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284Fwd: [anunda] The Sources of Instinct 1

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  • Christopher Wynter
    Nov 6, 1999
      In answer to the comments Charles Atfield
      posed earlier on this list, I would like to FWD
      these two posts I just placed on my own list ...
      which, if extrapolated, may give many possibilities

      >New Scientific research indicates that male and female
      >were at one time genetically identical.
      >Scientists studying genes on the X and Y chromosomes
      >have concluded that the biological element that determines sex in humans
      >evolved from a pair of identical chromosomes hundreds of millions of years
      >"We're reporting a time-line
      >by which this perfectly ordinary matched pair of chromosomes
      >evolved into today's X and Y," said researcher David Page
      >"The X is now bigger than the Y and it carries more genes.
      >But 300 million years ago, they were essentially identical."
      >For more than a decade, scientists have been on a quest
      >to understand how sex is determined during fetal development --
      >that is, why an embryo that carries two X chromosomes is female
      >and one that carries an X and a Y is a male.
      >But Page and his team wanted to broaden the scope of the inquiry.
      >"We wanted to know how did this system come to be during evolution,"
      >"How was this system put in place originally?"
      >By studying a series of XY gene pairs
      >in much the same way that geologists study fossils,
      >Page was able to craft a timeline of the evolution of X and Y chromosomes.
      >"After a while, we realized that the XY genes
      >were sorting themselves out according to their evolutionary age,
      >and when we thought about this question we realized
      >that the genes were shouting at us about the history of the sex chromosome."
      >Long ago, in addition to XX and XY, organisms that were the ancestors of
      >carried other non-sex chromosomes in matched pairs called autosomes,
      >The X and Y evolved from what was a perfectly ordinary matched pair of
      >but today's X and Y look different from one another.
      >"The X chromosome retained all of the genes of the ancestral chromosome,
      >but the Y has lost virtually all of the genes that it once shared with X,"
      >"We know of 19 genes that they both still share,
      >and we think they are remnants of the ancestral gene."
      >By studying the few shared genes on the Y chromosome that remain today,
      >and by comparing the genes that are common to the X and Y,
      >Page and his team were able to measure the amount of time
      >that has passed since the gene pairs were identical.
      >"We found all of the XY gene pairs and looked at them as a group
      >and found that the pattern and flow of the sex chromosome evolution
      >became obvious when we had them lined up."
      >"We now recognize that these shared genes are a kind of living fossil,"
      >"It's through the study of today's human X and Y that we can reconstruct
      >their past,"
      >"It's a kind of molecular archaeology�
      >"We're not looking at bones or fossils or even other species,
      >we're just looking within ourselves."
      >Christopher Wynter
      >Hobart Tasmania
      > * The information contained in this document is copyright.