Isotope Analysis Methods In order to investigate stable isotopes from human and animal bones, a very small sample of bone is needed for the analysis.
For instance, when an animal such as a cow or sheep eats a certain type of grass or plant they will exhibit an isotopic value in their bones or teeth that is representative of that particular type of grass or plant.
In addition, as humans consume animal protein, from resources such as terrestrial animals (e.g., cows, sheep, or goats) and aquatic resources (e.g., fish and shellfish) they will exhibit isotopic values that situate them within a particular "trophic level." A trophic level is most simply explained as where an organism (human or animal in these cases) is situated within a particular food chain.
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.
For example, one of the most widely studied aspects of human diet in North America has been the investigation of the introduction and development of maize agriculture (farming) as a major form of subsistence in the New World.
Carbon and nitrogen stable isotopes are those most widely used for dietary reconstructions.
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.
The small bone sample is then treated through a set of chemical procedures, depending on the particular analysis in question.