On the positive side, the question of left-handedness of amino acids is fascinating. Talk origins give a good summary:
http://www.talkorigins.org/indexcc/CB/CB040.html
Response:
- 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).
- 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.
- 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.
- Some bacteria use right-handed amino acids, too (McCarthy et al. 1998).
Basically, living things function badly with a mix of left and right-hand amino acids. This creates a selection pressure towards organisms that uses either eventually causing one form to be dominant. On top of that there are other factors that favors the production of left-handed acids (they are more commonly found in space than their right-handed counterpart, see http://www.nature.com/news/force-of-nature-gave-life-its-asymmetry-1.15995) thus it is not unexpected (and certainly not difficult to explain!) why we have mostly left-handed amino acids in life today; its more about choosing the right explanation from a set of competing explanations.
It is therefore either dishonest or grossly incompetent when it is claimed that this somehow proves creation...
Btw. did anyone notice the "left-handedness of amino acids" argument is lifted directly from the "Life? How did it get here" book?
