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Index to Creationist Claims,  edited by Mark Isaak,    Copyright © 2005
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Claim CB040:

The twenty amino acids used by life are all the left-handed variety. This is very unlikely to have occurred by chance.


Watchtower Bible and Tract Society. 1985. Life--How Did It Get Here? Brooklyn, NY, pg. 43


  1. The amino acids that are used in life, like most other aspects of living things, are very likely not the product of chance. Instead, they likely resulted from a selection process. A simple peptide replicator can amplify the proportion of a single handedness in an initially random mixture of left- and right-handed fragments (Saghatelian et al. 2001; TSRI 2001). Self-assemblies on two-dimensional surfaces can also amplify a single handedness (Zepik et al. 2002). Serine forms stable clusters of a single handedness which can select other amino acids of like handedness by subtituting them for serine; these clusters also incorporate other biologically important molecules such as glyceraldehyde, glucose, and phosphoric acid (Takats et al. 2003). An excess of handedness in one kind of amino acid catalyzes the handedness of other organic products, such as threose, which may have figured prominently in proto-life (Pizzarello and Weber 2004).

  2. Amino acids found in meteorites from space, which must have formed abiotically, also show significantly more of the left-handed variety, perhaps from circularly polarized UV light in the early solar system (Engel and Macko 1997; Cronin and Pizzarello 1999). The weak nuclear force, responsible for beta decay, produces only electrons with left-handed spin, and chemicals exposed to these electrons are far more likely to form left-handed crystals (Service 1999). Such mechanisms might also have been responsible for the prevalence of left-handed amino acids on earth.

  3. The first self-replicator may have had eight or fewer types of amino acids (Cavalier-Smith 2001). It is not all that unlikely that the same handedness might occur so few times by chance, especially if one of the amino acids was glycine, which has no handedness.

  4. Some bacteria use right-handed amino acids, too (McCarthy et al. 1998).


Jacoby, Mitch. 2003. Serine flavors the primordial soup. Chemical and Engineering News 81(32): 5.


  1. Cavalier-Smith T. 2001. Obcells as proto-organisms: membrane heredity, lithophosphorylation, and the origins of the genetic code, the first cells, and photosynthesis. Journal of Molecular Evolution 53: 555-595.
  2. Cronin, J. R. and S. Pizzarello. 1999. Amino acid enantiomer excesses in meteorites: Origin and significance. Advances in Space Research 23(2): 293-299.
  3. Engel, M. H. and S. A. Macko. 1997. Isotopic evidence for extraterrestrial non-racemic amino acids in the Murchison meteorite. Nature 389: 265-268. See also: Chyba, C. R., 1997. A left-handed Solar System? Nature 389: 234-235.
  4. McCarthy, Matthew D., John I. Hedges and Ronald Benner. 1998. Major bacterial contribution to marine dissolved organic nitrogen. Science 281: 231-234.
  5. Pizzarello, S. and A. L. Weber. 2004. Prebiotic amino acids as asymmetric catalysts. Science 303: 1151.
  6. Saghatelian, A., Y. Yokobayashi, K. Soltani and M. R. Ghadiri. 2001. A chiroselective peptide replicator. Nature 409: 797-801.
  7. Service, R. F. 1999. Does life's handedness come from within? Science 286: 1282-1283.
  8. Takats, Zoltan, Sergio C. Nanita and R. Graham Cooks. 2003. Serine octamer reactions: indicators of prebiotic relevance. Angewandte Chemie International Edition 42: 3521-3523.
  9. TSRI. 2001 (15 Feb.). New study by scientists at the Scripps Research Institute suggests an answer for one of the oldest questions in biology.
  10. Zepik, H. et al. 2002. Chiral amplification of oligopeptides in two-dimensional crystalline self-assemblies on water. Science 295: 1266-1269.

Further Reading:

Clark, Stuart. 1999. Polarized starlight and the handedness of life. American Scientist 87(4) (Jul/Aug): 336-343.

Guterman, Lila. 1998. Why life on Earth leans to the left. New Scientist, 160(2164): 16.
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created 2001-3-31, modified 2004-11-16