Immigration and the Ancient City of Teotihuacan in Mexico: a Study Using Strontium Isotope Ratios in Human Bone and Teeth

Abstract

Teotihuacan, in highland Mexico, is the earliest and largest prehispanic city in the New World, occupied primarily between ad1 and ad650. There are many distinctive areas within the city limits, including major ceremonial precincts, large pyramids and temples, residential areas, exchange sectors, thousands of residential compounds, and tunnels under the northern half of the city. Some of these residential compounds contain non-local architecture, artefacts, and burial arrangements known from areas on the Gulf Coast and in Oaxaca. The identity of the residents of these “foreign” compounds is uncertain. Were these local individuals adopting foreign customs, recent immigrants to the city, or a mix of locals and outsiders? After the fall of Teotihuacan, people with Coyotlatelco culture came to the city and contributed to its extensive looting. Some scholars have proposed a northern or western origin for these groups.We have measured the strontium isotope ratios (87Sr/86Sr) in human bone and tooth enamel from individuals buried in various areas of the city for information on their original place of birth. Strontium isotope ratios are signatures for local geologies. Strontium in human bone and tooth enamel comes from the food growing in local geologies. Strontium isotope ratios in human bone reflect the source of a diet around the time of death; ratios in tooth enamel reflect the source of the diet around the time of birth. Differences between enamel and bone ratios in the same individual indicate differences in local geologies and thus a change in residence. Our study indicates that a number of the individuals were born outside the city. Comparison with other isotopic methods for assessing residential change is also made.