LA MICROEVOLUCIÓN ODONTOMÉTRICA EN OAXACA

Abstract

Tooth crown lengths, breadths, and areas were compared from nine human skeletal samples from Oaxaca, Mexico. Five spanned the period from 1600 BC to AD 1521 in the Valley of Oaxaca; the others came from the Chinantla, Mixteca, and Pacific coast. Within the Valley, there was a dramatic reduction in tooth size over time. Total crown area declined from 1320 mm2 to 1262 mm2, a change of 4.4% or 9.4 darwins, which is noticeably larger than any previously reported rate of dental reduction in a recent human population. This reduction was accentuated in posterior tooth breadths, especially in the mandible, and was probably the result of natural selection in response to agricultural intensification and its consequent dental pathologies. The Formative sample from the coast exhibits smaller teeth than the Postclassic Valley, while those from the Mixteca and Chinantla possess far larger teeth than their Valley contemporaries. This suggests that different dietary adaptations, and thus selective regimes, were followed in the four regions.