Posted: Tue 25 Oct 2005 06:09 Post subject: Skin tone, hair and eye color
I joined this form after reading the well-written and reasoned essay by F. Sweeny on skin tone -- and have also been impressed by many of the posts here.
Anyway... the essay raises a number of questions. Does the geographic map of expected skin tones based on latitude take into account weather conditions, i.e. overcast, rainy climates; and ground conditions i.e. forested, snowy?
Here's my thinking... the Irish, or so-called celtics from the British Isles -- seem the most fair skinned population (very white, many with freckles or red hair and poor ability to tan), whereas scandinavians (further north) while fair skinned, seem a slight shade darker -- more golden and with the ability to tan.
In correspondence with these phenotype differences, the British Isles are dreary, cloudy and rainy; and perhaps more forested also. And further north there is more snow -- and you can get sunburned during the winter from the bright reflection off of snow.
To take this a step further -- the British Isles (and parts of continental europe just south of scandinavia) are in a high latitude, yet receive little snow (due to the gulf stream). These seem to be unique conditions -- high latitude and little sunlight due to clouds and lack of snow and also forested.
The pont of the essay is that the sunlight conditions are not unique, but similar to other areas. Yet, the skin tone is unique. Therefore, some other factor is needed to explain why say Innuits are darker than Northern Europeans given the same latitude/sunlight conditions -- that being a recent reliance upon grains deficient in vitamin D requiring a lightening of the skin to make up for that deficiency. But, if the sunlight conditions are not unique, then that factor alone is sufficient.
To put it in simply -- you need to wear sunglasses on a ski slope and skiiers get sunburned, even at high latitudes. [which leads me to questions about eye and even hair color... but enough for one post.]
Does the geographic map of expected skin tones based on latitude take into account weather conditions, i.e. overcast, rainy climates; and ground conditions i.e. forested, snowy?
Expected Skin Tone Map – From NIMBUS Satellite Measurements
Yes. But let me qualify this by saying that I did not personally measure UV intensity. [It is odd that my most popular essays are the ones where I relied on secondary sources, while essays where I did the research myself are usually ignored. Ah, well. <grin>]
In any event, the data on expected skin tone came from Nina G. Jablonski and George Chaplin, “The Evolution of Human Skin Coloration,” Journal of Human Evolution 39, no. 1, July (2000): 57-106. (Click on the title to bring up a pdf of the actual report.) On page 66, the authors explain:
Jablonski & Chaplin wrote:
The annual average values for UVMED were derived from readings taken from the NASA Total Ozone Mapping Spectrometer (TOMS) which was flown aboard the Nimbus-7 satellite between 1978 and 1993 (Herman & Celarier, 1996). The data represent the relative daily area exposure of UV radiation effective in causing skin irritation, computed at each 1·25 degree longitude by one degree latitude pixel, between 65S and 65N; the solar flux was measured at noon (Herman & Celarier, 1996). These readings were computed to account for the total ozone column and scene reflectivities (cloud and snow cover) in the same latitude-longitude pixel.
The point is that the authors did not try to take into account cloud cover, dust, depth of atmosphere, angle of incidence, etc. in order to predict UV intensity at the earth’s surface. Instead, they simply used NIMBUS satellite data showing actual measured surface UV intensity in Ireland and elsewhere.
rconn2 wrote:
the Irish, or so-called celtics from the British Isles -- seem the most fair skinned population (very white, many with freckles or red hair and poor ability to tan), whereas scandinavians (further north) while fair skinned, seem a slight shade darker -- more golden and with the ability to tan.
Whether the Irish Celts are lighter or darker than the Scandinavians is an interesting question that I really do not have an answer to. In our visits to Ireland, Mary Lee and I commented on the fact that the Irish look just like any other Europeans of the same latitude, and that the freckled redheads of popular imagination are as rare as anywhere else.
I think it is good to recall that, as mentioned by Omar in another post, the Celts came to Ireland from northwestern Spain around 500 BC (my mom’s ancestors hail from Asturias, where folk dances are still today performed by young people in Spanish plaid accompanied by musicians playing Spanish bagpipes). From my observation, the Irish Celts are no lighter than their ancestors, the Spanish Celts, who are no lighter than their neighbors the Basques, who have been in situ since they hunted wooly mammoths there.
The real problem is that nobody has done a serious study of actual skin-tone measurements since Biasutti’s 1939 work. All of the actual skin-tone charts are out of date.
Measured Skin Tone Map – from a 1939 Study by Biasutti
the Celts came to Ireland from northwestern Spain around 500 BC
I'm at a beginner's stage, but in my reading, where the "celts" came from, who they are, or even if the so-called celtic remnant is representative, is a confused mess. Nevertheless, a relationship with "celts" in NW Spain makes sense. Y-DNA studies show a preponderance of the Atlantic Modal Haplotype or an R1b which supposedly expanded from an Iberian refugia after the last glaciation. Yet the mtDNA data of European populations show no clear structure. I can't make any sense of it. Anyway, this is just beginner ramblings...
So, let me ask my other question: where/how you think the different European eye colors came about? My brother has a couple of siberian husky pups, and it's notable their blue eyes. Might this be an adaptation to UV glare from ice/snow? And if so, then why isn't this trait present in non-European populations at similar latitude/snow-ice regions? A dietary deficiency is used to explain a lighter than expected skin tone, so what explanation might there for this similary unexpected trait?
There are really 3 unique traits at European high latitudes -- fair skin, blue eyes and blonde hair. Your relatively recent dietary-deficiency explanation is fascinating, yet doesn't explain these others. Would these populations be blonde-blues yet with skin tone similar to Innuits, and the skin tone only changing in the last few thousand years? That doesn't seem to fit. There are many people with fair skin and fewer with light hair and eyes. It would seem the former came before the latter or at least in parallel.
Posted: Thu 27 Oct 2005 00:51 Post subject: Re: Skin tone, hair and eye color
rconn2 wrote:
In correspondence with these phenotype differences, the British Isles are dreary, cloudy and rainy; and perhaps more forested also. And further north there is more snow -- and you can get sunburned during the winter from the bright reflection off of snow.
I have thought about this too. I suspect that the Gulf Stream played a part in making northwest Europeans the world's "whitest" peoples. The warm Gulf Stream heats cloudy Europe to high latitudes that should be icy. Compare the peoples at the same latitude on the Pacific Ocean side. Han Chinese, Japanese, and Koreans are relatively white-skinned, too. But they are swarthy in comparison, although barely more so than Italians and Spaniards whose countries are about the latitude of North Korea. Manchurian and other folk further north, toward the Bering Strait, are progressively more Eskimo-like. And they need to be.
I wonder if Frank has a barely larger Jpg image of Biasutti's 1939 measured skin-tone map? I cannot read some of the text in its legend. I think old ("out of date") might be good in this one respect -- less perturbed by jet-age demographic travels.
George
warm Gulf Stream heats cloudy Europe to high latitudes that should be icy.
Yes, I agree. And if this is a unique condition, then no dietary deficiency is needed to explain unique skin tone. And then there's the correlated blonde-blue phenotypes prevalent near snow/ice that (perhaps) isn't explained by diet. It seems incongrous that blonde-blue populations would only change their skin tone to a much lighter shade in the past few thousand years.
In Mitochondrial studies, the U haplogroup, and Y-DNA R1's, have an ancient history in Europe (upwards of 40 to 50,000 KYA) -- well before the last glaciation. That's a verrrry long time ago. Polar animals have white coats; siberian huskies blue eyes... so this is a common adaptation (whatever the basis of the evolutionary advantage).
I'm not an evolutionary biologist... but it seems plausible that later waves of European immigrants mixed with the ancient (who had long evolved these phenotypes) and these traits quickly spread. Populations not so near the snow/ice, but in overcast and forested high latitudes would have gained the traits of fair skin, but retained a higher frequency of darker hair and eyes (as makes sense).
So, why don't eskimo's have blonde hair and eyes? Perhaps they haven't been in high latitude conditions as long. Diversity is indicative of being ancient -- Europe has unique and diverse phenotypes.
where/how you think the different European eye colors came about?
Beats hell out of me. Seriously, I am unaware of any research on this topic from a phylogeographical viewpoint. That blue eyes, fair skin, and blonde hair go together is a given. We all know that humans (indeed, mammals in general) use only a few pigments), melanin being the most common. And eyes, hair, and skin must use the same pigmentation mechanisms (total albinos lack pigmentation in hair, skin, and eyes). My guess would be that the nordic skin adaptation is based on breaking or weakening one of the links in the melanin production chain, and that this has a side-effect on hair and eyes. Again, I am unaware of any studies on this. (William, are you around? Have you heard of anything about any research on the evolution of eye color?)
This guess is supported by Carletoon Coon's hair-color map, published in The Races of Europe (New York, 1939), below. The congruence between Biasutti's skin-color map and Coon's hair color map is striking. On the other hand, the few differences between the two (France, Russia) would need to be explained.
winwinkel wrote:
I wonder if Frank has a barely larger Jpg image of Biasutti's 1939 measured skin-tone map? I cannot read some of the text in its legend.
Actually, the map that I posted was one of the many copies of Biasutti's map that appear in recent textbooks. It is from Robert Jurmain and others, Introduction to Physical Anthropology, 8th ed. (Belmont CA: Wadsworth, 2000). Here is a link to a more detailed hi-res picture: http://backintyme.com/Essay021215_files/image001.jpg.
More interesting, I think, is the original Biasutti image. A few years ago, I acquired a crumbling copy of his original book from a rare book store. I have just scanned the pertinent fold-out page in high resolution. The browning and fading are in the original. Here it is: http://backintyme.com/Essay021215_files/biasutti.jpg
Both of the hi-res pictures are too big to fit on your computer monitor, so I suggest that you download them to your hard drive and open them from there. That way you can zoom in as tight as you want.
The congruence between Biasutti's skin-color map and Coon's hair color map is striking. On the other hand, the few differences between the two (France, Russia) would need to be explained.
Thanks Frank! The big gif-files are great (views of Biasutti's map).
But I feel like taking issue with learned Mr. Biasutti's sharp boundary fencing Euro-white off from Oriental East-Asian phenotype. He shows no variation east of the Polish border. But my impression from more than 30 years of noticing is that Euro-white grades imperceptibly into the Oriental look of East Asia, across all the Eurasian continental land mass. There is no topographical foothold for drawing a "race"-boundary.
George
But I feel like taking issue with learned Mr. Biasutti's sharp boundary fencing Euro-white off from Oriental East-Asian phenotype.
You mean the line of big red dots labeled: "Limite approssimativo fra i domini leucodermii e xantodermi"? That is funny; I had never noticed it before now. I guess I am too used to working with copies (like Jurmain's), which leave it out.
It gives you a strange feeling to read physical anthropogists of the early 20th century. Those guys were so intense in delineating the sharp "racial" boundaries that they just KNEW had to be there, despite the lack of evidence. Did I ever show you Carleton Coon's final map of the major human subspecies? His boundaries are even more convoluted than Biasutti's, looping around to define Ethiopia as "Caucasoid." I guess it just goes to show that scientists are no smarter nor more objective than anyone else, but that the scientific process itself eventually accepts nature's evidence.
Incidentally, the line, "secondo la scala cromatica di F. Von Luschan" is why the map is considered obsolete. Von Luschan devised a set of little tinted ceramic tiles (about a dozen as I recall) ranging from off-white, through brown, to black. You classified someone's skin tone by finding the matching tile. Now that we know how easily people deluded themselves back then regarding bio-race, the Von Luschan system's subjectivity has thrown all such results into question. Nowadays, we use little electronic gizmos that measure skin reflectance at many wavelengths.
Posted: Fri 28 Oct 2005 15:56 Post subject: Blue eyes, fair skin, and blonde hair?
Frank said:
Quote:
That blue eyes, fair skin, and blonde hair go together is a given.
I have personally seen mixed-race children with natural blond hair and olive/dark/olive/beige complexions. Sometimes blue eyes can be found in people who are far from the "fair-skinned" European norm.
Posted: Fri 28 Oct 2005 18:02 Post subject: Re: Blue eyes, fair skin, and blonde hair?
Powell wrote:
I have personally seen mixed-race children with natural blond hair and olive/dark/olive/beige complexions. Sometimes blue eyes can be found in people who are far from the "fair-skinned" European norm.
I was talking about congruence between population maps, not allele-clustering in individuals. It is true that the genes for hair color, skin tone, and eye color are independent. This is why you see people like my son's father-in-law (beige skin, green eyes, kinky blonde hair, and strongly African features). But I was talking about regional variation. With a few exceptions, those regions of the planet where blonde hair is most common, blue eyes and fair skin are also common. In regions where fair skin is very rare, blonde hair and blue eyes are also rare.
Posted: Sun 30 Oct 2005 04:51 Post subject: Skin tone, hair and eye color
fwsweet wrote:
winwinkel wrote:
But I feel like taking issue with learned Mr. Biasutti's sharp boundary fencing Euro-white off from Oriental East-Asian phenotype.
You mean the line of big red dots labeled: "Limite approssimativo fra i domini leucodermii e xantodermi"? That is funny; I had never noticed it before now. I guess I am too used to working with copies (like Jurmain's), which leave it out.
Doubtless Professor Biasutti halved his abrupt "white"-Asian color-line problem by drawing two lines originally. My observation has been that the transition between the very European and Asian phenotypes is so broad, gradual, and vague, that -- in my opinion -- it supports debunking the "different races" notion. Blumenbach, too, in the 18th-Century remarked --
Johann Blumenbach wrote:
Although there seems to be so great a difference between widely separated nations that you might easily take the inhabitants ... for ... different species ..., yet when the matter is thoroughly considered, you see that all do so run into one another, and that one variety of mankind does so sensibly pass into the other, that you cannot mark out the limits between them.
(Quoted in Paul Bohannan, Social Anthropology, Northwestern Univ. 1963, p. 187. My omissions.)
Just so, my wife came back from touring far north-western China's Silk Road last year with pictures of ethnics living in that region (Xinjiang), who look more Caucasian than Oriental. The whole region, from 80° to 115° east longitude abounds with peoples ambiguous between Western and Eastern-looking.
fwsweet wrote:
It gives you a strange feeling to read physical anthropogists of the early 20th century. Those guys were so intense in delineating the sharp "racial" boundaries that they just KNEW had to be there, despite the lack of evidence. Did I ever show you Carleton Coon's final map of the major human subspecies? His boundaries are even more convoluted than Biasutti's, looping around to define Ethiopia as "Caucasoid."
I would like to see Carlton Coon's map of "human subspecies." I remember reading him remarking that humans are a "domesticated" species. I perceive a conundrum in that allegation. And moreover, for public policy reasons, I think it should be rejected.
fwsweet wrote:
Incidentally, the line, "secondo la scala cromatica di F. Von Luschan" is why the map is considered obsolete. Von Luschan devised a set of little tinted ceramic tiles (about a dozen as I recall) ranging from off-white, through brown, to black. You classified someone's skin tone by finding the matching tile. Now that we know how easily people deluded themselves back then regarding bio-race, the Von Luschan system's subjectivity has thrown all such results into question. Nowadays, we use little electronic gizmos that measure skin reflectance at many wavelengths.
Writing in 1963 Paul Bohannan had this to say about charting racial skin-coloring on the old system of color-printed cards.
Bohannan wrote:
The arch criterion of race in the phenotype is skin color .... [¶] Classifiers of races on the basis of color ... [did] introduce a phony scientism and match skin tone to a chart. These charts use to be supplied to all anthropologists going to the field. They consisted of about a dozen cards, some three inches wide by fifteen inches long. On each there were patches of perhaps half a dozen colors printed. In the center of each color patch there was a hole about the size of a quarter. The anthropologist got out his pack of cards, and [p. 193] then caught a subject. He made him take off his shirt (if he had one on) and lift his arm, because he wanted a patch of skin where the sun had never shone. He ran the cards along the patch of skin until he found a match -- when the color of the skin through the quarter-sized hole was the same as that on the printed card surrounding it. That gave him a number, which he wrote down. When he got all his subjects measured, he added up the numbers, divided by the number of subjects, and got what can only be called a "mean shade." I never owned a set of these cards -- their heyday was, in fact, before my time. But I did once use them in an anthropological laboratory in which all the students typed each other. The difficulty was that in all of the shades of pink, white, and beige on the cards -- and the colors ranged from Rubens to Rembrandt -- not one of them came anywhere near matching any of the subjects. When we tried to judge which color-patch was nearest, we all came out with different judgments: one man judged on the pink tones -- another on the tan tones -- and don't forget that white skin has green tones in it (as any painter can tell you) and black skin has a phenomenally wide range of tones. In the end, we proved ... by our charts that all of us, including one Japanese-American, were Caucasians.
(Bohannan, Social Anthropology, supra, pp. 192-193. My bold type.)
George
Posted: Sun 30 Oct 2005 13:04 Post subject: Re: Blue eyes, fair skin, and blonde hair?
Phil345 wrote:
Then whats the explanation for Solomon Islanders (and others from the South Pacific), that commonly have platinum blonde hair and ebony colored skin?
The explanation for why they have blonde hair and dark skin is because those two set of genes are independent and inherited separately. (As I mentioned, my son's father-in-law has a similar phenotype as does one of Barbara's uncles, as I recall.)
The explanation for how I reconcile this with my claim that blonde hair and light skin tend to go together geographically is that I cannot. I withdraw the claim. I guess I was thinking only about Europe, but even there I can be shot down.
Last edited by fwsweet on Sun 30 Oct 2005 19:19; edited 2 times in total
Joined: 04 May 2005 {Posts: 2021 } Location: santiago, chile
Posted: Sun 30 Oct 2005 15:20 Post subject: Re: Blue eyes, fair skin, and blonde hair?
fwsweet wrote:
The explanation for how I can reconcile this with my claim that blonde hair and light skin go together is that I cannot. I withdraw the claim. I guess I was thinking only about Europe, but even there I can be shot down.
Hi Frank,
In the Hispanic countries light skin is common. A little less common are blue and green eyes, but they are frequent as well. Red hair is less frequent but also is seen once in a while. But real blond platinum hair is very difficult to find. So when a person from Sweeden is seen in the street it call the attention.
I would like to ask you, Frank, if you know if the detailed genetics of the color of the eyes, hair and skin has already been studied? have the genetist found the genes itself?
If so. Are those physical caracteristics due to the lost of genetic material, like in albines?
It is curious, but colored eyes, light redish skin and blond hair are common in small primates, particularly in some African monkeys. So the genetic basis for those characteristics should be very old and simple.
[Do] you know if the detailed genetics of the color of the eyes, hair and skin has already been studied? Have the geneticists found the genes itself? If so, are those physical characteristics due to the lost of genetic material, like in albinos?
Yes, they have been studied. Because of the social significance of skin tone, the genes that govern the biochemical chains of events that produce and distribute melanin in the skin have been especially well-studied.
The best overall summary of how it works is Richard A. Sturm, Neil F. Box, and Michele Ramsay, “Human Pigmentation Genetics: The Difference is Only Skin Deep,”BioEssays 20 (1998): 712-21. Unfortunately, due to copyright restrictions I cannot provide the full text here, but the link will take you to an abstract and to a site where you can buy a copy for $25.
I suspect, however, that you are not interested in the genes that produce and distribute dermal melanin, that are identical in all humans (indeed, in all animals), but in the tiny variations (polymorphisms) within those genes, which yield the different skin tones that we see. To my knowledge, only two such polymorphisms have been identified so far. They are mentioned in Mark Shriver’s 2002 study and in the studies referenced in my essay The Paleo-Etiology of Human Skin Tone. Nevertheless, we can compute that there must be no less than three such polymorphisms in all, and no more than six. I predict that the other variable genes will be identified within a few years.
Regarding malfunctions in the chain, which produce the various forms of albinism, the best source is Ashley H. Robins, Biological Perspectives on Human Pigmentation (Cambridge UK: Cambridge University, 1991). Especially interesting is his chapter on Nelson’s syndrome, a kind of reverse albinism. It is a pituitary tumor that produces a dark brown skin tone even in Nordics.
Joined: 04 May 2005 {Posts: 2021 } Location: santiago, chile
Posted: Tue 01 Nov 2005 14:10 Post subject: Another question
fwsweet wrote:
...
Regarding malfunctions in the chain, which produce the various forms of albinism, the best source is Ashley H. Robins, Biological Perspectives on Human Pigmentation (Cambridge UK: Cambridge University, 1991). Especially interesting is his chapter on Nelson’s syndrome, a kind of reverse albinism. It is a pituitary tumor that produces a dark brown skin tone even in Nordics.
Hi Frank,
I have another question. Evolutionary theory mantains populations evolve to better addapt individuals to their environment. In the case of skin sort of make sense to have a different skin tone depending on the latitude one lives. However, what about the eye color.
Eyes are our "cameras" that allow us to see the environment. Therefore all the parts and characteristics of the eye are very important to our survival. It makes sense that mongolians, which evolved in high altitudes and cold wheather, have slanted eyes to protect the vision from light reflection.
However, what evolutionary benefit does the blue or green eyes have?
One can see in summer time people use dark glasses to protect their eyes, and it just seems a matter of common sense that a dark eyes would work better as a camera than a lighter eye. After all, if one see any "artificial camera" will find that the equivalent to the human iris are very dark indeed.
The only explaination I have for the spread of blue and green eye in northern populations is sexual selection. That is, people found more attractive those members of the opposite sex that have colored eyes.
I am wrong? Or are there any physical advantage to have colored eyes in certain environments ?
Finally, is there the genetics of the colored eyes already studied? I mean, are those genes already identified and mapped in the human genome?
I am interested in this issue because colored eyes call so much the attention to people in a way that, seems to me, is not proportional to its usefulness.
Posted: Tue 01 Nov 2005 16:16 Post subject: Re: Another question
oevega wrote:
The only explaination I have for the spread of blue and green eye in northern populations is sexual selection.
This seems possible to me, but it also seems unlikely. It seems possible because Luigi Luca Cavalli-Sforza (the grand old man of phylogeography) also suspects that many regional differences (even skin tone, in fact) are sexually selected. And I give great weight to whatever Cavalli-Sforza thinks. It seems unlikely because sexual selection also results in sexual dimorphism (where males look different from females), and there is no sexual dimorphism in human eye color. (There is sexual dimorphism in human skin-tone and size/weight.)
Nevertheless, I really do not know enough to answer any of your questions. Eye color is not significant to the U.S. "race" notion, and so it has fallen outside my field of interest. Given the pace of work on decoding the genome, however, I would not be surprised if someone had not published on it recently. I suggest that you start with the excellent Search engine at the NIH and type in "eye color" or "iris pigmentation" or some such thing.
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