Molecular Handedness
     WAY DOWN DEEP, WE'RE ALL LEFT HANDED.  LIKE PEOPLE, MOLECULES CAN BE
EITHER RIGHT OR A LEFT HANDED.  BUT EVERY SINGLE AMINO ACID IN OUR BODIES IS A
LEFTY.  IT'S IMPORTANT FOR THEM ALL TO HAVE THE SAME HANDEDNESS OR THEY
WOULDN'T FIT TOGETHER PROPERLY TO MAKE THE PROTEINS WE NEED.  THINK ABOUT A
LEFT HAND SHAKING WITH A RIGHT HAND -- IT JUST DOESN'T WORK.  BUT WHY DID THE FIRST
LIFE FORMS ON EARTH CHOOSE LEFT?

     Cronin: "One of the really big questions in the whole origin of life question is how
did this selection process come about."

     JOHN CRONIN IS A CHEMIST AT ARIZONA STATE UNIVERSITY, AND HE THINKS HE
MAY HAVE FOUND ONE ANSWER  BY STUDYING A 4.5 BILLION YEAR OLD METEORITE.  THAT
MAKES IT A BILLION YEARS OLDER THAN THE FIRST LIFE ON EARTH.  CRONIN FOUND IT HAD
A SLIGHT EXCESS OF LEFT-HANDED PROTEINS.  BUT WHY?  ONE THEORY IS THAT LIGHT
FROM NEUTRON STARS IN THE EARLY UNIVERSE ALSO HAD A HANDEDNESS AND
INFLUENCED THE MOLECULES.  

(Sfx: xylophone effects, swirling sounds)

     Cronin: "You can think of that light wave going away from you and ... spiraling
away from you, that spiraling can have either a right-handed or a left-handed direction
to it..."

     THIS HANDED, OR POLARIZED, LIGHT COULD HAVE DIFFERENT EFFECTS ON A
MOLECULE DEPENDING ON ITS HANDED SHAPE.  IT MAY HAVE CAUSED THE RIGHTIE
MOLECULES TO DEGRADE, LEAVING MORE LEFTIES AROUND.  SOMEHOW THAT TINY
EXCESS OF LEFT-HANDED AMINO ACIDS GAVE THEM ENOUGH OF AN EDGE THAT TEN OUT
OF TEN LIFE FORMS DECIDED TO USE THEM.  SO NEXT TIME YOU HEAR A LEFTY
COMPLAINING THAT THE WORLD WASN'T DESIGNED WITH HIM IN MIND, REMIND HIM THAT
ACTUALLY IT'S THE LEFTIES THAT HOLD THE SECRET TO LIFE.