Through the results of these studies, we are beginning to piece together a story of a very dynamic relationship between humans and their environments. For while the environment doesn't determine specifically how people settle, and what foods they eat, it does set limits in which people can operate, and understanding these limits is a major focus of archeology. Absolute dating of cultural deposits is an important interpretive tool for archeologists. Two techniques commonly employed by archeologists working in the region are radiocarbon and obsidian hydration. Radiocarbon dates are determined by measuring the amount of Carbon 14 remaining in an organic sample, usually charcoal or bone.
Atmospheric radiocarbon enters the life cycle of plants and animals during respiration.
After death Carbon 14 no longer enters the organism and begins to decay at a known rate. Sophisticated equipment is used to measure the remaining Carbon 14, the amount of which is used to calculate the age since death. Obsidian hydration dating is based on the rate at which obsidian absorbs water at its surface, which is dependent on temperature.