Archaeologica.org

What makes strontium isotope analysis especially interesting for archaeologists is that the parts of the human body where the isotopes collect--tooth enamel and bone--are formed at different stages of a person's life. Tooth enamel forms in a child's first few years and does not change as a person ages, so the strontium isotope ratio of enamel matches the geology in the area where a person spent his or her childhood. By contrast, the strontium in bone gradually changes over a seven- to ten-year period and reveals the region where people spend the last decade of their lives. By matching the strontium isotope ratios in bones and teeth to those in specific geographic regions, Price is able to tell whether a person migrated between childhood and death, and sometimes can even pinpoint where the person was born.

One of their most prominent studies addressed the origins of Yax K'uk Mo, who founded a dynasty in the Maya city of Copán in western Honduras. According to inscriptions, he arrived in Copán in A.D.. 426 when it was little more than a village. Some archaeologists had believed he came from Teotihuacán, an influential city in the Mexican highlands. After the king's tomb was discovered deep under a temple mound, Price's analysis revealed that he was born much closer to Copán, possibly in the Peten, the jungle of northern Guatemala.

"When I started this work with the isotopes, I didn't think people moved around very much. I thought they were pretty sedentary," says Price, "and I have changed 180 degrees as a result of this work. Almost every place we look we see a lot of mobility."

I also had trouble believing that people were not very mobile. My own family has a history of gypsy like behavior going back as far as there are records and I don't think we are the only ones. I can't wait until they test more people in other parts of the world.