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    But what is the logic behind this hormonal commotion?  Surely a

    stroke of good luck should make people more contented with life, not

    less.  It should trigger a burst of gratitude, not a restless desire to gallop

    off and grab even more.  But biology refuses to knuckle under to this

    common sense.

    The Arizona spadefoot toad lives in one of the driest deserts in

    the world.  Its survival is a miracle.  The toad needs water to live.  It

    depends on the precious liquid to provide the moisture without which

    its cells would shrivel and die.  And it needs whole puddles of the stuff

    in which to reproduce.  Yet months go by in the Southwestern desert

    without rain.  Sometimes those months stretch into years.  How does

    the spadefoot toad hold on to life?

    The beast follows a simple strategy.  When times are tough, it

    saves its energy.  As the desert grows dry and the sun becomes hot, the

    toad burrows under the sand and goes into hibernation, slowing its

    metabolic rate to a crawl, and conserving every drop of water and fuel

    stored in its flesh.  There the toad lies motionless, month after dreary

    month.  If the amphibian were to emerge from this lethargic state too

    soon, its poorly timed outburst of optimism could be deadly.  It might

    burn the water and nutrients it needs to see it through the coming

    months.  Digging back under the sand could not save it, for the reserve

    supplies  packed  into  its  body  would  be  gone.    So  in  its  days  of

    impoverishment, when the desert floor is parched, the wise toad stays

    quietly underground.

    What does bring the toad back to the surface?  A sudden burst of

    prosperity.  When a rare downpour soaks the Arizona land, the

    spadefoot toad is jolted awake by a hormonal surge.  He shakes off his

    sluggishness, is seized with enthusiasm, and scrambles into the open

    air and searching madly for a puddle.  When he finds one, he croaks

    for all he's worth, hoping to entice the ladies of his species to gather

    'round.  Within a short time, the puddle is a hotbed of social action.

    Males and females fling themselves into sexual orgy.  Within 24 hours,

    the spadefoot toad's paradisal puddle is filled with the results: a

    squirming horde of tadpoles.177

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