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

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Claim CB040:

Source:

Response:

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).

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