Zooarchaeologists study animal remains from archaeological sites. The combination of anthropological, archaeological, biological, ecological, and paleontological research focused on animal remains is a defining characteristic of the discipline. Despite its diverse, global, and interdisciplinary heritage, zooarchaeology shares two related goals: to understand the biology and ecology of animals and to understand the relationships between humans and animals through time and space. Zooarchaeological interpretations are based on the premise that a systemic relationship exists between humans and their environments, especially between humans and other animal populations, and that many cultural and biological aspects of this relationship are reflected in the archaeological record. The development of zooarchaeology owes much to an awareness of the importance of environmental relationships on human behavior and of the human impact on the environment. Zooarchaeologists combine theories, methods, and data from many fields to identify and interpret the animal remains recovered. Archaeological field methods and zooarchaeological laboratory methods are often the focus of much study and have important consequences for studies of former environments and cultures. Zooarchaeologists primarily study the bones and teeth of vertebrate animals and the exoskeletons of mollusks, crustaceans, and echinoderms, although other animals are also studied. During their preliminary study, zooarchaeologists identify the species and elements represented in each archaeological collection, estimate the age at death and size of the animals represented, consider the body parts represented, look for evidence of modifications and pathologies, and gauge dietary contributions. From these primary data, they explore site formation processes, paleoenvironments, environmental change, paleoeconomies, and subsistence strategies. The change from using wild animals to using domestic animals was a profound one and is studied by many zooarchaeologists. Aside from being debris left over from food preparation, exchange, and disposal, their bones, skins, and teeth were used as tools, ornaments, symbols, and other purposes. Animals also were used for labor or to provide goods and services such as protection, milk, and wool. Through the study of such phenomena, zooarchaeologists contribute important information to studies of former environments, relationships between humans and those environments, the impact people have had on the world in which they live, and the lives of people in the past.