Thursday, April 16, 2020

Stable Isotopes - Analysis of Human Bone

The recipient of numerous research grants and fellowships including prestigious Fulbrights, Danielle Kurin, an assistant professor of anthropology at the University of California, Santa Barbara, specializing in the analysis of human bones. She has concentrated her work on the examination of human remains in the pre-historic Andes, but has also analyzed bones in South America from the colonial and contemporary eras. She has also studied bones and carried out analyses in other parts of the world, including the United States--where she has aided law enforcement and the families of victims. She has also aided authorities in identifying and authenticating skulls and other bones shipped into the U.S. from abroad.

Kurin analyzes bones in terms of their various features in order to identify gender, age, size, health, disease, physical condition and other forensic characteristics. Among her specialties is stable isotope analysis.

Occurring in two main types, isotopes are atoms that belong to the same element, thus having the same number of protons, but with a different number of neutrons, resulting in a slight variation in their masses. Unlike radioactive isotopes, a stable isotope does not decay over time, due to its stable nucleus. This allows for its wide use in a variety of fields such as forensic science, archaeology, and ecology for analytical purposes. For instance, the presence and proportion of stable isotopes in a bone or tooth sample can be used by archaeologists to trace the origin and life history of a person. This is because different food types vary in proportion of stable constituent isotopes, which accumulate in various body tissues of individuals that ingest the food. So a person's tooth, for example, can provide a record of food consumed in childhood, adulthood and old-age.

The four most widely used isotopes in archaeology are isotopes of carbon, nitrogen, strontium, and oxygen. Ratios of isotopes are measured with the aid of isotope-ratio-mass-spectrometers (IRMS). Stable isotopes of carbon and nitrogen are used by archaeologists to explore a wide variety of questions related to diet. Stable isotopes of strontium and oxygen are often used for the purpose of investigating ancient human migration patterns by being able to associate their composition in bones or teeth to particular regions in the person's life history.. Kurin has been able to map particular regions in her Peruvian study area according to isotope ratios, and thus identify those individuals--by their remains--associated with different regions, as well as highlands and lowlands.