How did Herbert Spencer connect the division of labour with social evolution?

Herbert Spencer viewed social evolution as a process of increasing "individuation," where human societies progress from undifferentiated hordes into complex civilizations through an expanding division of labour.1

Spencer drew a detailed analogy between biological organisms and human societies, suggesting that as societies evolve, they develop specialized systems analogous to those in animals: a regulative system (government), a sustaining system (industry), and a distribution system (infrastructure like roads and telegraphs).1

He categorized this evolution primarily through the transition from military societies, where cooperation is enforced by power, to industrial societies, where cooperation is voluntary and spontaneous. For Spencer, this increasing complexity and specialization were essential components of a civilized social order, which he believed should prioritize the individual over the state.12