Strontium and oxygen isotopes in archaeological human remains can be used to identify migration patterns and, in some cases, the geographic origins of individuals in the past. Knudson and her collaborators have used these data to examine the geographic origins of sacrificial victims and colonists in a number of Andean archaeological sites, including the Bolivian site of Tiwanaku, which is shown above. In addition, the light stable isotopes of carbon, oxygen, and nitrogen can be used to determine paleodiet of individuals who lived in the past.