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Thread: Inbreeding.

  1. #1 Inbreeding. 
    Time Lord
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    What if a small group of animals get cut off from the larger population and start needing to inbreed somewhat in order to reproduce? Would the mutation rate increase for a while? After the population grows larger, can they become genetically diverse enough to be a stable breeding population again?


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  3. #2  
    Time Lord
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    Depends on species. Cows for example are intensely inbred, as we divvy sperm of just a few choice bulls. For humans I've heard 500 is sustainable...?


    A pong by any other name is still a pong. -williampinn
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  4. #3  
    Forum Radioactive Isotope skeptic's Avatar
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    The 'Eve' hypothesis would suggest a lot less than 500. Studies of mitochondrial DNA (passed down the maternal line) shows a genetic variability that is so tiny that some scientists suggest that all humans are descended from a single women - the ancestral 'Eve'. I am not convinced of this, but it is clear that, at one stage, the entire humans breeding stock consisted of a very small number of women.

    This means that Homo sapiens is intensely inbred, with all 6.5 billion of us descended from perhaps less than 10 women?
    http://www.bradshawfoundation.com/journey/eve.html

    There is also evidence from the limited genetic variability on the Y chromosome (passed down the paternal line) that at one stage, there were very few males.

    Note : this does NOT prove we all descended from Adam and Eve. For one thing, Adam and Eve are suggested by the Bible to have lived only a few thousand years ago, while the genetic evidence for the minimally numbered ancestors of humanity dates back tens of thousands, if not hundreds of thousands.
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  5. #4  
    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    Not that small, the estimates are around 10,000 last I've read. Mitochondrial Eve is the earliest common matrilineal ancestor of humans today, but she was just one of thousands alive at the time.
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  6. #5  
    Forum Cosmic Wizard paralith's Avatar
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    10,000 as the effective population size, which means adults of reproductive age. Total population size can be quite a bit larger than the effective population size.
    Man can will nothing unless he has first understood that he must count on no one but himself; that he is alone, abandoned on earth in the midst of his infinite responsibilities, without help, with no other aim than the one he sets himself, with no other destiny than the one he forges for himself on this earth.
    ~Jean-Paul Sartre
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