Racemization and oxidation studies of hair protein in the Homo tirolensis.

Amino acids contained in fossil materials show an increasing extent of racemization with age, postulating time and temperature as the two major variables. The recent discovery of the Homo tirolensis made possible a comparison between racemization rates of the amino acids found in hair at identical ages (5200 years of age) but at different diagenetic temperatures ("Ginger," found in the hot, dry sand of Egypt; H. tirolensis, found on a glacier of the Otztaler Alps). The rate of racemization was higher in the H. tirolensis, which is surprising and in contrast to current concepts. Ortho-tyrosine and di-tyrosine, parameters for OH-radical attack, were also higher in the H. tirolensis, suggesting a role for free OH-radical involvement in the racemization process.