XPost: sci.military.moderated   
   From: nmm1@cus.cam.ac.uk   
      
   In article ,   
   henry@spsystems.net (Henry Spencer) writes:   
   |> In article ,   
   |> Nick Maclaren  wrote:   
   |> >|> Not in the long run -- not enough genetic variety (mitochondrial DNA in   
   |> >|> particular comes only from the mother)...   
   |> >   
   |> >Yes, with the probable exception of your remark about mitochondrial   
   |> >DNA.  Were it inherited solely from the mother...   
   |>   
   |> It is.  Mitochondria have their own genetic material -- ...   
      
   See the other postings.  It isn't quite as simple as that, but that   
   is a very good first approximation.   
      
   |> >then all that is   
   |> >needed is one woman with sound mitochondrial DNA ...   
   |>   
   |> Note that I said "variety".  You assume that there is one optimal (or just   
   |> permanently adequate) choice of the genes involved, but that's a huge   
   |> assumption and quite unjustified.  You want *diversity* in this, as in   
   |> other genetic material, to cover against the possibility that different   
   |> combinations will be needed for different future challenges.   
      
   No, I am not.  If you work out the statistics for sexual and asexual   
   reproduction, you can see why we have very little mitochondrial   
   variation.  Variety within our mitochondrial DNA isn't a major   
   factor in our survival.  I don't know the exact figures involved,   
   but there is effectively no mitochondrial variation in quite a lot   
   of human populations.   
      
      
   Regards,   
   Nick Maclaren.   
      
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