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Is it possible that white people are genetically older than

  1. Aug 13, 2015 #1
    is it possible that white people are genetically older than black people?

    I visited the natural sciences museum in dc and saw a mural of what was supposed to be the first man and they were black. now i'm wondering were white people a product of evolution or is it because white people migrated away from Africa? if we evolved from primates why are some small monkeys born with pink skin? I've also noticed this in cats too. in the monkeys case the loss of melatonin isn't because they moved to a colder climate and needed the vitamin d?
     
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  3. Aug 13, 2015 #2

    Ryan_m_b

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    Current consensus is that white skin evolved as human populations migrated into more northern latitudes. In these areas decreased light levels lead to an increase in vitamin D deficiency. Thus there was a selective pressure for less melanin in skin in order to absorb UV light.
     
  4. Aug 13, 2015 #3
    this doesn't explain the monkeys, cats and pigs though which all predate us?
     
  5. Aug 13, 2015 #4

    Ryan_m_b

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    Monkeys, cats and pigs do not predate on us. The nice thing about being human is that we're apex predators; nothing predates on us. I don't know why they're born pink but clearly many animals either manage to get enough UV through their fur or synthesis it another way.
     
  6. Aug 13, 2015 #5
    your right, their the same age as in terms of evolving from protozoa but when they forked on the tree they have become almost perfected in terms of purpose, maybe we have too but that is debatable.
     
  7. Aug 13, 2015 #6

    Bystander

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    I think the OP intends "predate" to mean "occurring/appearing earlier than humans."
     
  8. Aug 13, 2015 #7
    yes that is what I meant.
     
  9. Aug 13, 2015 #8

    Ryan_m_b

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    Ah apologies. In which case my answer still stands, animals cover their skin with fur/feathers/hair which limit UV light going in. This would create selective pressure for light skin. Interestingly it seems this is still somewhat of an open question. This paper:
    http://www.ncbi.nlm.nih.gov/pubmed/20412916

    Looked into whether or not cows synthesised vitamin D in oily secretions (theorised in other animals) in the fur but can't find evidence of it.
     
  10. Aug 13, 2015 #9
    it's hard to imagine a cat would even be able to absorb any uv through the hair. look at these pictures:
    acre-cat.jpg
    cat%2Bwallpaper%2B1.jpg

    any explanation on why the gums, paws and nose are opposite colors?
     
  11. Aug 13, 2015 #10

    SteamKing

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    The mechanism for the synthesis of vitamin D3 in land mammals is not completely understood, as can be seen in this abstract:

    http://www.ncbi.nlm.nih.gov/pubmed/20412916

    It is known that land mammals do synthesize some of this vitamin by exposure to sunlight, and the rest may come from food which the animal consumes.

    It is possible that sufficient amounts of the vitamin are generated by exposure of oils on the fur to sunlight, which oil the animal then ingests during grooming.

    http://www.news-medical.net/health/Vitamin-D-Biochemistry.aspx
     
  12. Aug 13, 2015 #11
    I read the ingredients of meow mix, they add d3, can this be the only source of d3 or do they need uv light to synthase besides that? that is my last question, the rest I will learn in time.
     
  13. Aug 13, 2015 #12

    SteamKing

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    Cats are well known for grooming their fur constantly. If they are exposed to sunlight (i.e., not a strictly inside cat), they should synthesize some D3 if it comes from the oils on the fur. Being obligate carnivores, their diet may contain sufficient D3 to remain healthy.

    https://en.wikipedia.org/wiki/Carnivore
     
  14. Aug 13, 2015 #13
    thanks much, :smile:
     
  15. Aug 13, 2015 #14

    phinds

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    As has been pointed out, this is actually backwards. I remember reading about this many years ago, so it's not some new discovery.
     
  16. Aug 13, 2015 #15
    post a link please.
     
  17. Aug 13, 2015 #16

    phinds

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    As I said, it was some years ago and I don't even remember where I read it. You can disbelieve what we are telling you if you like but if you are really interested I would think a modest amount of research on your part would turn up confirming evidence.
     
  18. Aug 13, 2015 #17
    will do, I plan to look at the genome.
     
  19. Aug 13, 2015 #18

    Pythagorean

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    Well, firstly, all humans originated in Africa; there's some contention about when, why, and how, but it's generally agreed that all humans originated from Africa.
    https://www.ncbi.nlm.nih.gov/pubmed/16826514

    Secondly, as you sample DNA from humans further away from Africa, you get more bits of DNA from our cousins (like Neanderthals) showing up in human DNA, whereas Africa has more "pure" homosapiens. The neanderthals were already in Europe and the Middle East when homo sapiens migrated through those regions, and some cross-breeding occurred:

    http://www.sciencemag.org/site/special/neandertal/feature/index.html



    Human-cousins.jpg \\

    Of course, people of all races born today didn't precede each other by anymore than the the difference in their birthdates, but as far as evolutionary history, all humans of all skin colors essentially descended from dark-skinned humans (and neanderthals to a limited degree). So you could say that Africa's ancestors are the ancestors of all ancestors :)
     
    Last edited: Aug 13, 2015
  20. Aug 13, 2015 #19
    so did the evolutionary tree split from the primates being on connected continents then splitting or was it later than that?
     
  21. Aug 14, 2015 #20

    256bits

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    Since all or most land animals have light skin, AFAIK, wouldn't there be a also a selective pressure for an animal with no fur covering to have a darker skin for UV protection. But darker skin should have an energy demand through the production of protection, which with a lighter skin the animal does not have.
    Lighter skin should have the advantage over dark, at times when energy input supplies are limited.
    Woman, for example, have usually of a lighter skin tone than males, and could not the "feeding for 2" have something to do with that.
    Has there ever been any investigations on the energy demand of skin color and fitness.
     
  22. Aug 14, 2015 #21
  23. Aug 15, 2015 #22
    There are differences between animals in their ability to synthesize vitamins (or not) and their requirements. Species can lose the ability to synthesize certain compounds, if they can easily get them from their food. At that point there will be no need to maintain the gene. Meat in general is a very good source of all sorts of vitamins. Also gut bacteria might produce certain vitamins. Humans have probably lost more such genes than most species, because we are omnivores.

    And I don't know the exact mechanics of skin color, but isn't it just a quantitative difference in melatonin production? Such traits can evolve extremely rapidly (in both directions) and revert easily, since at no point does loss of the mechanism itself occur. Just a difference in degree of expression.

    Anyway, it would be best talk about the trait of a certain skin color, rather than 'white/black people'. And not 'perfected' species either, since every species is well adapted to its environment, but at the same time environment generally undergo continues change. At best you say that the feline body plan is very common (having evolved in multiple lineages), so it's probably just very efficient for predators to look like that.
     
  24. Aug 15, 2015 #23
    I'm sure that I get things wrong sometimes and I don't mind it when people point that out. I'll be the first to admit that I don't exactly post with citations and references...

    However, I do mind when someone tell me I'm wrong, but doesn't even take the effort to point out what he doesn't agree with. Then you are just being rude. If you want to discuss something specific I'll reply but otherwise I'll leave it at this.
     
  25. Aug 15, 2015 #24

    256bits

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    Just for the record,

    Melatonin
    https://en.wikipedia.org/wiki/Melatonin

    melanin
    https://en.wikipedia.org/wiki/Melanin

    And, it might be worthwhile mentioning,
    Melamine
    https://en.wikipedia.org/wiki/Melamine
     
  26. Aug 15, 2015 #25
    Ahh yes mixed the names up. Yesterday I wanted to buy some (melatonin pills that is), but the government here has lowered the allowed amount that can be sold legally (100x less than it was before), so I suppose I'll go to sleep without it (although I was never quite certain if it actually did anything or was just a placebo). I guess the word was on my mind in any case.
     
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