Paleoecologists study the interactions among ancient organisms and their environment. The records they collect provide a long-term perspective on how an ecosystem has developed, showing how environmental influences, like climate, fire, and humans, have shaped the ecosystem through time. On the Colorado Plateau, packrat middens, tree-rings, and lake and bog sediments provide rich data on ecosystem development during and after the most recent glacial period. The records also help anthropologists understand the social dynamics of ancient Puebloan cultures.