Dictionary of Human Evolution and Biology

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Amino Acid Racemization

Nonradiometric dating technique in which the ratio of an L-amino acid to its D-amino acid is measured; fossil material can be dated directly. After the death of an organism, the proteins break down into free amino acids. In life proteins contain L-amino acids, but after death these slowly invert into D-amino acids, a process called racemization; different amino acids have different conversion rates. Amino acid racemization includes periods that range from a few hundred years to several hundred thousand years; however, amino acid racemization rates are very sensitive to temperature and pH. If these factors significantly influence the rates, the dates obtained can be unreliable. Aka amino acid dating.

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