These isotopes have been used most commonly to study diets of marine versus terrestrial (land based) animals and the intake of particular types of plant resources (for example maize and millet). Isotopes can be used to assess diet because a direct relationship exists between the type of food being consumed and the corresponding isotopic "signature" found in the bone collagen of both humans and animals. Isotopic indicators of environment are most often investigated through the study of oxygen isotopes.
The mass spectrometer works by measuring the masses and relative concentrations of atoms and molecules.
These are compared using standard reference materials that are set by the International Atomic Energy Agency in Vienna.
The isotopes most widely studied to address these questions are Carbon-13 ( isotopes.
The exploration of isotopic identifiers of mobility, environment, and subsistence in the past also has contemporary relevance in that it can aid in informing policies relating to heritage protection, resource management and, sustainability and perhaps most significantly, help us to learn more about the remarkable ability of our own species to adapt and survive in any number of environmental and cultural circumstances.
The use of global and national (NIST) standards as reference material means that isotopic results can be compared across archaeological sites.
However, it is important to remember that the isotopic values of a particular time and place must also be determined in order to understand the various local processes (environmental and cultural) that are constantly at work.
Isotopes and the Study of Environment Many scientific fields utilize isotopic analysis to study past climate and environment. It is important to determine the environmental setting of a particular time and place in order to gain a better understanding of the factors that could have influenced the way a community developed.
Long and short term changes in climate can have a dramatic impact on the ways in which people may procure or produce their food.
In addition, these types of changes can influence where and/or when people may move throughout the landscape.
For instance, a shift in climate from a hotter or more arid environment to one that is wetter and milder, may have allowed people to move into a new area to make use of land resources that were previously unsuitable for farming or herding animals.
Strontium (O) isotopes are most commonly used to reconstruct past movements of both people and animals within a particular time and place.