The Effect of Temperature on Protein Decay in Bone: Its Significance in Nitrogen Dating of Archaeological Specimens

Abstract

The inability to control for variables which affect protein decay is the major problem limiting the use of nitrogen as a chemical method of dating archaeological bone specimens. Of these variables, soil pH, ground water, and temperature are the major factors. In laboratory simulation experiments, we determined the effect of temperature on the time dependent decay rate of bone protein. In this research, 100 mg samples of ground cow bone were sealed in test tubes containing 5 ml of water and heated at temperatures varying from 100 degrees C to 140 degrees C for time periods up to 5 hr. Nitrogen concentration for each sample was determined using a modified micro-Kjeldahl method developed in our laboratory. Using standard regression analysis, we determined the decay rates of nitrogen for each temperature. By extrapolation from these data, we were able to show that differences in mean annual temperature between archaeological sites can have a substantial effect on the decay rate of bone protein.