What is one factor cited by Carneiro as influencing the formation of states?

Carneiro suggests that population increase is a significant factor influencing the formation of states because as populations grow, the demand for resources intensifies. This heightened competition for limited resources can lead to more complex societal structures, including the establishment of governance systems to manage these challenges. Larger populations require organized forms of leadership and resource distribution, resulting in the emergence of state structures to maintain social order and address conflicts over resources.

While other factors like isolation from other societies, cultural uniformity, and the presence of agriculture can play a role in societal development, they do not directly address the necessity for organization and management brought on by population pressures, making population increase a central theme in Carneiro's theories on state formation.