    22

    22

    22

    ac

    pop-em beads.  When the pretzel let the finished product go again, it

    had unwittingly made a mirror image of itself.

    The replica had the same property as its pretzel-like parent.

    Molecules of sludge were attracted to its surface.  Each segment of

    surface would pull toward it a very specific atomic shape.  So the

    replica's exterior acted like a paint-by-numbers canvas, drawing

    precisely the correct component to exactly the right spot.  Once all the

    new molecules were lined up in order, they'd snap together.  The

    result: yet another spanking new copy, ready to unpeel from its parent

    and drift away.   The fresh-born copy, in its turn, would attract other

    wandering molecules to its face, where they would line up, pop

    together, then uncouple to be carried off by the currents of the

    sludge-filled early seas.

    The molecules with the peculiar ability to make copies of

    themselves are called replicators.45  And replicators, like the

    innovations that had preceded them, would move the universe one

    more step up the ladder of complexity.

    For eons, replicators would drift through the chemical soup of

    the early earth, casually copying themselves.  But eventually, the

    population of molecular xerox machines would grow overwhelming,

    and the supplies of untouched organic sludge would begin to run

    short.  That's when the replicator that could do more than merely

    reproduce itself would have an edge.

    The replicators that could do more, says Dawkins, were those

    that "learned" to make copies from more than just raw sludge.  They

    could take apart their competitors and reassemble the components for

    their own purposes.  Other replicators arose who could defend

    themselves.  The first defense was probably a simple chemical armored

    shell--like those that protect some bacteria.  But over time, the armored

    suits became more intricate, developing muscular whips to provide

    speed, movable fins for steering, and someday way, way down the

    road, hands, feet and brains.  The descendants of the early replicators

      cidentally--snapped the molecules it was embracing together like

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