Panoramic accounts of long-term socio-political change tend to marginalize the role of animals. Taking a materialist stance, we re-evaluate the ways livestock shaped the emergence of the tributary mode of production out of a kinship-ordered mode of production. This explicitly Marxist analytical framework foregrounds the interplay between value, wealth, and labour, while attending to the economic specificities of livestock that make it particularly dynamic. Drawing on ethnohistorical data, we identify wealth in livestock as heritable, expandable, flexible, and convertible, while inherently unstable. We offer the first synthesis tying these qualities together and present a holistic picture of how these qualities can catalyse the class formation by promoting differential accumulation of wealth, economic growth, and direct appropriation of value from producers. These dynamics offer an animal-centric explanatory lens to view the long-term trajectory of northern Mesopotamia from the Neolithic through the Late Chalcolithic (9700-3500 BCE), where caprines, cattle, and pigs were central to the development of urbanism and states. While our analysis is specific to the social formations, species, and human-animal relations in northern Mesopotamia, the framework we present can be applied to contexts globally to better understand the animal side of political economic dynamics of early complex societies.