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Thread: Technological Advancement and Human Development

  1. #1 Technological Advancement and Human Development 
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    I was wondering if there is any evidence of technology affecting human development/evolution. Has any research been done on the subject? My hypothesis is technology can affect our evolutionary pathway and was hoping to back this claim up with some evidence to make it less speculative. I'm writing a research paper for a school project on the subject, and have had difficulty locating hard facts. Any information or nudges towards the right direction would be greatly appreciated.


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    quite a few examples....just a couple

    cow milk digestion
    alcoholic tendency and length of exposure time for that ethnic group
    technology to live in high Asian mountains or cold climates and morphological changes observed in Sherpa and Ekimo


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    Not sure whether you'd call it technology, but it's probably associated with processing food, or cooking methods at least. There is some discussion among dentists and orthodontists that in some countries, the lower jaw is getting smaller and is therefore the reason why so many people need treatments to accommodate, or reduce, the standard number of teeth - which doesn't seem to be changing. Yet.
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    And there is the question. Do we evolve because of tech development or does tech develop as we evolve. I believe that as we evolve we create the technology to improve life. However I believe at some point we will begin using technology to evolve our species. Genetic manipulation, Cybernetic implants, eventually the line between which came first will blur. Our ancestors developed tools as they evolved to make things easier.
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    The human alimentary canal is the smallest for our size of any primate.
    The obvious reason for this is
    1. Due to the technology of cooking we do not need a long gut for digestion
    2. Reducing the bulk of the gut also reduces body weight, giving us the selective advantage of being able to run better.
    Endurance running hypothesis - Wikipedia, the free encyclopedia

    So this is an evolutionary change due entirely to the fact that humans have the technology of fire and cooking.
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    Without fire, serious clothing and hunting gear, and maybe even domesticated milk animals, we would never have been able to inhabit central Eurasia far from the ocean with its vitamin D sources.

    Hence, no white skinned people.
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    The development of medical technology has changed, in some cases dramatically, what can be considered fit in evolutionary terms. Consequently the mix of alleles in the population is different from what it would otherwise have been. That's evolution.
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    Quote Originally Posted by iceaura View Post
    Without fire, serious clothing and hunting gear, and maybe even domesticated milk animals, we would never have been able to inhabit central Eurasia far from the ocean with its vitamin D sources.

    Hence, no white skinned people.
    Huh?

    All we need is sunlight to make vitamin D. And even near the coast, in places where because of fog, it still wasn't sufficient we evolved blond and red thin hair to maximize the ability to create vitamin D.
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    Quote Originally Posted by lynx
    Without fire, serious clothing and hunting gear, and maybe even domesticated milk animals, we would never have been able to inhabit central Eurasia far from the ocean with its vitamin D sources.

    Hence, no white skinned people.
    Huh?

    All we need is sunlight to make vitamin D. And even near the coast, in places where because of fog, it still wasn't sufficient we evolved blond and red thin hair to maximize the ability to create vitamin D.
    Just quit replying to my posts. Just quit. Please.
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    Lynx fox, though, is usually correct in his replies.
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    Quote Originally Posted by skeptic
    Lynx fox, though, is usually correct in his replies.
    So let him post his "correct" stuff without claiming to be replying to my posts. Leave me and my actual arguments out of it.
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    ....and my actual arguments out of it.
    Make some....and bother to back them up with evidence once in a great while. Request denied.
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    Quote Originally Posted by lynx
    Request denied.
    OK. More threads full of me trying to find some way to state an argument or make an observation that you and your posse can't misrepresent, namecall, or just stupidly fuck up and then mock (as here, above - "huh?" ). More threads devoid of humor, creativity, speculative banter, mutual exploration of real issues in a spirit of inquiry, less fun and more hassle forever.

    Dunno what your problem is, but psychiatry is looking more and more like the arena of analysis. This shit is motivated, has to be.
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    Iceaura

    Without meaning to be disrespectful, but you bring upon yourself the fact that Lynx Fox and myself (and others like us) do not take you seriously. You are too credulous towards web sites that are not based on good science. Lynx and myself, and others, can be convinced of other view points, but you have to use references that are reputable to support your case.
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    Quote Originally Posted by skeptic
    Without meaning to be disrespectful, but you bring upon yourself the fact that Lynx Fox and myself (and others like us) do not take you seriously.
    All disrespect intended and more, I do not care in the slightest whether guys like you and lynx take me seriously. Trust me - that's not an issue.

    What I care about is getting what could be a fine, interesting, reasonable discussion about an actual matter of interest fucked up by playground bullshit from imbeciles, time after time after time.

    All I did here was post an observation relevant to the OP, an example of a definitely evolutionary item of human development that came about as a result of human technological progress, and not otherwise.

    Humans acquired the opportunity of living in a new and somewhat isolating environment that punished darker skin by the influence of their new technological capabilities, as surely as if they had been isolated geographically by wandering over a mountain range. A simple and suggestive, in my view, example relevant to the OP. Why that response?
    Last edited by iceaura; May 18th, 2012 at 05:39 PM.
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    There is no bullshit, and no imbeciles.

    There are merely people with a strong respect for good science demanding good science.
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    Though I wish ice wouldn't be so testy about people disagreeing with him, I have to admit that I find the "sunlight absorption of vitamin D" theory somewhat unconvincing as the primary motivation behind light skin. In the regions where it occurs, the humans would be wearing clothing over most of their body whenever they go outside anyway. Surely the body could have found another vitamin or something to replace it, and more easily than changing its skin color and hair composition. Also it's clear that other mammals manage to survive in the same areas without lightening their skin tones.

    I'm leaning toward a thermal motive. I'm not sure if black body radiation would be reflected by lighter colors of skin or not? Maybe the frequency of the radiation emitted by a human being at 98 degrees F is too low for it to make a difference? But reflecting body heat inward would seem like a more plausible reason for the change.
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    Quote Originally Posted by skeptic
    There is no bullshit, and no imbeciles.
    Whatever. Reread posts 6 and 8 at your leisure, and find another explanation then.

    Quote Originally Posted by kojax
    Though I wish ice wouldn't be so testy about people disagreeing with him
    I wish that disagreement were the problem here - no one has disagreed with the actual content of post 6 so far, for example, except you just now.

    Which then informs actual discussion: because the evolutionary pressure involved does have some bearing on the nature of the technological influence. If vitamin D is not the central factor, the influence of the tech - opening up a new environment in which vitamin D is in short supply, in my version - is harder to explain.
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    OK. More threads full of me trying to find some way to state an argument or make an observation that you and your posse can't misrepresent, namecall, or just stupidly fuck up and then mock (as here, above - "huh?" ). More threads devoid of humor, creativity, speculative banter, mutual exploration of real issues in a spirit of inquiry, less fun and more hassle forever.

    Dunno what your problem is, but psychiatry is looking more and more like the arena of analysis. This shit is motivated, has to be.

    All disrespect intended and more....

    Stay away from personal attacks--you are already on thin ice for exactly this.


    --
    Humans acquired the opportunity of living in a new and somewhat isolating environment that punished darker skin by the influence of their new technological capabilities, as surely as if they had been isolated geographically by wandering over a mountain range. A simple and suggestive, in my view, example relevant to the OP. Why that response?
    Because you didn't explain it, seemingly used a bad example, and provided no scientific link which might have brought clarity to your comment.
    Last edited by Lynx_Fox; May 18th, 2012 at 08:02 PM.
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    Quote Originally Posted by kojax View Post
    I have to admit that I find the "sunlight absorption of vitamin D" theory somewhat unconvincing as the primary motivation behind light skin. In the regions where it occurs, the humans would be wearing clothing over most of their body whenever they go outside anyway. Surely the body could have found another vitamin or something to replace it, and more easily than changing its skin color and hair composition.
    Kojax

    I do not think you are correct here. If you look at the regions where UV is strong, and most human skin colour is dark, you will still find a wide range of skin tones. It appears that it takes little genetic change to significantly change human skin colour. This makes it a very easy alteration for evolution to work on to solve the problem of inadequate vitamin D.

    When most of the body is covered, and only a few patches like face and hands are exposed to the sun, that just makes it even more vital that the UV is used on those small skin areas to make as much vitamin D as possible. We know from empirical studies that vitamin D depletion is common in dark skinned people who now live in cold climes. Vitamin D is made in much greater quantity by pale skinned peoples under those conditions.

    Which means the empirical evidence supports white skins evolving to permit more vitamin D to be made.
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    Wow... Yes sometimes Lynx Fox can be frustrating but his comment on the assertion made regarding Vitamin D and Oceans is correct. We get our Vit D through sunlight. People, myself included, who spend most of their time indoors, end up with Vit D Deficiency Which is Why I now take 2500mg once a week. And Lynx is usually correct on his posts. When I first started posting I thought it was something personal until I realized that it was simply a need for evidence to back up my statements. If one posts evidence with their claims of something as fact then good. If you dont understand why your assertion is wrong ASK. It does wonders.
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    Also skin pigmentation is used as protection. The leading theory is that skin color adapts to intense sunlight irradiation to provide partial protection against the UV fraction which produces damage and thus mutations in the DNA of the skin cells.

    . "Colloquium Paper: Human skin pigmentation as an adaptation to UV radiation". Proceedings of the National Academy of Sciences 107: 8962–8
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    Quote Originally Posted by dmwyant
    Wow... Yes sometimes Lynx Fox can be frustrating but his comment on the assertion made regarding Vitamin D and Oceans is correct. We get our Vit D through sunlight. People, myself included, who spend most of their time indoors, end up with Vit D Deficiency Which is Why I now take 2500mg once a week. And Lynx is usually correct on his posts.
    As his statements about Vitamin D repeated the basis of my post, 6, I am inclined to agree that yes, he and I were correct in our assessment of the role of Vitamin D.

    But that was mostly irrelevant to the OP. The part of post 6 that was relevant to the OP was the role of technology in setting humans up for an evolutionary pressure they were otherwise not subject to, and consequently the evolution of more transparent skin better able to utilize what little UV light was available. It was an example of technology having great influence on human evolutionary development, in what I think is a particularly interesting way with a lor of implications. That's what the OP was about, recall? It was simple. It was obvious. It was stated directly, with the subtlety of coastal migration of dark-skinned people to high latitudes taken care of, the corners nailed down in a few sentences.

    It takes quite a bit of sophisticated technology for humans to survive in typical inland low-UV environments, to have the opportunity to adapt to them at all. Lynx simply missed that, failed to follow post 6. Once again, he "replied" to something he hadn't understood, or had misunderstood, and demanded that somebody else assume accountability for his failures and insult. For the fucking umpteenth time. And I want him to stop doing that, with my posts.


    Quote Originally Posted by lynx
    Because you didn't explain it, seemingly used a bad example, and provided no scientific link which might have brought clarity to your comment
    There is no way for me to predict what you are going to fuck up in my posts. For example: What part of my post 6 should I have imagined needed a link for you? The part about Vitamin D - should I have assumed you were unfamiliar and needed persuasion? The time and space location of the evolutionary development at issue? There are all kinds of assumptions buried in there, dozens of links would be necessary if I were to attempt to deal with them all. No one can carry on a discussion if they have to defend themselves against the kind of harassment you guys specialize in.

    It was a great example - interesting and suggestive, directly relevant and unarguable (so a reasonable person would think), simple and straightforward. It could have launched a really good discussion about the influences of technology on human evolution.

    It was fun, damn you.

    You guys have a real problem here, and banning me (again) won't help you at all.
    Last edited by iceaura; May 19th, 2012 at 05:55 PM.
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    survive in typical inland low-UV environments,
    Such as? Nearly all the low-UV environments are along the coast or very high North latitudes and/or seasonal. I followed what you were trying to say, but even with your recap it honestly doesn't make much sense. (hence the "huh?") Are we to assume humans 80K or so years ago, for example humans had enough sea fairing technology that dietary sources from sea fish were significant enough to put selective pressure on skin color? Do you have examples of dark skinned coastal sea peoples living in foggy low-UV conditions? In short, I was questioning your example and with a single word asking for more. But instead of explaining it, (and linking it to science), you choose to take personal offense.

    I don't doubt at all that there is strong feedbacks between technology, such as clothing, and evolution of skin pigment and other characteristics which are still happening today.
    --

    dmwyan, dark skin also protects from crashing folic acid levels associated with overexposure--low folic acid creates severe birth defects.
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    Quote Originally Posted by lynx
    I followed what you were trying to say,
    Bullshit. Your reply was clueless.
    Quote Originally Posted by lynx
    Such as? Nearly all the low-UV environments are along the coast or very high North latitudes and/or seasonal. I followed what you were trying to say, but even with your recap it honestly doesn't make much sense. (hence the "huh?") Are we to assume humans 80K or so years ago, for example humans had enough sea fairing technology that dietary sources from sea fish were significant enough to put selective pressure on skin color? Do you have examples of dark skinned coastal sea peoples living in foggy low-UV conditions?
    So now I have to provide scientific links establishing the existence of Inuit and Lapps and Mongols and Japanese and the Reds around Vancouver or Hudson Bay, explain to you how avoiding a possible objection by restricting the example (to avoid pointless quibbling over irrelevancies) does not affect the main point, explain to you how evolutionary pressures such as winter can be "seasonal" but still be important, even without fog - I'll probably need a link, one of those scientific ones, for that - and so forth.

    And another thread bites the dust.

    I've got a better idea. How about you just go fuck yourself?
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    So now I have to provide scientific links establishing the existence of Inuit and Lapps and Mongols and Japanese and the Reds around Vancouver or Hudson Bay,
    Since none of those are central Eurasia they aren't germane to your example--ok Mongols might fit if they evolved where they are today (is there proof of that?).

    I've got a better idea. How about you just go fuck yourself?
    Bye.
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    Well... Back to the subject. It seems to me that we have examples of both technology leading to evolution and evolution leading to technology. My question would then be, without utilizing genetic engineering, which is going to be more common? Are we going to evolve more because of our technological advancements or will our technology advance when we take another significant step toward ascension?
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    Quote Originally Posted by iceaura View Post
    Quote Originally Posted by lynx
    Such as? Nearly all the low-UV environments are along the coast or very high North latitudes and/or seasonal. I followed what you were trying to say, but even with your recap it honestly doesn't make much sense. (hence the "huh?") Are we to assume humans 80K or so years ago, for example humans had enough sea fairing technology that dietary sources from sea fish were significant enough to put selective pressure on skin color? Do you have examples of dark skinned coastal sea peoples living in foggy low-UV conditions?
    So now I have to provide scientific links establishing the existence of Inuit and Lapps and Mongols and Japanese and the Reds around Vancouver or Hudson Bay, explain to you how avoiding a possible objection by restricting the example (to avoid pointless quibbling over irrelevancies) does not affect the main point, explain to you how evolutionary pressures such as winter can be "seasonal" but still be important, even without fog - I'll probably need a link, one of those scientific ones, for that - and so forth.
    Leaving out the personal attacks, he does make one good point: there are cases of dark skinned people living in many of the same environments as lighter skinned people. Eskimos appear just as well adapted to their environment as Scandanavians are to their similarly cold wintery peninsula. The simplest explanation would be that Eskimos depend primarily on a diet of fish, while Scandinavians don't, and hence do not need sunlight to get their daily dose of vitamin D. (As much as I dislike the vitamin D theory.... it's probably correct.)

    As for the thermal notion, I really can't find much on it. This site here mentions in passing that the human body mostly emits Infrared at 10 microns. Not exactly peer reviewed, but not crack pot either:

    Infrared Waves

    This site happens to mention 10 micron IR in reference to the greenhouse effect on Earth, as green house gases apparently block that wavelength from leaving.

    An Explanation of the Greenhouse Effect

    The Central Point
    Energy from the sun heats the Earth but the heat can't escape easily because the outgoing micron window is partly smudged by greenhouse gases. It is more elegant and more precise to say Earth's
    ε
    (epsilon or emissivity) is less at 10 microns than it is at 0.5 microns because of greenhouse gases. The Earth would be an ice planet if not warmed by the greenhouse effect.
    So, basically, for a human to get the same effect, their skin would have to have the same basic reflective properties as greenhouse gases have. I hope someone somewhere has conducted a study or something on this, so I can put my own hypothesis to rest, or confirm it if I'm lucky.

    Just anecdotally, I note that the skin of lighter skinned people often seems cooler to the touch than that of darker skinned people. That could just be perception, seeing a lighter color and thinking about cold, but another explanation would be if more of the light skinned person's body heat is being maintained below the epidermis, while more of the heat of a darker skinned person's heat is maintained at the epidermis. Both groups would need to maintain a 98 degree F body temperature overall, but from a cooling perspective, a person living in a hot environment would benefit from having most of their body heat concentrated on the outer surface where it can radiate away, to prevent overheating. But if you live in a cold environment, you wouldn't want to radiate away any more heat than you had to.
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    Wow I sure missed a whole lot in my ten day absence haha.
    Thanks everyone for the ideas/input. It has really made my paper come together nicely.

    As far as the development of skin tone, part of me has to agree with ice about the impact our technologies (clothes/fire/hunting gear) had on skin tone. It would make sense that as early humans migrated to Europe these technologies played a large role in being able to settle and inhabit the new area.

    At the same time I believe the necessity to maintain a stable body temperature had the most to do with it. Lighter skin would reflect body heat inwards while dark skin that was hot towards the surface would radiate heat outwards (Similar to how a white tee shirt reflects body heat inwards while black shirts cool down faster). Therefore it would be reasonable the two factors intertwined to create the mutations in skin color.
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    Leaving out the personal attacks, he does make one good point: there are cases of dark skinned people living in many of the same environments as lighter skinned people. Eskimos appear just as well adapted to their environment as Scandanavians are to their similarly cold wintery peninsula.
    They are both light skinned. Even my own Algonquian ancestry is significantly lighter than more Southern Native American Indians. I'm not sure how fast the genes that result in pigmentation respond, but it appears to be pretty quick process--a few tens of thousands of years.

    --

    I'm not where discussion of radiating energy is coming from in the last two post. Skin, regardless of color is an almost perfect blackbody radiating surface--they both radiate the same. Other morphological differences such as body size, slenderness, percent of body fat, circulatory system differences, and density of sweat glans, and metabolic rates are all differences that from individual to individual and might related to group geographic ancestry.
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    [QUOTE=Lynx_Fox;326335]
    I'm not where discussion of radiating energy is coming from in the last two post. Skin, regardless of color is an almost perfect blackbody radiating surface--they both radiate the same. Other morphological differences such as body size, slenderness, percent of body fat, circulatory system differences, and density of sweat glans, and metabolic rates are all differences that from individual to individual and might related to group geographic ancestry.
    It comes from my earlier post citing the following paper.
    Colloquium Paper: Human skin pigmentation as an adaptation to UV radiation
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    Excellent article. It also seems noteworthy that niether the pigmentation chart, or this pretty detailed article, mention the nutritional differences having an effect on vitamin-D and or selective evolutionary pressure to depigment.
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    tommyd - To the original question, I watched a BBC doco "Origins of Us" which included the assertion by Dr Alice Roberts (anatomist, osteoarcheologist, anthropologist, paleopathologist according to wikipedia) that elements of the anatomy of the modern human hand are an evolutionary consequence of ongoing tool use. She made the point that they were less suited to tool making (as in stone tool knapping) than for grasping a carcass and butchering it with a flint blade.

    I tend to have an ongoing issue with how evolution is described and presented - this series included - as they tend to make the process sound purposeful and adaptations inevitable. Granted that television documentaries have to keep it simple I still think evolution is an area that could do with better treatment. I'd love to see some that explore the processes of change, like mutations arising and spreading within a genepool and examples of how selective processes would result in particular traits becoming reinforced and ultimately pervasive within a species.
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    Quote Originally Posted by Lynx_Fox View Post

    I'm not where discussion of radiating energy is coming from in the last two post. Skin, regardless of color is an almost perfect blackbody radiating surface--they both radiate the same.
    Most of the radiation you emit isn't getting radiated by your skin itself. It's getting radiated by the tissue underneath, and then passing through your skin on the way out.
    If your skin is more reflective to the right frequencies, then some of it wouldn't make it out. It would get reflected back inward.

    Think about how those micro-thermal blankets work. You know, the ones that are all chrome colored, and fold up so they can fit in your pocket? The material itself isn't thick enough to provide much in the way of thermal mass, nor does it do much to block heat being conducted away by contact with the air around you, but it reflects a substantial fraction of the IR radiation your body is emitting right back onto you.


    How Does a Thermal Blanket Work? | eHow.com
    Last edited by kojax; June 10th, 2012 at 01:34 AM.
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    You skin isn't a thermal blanket. Like almost all complex large heterogeneous materials it is nearly a perfect blackbody to IR.
    But don't take my word for it...it's been measured so we don't have to speculate.

    "Human skin is nearly a perfect blackbody as it has an emissivity of 0.98, regardless of actual skin color."
    Thermal Testing - Science


    Though your question leads me to wonder, if nature has come up with any mechanisms or examples of changing IR emmisivity to regulate heat. I can't think of any.
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    Quote Originally Posted by Lynx_Fox View Post
    Though your question leads me to wonder, if nature has come up with any mechanisms or examples of changing IR emmisivity to regulate heat. I can't think of any.
    Polar bear fur. White to reflect IR, and with hollow hairs to provide convection resistance.
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    Quote Originally Posted by adelady View Post
    Not sure whether you'd call it technology, but it's probably associated with processing food, or cooking methods at least. There is some discussion among dentists and orthodontists that in some countries, the lower jaw is getting smaller and is therefore the reason why so many people need treatments to accommodate, or reduce, the standard number of teeth - which doesn't seem to be changing. Yet.
    You might like to read about Weston Price. Warning, before I even mention this, I want to give sort of a disclaimer: 'don't try this at home.'

    Weston Price was a dentist who traveled around studying groups of primitive people. He found that the small jaw with the crooked teeth was actually a preventable, non-genetic deformity caused by malnutrition of the mother during pregnancy (and other people later on have observed it happening with exposure to toxic chemicals and drugs during pregnancy also).

    The people in the primitive tribes all had large, perfectly formed jaws with plenty of room for all 32 teeth including the wisdom teeth, and in some tribes, almost everyone had zero cavities - the Maori of New Zealand, and the Inuit of the Arctic, for example. The people in the cities who had come from families that were eating a modern nutrient-deficient diet had the deformities.

    He found that if you took a pureblooded person from the primitive groups, and gave them the malnourishing modern foods, they would start to have children with the deformities, even though they themselves had large, perfectly formed jaws with straight teeth, and broad faces, and healthy bodies. These deformities would happen to the very first generation of children born to parents who started eating a modern diet.

    The reason I said 'don't try this at home' is because now there is a 'Weston Price Diet,' and they tell you to eat particular things, some of which are dangerous to eat - and I know, because I have tried it myself and gotten severe food poisoning and other reactions to some of the foods that they talk about eating. Don't use cod liver oil and don't eat bone marrow. I haven't had the chance to try some of the other foods yet. You can follow the basic principles without eating the particular foods that are dangerous, though.

    Reading about Weston Price made me feel much better, because I myself have this jaw and tooth deformity. I am happy to know that it is not hereditary, and that I can prevent my own future children from having these face and jaw deformities.

    There are several other deformities associated with this, such as a weak chin, a long narrow face, narrowness of the hips and pelvis, narrowness of the whole body, and possibly also eye deformities that cause poor vision.
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    Quote Originally Posted by longhairlover View Post
    The reason I said 'don't try this at home' is because now there is a 'Weston Price Diet,' and they tell you to eat particular things, some of which are dangerous to eat.
    Be careful about your food claims.

    The truth is that 'primitive' societies have nutritional diseases or malnutrition to a far greater degree than modern peoples. You mention the New Zealand Maori, about whom I know quite a lot. They had a crappy diet. Starvation was common. Life long health defects due to periods of malnutrition were very common. The Maori had, as one of their staple foods, the root of the bracken fern, which we now know is laden with natural carcinogens. As a result, many died by early middle age from assorted cancers.

    Rickets was once very, very common in Europe, before the modern era. Also in Asia.

    Today we have access to excellent and healthy food. While it is true that some people abuse this and get obese as a result, the opportunity is there to eat in very healthy ways. As always, the best guide is good science.
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    Quote Originally Posted by skeptic View Post
    Quote Originally Posted by kojax View Post
    I have to admit that I find the "sunlight absorption of vitamin D" theory somewhat unconvincing as the primary motivation behind light skin. In the regions where it occurs, the humans would be wearing clothing over most of their body whenever they go outside anyway. Surely the body could have found another vitamin or something to replace it, and more easily than changing its skin color and hair composition.
    Kojax

    I do not think you are correct here. If you look at the regions where UV is strong, and most human skin colour is dark, you will still find a wide range of skin tones. It appears that it takes little genetic change to significantly change human skin colour. This makes it a very easy alteration for evolution to work on to solve the problem of inadequate vitamin D.

    When most of the body is covered, and only a few patches like face and hands are exposed to the sun, that just makes it even more vital that the UV is used on those small skin areas to make as much vitamin D as possible. We know from empirical studies that vitamin D depletion is common in dark skinned people who now live in cold climes. Vitamin D is made in much greater quantity by pale skinned peoples under those conditions.

    Which means the empirical evidence supports white skins evolving to permit more vitamin D to be made.
    I have been thinking about this. I wonder how much nutritional effort it takes for the body to produce dark skin? What if the main reason for white skin is simply the lack of a need to provide protection from UV, because the humans in Scandanavia were typically wearing clothing over their whole body and therefore didn't need it?


    Quote Originally Posted by Lynx_Fox View Post
    You skin isn't a thermal blanket. Like almost all complex large heterogeneous materials it is nearly a perfect blackbody to IR.
    But don't take my word for it...it's been measured so we don't have to speculate.

    "Human skin is nearly a perfect blackbody as it has an emissivity of 0.98, regardless of actual skin color."
    Thermal Testing - Science
    I'm not sure if emissivity tells us the whole story. However it is interesting to know that white and dark skin are able to dissipate heat at about the same rate.

    It certainly eliminates the black-skin-as-a-means-of-cooling, possibility.



    Quote Originally Posted by Lynx_Fox View Post
    Leaving out the personal attacks, he does make one good point: there are cases of dark skinned people living in many of the same environments as lighter skinned people. Eskimos appear just as well adapted to their environment as Scandanavians are to their similarly cold wintery peninsula.
    They are both light skinned. Even my own Algonquian ancestry is significantly lighter than more Southern Native American Indians. I'm not sure how fast the genes that result in pigmentation respond, but it appears to be pretty quick process--a few tens of thousands of years.

    --
    Eskimos subsist quite a lot by fishing, though, don't they? Why would they need to lighten their skin color to get a sufficient amount of Vitamin D?

    That doesn't make sense if they're getting plenty of vitamin D from the fish.
    Some clocks are only right twice a day, but they are still right when they are right.
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    The primary vit D deficency disease is ricketts which wil cause deformations in bone development particulary deformity of the birth canal. Women with a ricketts deformed pelvis will die in childbirth. That is a very direct and potent driver for evolution.
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