is, though, we really don’t know for sure.

Used to be you did, but not so much any more.

Yes, it’s evolution. Whether the racial differences we see are the result of adaptation to the environment, genetic drift, the founder effect, or some combination of all of those is hard to tell. Had human populations stayed isolated for 1M years or more, we might very well have evolved into different species (even if interbreeding were still possible). As it is, it’s unlikely that any human population has been completely isolated for more than 10-20k years, and once the age of exploration began, even the most isolated populations were isolated no more.

5

Spencer Wells, who is the geneticist involved in using DNA to trace the paths that early humans took out of Africa, has said that the Khoisan people are probably pretty similar to the original humans from 10,000 years ago. They’re medium brown skinned people with epicanthal folds.

6

Just to be clear, I’m talking only of H. sapiens in that last post, even thought I used the term “human” which could apply to any species from the genus Homo.

7

Not 10k years. More like 50k or 60k. And it’s a mistake to think that the Bushman have remained unchanged for all that time, but they may give us a hint at what our early ancestors looked like. Maybe not so much at the dawn of our species (some 200k years ago), but at the time we left Africa and branched out-- some 60k years ago.

8

Okay, thanks for the info. Another question I suppose.

Why would people have chosen to live in such harsh climates? I suppose this might go past the scope of human evolution and further into human civilization. Surely our ancestors were chasing food and whatnot, but why would you choose to live in Scandinavia? It seems to have very few advantages to the areas to the south. The winters are barely tolerable with all of the modern advancements in technology. I have no idea why the modern man wouldn’t say, “Hell that place we were about 20 years ago was a lot warmer, why don’t we go back?” This question really becomes more and more interesting, I guess as we get closer to modern times, in that we had more technologies to determine such things. Probably isn’t a good one for GQ but still I’ll throw it out there if anyone is interested. I’ve never understood how people lived here 1000 plus years ago without wanting to find someplace warmer.

9

Keep in mind that people didn’t migrate from Ethiopia to Denmark in one generation-- at least not 50,000 years ago. Each generation probably moved to a region that was only incrementally different from where their parents lived, if they moved at all. If you migrate only 5 miles per year, that’s 100 miles per generation. Doesn’t take long to add up. The early inhabitants of the far north were probably following game animals. There’s lots to eat up in Scandinavia, so you go where the food is (and where other people aren’t).

10

The National Genographic program webpage has lots of good information about the migration of early H. sapiens. Note that we seem to have made a bee-line for Australia almost as soon as we left Africa, and then went north much later. Click on the links and watch the videos. This project is headed up by the geneticist Spencer Wells, who was mentioned earlier in this thread. You can sign up to participate in the project and have your DNA analyzed for about $100. I did it, and it was kind of fun.

11

While the Khoisan represent one of the earliest lineages to have split from the rest of humanity, it doesn’t necessarily follow that they preserve the physical traits of the common ancestral population. The Khoisan have had just as much time to undergo evolutionary change as everyone else, and it would be difficult if not impossible to sort out which of their traits are similar to ancestral populations, and which they evolved separately. Some pygmy groups seem to be just about as ancient, and they have quite different physical traits than the Khoisan, notably a much darker skin.

12

So, what has led some geneticists to look to them for an idea of what humans may have started out like, instead of some of the other groups? Genuine question here.

13

Race has no technical meaning and the general racial classifications (Asian, Negro, Caucasian, AmerIndian) are essentially useless for even a superficial analysis. Examining evolutionary pathways generally falls into two categories of research; genetic analysis (looking for commonality and differences in the gene code, generally classified by Y-haplogroup) and cladistics (looking for commonality and differences in physical characteristics that derive from the same core features). Note that the latter is different from morphology, which seeks to classify organisms by common functionality or appearance regardless of prior development; strict morphological approaches can result in confusing similar characteristics as being plesiomorphically common when they may actually be a result of convergent evolution; for instance, despite a similar coloration, the Aboriginal Australians are no more closely related to any ethnic group in Africa than supposed “white” Europeans or any of the various ethnic groupings of Asia.

As for the varying characteristics of humans that define various specific ethnic groupings, they are in part a result of adaptation–the dark, oily skin of peoples who developed in the tropics help protect against conditions there, while the fair and dryer skin of native Scandinavians helps to maximize the benefit of the small amount of sunlit obtain in their indigenous lands–but are also in part a matter of endogamy and homogamous sexual selection (i.e. you tend to marry people who look like you and your family). There is, so far as I’m away, no evolutionary advantage to red hair and/or freckles, but these characteristics are common, and in some areas predominant, in the Nordic lands, Scotland, and Ireland, and are found indigenously nowhere else. The Ainu people of Japan are phenotypically different from the immigrant Yayoi people (despite some early interbreeding) who came to dominate the Japanese Archipelago, which is due to homogamous marriage. The phenotypes for skin color are have high lability, which means that they change or are “diluted” in combination which makes them essentially useless for tracing any genuine cladistic legacy.

As for protohuman ancestors, we really have only a very limited idea of what they look like. Skeletal remains exist but tissue and hair don’t fossilize and are rarely preserved, so all assertions about their hairiness and skin color are based upon suppositions rather than direct evidence. The skin of chimpanzees–the closest extant species to humans in family Hominidae–is as pale as George Burns (and with surprising facial similarity). It seems likely that as members of genus Homo became more upright in stature, they lost body hair and acquired (or expressed previously inactive) skin pigmentation characteristics, but this is based upon a number of assumptions the degree and timeline of which are in no sense universally accepted. It seems likely that, if the predominate “Out Of Africa” hypothesis is correct, the common ancestor to modern H. sapiens was probably brownish, slighly-to-moderately hairy, had nappy head hair, and somewhere roughly between 150-170cm in height (male). Humans diverged out of Africa (which, despite claims to the contrary, has a highly phenotypically diverse group of ethnicities) sometime around or after 80kY BP, and rapidly spread through Eurasia, migrating into Australia around 30-40kY BP, and into the Americas about 12kY BP.

As for the question of moving into less hospitable climates (which I see upon preview, also noting that several people have already made my above answer moot–must learn to be more succinct sigh) the answer is that it’s a balance between resources and competition; when there is high competition for limited or scarce resources in more hospitible regions small populations will migrate to untapped lands rather than compete directly. Technologies in firemaking, toolmaking, shelter, food preservation, et cetera make this possible. And human beings are suprisingly adaptable, despite our lack of physical resistance to elements; someone who has grown up in cold climates won’t find the tropics hospitable but abhominably hot, and vice versa. There are, as John Mace noted, vast food and fuel resources in the Nordic lands that allowed populations to settle, grow, and thrive, and then conquer the rest of the world one IKEA store at a time. It’s a conspiracy, I tell ya. Those milk-fed bastards are going to leave us clutching nothing but a ENETRI storage system while they make off with the gold, and jewels!

Stranger

14

Two main things. As **Colibri **mentioned, they seem to be one of the oldest groups of humans still around-- ie, they are roughly equally genetically distant from all other extant groups. Then, as I mentioned, they seem to have a mosaic of traits seen in modern racial groups-- although they are a distinct, fairly isolated population they look as if they are racially mixed. But we know they aren’t racially mixed, so that would lead us to think that continue to exhibit many of the ancestral features that have been selected for in different population that we see today. Lots of speculation there, though, with no good way to prove the hypothesis yet.

15

I am not singling you out but this statement has the flaw that I see every time there is a discussion of the “Out of Africa Hypothesis”. What about the “Stayed in Africa” part of the hypothesis? Africa has more human genetic diversity than any other place in the world and has many populations are not very similar to each other at all even though they have black skin. It was probably a very small group that moved out of Africa and went on to populate the rest of the planet with a set of traits that passed through a strong bottleneck.

It seems a little odd (and more than a little racist) to say that one African population is “similar to the original humans from 10,000 years ago”. What about the human populations that never left there in the first palce?

16

Cold regions can’t support as many humans as warm regions, but they can still support some. And if there’s not already any humans there to compete with, a few folks might have considered a move attractive.

17

True, except that a major bottleneck probably happened before we left Africa, so it’s likely that there wasn’t a whole lot of genetic diversity to begin with.

18

Exactly. Anthropologists now think people didn’t settle in resource-poor areas so much as get driven into them by other people. The older view was that they had chosen to live there because their technology was poor or they were “backward”; now we realize there’s evidence that these small, backward groups barely scraping by were literally marginalized by more successful, aggressive groups. See Guns, Germs, and Steel, by jared Diamond.

Sailboat

19

Well, that and getting sucked into the North by retreating glaciers. Once the ice age brought glaciers down to interfere with people’s lives, they adaprted to those conditions. As the glaciers retreated, the people already content with more pleasant temperatures (5° - 16° C) would have followed the game into the newly exposed lands.

20

Expertise in genetics doesn’t necessarily make one an expert in evolutionary biology; and anthropologists in particular may not be all that familiar with general biology or evolutionary theory.

It is a very common fallacy, even among some biologists, to suppose that populations or species that belong to basal lineages (that is, those that branched off first) necessarily resemble common ancestors. Sometimes this is so, sometimes not.

Take for example the monotremes (platypus, echidna) among mammals, or the edentates (sloths, armadillos, anteaters) among placentals. Each of these are the most basal clades among their groups, but they represent surviving lineages that are highly specialized. They probably resemble ancestral forms very little, although they do retain some ancestral traits, especially in the skeleton.

Some of the traits of the Khoisan may indeed be ancestral, but others may not. It’s just tough to figure out which are which.

Lets look at a few of the traits:

Peppercorn hair (different from the “wooly” hair of most Africans, including pygmies): A very rare type, found in Khoisan and the negritos of the Andaman Islands of the Indian Ocean. (These latter could represent a basal lineage among the groups that left Africa.) Given this bizarre distribution, this could be a shared ancestral condition. It is possible it could also be convergent.

Medium brown skin: Found in so many human populations it probably doesn’t mean much, especially since surviving Khoisan are mainly subtropical. Other possible basal populations are often very dark, including pygmies and negritos.

Epicanthic fold. Also found in Asian populations, who show almost no other resemblance to Khoisan. Possibly a shared ancestral condition, but my guess would be it is convergent.

Short statute: Found in Khoisan, pygmies, and Andamese. Possibly a shared ancestral condition, though possibly an adaptation to relatively unproductive environments.