M.A. Theses: Jerome H. King, 1997

Prehistoric Diet in Central Baja California, Mexico

Analysis of stable carbon and nitrogen isotopes in human bone has proved a useful method of investigating prehistoric diet in many different environmental settings. This study attempts to apply the technique in the Central Desert region of the Baja California peninsula, where the aridity of the region and the wide variety of dietary resources present special difficulties.

This study comprises several separate analyses: 1) stable isotope measurements of a sample of prehistorically important food items, in order to determine whether they display the consistent isotope measurements required to make quantitative estimates of dietary composition; 2) stable isotope measurements on both the protein and mineral fractions of bone in a sample of mammals from the region, in order to test whether the size of the increment between these measurements is related to tropic level, and whether this increment is useful in making dietary estimates; and 3) stable isotope and radiocarbon measurements of a small sample of human burials from two sites, one on the Gulf of California coast and one inland, in order to determine whether these groups had significantly different diets, and to evaluate previous estimates of dietary composition based on archaeological and historical evidence.

The results show that carbon and nitrogen stable isotope measurements can distinguish between the major dietary resources. As expected, the increment between the protein and mineral fractions of animal bone is related to trophic level, although interpreting this increment in humans is complex due to their varied diet. The results from the two human collections indicate that both groups made nearly exclusive use of nearby resources rather than traveling widely on a seasonal round. Quantitative estimates of diet are not possible because of the large number of isotopically labeled resources. However, a comparison of the human isotope measurements with those of a series of experimentally calculated diets suggest that previous assessments of diet can be improved.