I have understood generally for a while there is a significant preference in "life" for so-called "left-handed" (chiral) molecules, though I'm reading things now that say "life" sugars are right-handed, while "life" amino-acids are left-handed.

I'm wondering: how simple do these molecules get (particularly the molecules that are in intelligent life, if there happen to be any that are exclusive to intelligent life)?


Don't get hung up on the "left-handed" and "right-handed" designations for amino acids and sugars. Those are just conventions for distinguishing one mirror image (enantiomer) of a chiral molecule from another. It just so happens that based on a particular way of drawing (Fisher projection) amino acids and sugars that it appears that the configurations are "left-handed" or "right-handed."

As for how simple chiral biological molecules get, the simplest ones that I can think of are alanine or lactic acid. I'm not sure what you consider "intelligent", but these are likely to be found in all life (as we know it).

  • $\begingroup$ I'm not trying to get hung up on it, as I understand it has to do with how it bends light (at least in one classification system), but that's probably good advice for others with a similar question. I'm only looking for directing further research as far as needed for science fiction (a story I have in mind that probably will never get written), and Google wasn't really able to "understand" my question. These two look like a good enough starting point - Thanks! $\endgroup$ – Code Jockey Oct 20 '14 at 13:50
  • $\begingroup$ as far as "intelligent", I was going for anywhere from things that have a "central" nervous system to things that we consider self-aware - pretty loose definition, really $\endgroup$ – Code Jockey Oct 20 '14 at 13:52

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