Final answer:
Pantribal sodalities and age grades are integral to wider political systems because they help mobilize groups and form alliances beyond lineage-based kinship, playing a significant role in social integration and governance.
Step-by-step explanation:
Pantribal sodalities and age grades are described in a chapter on political systems because they act as organizing principles that mobilize local groups and link them into broader alliances which go beyond kinship ties. Such systems are essential in understanding the spectrum of political organization, where at one end power is shared widely, and at the other, power is centralized. Pantribal sodalities often transcend local kinship groups to form wider alliances that can mobilize groups for war, trade, or cultural activities. Age grades, on the other hand, are divisions of society based on age, which can also create cohesion across kinship lines and provide a structured progression of roles and responsibilities within a society.
These institutions are crucial in explaining how societies organize and govern themselves, especially in the context of tribes and chiefdoms, which may lack a centralized authority like a modern nation-state. In many cases, these forms of organization serve as the foundations of political order and can have a significant role in decision-making, conflict resolution, and social integration. They are not exclusive to nation-states but are essential components of various forms of sociopolitical systems.