|
|
|
|
|
| | Blue eyes...Page 1 of 3 (1, 2, 3) | ... and green eyes, or red hair or blond hair. What causes this in evolution? If you go wayyy back through history, all of the world, except for what we now know as the EU, you would find people with dark/black hair, and black/brown eyes.
Someone I used to work with mentioned this to me once, and I sat and thought about it for a minute and realized, ya, it was true. So why only in Europe would you suddenly have variations of hair and eye colour?
So far I've only heard two explainations, and one is rather far out there. The first one is diet. Personally, I dont think thats a factor, because there are climates in the EU that are quite similar to many other civilized regions throughout the world.
The second, which was presented to me by the person who originally mentioned this to me, believes that something other worldy tampered/adjusted evolution on earth at some point to introduce new bloodlines. Wacky I know, but I'm really very interested on this subject lately and would love to hear other peoples ideas. | |
|
| Blue eyes...
Posted: 1/27/2007 7:08:26 PM | | I think it was the Vorlons. | |
|
LBP
| | Joined: 12/27/2006
Msg: 3 | |
| Blue eyes...
Posted: 1/27/2007 9:11:06 PM | There's more than one theory (besides Vorlons, although I like that one). In areas where there is less sunlight, like Europe, it could be because darker skin filters out ultraviolet rays better. Having lighter skin prevents vitamin D deficiencies in those environments.
I think it has to do with a combination of factors. Natural selection, geography, and the crew of that one crashed Vorlon ship. | |
|
| Blue eyes...
Posted: 1/27/2007 9:50:37 PM | Right, it has to do with pigment density and light gathering for photo-receptor regulation of vitamin D3 and melatonin activity in the brain - those critical photo receptors are present in the eye.
This is also directed by melano-receptors present in all epithelial tissue, they are connected to nearby cells that convert vitamin D from an an inactive to an active form.
Vitamin D3 plays a crucial role in the regulation of dozens of cellular and tissue level actions in the body, including bone formation, blood cell maturation, and immune system control and brain chemistry. It also plays an important role in fat cell energy storage and in use of fat stores to make steroids in the adrenal glands.
Its beens shown to be tied to cancers of the colon, the lung, the skin, breast and prostate cancer. In breast tissue, this week, scientists reported that the progression of early cancers to cancers that spread and were resistant to drug therapy, differed in patients by their vitamin D levels in these tumors. The more vitamin D, the slower the tumor growth.
Now pay close attention: vitamin D looks very much like cholesterol.
Low density lipoprotein (LDL, the 'bad' cholesterol that is high in patients with shitty diet, poor sleep habits and who smoke and drink excessively) has a ton of cholesterol. And this binds to and activates vitamin D receptors through out the body that normally aren't activated.
Thats tied to...leukemia and lymphoma. When? Why, when you have an absence of cellular growth controllers and those are found primarily in dietary lipids. What else?
When you have excess insulin. When do you have excess insulin?
Stress. Smoking. Lots of caffeine. Shitty sleep habits. See a pattern here?
Some really nice work was done in the last few years to study of all things, coat color variation in ice age species and modern species living in cold climates - comparing those that migrate verus those that remain in fixed ranges (same ecosystems).
And lo and behold, from these studies emerges a very, very interesting story of melanocortin production and variable melanin pigment in animal coats, in those that have population variation in coat- and eye color, and for those species that have season variations - cold versus warm season - as a protective mechanism in cold climates, in both predator and prey species living in snowbound conditions for parts of the year.
And that work, has been extended to humans.
Its has been tied to very interesting variation in melanocortin and vitamin D3 roles in not just hair and eye color, but in mood regulation, immune function...due to that important gene regulation of melanocortin receptors (MCR) in brain.
The most interesting link lies in recent studies of energy metabolism, namely differences coupled to traditional foods that are significantly different for tropical warm indigenous humans versus those that migrated long ago, to colder climates with growing season variations.
It has to do with fundamental differences in fat and carbohydrate metabolism in aboriginals versus light colored Asians and Europeans. Published just this year (2007).
And that has been tied to higher incidence of diabetes, cardiovascular disease, and cancer when the wrong diet is consumed by these peoples (tied to skin pigment density). So we have a very nice tie in to racial/ethnic variation in the susceptibility to certain diseases.
Ultra-fvcking cool. | |
|
| Blue eyes...
Posted: 1/27/2007 10:23:20 PM | OP "If you go wayyy back through history,"
Is there written history of any consequence earlier than 6,000 years ago?
Such an eyeblink doesn't seem long enough to be of any consequence, for eye colour mutations. | |
|
| Blue eyes...
Posted: 1/27/2007 10:44:48 PM | Oh snap! I would have thought you had a ready answer for that one, Don.
Estimate are between 15-20,000 years ago. I'll bet it goes back much further though, probably 40,000 yrs, about the time of large group human migrations in Europe and parts of Asia.
On eye color genetics: another fascinating story, OCA2 and albinism.
http://dienekes.blogspot.com/2006/11/human-eye-color-explained-by-three-snp.html | |
|
LBP
| | Joined: 12/27/2006
Msg: 7 | |
| Blue eyes...
Posted: 1/28/2007 12:00:17 AM | And that has been tied to higher incidence of diabetes, cardiovascular disease, and cancer when the wrong diet is consumed by these peoples (tied to skin pigment density). So we have a very nice tie in to racial/ethnic variation in the susceptibility to certain diseases.
This has actually been a bit of interest in mine because I'm half aboriginal. I may look white but gain weight like a native. Tends to go to the centre. I've been told I'm at a risk for diabetes because of how I gain weight so need to keep my weight below a certain level. Both my sisters had justational diabetes during their pregnancies. Growing up you start to realize that foods just impact you differently than they do other people. I figured it was just some genetic family thing though but didn't realize until a few years back that race had something to do with it too.
My aboriginal father has diabetes. He doesn't drink or smoke but has weight issues.
The eye/skin color thing has always been interesting to me too because of the way I look. I noticed a weird trend in the aboriginal side of my family and have since noticed it in a few others too. Half natives I knew with blonde hair and blue eyes all had a white parent who had red hair (not necessarily blue eyes but came from families where blue eyes tended to dominate). Our siblings varied in color but quite a few looked more white than native even if they didn't share the blue eyes/blonde hair. I have no doubt there are blue eyed genes floating around in a lot of native's bloodlines. But I wonder if it has to do with that, or perhaps those with red hair carry a set of genes which triggers blonde hair/blue eyed kids more often regardless of race of their mate.
Redheaded Vorlons? | |
|
| Blue eyes...
Posted: 1/28/2007 2:56:30 AM | | I guess it depends upon what your thoughts are on evolution, from a purely pragmatic perspective, I guess for the same reason butterflies are all the colors of the rainbow. | |
|
| Blue eyes...
Posted: 1/28/2007 3:36:27 PM | hmmmmm, LBP
Both of my parents have dark brown eyes. I have hazel eyes. When I was up north, some would tell me I have "evil eyes" as at times, they would change into a very light green colour.
My Mom says that her great great grandmother had red hair and hazel eyes. Apparently, this was due to her lineage as half scot. She says that every generation since has had one daughter with hazel eyes. Strange, isn't it?
Cheers, Raven | |
|
LBP
| | Joined: 12/27/2006
Msg: 10 | |
| Blue eyes...
Posted: 1/28/2007 4:48:40 PM | My Mom says that her great great grandmother had red hair and hazel eyes. Apparently, this was due to her lineage as half scot. She says that every generation since has had one daughter with hazel eyes. Strange, isn't it?
That's kind of like my family with thyroid disorder. Only one per generation gets it. I lucked out, I'd rather have hazel eyes lol.
Well I heard a story which I'm not sure is myth or not but makes sense. When the poor Irish came over they diddled a lot of natives. That's why you see a lot of natives with an auburn tinge to their hair. I think there is a lot more Irish/Scottish blood running through native's veins than many would like to admit. That's the Canadian government's fault though. I wonder how many women had relationships with white men but kept it secret because they couldn't marry them. They would have to leave their home and never return if the Canadian Government found out.
Once a native woman married a white man she was never allowed to move back to the reserve even if they divorced. I'm not sure when they changed it but I can see all kinds of 'secret' relationships going on because of it. | |
|
| Blue eyes...
Posted: 1/31/2007 1:52:55 AM | It's a very interesting topic. That we migrated from Africa originally, and all of these changes happened to our appearence. I need to think about it for a loooong time before I can give an answer on here that will be to my satisfaction. My first answer will be this one...
I think we are presuming that all Africans, and Asians have always had Brown eyes, because I doubt if eyes have remained in tact through fossilisation. So firstly we have to question this assumption.
And then I shall think about this some more.. | |
|
| Blue eyes...
Posted: 1/31/2007 4:02:18 AM | I don't see why this is such a big mystery. Genetics are forever being changed by outside forces. That what genetics are there for, a rewriteable survival code. I would think UV light and chemicals play a large role in some of the most severely unexpected mutations. UV light can break down damn near anything and with the synergistic effect of all the chemicals going into our bodies these days nothing truly surprises me. Just tapwater contains hormones, antibiotics, birth control meds, ibuprofen... and much much more. Scientists are only now beginning to really rethink the "safe" levels of certain chemicals under the new information that their are synergistic effects to even these so called safe levels.
As to why in one area? Circadian Rhythms, perhaps, or some larger pattern. | |
|
| Blue eyes...
Posted: 1/31/2007 4:43:50 AM | | Just reading about Blue Eyed Black Lemurs that live in Africa. This goes against the oppinion that environment causes the change in eye colour, because obviously these Lemurs live in the same environment as African people. Still studying this further..... Hmmm lives on coffee plantations, that's interesting. | |
|
| Blue eyes...
Posted: 1/31/2007 8:37:32 AM | PP: http://en.wikipedia.org/wiki/Lemur
They live only in Madagascar and a few outlying islands, not Africa. Thats an important distinction - they're genetically isolated.
"The term "lemur" is derived from the Latin word lemures, meaning "spirits of the night," and likely refers to the large, reflective eyes which many of the nocturnal lemur species have." The smaller species are active at night due to predation pressures. The larger species are active in the daytime. Lemurs live in the forest canopy, where light levels are lower from leaf shadowing during the daytime.
Their eyes are adapted to low-level light gathering. One species is blue-eyed, a nocturnal species.
This species is also critically endangered, one step from extinction.
You can think on this topic all you want. I'm done with it. | |
|
| Blue eyes...
Posted: 1/31/2007 9:51:15 PM | Yeah, i think it's geneteics pretty much, just different alterations of chemicals that occurred randomly in the iris that result in different absorbancies of light waves.
Did you know that approx 90% of Icelanders are blue or green eyed
Most asians are brown eyed
Most africans are brown eyed | |
|
| Blue eyes...
Posted: 2/1/2007 1:03:50 PM | | One factor that is most often ignored in any discussion about inherited traits or changing physical characteristics is that they don't have to have any benefit to survival. They only need to benefit reproduction. See the the tail of male peacocks. It's likely that blue eyes, red hair or many other variations just helped the proto blue eyed, red head get laid. | |
|
LBP
| | Joined: 12/27/2006
Msg: 17 | |
| Blue eyes...
Posted: 2/1/2007 6:07:49 PM | ^^ yeah there was a discussion in a blonde thread about that.
That the blue eyed/blonde haired trait was rarer so more valued. But then came "gentle man prefer blondes" and we all become unintelligent bimbos  | |
|
| Blue eyes...
Posted: 2/2/2007 5:00:07 PM | I get the "yeah you look German" statement often.
I have always wondered....How the heck do you look German?
I suppose because I have light brown hair, fairly light skin and blue/green eyes?
Funny thing is. My mother who is German (imagine that)....has dark hair (or did before she went white) brown eyes and has an olive complextion. So did her father. (who was an SS solider.) My father who is of French descent is who I take after in my coloring.
I guess many people, because of Hilter's insanity still believe that all Germans are blonde haired and blue eyed. Nope.... | |
|
| Blue eyes...
Posted: 2/3/2007 7:32:26 AM |
But then came "gentle man prefer blondes" and we all become unintelligent bimbos
Oh dear. My outburst of laughter once again resulted in tea being expectorated everywhere.
*sigh* This keyboard won't last long...
BTW, the term 'German' refers to a nationality (language and culture), not ethnic extraction. | |
|
| Blue eyes...
Posted: 2/3/2007 1:37:43 PM | | i took a gentic class,years ago and brown eyes are dominant over blue eyes. example :so say you have a man,with brown eyes, and a womenwith blue eyes, who have a child most likely that child will have brown eyes. | |
|
| Blue eyes...
Posted: 2/3/2007 4:27:26 PM | In the simplest application of the Punett square (two alleles, B and b), if the man has double brown eye genes (BB), the child will have brown eyes, but will carry the blue eye gene as a recessive (Bb). If, on the other hand, the man is carrying the recessive himself (Bb), the child has a 50/50 chance of having blue eyes (bb), otherwise the kid'll also be a (Bb).
Of course, real life tends to be a little more complicated than that, but all in all it's not an unreasonable approximation. | |
|
| Blue eyes...
Posted: 2/3/2007 5:57:41 PM | Hey, all:
Hey, Hilbert: If I may, in your effort to make it simple you actually did not create a Punnett Square since this is a 2-dimensional diagram that includes both paternal and maternal genetic contributions. As provided, at best we can only say the offspring will be either XB or Xb, where X is the unknown maternal contribution.
This is getting away somewhat from the topic at hand, though. These are some of the proximate answers to the question, but the ultimate answers lie in both natural selection and our modern understanding of genetics, what most call the Modern Synthesis. In fact, all the biochemistry on the planet is just putting into effect what natural selection and genetics have determined, and doesn't mean diddly-dump until there is a genotype to be expressed.
Some of ultimate answers have to do with climate perhaps, but probably much more to do with the social nature of humans, our color vision, communication, sexual selection as a survival tool, and the ability of a mutation to spread in a population. This plasticity is probably one of the most important features, along with our social development and mating strategies. There may also be a founder effect, in which a population with a high percent of blue migrates into a new area or habitat isolated from outside genetic pressures, and the population grows with the eye color intact. Then, when the isolating barriers are dropped other influences such as the social and sexual ones maintain the high percent of blue eyes.
There is a lot more to be said here, but this is interesting.
By the way, my eyes are considered "hazel", but I have always felt short-changed by the name: the outside concentric circle is greenish-grey, while the inside circle is light brown. Oh, well.
David
Messages done with sustainable energy, with Wind and Sun! | |
|
| Blue eyes...
Posted: 2/3/2007 5:59:54 PM |
Hey, Hilbert: If I may, in your effort to make it simple you actually did not create a Punnett Square since they are a 2-dimensional diagram that includes both paternal and maternal genetic contributions. As provided, at best we can only say the offspring will be either XB or Xb, where X is the unknown maternal contribution.
I thought the original message stated that the mother had blue eyes, in which case we know she's a (bb). | |
|
| Blue eyes...
Posted: 2/4/2007 12:25:20 PM | Hey, all:
Hey, Hilbert: Okay, I understand. For the example, genotype ratio would be 1 Bb : 1 bb, and phenotypes, half offspring brown-eyed, half blue-eyed. Of course this is an example, since actual human eye color is determined by several alleles.
Hey, Pincho:
Just reading about Blue Eyed Black Lemurs that live in Africa. This goes against the oppinion that environment causes the change in eye colour, because obviously these Lemurs live in the same environment as African people. Still studying this further..... Hmmm lives on coffee plantations, that's interesting.
I was both confused and yet understood your comment about where lemurs live--Madagascar is certainly similar to adjacent Africa in many ways, including in general its climate and certainly its latitude. Much of the vegetation is similar since Madagascar broke away from the African mainland with a consistent flora and fauna and only developed unique flora after the break. Far more unique is the fauna, above all the Lemurs, which are found only in Madagascar. That is where I became confused about your note. I don't know if you were confused about what you read, or if the lemurs you read about were imports from Madagascar. And living on coffee plantations is an accident of geography and human activity.
In either case, you are probably correct in comparing humans and lemurs and guessing that climate is less important than other factors. As I said, other things such as rate of mutation, adaptive radiation and founder effects driving speciation in lemurs can probably be looked at for that group as well as in eye color in humans. Species of lemurs are highly variable in color and many other aspects, and have served as great examples of island biogeography,
natural selection, and speciation. They also share the primate characteristic of color vision, which goes hand in hand with hand with color variability.
One sad fact, not related to the topic, is that all the species of Madagascar's lemurs are highly endangered, many have been rendered extinct, and many more will be. This is due entirely to human-caused habitat loss--destruction of habitat for agricultural and other human uses--the facts do not tolerate any other excuse. I dare say some produce in our stores could be at the expense of lemurs.
There is somewhere a reference that states that humans with light-colored eyes are more sensitive to bright light, suggesting there may be some limited truth to higher latitudes not selecting against lighter-colored eyes, but on an annual basis high latitudes with a lot of snowfall seems to negate this favor. In Summer you have brighter light in higher latitudes and in Winter you do, too, due to snow. I have heard that lighter-colored eyes are more prone to
cataracts, but that probably needs to be verified, and cataracts hardly have a selective disadvantage, since it is a disease of later life. In fact, given early human evolution, because life expectancy was so low, cataracts were probably a feature of the very distant evolutionary future. But all we do is bleat, and refuse to see the Big Picture.
David
Messages done with sustainable energy, with Wind and Sun! | |
|
| Blue eyes...
Posted: 2/4/2007 3:16:41 PM | Actually, climate, latitude and sun sensitivity has a lot to do with melanocortin receptor gene expression variation, agouti variation and mutation in eye and hair color - in humans and in other animals.
http://www.nature.com/jid/journal/v111/n1/full/5600298a.html | |
|
|
|
Home
login 
