WP: Scientists Find DNA Change That Explains White Skin

Scientists Find DNA Change That Explains White Skin

By Rick Weiss
Washington Post Staff Writer
Friday, December 16, 2005; Page A01

Scientists said yesterday that they have discovered a tiny genetic mutation that largely explains the first appearance of white skin in humans tens of thousands of years ago, a finding that helps solve one of biology's most enduring mysteries and illuminates one of humanity's greatest sources of strife.

The work suggests that the skin-whitening mutation occurred by chance in a single individual after the first human exodus from Africa, when all people were brown-skinned. That person's offspring apparently thrived as humans moved northward into what is now Europe, helping to give rise to the lightest of the world's races.

Leaders of the study, at Penn State University, warned against interpreting the finding as a discovery of "the race gene." Race is a vaguely defined biological, social and political concept, they noted, and skin color is only part of what race is -- and is not.

In fact, several scientists said, the new work shows just how small a biological difference is reflected by skin color. The newly found mutation involves a change of just one letter of DNA code out of the 3.1 billion letters in the human genome -- the complete instructions for making a human being.

http://www.washingtonpost.com/wp-dyn/content/article/2005/12/15/AR2005121501728.html

Evolution? :wow:

one of Noah's kids was white. :eyes:

...only like the bits of science that "support" what they already want to believe? I guess they've had plenty of practice, what with using the Bible the same way. ; )

white skin is a mutation or a genetic defect, would you? ;-)

Curse of Ham
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Curse of Ham (also called the curse of Canaan) refers to the curse that Noah placed upon Canaan (the son of Ham) after Ham saw Noah naked because of drunkenness in his tent.

Most Biblical scholars see the curse of Ham story as an early Hebrew rationalization for Israel's conquest and enslavement of the Canaanites, who were presumed to descend from Canaan.

Much more controversially, however, the "curse of Ham" has been used by some members of major Abrahamic religions to justify racism and the enslavement of people of African ancestry, who were thought to be descendants of Ham (often called Hamites), either through Canaan or his older brothers. This racialist theory was common during the 18th-20th centuries, but has been largely abandoned even by the most conservative theologians since the mid-20th century.


snip


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

And they created the story to fit their belief. Gee how much more of the bible is fiction?

The curse would have to be on whichever line was white based on the article if the white people were not the first people.

that this "white-skinned one" was especially endowed with blessings, or whatever.

anomolies that are light-colored (white buffalo, anyone?) see to be thought of as "holy". don't ask me about why, or even whether it always holds. just sayin' ... seems more likely the social interpretation would be of something "special" in a religious sense.

Shem is traditionally viewed as the founder of the Semitic people, Ham was viewed as founder of the Hamitic People (Egyptians and the Blacks of Africa etc) and Japheth the Founder of the Indo-Europeans and other races. Thus the person with the White Gene has to be Japheth, through that does NOT explain the light skin of the Semitics. Thus Noah must have had the White gene but it skipped Ham. Then the Egyptians are not 100% black, so some white gene must have been in Ham.

It is tough trying to fight facts into a allegoric story.

"The work also reveals for the first time that Asians owe their relatively light skin to different mutations. That means that light skin arose independently at least twice in human evolution, in each case affecting populations with the facial and other traits that today are commonly regarded as the hallmarks of Caucasian and Asian races.

Several sociologists and others said they feared that such revelations might wrongly overshadow the prevailing finding of genetics over the past 10 years: that the number of DNA differences between races is tiny compared with the range of genetic diversity found within any single racial group.

Even study leader Keith Cheng said he was at first uncomfortable talking about the new work, fearing that the finding of such a clear genetic difference between people of African and European ancestries might reawaken discredited assertions of other purported inborn differences between races -- the most long-standing and inflammatory of those being intelligence.

"I think human beings are extremely insecure and look to visual cues of sameness to feel better, and people will do bad things to people who look different," Cheng said."

Who knew? :evilgrin:

and destory like one too. I always suspected we were a bad mutation.

Which have traditionally been considered a different 'race' than black Africans. Not as black; I suspect that they'll find some other mutation leading to extremely dark skin, butthat some of the variation is pre-emigration from Africa.

i guess that explains why his mutant gene was passed on.

If this guy had accidently bashed his own head in on a rock. Black King Arthur? Benevolent colonialism? Maybe they would have left Norway as an iceberg, the way it was meant to be. It probably wouldn't have been that much different than it played out originally, though. Skin colors didn't create war and slavery, they just provided a common excuse for it.

n/t

:D

About the same odds as the Idiot saying anything of human value. Shows how massive this is. Race has nothing to do with biology, as we all (?) know.

entire race. You just met some mean-ass people - but they were mean because they were assholes. Color is secondary, always is.

In anything, 'white' skin is light brown...

Just being specific and to voice a subtle point.

combination of the above with a little green, or blue, in the shadows.

Big 'my bad'.

I was trying to illustrate how stupid the word 'white people/white skin' is and I forgot about my other brothers and sisters and their skin tones.

When and if we all realize we are ALL humans, our earth and humanity will take a giant leap forward.

it's very dark brown

watch how soon all Humans become ONE.

I just got driven out of a job for white skin.. i was viciously harassed, had things thrown at me, hit with boards, threatened to be stabbed, the machine operators refused to do what they are supposed to do.. stop the belt with a jam, or there is no way to safely do it, the not only stop it for other blacks but back it up, i had seriously racial slurs and threats. the factory is 98% black, about 200 a shift. a national trade name.

I grew up in the Pacific North West, i never experienced prejudges either way, I helped organize civil rights marches in the 60's, accompanied Rosa Parks from San Francisco to Seattle on a train, I spent 2 years in Africa in the peace corps..

living in the south is a real eye opener..

Prejudice works both ways and is equally as wrong.

Restating... the day all humans realize that we are all in this mess together, the sooner we will solve the host of problems we face here on earth.

really caught off guard at how much they seriously HATE us... i grew up in the woods. I am sorta Agora Phobic and dont get out much i guess.

many others think I am of Turkic extraction.

In truth, I'm a huge mix of ethnicities; in addition, few of my direct blood relations "look" like they are steriotyped as. My Hungarian-Jewish grandfather probably would have been accepted into the SS (he has a Germanic family name). My Russian/Polish/Jewish was darker than most African Americans. My southern Italian relatives are North European white.

Just goes to show how much baloney the whole racial/ethnic/nationalistic obssession so many share is.

On the bright side, everyone aside from northern Europeans believes I'm one of "them"...therefore, I'm rarely stereotyped by anyone off the bat and can actually skip straight to "gasp" friendly conversation.

and you will know the true meaning of white, my friend.

Otherwise, I believe you!

I think I glow in the black light.

(red head/fair skinned talking here)

DNA.

I know it will be lost on most of the people who could use the lesson, but it is absolutely gobsmacking how many issues have come up because of one little letter of DNA code.

When I was in University in 1999, a guy stood up in my anthropology class and asked the professor to explain why "black people can jump higher". He had no evidence to back this up, just "they have stronger/longer tendons". Sigh.

Yknow, I really don't understand why the religious right doesn't embrace these kinds of discoveries.. the mind-boggingly complex idea of evolution and deviation is so fascinating that I could see people chalking it up to a "higher power".

The professor was an "old Black Panther" (his description) -

We read Jon Entine's: Taboo. Why Black Athletes are Better and no one wants to talk about it.

Very enlightening.

There are "genetic" differences that DO occur in different populations of the world. This is not about "race", but about genetics. Just like certain diseases only occur in certain ethnic populations.

white people always think of themselves as superior but they're only here because they're mutants

PS i am JOKING you no sense of humor having no goodniks

cyanobacteria thinks that about everyone.

That's the way evolution works.

Deal with it!

;)

were kinfolk. :rofl:
:hi:

;-)

aside from that you are correct.

And they got Granddad's voice just the way I expected him to sound.
:applause:

n/t

John Billingslea is his name, did Jet's voice in english dub of cowboy bebop, something all humans should watch at least once...

people. He wouldn't have been black and he wouln't have been white either. Something in between, like the hispanic race. (A very attractive people btw)

Mitochondrial "Eve" is believed to have lived about 150,000 years ago:

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



People do often confuse the idea of a common ancestor with the implication that we have no other ancestors. However, given sexual reproduction, everyone has lots of ancestors. But Eve represents an unbroken chain that links to ALL human beings.

Also, there's Y-chromosome Adam:

http://en.wikipedia.org/wiki/Y-chromosomal_Adam



However, the Most Common Recent Ancestor is believed to have lived as recently as 1000 CE/AD. The estimate - although it is disputed - is anywhere from 3000 BCE (BC) to 1000 CE (AD):

The MRCA of all living humans lived within historical times (3000 BC - 1000 AD), according to a non-genetic model reported in a 2004 article by Douglas Rohde, Steve Olson, and Joseph Chang, "Modelling the recent common ancestry of all living humans".

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

Which have been fairly cruelly dealt with by their oppressors. Mostly Black Africans. Bantus, to be precise. And it continues to the present.

The San and Khoe show a greater degree of genetic diversity, and are more likely to be representative of earlier humans than blacks.

thanks for posting!

it's kind of sad that mr. cheng was uncomfortable about discussing his findings. i guess any number of various groups with various beliefs will read into this what they want to. this doesn't change the fact that people are more the same than they are different - genetically speaking.

Some scientists suggest that lighter skin offered a strong survival advantage for people who migrated out of Africa by boosting their levels of bone-strengthening vitamin D; others have posited that its novelty and showiness simply made it more attractive to those seeking mates."

I guess that's why albinos are so darn popular.

...

what they said is that in places where there is not much light (like norway) it was better for
folks to have a lighter skin particularlyl if they didn't have a good source of vit D in their diets.
around the equator it's decidedly better to have the pigment protection because you get plenty of light all year round.

Albinos who have no pigment have no protection from the sun.
it's also a different gene.

mimi

Just attractive because of being different. Aren't you attracted to "novelty"?

the white gene dominant? So one person becomes white and suddenly they're springing up all over?

re: novelty---where are all the people having sex with little people (formerly aka midgets, dwarfs, etc.)?

Secondly, lighter skin can be an advantageous adaptation (hence the proliferation).

Lastly, novelty is frequently and attractant in evolution.

there are some cultures that view lighter skinned individuals as more valuable...which is definitely racist.

One of my former best friends (very nordic, natural blonde) married an Indian fellow who boasted prior to their marriage that he was looking forward to the birth of lighter children, I thought he was joking....who gives a shit what color the children are...

but he was dead serious....

In fact we later found out he was a neo-nazi...which I could not even fathom...and it was his opinions on this matter that made me break off all contact with my friend.... to this day I wonder if she is still with him...

I mean, weren't most "white" people seen as ghosts or evil spirits or some such when other peoples first encountered them?

The evolutionary principle of gradualism holds that most successful mutations are gradualistic ones. Minor changes accumulated over periods of time.

It wouldn't have been the case that a dark-black-skinned community would suddenly have sprouted a Norwegian-white child. And if they had, it may well have NOT been an advantage; in evolution, rapid or major changes are likely to result in deficiencies.

ON EDIT: I just reread the article and it says it was just one base-pair. That IS pretty interesting. I wonder how that would have resulted in a selective advantage. Generally, though, gradualism is the rule of thumb.

I would bet, however, that there are other pigment genes that also played a role, so the shift may not have been as dramatic.

SECOND EDIT: Okay, so it says this is responsible for 1/3 of the genotypic variance in skin color. That makes more sense. So it WOULDN'T have been a sudden transformation from dark black to Scandinavian-pale. It would have been somewhat gradual, and my guess is that other genes had already altered skin color somewhat. Plus, there are environmental factors to take into account.

It's not racist, it's simply an affirmation of ancient cultural beliefs. There's a big question about why redheads are so common today, when standard breeding practices should have quashed the genes and kept it minimized to a rare mutation that only popped up at random. What we find, however, is that certain population groups have a far higher rates of red headedness than they statistically should. The Scandinavian countries are an excellent example of this, with a substantial portion of their population being either blondish red, or pure red, when statistically the numbers shouldn't exceed 1%.

So what happened? In all probability, religion happened. We know that many ancient societies, especially those found in northern Europe, considered the color red to be holy. We find red ocher all over their burial sites, and it's frequently used in religious cave paintings. If they considered it religious, a person with red hair would have probably been seen as touched by the gods in some way and would have been highly sought after as a mate. Two redheads reproducing together would have been seen as begetting a truly god-touched child. SOCIAL and RELIGIOUS beliefs made certain traits more attractive, and allowed a gene that would have otherwise vanished to multiply through the population.

Today there are hundreds of millions of people throughout the world who can trace their lineage back to these groups, but 10,000 to 15,000 years ago they consisted of no more than a few hundred thousand people. In communities that small it's relatively trivial for a small genetic alteration to become prevalent if it's deliberately encouraged. Population growth within that group would then have perpetuated that mutation out to their larger pool of descendants. The same type of socially driven selective breeding is sometimes cited as a possible origination of almond shaped eyes in some Asian populations and height variations among some African ones. Cultural and religious values drove differing perceptions of beauty that over the long term shaped the genetic profile of the entire population (evolution 101 here). There's no reason to believe that similar factors might not have played a role in the propagation of the caucasian genes that lightened skin. It's almost a given that the vitamin D thing played a role as well since lighter skinned people are physically better adapted to northern climates, but the fact that the Intuit are darker skinned is a clear indication that environmental adaptation cannot be the only factor at work here.

Use that sunscreen & find a good dermatologist. (I'd rather take precautions than trade Fish Tacos & Oyster Po'boys for Lutefisk.)

Texas is situated between Latitude 26° N and 37° N; according to the World Health Organization, the months in the year when sun protection is necessary in these latitudes range from "February to November" to "all year."

www.texascancercouncil.org/skincancer/bp3.html

> This supposition strikes me as stupid:
>
> Some scientists suggest that lighter skin offered a strong survival advantage
> for people who migrated out of Africa by boosting their levels of bone-strengthening
> vitamin D; others have posited that its novelty and showiness simply made it more
> attractive to those seeking mates."
>
> I guess that's why albinos are so darn popular.

All things in moderation! Lighter skin actually can be a useful adaptation
if you live in sunlight-poor regions precisely because of the increased
vitamin-D production efficiency that it affords. On the other hand, it's
clearly counter-adaptive when one considers skin damage from the sun.

So folks evolved varying levels of pigmentation roughly appropriate for
their latitude. Nowadays, we all move around the world freely, so the
various adaptations are less-well-tuned, but these sorts of genetic
optimizations came about for good cause.

Tesha

of the mutation.

Humans like to form tribes. Specifically against neighboring tribes. When population density is low, the gene would be transmitted: mates would be in short supply. It wouldn't have been an overly glaring difference so as to be stigmatized; but I'm not sure there's a greater chance of lighter skin being stigmatized than there is of its being postively valued. But the mutation would easily have spread within a clan or tribal area.

If the slight variation in color was taken as a distinctive feature of a tribe, it would have been favored, and therefore accentuated.

Even a trivially slight difference in reproductive success can account for population shift quite nicely over time, whether that difference results from survival or selection by prospective mates. (Consider the wonderful variety in plumage/coloration and mating rituals, some seemingly bizarre, among animals.)

Means I can't jump, have no rhythm and will never be odds-on favorite in a boxing match. Damn you, Darwin!

Send in the Sentinels!

A single individual with a mutation on skin pigmentation does not address the other physical characteristics such as nose, lips, and eye features that are differentiators between Asian, European, and African races. What about red, blond, and brown hair that is thin, versus thick curly hair or straight and thick black hair?

It just seems to me (without the benefit of access to the data or specialization in genetics) that the path to the racial differences is more complex than a single individual's mutations.

It seems more probable that something like a disease or environmental influence would be a probable cause for a genetic mutation, such that the mutation occurs in numerous people at relatively the same time. And then propagation takes its course, with the more common genetic variety that drives all cell mitosis.

I am not a biologist, but I did sleep in a comfortable bed last night.....

"Leaders of the study, at Penn State University, warned against interpreting the finding as a discovery of 'the race gene.' Race is a vaguely defined biological, social and political concept, they noted, and skin color is only part of what race is -- and is not."

It's JUST about skin color - not the other variations you mention.

and they estimate this gene "is responsible for about one-third of the pigment loss that made black skin white". If, by 'an environmental influence', you mean some chemical, then I'd think it very unlikely that it would affect one specific point in many people's DNA. There are theories that viruses sometimes insert DNA into normal cells, where it then gets propagated as a 'normal' part of the host species, but again, they're looking at a specific change at one point that has a definite effect - just one 'letter of DNA code' (which presumably means either one of the 4 ACTG 'letters', or maybe 1 of the 64 'triplets' of those letters that code for a particular amino acid). It would be quite a coincidence if a virus replaced one letter with another, and did the same in many people, I'd have thought.

Differences such as hair colour and so on are part of human variation, and there are regional characteristics, but don't often form part of most people's definition of 'race'. Blond, red, brown and black haired people are normally all put together as one 'race', as long as the skin colour is white. Some facial shapes are noted as differences, but there can be significant variation of those too inside one 'race' (as well as, of course, between sexes, while skin colour doesn't seem to be sex-linked at all) - and the genes are probably very complicated for it. What's surprising here is that they've found one point in the DNA code that's responsible for as much as a third of an obvious variation in the population of the world.

I'd be interested to know if this mutation is common in people close to Europe - North Africa, Arabia, Central Asia, India. Knowledge of that might throw light on early migration and development of different language groups (or it might show that mixing in those areas is enough to hide any evidence about that).

I beleive that radiation is known to cause cell mutation. I don't know if that implies DNA mutation or modification as well. It seems very certain to me that environmental factors have a definite effect on the development of certain features. Look at what diet has done to humans in the last 100 years. Groups that eats a modern diet have seen their average height increased by over a foot.

My argument is that it seems more probable that some influence common to a large population body would produce some change that is shared amongst numerous individuals, as opposed to a single mutation manisfesting itself in a change that gets adopted very widely due to subsequent social factors.

and those are the only mutations that can be passed to your offspring. The only ionizing radiation from the sun that can penetrate the atmosphere is UV, and that only penetrates a millimeter or two into your body.

FWIW, I have read that about 99.9% of genetic mutations result from oxidative stress at the cellular level (i.e., free radicals produced by badly running mitochondria), and the chief external factor affecting oxidative stress is diet, not radiation or chemicals.

I have always felt that societal hangups about skin color are scientifically asinine. "Race" is a sociological construct, not a biological one, and of all the factors to use to define a "race," skin color is about the least relevant one can imagine.

... in multiple individuals. Mutations are largely random events (well, okay - so it's a little more complicated. There's evidence that certain regions are more prone to mutations, etc., but I'm not as familiar with all of that and it's complicated). The chances that the same, singular mutation would occur in multiple individuals. By and large, mutations arise in single individuals that are then passed down. And the idea that a skin color mutation would arise in a single individual is not so far-fetched. With computer-modeling, it's been shown that a dominant mutation or even a recessive allele that codes for a trait with a selective advantage will within 50 to 100 generations spread through the entire population. As for all Europeans descending from one person... well, it's not all that farfetched, considering that scientists have traced human mitochondrial DNA to a single "Eve" from South-East Africa some 500,000 years ago, meaning we're all descended from the same woman.

concept is a non-starter.

We each do have different colored skin - and similiar color may be concentrated in populations that may - or may not - have other characteristics.

There Is not a damn thing beyond color that can be tied to the letter change in the 3.1 billion letters in the DNA code.

Race does not exist.

But feel free to comment on skin color.

I agree that scientifically, DNA has no racial marker. But that is a different discussion.

The skin color differentiation is being tagged to a single individual, with some not fully explained sociological reason as to why this single individual's genetic makeup became dominate throughout Europe. I guess the same argument would apply to why Asians have their unique eye lid shape. One person had the DNA for it, and 10,000 years later, the DNA has propagated to 6 billion decendants.

I agree that the DNA mutation is the reason for the skin pigmentation difference and the eye. It just does not seem intuitive to me that a single individual's DNA propagated throughout an entire population base in 10,000 years. If it was a single trait, I think you can do the math to show it is mathematically possible. But is it practically possible given species behavior?

You need the opportunity and the ability of the species to travel large distances and spend alot of time spreading the seed around. That just does not jive with the study's suggestion that the differentiation took 400 generations. A whole lot of those years, you would have a hard time tracing a connection from a tree dweller in Italy with a cave dweller in Finland. Yet they both end up with white skin, straight hair, thin as opposed to broad noses, no Asian eyelids, and the complete inability to keep rhythm.

that preceeded and lived along side modern Humans all those years?

But if Lucy is mother of us all say 5 million years ago - why? What happened to the other branches?

To say I have no clue would be honest but then I'd have to stop posting on this topic!

:toast:

:-)

Just like we did to almost all the mega-fauna when we got to North America oh those many years ago.

It's just not going to happen. There are MILLIONS of base pairs. The same advantageous mutation is just not going to happen in multiple individuals. All those similar traits you're talking about come about because of mutations in single individuals. It's hard to believe, but evolutionary biology shows that most major groups have singular founders. 400 generations is NOT an absurd timetable at all. It's perfectly consistent with human patterns of gene flow. Genetic markers - mitochondrial DNA, Y-chromosome haplotype trees - they all illustrate human phylogeny (descent). It's not only mathematically possible, it has been proven. Evolution occurs through random mutations arising in individuals. It does not and cannot occur through multiple individuals independently having the same mutations.

Moreover, there has always been a high degree of gene flow among human populations. Human populations have NEVER been truly isolated. The most isolated would probably have been Native Americans, and even there, the isolation was relatively recent and later reversed after the Americas' "discovery." You can see this with reconstructions of the human genome, tracing population patterns and gene flow. Populations have historically been very mobile. The whole concept of race and ethnic heritage is actually completely wrong, because all human populations have even through recent history had a high degree of interbreeding.

If people had not been interbreeding and gene flow did not occur, speciation would have occurred and humans in different parts of the world would be different species, probably incapable of mating with each other. But the fact that we're all extraordinarily similar genetically illustrates that high gene flow has been constant throughout human history.

The advantageous (as far as living in northern climates) mutation does not have to be exactly the same in multiple individuals to approximate the same basic feature benefit does it? Scandinavians and Italians are both considered to be Caucasian, but they have different skin pigmentations. So if you had an external influence, such as diet, naturally produced aerosols, etc that impacted the DNA, you could get different individuals with a genetic mutation whose result was a lighter skin than those of their darker skinned ancestors. I don't think the study is claiming that their genetic mutation discovery is the ONLY way skin could mutate to white, I think it is saying this is ONE way it could. I don't see how they could possibly claim that this DNA pattern is the only method of producing white pigment. Biology and chemistry seem to be sciences that are dominated by observation as opposed to theory, and clearly, no one has observed all trillions and trillions of combinations possible.

I disagree that there has always been a high degree of gene flow among human populations. The Dark Ages are an example of a time when travel was extremely limited. The roads built by the Romans became overgrown, and anarchy reigned in the forests that covered Europe. Grimm's fairy tales are a reflection of this collapse of distributed and fluid society.

Aboriginal Australians, and other Maori tribes in the South Pacific are the most genetically isolated peoples of the earth to the best of my knowledge. The rise of sea levels cut off the ability of dead reckoning navigators to move between the islands for over thousands of years until technology shrank the distances. These people are probably the closest example of a closed genetic system (although it has been opened in the last several hundred years) that exist on earth. Maybe there are some South American tribes that have managed to stay similarly isolated, I am not sure. I would guess that there are very interesting genetic studies going on in these populations that will bring out very interesting concepts in the years to come.

I am not informed enough about the science of speciation to refute what you are saying about this, but again this strikes me as a truth that is directly in conflict with what one can observe in the world today. Humans, cats, dogs, cattle, and birds existed on all continents for tens of thousands or millions of years. There is no evidence of interbreeding of Asians, Europeans, or Africans with American Indians ( pre 1500). The same is true of the various continental animals. Yet it is possible for an Amazon Indian to breed with a Mongolian. Speciation did not occur, even without interbreeding. The same argument applies to cats, dogs, birds, lizards, etc. So I am not buying into what you are saying, I think further study and thinking is needed here, or I have some major misconception.

Finally, I don't understand what you mean by the concept of ethnic heritage being totally wrong. Ethnic heritage is a social abstraction, not a scientific one. There are clear ethnic practices among different groups. I hope it is unnecessary to point out how different ethic practices around the globe are. These practices exist. I don't know what you mean is wrong, but denying their existence is to deny clearly observable fact.

Although I am a probable Biology major and my biology class this past semester was heavily about population genetics.

Let me quickly address your point about ethnic heritage - that was a poor choice of words on my part. What I meant was the whole idea of genetically pure heritages for various "nations" has been shown very much to be false.

Mitochondrial DNA studies and Y-chromosome studies all show that there has been tremendous gene flow throughout the human population, at least of the Old World. The key factor in human populations is isolation-by-distance. Yes, someone from England in 1500 would not have interbred with someone from China. But over the course of generations, there has been a great deal of gene flow through neighboring populations. That is illustrated by studies of DNA, particularly mitochondrial DNA and Y-chromosomal DNA, which illustrate patterns of migration and gene flow. And particularly when you're talking about Europe alone, the idea of a single mutation spreading through the population over 400 generations is VERY credible. It doesn't need to be a lot of people - just some. Even if most people never left the village, a small group of people doing so would result in a high degree of gene flow in populations. As for you cats and dogs example, cats and dogs aren't a good example because domestic cats and dogs are not subdivided into multiple species - they're all classified as different breeds selected by human beings. As for birds - try to mate a South American bird with an African bird. Most likely, they will not be able to produce viable offspring, or any offspring at all.

Now, with the New World there of course was a long time when there was little contact, but they've been in contact with Old-World humans for centuries by now. Mathematical models indicate that the most recent common ancestor of all (or at least the vast majority) of human beings lived between 3000 BC and 1000 AD. This doesn't of course mean that that's the only human line - just that that individual line is in all human beings. Obviously, as you say, that's more speculative. But most population biologists find that credible.

I don't think the scientists are claiming that this is the only mutation affecting skin color. And as they say, this only explains about 1/3 the shift. The point is, however, that there's no reason it couldn't be. But even with just a few individuals from neighboring communities exchanging genes and interbreeding, gene flow is strong. And considering that the founder populations of most Europeans was probably a contingent of only 1,000 or so by most estimates, it's not at all difficult to see how a mutation that arose in one could have, over a few generations, have become widespread. Environmental pressures will play a major role in determining phenotype. But genetic factors play a role too. It simply isn't credible genetically that the same phenotype would arise in multiple individuals due to the same or even different mutations. Most likely, if different genes were altered, different phenotypes would result.

I don't think anybody is claiming that we know exactly what happened with skin color. What I'm trying to get at is that you don't seem to think that a single mutational event a few hundred thousand years ago that could have spread to all Europeans. What I'm saying is that's not true - it very well could have. Mathematical and computer models illustrate how it could have happened and DNA evidence largely proves that large-scale gene flow patterns exist and have existed throughout human history.

but there are some points that simply have to be wrong, and deserve some investigation.

Mathematical models are interesting. In the mid 70's I did research on mathematical models for predicting weather patterns based on observed data points of the atmosphere over the Pacific ocean. It was a great model. But it didn't work because it couldn't account for too many variations. Resolving that problem was so computationally complex that by the time you arrived at a solution, the weather you were trying to predict would have already occurred.

If a mathematical model showed that the common ancestor to all humans lived between 3000 BC and 1000 AD it is missing a key factor in the equations. That key factor it a practical accounting for observed history and human behavior.

Between 3000BC and 1000AD significantly large population of humans lived in South and North America. Most of these had no interbreeding with Europeans, Africans, or Asians until the last 500 years. These cultures were not really open to the potential of wholesale interbreeding until the last 100 years or so, once tribal life had been completely obliterated and the vast majority became assimilated into the modern society. Even so, there are still populations in the Amazon and Eskimo tribes that are isolated from interbreeding.

While a mathematical model can use number progression to show that the DNA can freely pass among the species, it won't account for families that would not allow their daughters to mix with outsiders. Any accounting for this social resistance to biological propagation is a guess, because quality data simply does not exist to properly measure this. Its the same problem I had with weather prediction, a lack of quality data on which to do the math.

In regards to African birds not being able to mate with South American birds, that is simply not the case on the whole or in the large. Cross species propagation has been repeatedly observed of this nature. African bees have militarized passive honey bees. Mallard ducks are inter-breeding with Hawaiian and New Zealand species of duck that are unique, and threatening to make that unique species extinct. There are many, many examples of this. national geographic article

I could very well be wrong, because I am not doing the math, and am not familiar with the models that are being touted, or how much peer review they have gone through. But it sure seems to me that there is some dry labbing going on here, and the math nurds are not giving due consideration of how hard it is for a smelly, lilly white Calvinist with a penchant for calling a native Americans blaspheming savages to get laid by the same. Since most of the ones that did accomplish the feat did so at the point of a gun, the natural reaction for the tribes would be to move their daughters and wives further away from contact. But how does that calculate in a differential equation or an enumeration model?

American populations WERE isolated for hundreds of years, which is also a big reason why Americans wound up being so susceptible to disease. Modern Native American populations, however, have been in contact with Europeans for centuries, and there are very few Native Americans who have no European blood in them somewhere. Yes, there are probably isolated tribes in the Amazon, for instance, and in Central Africa for which there has been no exchange of genes. But I'm talking about the vast majority.

Moreover, when I discuss gene flow in this example, I'm also specifically discussing the question of a gene spreading through the European population. That is far from unlikely, especially because early human populations in Europe were likely to have been relatively small. And again, it's not just mathematical models being discussed - there is hard evidence in the form of DNA evidence, especially through mitochondrial DNA - which traces the female line - and Y-chromosome DNA, which can follow the male line. Most Europeans can be traced to a single community. As another example, most Native Americans can be traced to a single group of about 20 or 30 individuals who crossed the landbridge tens of thousands of years ago.

As for cross-species propogation - yes, there has been quite a bit, but truly reproductively isolated populations generally are considered different species. Of course, the problem here is that the definition of a species is unclear. There are many competing theories about what makes a species as "species." Generally it's considered to be a reproductively isolated community of morphologically similar individuals living in the same niche.

Gene flow is measured through genetic markers, primarily using the prevalence in populations of heterozygosity of alleles (in other words, the prevalence with which members of a population have 2 different alleles for the same gene and the similarity of those alleles in other populations). One of the primary measures is a value called FST. Measured on a scale of 0 to 1, 0 implies absolutely identical populations with perfect gene glow. A value of 1 indicates that populations are completely reproductively isolated and there is no gene flow. The average human FST for the entire human population is 0.15. North American coyotes, by contrast, have an FST value of 0.3, and North American gray wolves have a gene flow of 0.85. Of course, a lot of reproductive isolation among animal species is due to the effects of fragmentation of habitats due to human development. But the point is that there is a very large, measurable level of gene flow within human populations. And gene flow does not mean that everybody's mixing with everybody - all it requires is a few individuals being exchanged between neighboring communities. That has been the norm throughout human history, even if the vast bulk of people remained in the same place. And again, this isn't just mathematical modelling - this is from hard DNA evidence from which one can dissect population movements.

Now, that doesn't mean that no populations are geographically isolated from each other. The key factor IS distance, as you probably would have guessed. Among the vast bulk of human populations, FST values climb from 0 at no geographic separation, to 0.3 among populations separated by 5000 miles. And some of this is, of course, due to increased human contact and globalization. Even historically, however, DNA models indicate that for the vast majority of human beings, especially on the Old World continents, there HAS been a very high level of gene flow. And particularly for this example - early Europeans - it's not even a very controversial point. The small population of early European Homo sapiens is the key factor here. And remember - people often misinterpret ideas about common descent to imply that a common human ancestor would have been the sole ancestor at a certain point, which isn't the case. Humans reproduce sexually, so everybody has countless ancestors - it's just that there are probably a couple lines that reach all the way back pretty universally.

A lot of this is explained in various literature and papers, of course. Much of which I don't have access to; I'm mostly relying on material that was taught to us in lecture. But I did find this good webpage on this in a Google search, which would be worth your time:

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Primates.html

In particular, I want to point out these passages; The first relates to the founder effect, which would explain how a single mutation would eventually spread throughout the entire European population:

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Polymorphisms.html#FounderEffect



The second just illustrates my point about gene flow in human beings as a whole:

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Primates.html

:evilgrin:

The "Dark Ages" was a time of huge amounts of human moving about. Islamic invasion of Europe, Arab raiders establishing a vast empire where it was easy to travel through, China was still China. Just Europe was backward.

My own research shows the less sun I get, the whiter I get.

Last winter I tested this out.
1> I was white
2> I went to Key West
3> I spashed in the water
4> I sat out in the sunshine.

I was looking for a dark tan but ended up with a reddish hue.

During the test I went through some slight discomfort but about a week later the red hue wore off and I ended up with a nice tan.

now I'm white again and looking to perform the test again.

Dap

Similar hypothesis and methodology for me.

However, after the splashing in the wather for a while and the onset of the red hue, a week later the red hue began to wear off, my skin began to peel off, and I became white once again.

Perhaps we should share notes and decide if methodological flaws are evident.

I did the same thing. After the red hue wore off, my outer skin peeled off and I was white with small dark brown and beige polka dots.

I wanted to add, after each splashy, sunshine session, I showered and applied Aloe Vera Gel (the green stuff)

Although I tend to peel, I didn't peel too much.

Dap

I start out... I would call it not so much "white" as "basically transparent."
I sit in the sun for 20 minutes with sunblock 45 on.
I become a lobster.
Two weeks later I am "basically transparent" again.

:)

Sheesh these biologist really need to get with the program. All of that stuff is impossible. There is no such thing as DNA or genetic change it is all intelligent design and only happened within the last 6000 years.

Where's that gene?

You mean to tell me that all them white folks are genetic MUTANTS??!? Ewwwww!

I kid; I kid because I luv. :crazy: :D

On a serious note, I hope that this info gets crammed down those ignorant moronic fundies' throats. You know they'll spin this into an affirmation that an intelligent designer does exist and did willfully manifest this manifestation to bring forth a people truer in his image and grace. So sayeth the lord! Now, where's that smilie that I'm looking for.... oh there it is...:sarcasm: :sarcasm:

they will say that this 'intelligent designer' needed a do-over?

My children- redhead Irish/blonde Germans tend to such pale skin that they can trace their wrist veins to the elbow. But when my son was in Shanghai, he noticed that the local Chinese had paler skin than he did. He's been all over rural China, and he says skin tones are all over the place. So much for race.

true. i work in an ESL school and the skin tones of the asians vary greatly. i remember seeing an asian woman with true SnowWhite coloring roasting herself on a beach in Waikiki. She was a bright lobster red when i saw her and i often wonder how she felt that night and the next day!

Kind of like "the four humors" and stuff like that.

It's so hard to define. So, what good would it be to anyone? I mean, it's great that it may have helped doctors to identify certain genetic traits of certain patients, based on their looks. That would help the doctors treat them better.

But now that doctors can literally get inside the cells (and genetic code) of each individual, and read it, who needs to go by old-fashioned methods such as appearance, to judge what a person's genetic tendencies might be?

Race is an outdated concept that is not scientific.

"In fact, several scientists said, the new work shows just how small a biological difference is reflected by skin color. The newly found mutation involves a change of just one letter of DNA code out of the 3.1 billion letters in the human genome -- the complete instructions for making a human being."

There are instructions how make a human being?

how do you think you got from being a single cell to being a grown human?

Your blueprints. Encoded in your DNA.

I guess if they want to continue to have a master race, they will have to kill themselves since they are a watered down, unpure version of the African!!!! Ha! What poetic justice!!!!!

are related to them. Live with the horror....

Have already started to have things carved off of my skin on a regular basis.

Guess things would have been okay if my ancestors had only had the good sense to stay the hell in Ireland where they belonged.

maximum amount of sunlight during the short winter days, allowing for sufficient Vitamin D in the days before Vitamin D-fortified milk and foods.

The approaching alien spaceship armada sends a radio message in advance to let us know that they are our long lost brothers who abandoned the Earth colony after a horrible disfiguring disease infected the inhabitants. But now they are back and they HAVE GOOD NEWS!

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If any of you are still white, we can cure you!

Is it still being published, or would I have to dig through my local library to find a copy.

Most libraries will have it.
The Wind from the Sun (ISBN 0151968101), 1972

Also found in "The Collected Stories of Arthur C. Clarke"

I'll definetly look it up.

Happy mutant here. Super freak! Going to the lounge, I need a drink.

evolved due to geographic and environmental reasons. Different mutations for different climates and of course eye color which was probably a mutation as well.