SETI ET lefthanded or righthanded?

John Bush (
Wed, 9 Jun 1999 15:46:54 -0700 (PDT)

Two questions, assuming ET life is based on carbon: 1) We know that except for very minor differences, the genetic code is the same for all species on earth, from the simplest bacterium to the most complex radio astronomer. A most intriguing question in my view is: "is the genetic code universal?" If we find life-as-we-know-it (carbon-based) on Mars, Europa, a nearby star system, another galaxy, will we find it to have the same genetic code, the same 20 amino acids as earth based life? What are the implications if we all use the same code? 2) Life on earth is based on left-handed amino acids, right-handed sugars (e.g. dextrose). There's some evidence of preferred -handedness or chiriality from some of the carbon compounds found in certain meteorites (carboniferous chrondites?) but I'm not sure how compelling it is. Anybody know? Anyway whether the answer to 1) is yes or no, it's still probable that any carbon-based life-as-we-know-it will involve the manufacture of sugars for the basic energetics of life. So the question is will the sugar be right-handed? What are the implications if half the worlds are left-handed and half are right-handed? Too bad there aren't more biologists interested in SETI - perhaps they would have more insight into these matters than the astronomers. __jeb

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