[Aztlan] THERMAL ALTERATIONS IN ARCHAEOLOGICAL BONES found close to Mexico City

[Mario Cabrejos]

Archaeometry
Volume 49 Issue 4 Page 713-727, November 2007 
doi:10.1111/j.1475-4754.2007.00331.x 

THERMAL ALTERATIONS IN ARCHAEOLOGICAL BONES
  a.. C. MA. PIJOAN, 
  b.. J. MANSILLA and 
  c.. I. LEBOREIRO 11Dirección de Antropología Física, INAH, Gandhi s/n, Polanco México D.F., México, 11560 
  d.. V. H. LARA 22Universidad Autónoma Metropolitana-Iztapalapa, Michoacán esquina La Purísima, Apdo. Postal 55-534, México D.F., México and 
  e.. P. BOSCH 33Instituto de Investigaciones en Materiales, UNAM, Circuito Exterior, Ciudad Universitaria, 04510 México D.F., México
Abstract
Archaeological bones, found close to Mexico City (Tlatelcomila), with alterations due to probable thermal exposure attributed to a possible case of cannibalism, have been characterized by XRD, SAXS and SEM. It is shown how these non-destructive techniques, which are not conventionally used in archaeological research, may provide useful information. The deterioration degree of the bone structure is quantified through parameters such as gyration radius or fractal dimension. As some of the reported modifications could be attributed to diagenesis, a discussion is presented in terms of bone crystallinity and ionic exchange. Furthermore, the hydroxyapatite crystallite size increased depending on colour: this feature is not explained by diagenesis-it can only be attributed to temperature. We conclude that the samples were thermally treated. Indeed, thermal treatment alters the structure and morphology of bone at a very fine level (microscopic and nanometric), while morphology follows the structural modifications. It is determined that the studied human bones were treated at three different temperatures close to 100, 250 and 600°C. Therefore, they were either boiled (barbacoa) or grilled.