Zooarchaeology (sometimes called archaeozoology), also known as faunal analysis, is a branch of archaeology that studies remains of animals from archaeological sites. Faunal remains are the items left behind when an animal dies. These include bones, shells, hair, chitin, scales, hides, proteins and DNA. Of these items, bones and shells are the ones that occur most frequently at archaeological sites where faunal remains can be found. Most of the time, a majority of these faunal remains do not survive. They often decompose or break because of various circumstances. This can cause difficulties in identifying the remains and interpreting their significance. Zooarchaeology serves as a "hybrid" discipline: combining the studies of archaeology and zoology, which are the study of past human culture and the study of animals respectively. Therefore, zooarchaeologists may also be: anthropologists, paleontologists, archaeologists, zoologists, ecologists, etc. However, the main focus of Zoo-archaeology is to not only find remnants of past animals, but to then identify and understand how humans and their environment (mainly animal populations) coexisted. Zooarchaeology allows researchers to have a more holistic understanding of past human-environment interactions, thus making this topic a sub-field of environmental archaeology. Whether it is diet, domestication, tool use, or ritual; the study of animal remains provides a great amount of information about the groups that interacted with them. Archaeology provides information on the past which often proves invaluable for understanding the present and preparing for the future. Zoo archaeology plays a valuable part in contributing to a holistic understanding of the animals themselves, the nearby groups, and the local environments. Development The development of zooarchaeology in eastern North America can be broken up into three different periods. The first being the Formative period starting around the 1860s, the second being the Systematization period beginning in the early 1950s, and lastly the Integration period which began about 1969. Full-time zooarchaeologists didn't come about until the Systematization period. Before that it was just a technique that was applied but not specifically studied. Zooarchaeological specialists started to come about partly because of a new approach to archaeology known as processual archaeology. This approach puts more emphasis on explaining why things happened, not just what happened. Archaeologists began to specialize in zooarchaeology, and their numbers increased. Uses One important aspect of zooarchaeology is using morphological and genetic evidence to answer questions zooarchaeologists have about the relationship between animals and humans. These questions include: What was