Blue eyed ice queens and brown eyed tarts?

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I’m interested in blue eyes. Specifically, I wonder why they’re around at all. Unlike blonde hair, there’s only one region of the world where blue eyes are extant at high frequencies, and there is a pretty regular drop off as a function of distance. It seems that variants of OCA2 are associated with blue eyes in Europeans. If you check Haplotter it looks like the region around this gene has been subject to a powerful bout of recent selection (i.e., within the last 10,000 years). Why this selection? Well, there’s no definitive explanation yet. But I don’t want to focus on hypotheses for why OCA2 has been subject to selection as much as what correlates there seem to be with the phenotype of blue eyes. Specifically, behavioral correlates.

There’s a fair amount of recent work in this area, but reading Racial Adaptations I stumbled upon some older studies, and, a model to explain the outcomes which I’m not really qualified to judge. So I’m going to report and let you decide, and hopefully, inform (especially those of you with cognitive neuroscience backgrounds).


So here I go. From page 66:

…eyes of different colors are related to differents in perception and innate behavior, as psychologists have discovered.23 Some of their tests have shown that dark-eyed persons are more aware of color and lighter-eyed ones of form; the former prefer bright hues and the latter lighter ones. Light eyes tend to envision panoramas, dark ones to concentrate on details

I don’t know anything about fashion or design, but I wonder if those of you who know this area (assman?) might be able to map some macrosocial trends back to these individual differences? After all, the vast majority of Scandinavians are blue eyed, and they’ve produced a fair amount of modern design. While Italians are well represented in the world of fashion and the arts. And the frequencies of eye colors are probably inverted in these two populations.

In any case, moving on, later on the page:

Behavioral variations are focused on the differences between “self-paced” and “reactive” responses to sudden stimuli. In the first subjects follow a well-known plan of animal behavior of pausing and deliberating before decision. In the second the subject flies into instant action (in animals), to attack or to flee. Of course, these behaviors are elaborated in man to govern many more-complex and subtler actions in speech and deed.

Light-eyed subjects are more likely to be self-paced, dark ones reactive. These differences are statistically significant and are patently genetic because they are equally represented in all age groups from kindergarten through professional life. When the iris color categories are extended from two to three, the subjects in the middle, with the mixed, green-to-hazel eyes, are found to share the benefits of the two extremes.

In one experiment ten of each of blue-eyed male, brown-eyed male, blue-eyed female, and brown-eyed female college students were wired to polygraphs and shown arousing pictures of sex and violence with appropriate sound effects. The brown-eyed subjects and the females responded more emotionally than the blue-eyed and male ones did.24

In another test, the same investigator gave Rorschach tests to forty blue-eyed and forty brown-eyed males. The blue-eyed ones fared better with form than with color and vice versa.25 In both tests only pure blue-eyed and pure brown-eyed persons were used.

That’s a lot to throw at you, but pretty much line with more recent work. The author does note that these studies were performed upon subjects of European ancestry. Whatever differences one can see between groups of blue and brown eyed Europeans, obviously it wouldn’t predict to other genetic backgrounds. East Asians tend to exhibit some of the same behavioral tendencies vis-a-vis Europeans that blue eyed Europeans exhibit vis-a-vis brown eyed ones. Obviously brown eyes can’t explain this since East Asians have brown eyes. This isn’t that strange, lots of the recent research in regards to human evolution suggests that East Asians and Europeans can converge upon the same phenotype via alternative genetic pathways. Blue eyes may simply be a byproduct of selection for another phenotype.

But on to the author’s model, which requires some knowledge of cognitive neuroscience and brain chemistry to evaluate. From page 74:

Few people other than ophthalmologists seem to have looked at retinas, nor to have considered it remarkable that the fundus is of virtually the same color as the person’s skin and for obvious reason that the underside of the retina is epidermis

At this point the author draws upon some photographs of the retinas of various racial groups, and observes the variation in color. He takes lithographs of these photos and basically measures the amount of light which can penetrate them. Here is the exposition that is relevant:

The Negro and the mulatto get 1.75 fcp; the Hindu and the American Indian 1.16 fcp; the brunet European 0.66 fcp; and the Chinese, the blond and the albino get 0.22 fcp. The Negro’s and the mulatto’s retinas let through eight times as much light as did those of the Chinese, the blond, and the albino.

OK, here’s the part where he lays out his argument for color and behavior:

Once inside the cranial cavity, neural impulses produced by the visible light that has passed through the retinal screen follow one of two paths. One lot goes to the hypothalamus…This part of the brain is the primary control tower of the central nervous system for almost all of the self-starting and self-regulating activity of the body-the sleep cycle, body temperature, the digestive process, fighting and loving.

These activities are managed by the production inside the hypothalamus of regulatory hormones. In some cases directly, but more commonly indirectly, these hormones control the fabrication and release of other, more specialized hormones in the pituitary, or “master gland,” seated in its bony saddle at the base of the braincase.

Two of these pituitary hormones become the raw material for making MSH (melanosome-stimulating hormone), so named because it darkens the pigment in amphibia and other cold-blooded animals. In man as in other mammals, it has yielded its pigment-darkening role to the built-in enzymes of the melanosomes themselves. Its only retention of its earlier function is to darken melanosomes.

Meanwhile, the rest of the neural impulses flow through a complicated channel into the brain’s third ventricle. From there they continue through several different parts of the brain stem into the pineal gland.

…Among other hormones, the pineal makes melatonin, which flows onto the cortext…Melatonin is an inhibitor; MSH is a stimulator, and one of its results is the secretion of a substance that switches melatonin making in the pineal on and off in countermeasure with is own rate of flow. Thus, the more light the retina lets in, the more MSH will be secreted and the less melatonin.

MHS has two divisions…one affects the peripheral nervous system only, the other may reach the brain, while melatonin bathes only the latter…all else equal, the stronger the light that penetrates the retina the more automatic are the responses to it, and the weaker the light the more the same responses fall under the control of the learning and thinking part of the brain….

To show those who may doubt that MSH and melatonin really affect the behavior of mammals…the National institute of Child Health and Human Development of Bethesda, Maryland, removed the pineal glands from some black rats (hair color, not skin color), pretended to do so with others, and left a third lot unscathed. The victims of real surgery became hyperactive and nervous, but when she injected melatonin into them they calmed down; both the other lots behaved normally throughout.29 Other researchers have given their animals shots of melatonin without operations. These injections reduced their avoidance responses,30 making them pause in the face of danger, rather than fight or flee. These are the “self-paced” and “reactive” responses found among blue-eyed and black-eyed students.

But not all our melatonin is made in the pineal gland. In daylight the choroid, which encases the retina, makes more of this hormone than the pineal does, and in darkness the pineal secretes more than the eye does. This discovery was made by experiments on chicks and rats.31 If one seeks to apply it to man, it might be well to remember that the stroma, or outer part of the iris lying above the lens, is mesoderm and an extension of the vascular choroid, also mesoderm, in contrast to the retina, which is ectoderm, like the pigmented layer of the skin. An investigation along this line might possibly explain the differences found in reactions blue blue- and brown-eyed subjects by psychologists mentioend earlier, because blood from the choroid flows direclty into the main bloodstream, some of which feeds the brain.

That was a lot to throw out there, but the main reason I’m posting this is so that cognitive neuroscience people can throw cold water on this model or not. Obviously a lot has happened in neuroscience since the 1970s, when the author thought this idea up. Myself, I tend to get confused on the various biochemicals which modulate brain chemistry and all the different pathways and modulations, so clarification would be nice too. Two points I’d also like to point out. 1) the Chinese clustered with the blond European in terms of the retina light values. 2) If the amount of light which manages to get through the retina is a major issue, that can explain variation by latitude and climate in terms of temper and personality, since obviously the amount of sunlight and radiation which reaches the surface varies a great deal.

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43 Comments

  1. Damn! I was just reading up on MSH yesterday in connection with MC1R . . . I like this idea though, thanks for posting all that. Will chase this up later.

  2. Fascinating to see the physical background on this topic. There is lots of anecdotal information out there. The one that I am most familiar with is race car drivers. In my experience, at both the amateur and professional levels, blue eyed drivers are way more heavily represented than would be expected by chance. More so even in rally drivers, where Scandinavians in particular excel. I’ve been in groups of drivers where upwards of 80% were blue-eyed. 
     
    I can’t put my hands on it, but I believe that phenomenon has been studied, along with other professions requiring special abilities in visual processing and “self paced” tasks. I would guess fighter pilots would fall into that category and data should be readily available.

  3. Why am I not surprised by any of this… 
     
    And this sort of analysis actually has much broader and extremely specific implications, which I suspect that very, very few people have actually considered…

  4. A long time ago (1980s) I remember seeing a claim that there was a study showing blue eyed overrepresentation among American CEOs. I haven’t been able to find any such thing online though. 
    As for the racecar drivers, wouldn’t the first guess be that someone with a tendency to reactive (rather than self-paced) behavior would have an advantage? Maybe I’m not properly assessing the actual demands of racecar driving though.

  5. I’d like a wee bit more time to reflect on this.

  6. There’s a claim that fighters aces were unusually likely to have blue eyes – supposedly 80% did. I’d like to see the documentation.

  7. Dogs like Huskies also have blue eyes – maybe it’s a Northern thing?

  8. Interesting that people in western Anatolia apparently don’t have eyes. 
     
    Also interesting how well the fraction of light eyes correlates with closeness (in some sort of vague population mixing sense) with the nominal PIE heartland. 
     
    More seriously, the contours are light eyes plotted are interestngly different from the what I would have expected from the MtDNA haplogroup distribution, e.g. Finland (of course) being more light eyed.

  9. Carleton Coon was a loser and an anthropologist. Razib, I think that it’s a waste of time to seriously entertain any of his hypotheses. (And I’m not attacking Coon for being politically incorrect. Luigi Luca Cavalli-Sforza is also politically incorrect, but he is a geneticist who carefully examines the evidence and considers alternative explanations. Coon was someone who went looking for the evidence to support his fixed ideas about European “superiority”.) 
     
    “Light eyes tend to envision panoramas, dark ones to concentrate on details” –> I don’t understand how one can rigorously demonstrate this difference in an psychophysical experiment. Does Coon explain at all? 
     
    The distinction between “self-paced” versus “reactive” phenotypes: Rorschach tests?! I automatically dismiss all research done by an investigator who uses Rorschach tests. Moreoever, I automatically dismiss anything said by someone who approvingly cites a Rorschach study. 
     
    This statement puzzles me: “all else equal, the stronger the light that penetrates the retina the more automatic are the responses to it, and the weaker the light the more the same responses fall under the control of the learning and thinking part of the brain.” WTF?! This statement is not even wrong; it just doesn’t make any sense. 
     
    We know from studies of albinism that the pigmentation of the eye is related to visual performance (acuity, color discrimination, etc.), probably because of two factors: (1) pigmentation of the iris, which might affect the spectrum that reaches the retina; and (2) backscatter of light from the pigmented epithelium to the photoreceptors. (Razib: I’m sorry to be pedantic if you know this already, but light hits the photoreceptors first, before it passes through the pigmented part of the retina. So, in other words, light that penetrates the pigmented layer doesn’t get detected by any photoreceptors; it just gets absorbed by bulk tissue.) Dedicated cells in the retina detect ambient light levels to ultimately drive melatonin production. I would be surprised if skin/eye pigmentation appreciably affects the sensitivity of these cells. 
     
    I doubt that variation in pigmentation has any appreciable effect on pineal responses to light. There is circadian variation in the amount of light that reaches the retina within an individual. Coon conflates this circadian variation with overall differences between individuals/populations due to pigmentation.

  10. chairmanK, pedanticism is good. i admitted my ignorance in this area. as for coon, if you want a lot of phenotypic level data he did a good job of collating it. i’m traveling right now, but i’ll place the references that coon has in the notes so that people can look up the original research. also, could you email me? i have a ? for you (just click my name in the post or use the contact box).

  11. Also interesting how well the fraction of light eyes correlates with closeness (in some sort of vague population mixing sense) with the nominal PIE heartland. 
     
    Very vague, in that case… 
     
    More seriously, the contours are light eyes plotted are interestngly different from the what I would have expected from the MtDNA haplogroup distribution, e.g. Finland (of course) being more light eyed. 
     
    MtDNA? The majority of Finnish mtDNA haplotypes are run-of-the-mill European.

  12. Fighter aces as well as racecar drivers? Of course in the case of figher aces there may be other selection issues, as a quick look at the top fighter aces of WW II demonstrates. 
    Personally I have much more confidence in the observed correlations that are mentioned than in the proposed mechanism. Differences in temperament associated with eye color are well documented, so other mental differences wouldn’t be shocking. If the supposed ‘forms vs colors’ difference is real, then I’d expect differences in spatial ability, for example.

  13. I remember reading in a college anthropology textbook that blue eyed people are slightly more sensitive to high frequency (blue) light. This makes a little sense, since melanin is brownish (browns are unsaturated ‘warm’ (low frequency) colors). But I’ve never seen this confirmed elsewhere (and I don’t remember the name of my textbook).

  14. “While Italians are well represented in the world of fashion and the arts.” 
     
    I doubt this has anything to do with fashion or the arts.  
     
    The majority of the great Italian fashionistas (all, actually) are from the north, which is well-represented by blue-eyed folk. Around the middle of Latium you see a difference in coloring that’s noticeable. 
     
    To say nothing of French domination of the fashion industry…. 
     
    But as a pale-eyed type, I do find this interesting.

  15. Re: fashion, some Italians are and some aren’t from the north — Versace, Ferragamo, and Ennio Capasa (who does Costume National) are southerners, while Armani, Ferre, and Zegna are northerners. Their eye colors reflect this, if you do a google image search. 
     
    You’d really want a good sample size — go through all Italian names in the style.com list of designers and see how many had blue eyes (not who’s north vs. south — which is harder to find out anyway). You could get more data by finding out which non-Italian named companies have Italian head designers. 
     
    If it were a question of Italian models, I’d be on it. As it is, someone else can take the project.

  16. And for those who want a less crypto-homo project, you could look up the elite architects from Spain and Italy. It would be easy to tell with them if light eyes were more frequent than expected.

  17. The majority of the great Italian fashionistas (all, actually) are from the north, which is well-represented by blue-eyed folk. Around the middle of Latium you see a difference in coloring that’s noticeable. 
     
    lot less than scandinavia.

  18. I would really like to know if we’re talking about correlation to the blue-eye phenotype or to the blue-eye gene. Are there any studies which look in to that? (Shouldn’t be hard to do. I, for example, have brown eyes, but since my mother has blue eyes I know that I carry the gene.)

  19. I know several ex-fighter pilots. There definitely is a fighter-pilot personality (at least in Israel – all of whom have been selected by the same air-force regime) – a distinctive mixture of daredevil and self-control.

  20. I would really like to know if we’re talking about correlation to the blue-eye phenotype or to the blue-eye gene. Are there any studies which look in to that? (Shouldn’t be hard to do. I, for example, have brown eyes, but since my mother has blue eyes I know that I carry the gene.) 
     
    phenotype. the mendelian character of inheritance has been known for a long time, but they are only looking for ‘homozygotes’ for blue eyed gene which express. only in the past few years has OCA2 become the definite culprit. there are association studies in the works i’m assuming out there.

  21. I think blue eyes, like blonde hair, do occur as a rare variant in a few non-european-ancestry populations.  
     
    Disregarding these rare exceptions, blue or grey eyes, fair hair, and very pale skin are almost exclusively north european characteristics. I would speculate that during the settlement of northern europe after the last ice age there was strong selection for rapid loss of skin pigmentation, and the depigmentation of hair and eyes was a by-product. As blonde hair and blue eyes are (largely) recessive traits, we should look for genes which affect skin pigmentation in the heterozygote state and also affect hair or eye pigment when you get a ‘double dose’.

  22. empiricus: Also interesting how well the fraction of light eyes correlates with closeness (in some sort of vague population mixing sense) with the nominal PIE heartland. 
     
    Huh? Light eyes are the most common around the Baltic Sea and for a PIE homeland that’s, uh, maybe a mildly more credible candidate than Sri Lanka. Wherever you’re putting the PIE speakers, if this map were accurate then, they’d be mostly dark-eyed. 
     
    More seriously, the contours are light eyes plotted are interestngly different from the what I would have expected from the MtDNA haplogroup distribution, e.g. Finland (of course) being more light eyed. 
     
    You’d be even more baffled, then, if you noticed the near-perfect fit of the contours of the highest mapped proportion of light eyes and those Y chromosome lineages that in Europe are only found in Finno-Ugric peoples and peoples with FU admixture…

  23. To me, heavy skepticism seems warranted whenever alleged personality correlates of some trait seem to balance out in an aesthetically pleasing yin/yang kind of way. 
     
    But then, it may just be my baby-blues.

  24. David B, 
    I think blue eyes, like blonde hair, do occur as a rare variant in a few non-european-ancestry populations. 
     
    I knew a girl who was 5′ 8″ with light brown hair, blue eyes and light olive skin – she seemed French – but turned out to be a Turkmen from Northern Iran! She said that blue eyes were uncommon in Turkmen, but not unknown.

  25. Razib: 
     
    Why the fixation on Italy? France is the center of couture. Brown-eyed girl Chanel literally created modern women’s fashion.  
     
    Set up a testable relationship between eye color and fashion, I’d be interested to see it.  
     
    I think that science has better things to do than this, like deal with string theory, or figure out what dark matter or dark energy is. 
     
    Agnostic: 
     
    You left out Miuccia Prada and that Missoni girl. The two best designers extant, bar none. 
     
    Now I’m going to sign up for piloting courses, which my eye color predicts will make me an ace. :)

  26. I think that science has better things to do than this, like deal with string theory, or figure out what dark matter or dark energy is. 
     
    which is why you are reading a blog about string theory? and i assume that (no offense behavior geneticists) this sort of stuff is a bit more accessible so far as scientific fruit goes, both in terms of speculation and tractability.

  27. As blonde hair and blue eyes are (largely) recessive traits, we should look for genes which affect skin pigmentation in the heterozygote state and also affect hair or eye pigment when you get a ‘double dose’. 
     
    OCA2 (blue eye gene) does have an effect on skin color. and yeah, that’s the obvious selective factor for the reason you pointed out, it has an effect on heterozygotes from what i recall.

  28. I think blue eyes, like blonde hair, do occur as a rare variant in a few non-european-ancestry populations.  
     
    yes, but the probability drops off as a linear (depending on how you transform it) function of the distance from north central europe for blue eyes. for blonde hair there is a secondary region of relatively high frequency besides europe, in australasia. that’s the distinction i was trying to make.

  29. I?ve seen two unpublished studies that may relate eye color to personality. One found that light-eyed women were less agreeable than dark-eyed women (in a sample of Australian subjects of British origin). The other found that light-eyed and light-haired women had a more feminine digit ratio than dark-eyed and dark-haired women (in a sample of British subjects). This would suggest that light eyes and light hair are associated with a higher level of prenatal estrogenization. 
     
    Neither study has been published to date. The reasons for refusal seem to be either methodological (the British study did not adequately screen out subjects who may have artificially changed their hair color) or thematic (the subject does not fall within the journal?s areas of interest). Reading between the lines, I get the impression that many journal editors are uncomfortable with this kind of research. 
     
    I suspect there is some incipient sex-linkage, i.e., European women may be somewhat likelier to have non-brown eyes and non-black hair. If this sex-linkage is mediated by prenatal estrogenization there may also be some impact on personality and temperament. But I really don?t know, and unfortunately there are still more questions than answers.

  30. “Best designers extant, bar none” — there is a large sex gap in who is considered the best designers! Regardless of whether the clothes are for men or women. 
     
    Miuccia Prada has brown eyes, so again that’s what we need to look at, not where she’s from. There are 10,000 pictures of the Missonis, but none are large enough to get a good view of their eye color… 
     
    If lighter eye color goes along with better ability to think things over, sit still, etc., eminent scientists would be more likely to have non-brown eyes since they’re introverted and reflective. I’m sure someone’s looked at that at some point, but a quick google search didn’t turn up anything. 
     
    The stuff about reflecting vs. responding instantly is a difference b/w introverts and extraverts — that’s what makes extraverts better flirts, on average. They can keep on their toes verbally — when you have to reflect before you speak, it kills the momentum of flirtation.

  31. Agnostic,  
     
    “there is a large sex gap in who is considered the best designers! Regardless of whether the clothes are for men or women.” 
     
    I return to GNXP from time to time and I read this. It so happens that fashion is something I know something about, so here goes. 
     
    It’s difficult to say who is the “best” designer – that’s completely subjective. But most observers concede that the designer who has had the most effect on modern couture is Chanel. Possibly the greatest of the old-style couturiers was Lanvin. French couture was and is male-dominated, but that doesn’t make their designs better. 
     
    As far as the present is concerned, I’m not the only one who things that Prada and Missoni stand above the best by an order of magnitude. No gimmicks, no fireworks – just great stuff.  
     
    Fashion is a difficult industry in which to make it – you need backing. Both Prada and Missoni took over family businesses.  
     
    “Miuccia Prada has brown eyes, so again that’s what we need to look at, not where she’s from.” 
     
    Are you serious? Do you honestly believe that a case of one designer with brown eyes proves anything??? 
     
    Razib, 
     
    Why so irritable? I gave the example from physics as a example of how legitimate scientists can disagree about real issues. But is someone’s eye color indicative of anything in the fashion industry, given the fact that the fashion industry is essentially controlled by huge moneyed interests and has little to do with innate talent?

  32. Woah, I didn’t say that men or women tend to make better fashion designers (although males do outperform females in fashion design* ) — the sex gap I meant is what type of designers males vs. females tend to prefer. The rockstar designers have a larger male fan-base, and the more sensible yet smart designers much less so.  
     
    Are you serious? Do you honestly believe that a case of one designer with brown eyes proves anything???
     
     
    I don’t — the point of this thread is to see whether certain large-scale trends may correlate with light eyes. You said that contrasting Italians with Scandinavians didn’t bear on the blue vs. brown eye issue, since most of the Italians are from the more blue-eyed north. But that’s only true if the Italian designers actually are blue-eyed, right? Just assuming they are based on geography doesn’t work. 
     
    * http://akinokure.blogspot.com/2006/01/politically-incorrect-fashion-ii-sex.html

  33. I tried to determine the eye colors of the following all-time great NFL quarterbacks, which I assembled by combining a few “best” lists from the web. (A question mark indicates that I found no clear picture or description.) 
     
    Joe Montana – blue 
    Johnny Unitas – ? 
    John Elway – blue 
    Dan Marino – blue 
    Joe Namath – blue 
    Roger Staubach – blue 
    Jim Kelly – blue or mixed 
    Sonny Jurgensen – ? 
    Dan Fouts – blue 
    Bart Starr – ? 
    Steve Young – blue or mixed 
    Terry Bradshaw – blue 
    Kenny Stabler – ? 
    Fran Tarkenton – ? 
    Y.A. Tittle – ? 
    Bob Griese – blue 
    Len Dawson – ? 
    Archie Manning – blue 
    Brett Favre – mixed 
    Troy Aikman – blue 
    Peyton Manning – mixed 
    Tom Brady – blue 
     
    Interestingly enough, I haven’t yet found a QB on the list with unambiguously brown eyes. The closest so far is Peyton Manning, whose irises are a kind of bluish-greenish hazel with a halo of brown around the pupils.

  34. Why so irritable? I gave the example from physics as a example of how legitimate scientists can disagree about real issues. But is someone’s eye color indicative of anything in the fashion industry, given the fact that the fashion industry is essentially controlled by huge moneyed interests and has little to do with innate talent? 
     
    i have no idea what eye colors has to do with fashion, i was asking, as you might note from the tone of my post. you made an assertion about eye color in northern italy which i added some quantitative data to. i don’t really care much about the whole fashion angle that much. you might or might not be right about that, but you aren’t right to minimize eye color difference from scandinavia to northern italy.

  35. which I assembled by combining a few “best” lists from the web. 
     
    quarterback ratings? those aren’t perfect, but they’re a precise quantitative metric.

  36. precise quantitative metric 
     
    Yeah, I just wanted to informally explore the subject to see if it might warrant further investigation. Quantitative metrics are important, but I believe that passer ratings have increased too much over time to be of much use in comparing quarterbacks across different eras.

  37. prolly best within the last 5 years? the sample size isn’t tiny.

  38. As I recall, there is a correlation between blue eyes and behavioral inhibition. (I think this is from Jerome Kagan’s work on temperament.) I’ll try to look it up. 
     
    agnostic said: 
    The stuff about reflecting vs. responding instantly is a difference b/w introverts and extraverts — that’s what makes extraverts better flirts, on average. They can keep on their toes verbally — when you have to reflect before you speak, it kills the momentum of flirtation. 
     
    I have the same problem about missing opportunities when girls make it obvious that they want to be kissed. The solution is practice, lots of practice. 
     
    And yes, I have blue eyes.

  39. I may have dreamed this up, but I think I read somewhere that some Native American tribes had a significant proportion of blue or blue-grey eyes, not resulting from European admixture (because they already had it when Europeans first met them). Sorry I can’t give references.

  40. David B, 
     
    I recall reading that Chief Red Cloud of the Sioux has blue eyes – not sure if the Sioux had any European admixture at that time? 
     
    Though European genes might have passed to them through other neighboring tribes, who were linked in a chain of contact with colonists in the East??

  41. I’ve got a question of prime importance for you all. 
     
    The “tart” pic to the right of Paltrow is of whom?

  42. Is that Lindsay Lohan?

  43. I’m surprised there’s been no comment on a potential contribution of SAD and circadian rhythm disorders. Anyone know if the prevalance of these is skewed in blue eyed populations?

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