The extent of protein degradation within this closed system yields an estimate of the age since death of the organism. At a widely publicized news conference in August of 1972, Dr.isomer which is initially absent in skeletal material.In turn, proteins are composed of folded strands of 20 different smaller subunits called "amino acids".All amino acids, except for one (glycine), come in two different forms known as the levoratory (L - left) and dextrorotary (D - right) forms.These two forms are called "enantiomers", "chirals", or "stereoisomers", which basically means that they have the same molecular and structural formula but cannot be superimposed on each other no matter how they are oriented in space.
Currently, these techniques are used to estimate the age of fossils, determine the life span of bowhead whales, and detect evidence of extraterrestrial life.The D/L value yields an estimate of the time elapsed since the death of the organism: older fossils will have higher D/L values (closer to 1) (see Fig. However, for the use of amino acid racemisation (AAR) as a reliable dating tool, analysis of proteins from a closed system within fossils is vital. Dating Pleistocene archaeological sites by protein diagenesis in ostrich eggshell. This is achieved by chemical isolation of a fraction of proteins (intracrystalline) which behave as a closed system during diagenesis. The rate itself of hydrolysis "depends on the strength of the individual peptide bonds, which in turn is determined by the characteristics of the amino acids on either side of the bond, the presence of water and the temperature."All of these are confounding factors, which, if not known exactly over extended periods of time, would play havoc with any sort of age determinations.Even the process of preparing a specimen for racemic dating can affect the D/L ratio.