In this presentation, Dr. Surovell examines the social organization of nomadic peoples in three case studies, two archaeological and one ethnographic. The archaeological cases, Barger Gulch Locality B (Colorado) and the La Prele Mammoth site (Wyoming), concern the first peoples in the Americas at the end of the last Ice Age. The ethnographic case centers on Dukha reindeer herders in northern Mongolia. Specifically, Todd looks at the question of whether and why people move together as large groups or as autonomous households, in the latter case generating the kind of fission-fusion dynamics typical of recent hunter-gatherers. Dr. Surovell concludes that, in every case, fluid group membership was the norm and argues that the interplay of cooperation and conflict has resulted in the use of a common organizational strategy among nomadic peoples. Furthermore, the transition to sedentary life must have necessitated novel cultural practices to cope with the loss of the ability to mitigate conflict through mobility.