Fun with Science Club®


			Human bones and teeth carry information about where we live. Beth Tyler 06.08.01 Teotihuacan was a city in Mexico from 2000 to 1400 years ago. Archaeologists who study Teotihuacan have discovered a complex city where many people lived. Along with ancient tools, art, and buildings, they have uncovered hundreds of human skeletons. Two American archaeologists and one Mexican archaeologist wanted to know if ancient people moved into the city from other places (immigration). To do this, they analyzed substances in the bone and teeth of 72 human skeletons. Human bones and teeth contain substances found in the local environment. Different environments have different amounts of certain substances. When people eat the food growing around them, their body absorbs the substances in that food. Because of this, substances in the human body can tell where a person lived. Human teeth are constant, meaning they do not change over time. Because they don’t change, human teeth contain only the substances found in the place of birth. Human bones, on the other hand, change over time. Until a person dies, bones continue to absorb the substances from food growing in the local environment. In this way, bones tell about the place a person lived when he or she died. The three archaeologists studying immigration in Teotihuacan looked at the substances in the bones and teeth of the skeletons. If there was a difference in the substances in the teeth (revealing the place of birth) and the bones (revealing the place of death) the archaeologists concluded that the person had moved into Teotihuacan from a different place. The more different the bones and teeth were, the longer the person had lived in Teotihuacan, away from his or her place of birth. Using this technique, the archaeologists discovered that many people had moved into Teotihuacan from other places.


			Price, T. Douglas, Linda Manzanilla, and William D. Middleton. 2000. Immigraiton and the ancient city of Teotihuacan in Mexico: a study using stontium isotope ratios in human bone and teeth. Journal of Archaeological Science 27: 903-913.