How did division of labour fit into Herbert Spencer’s theory of social evolution?

In Herbert Spencer’s theory of social evolution, the division of labour serves as the primary mechanism through which human societies progress from "undifferentiated hordes" into complex civilizations.1

Spencer viewed this process as part of a broader evolutionary scheme characterized by increasing "individuation." He posited that as societies evolve, they transition from primitive military structures—where cooperation is enforced by authority—to advanced industrial societies, where cooperation is voluntary and spontaneous.1

It is important to clarify that while Spencer utilized the concept of the division of labour to explain social complexity, the sociological application of the term is more famously associated with Émile Durkheim, who argued that specialization arises from changes in social structure, such as population density, rather than solely from a desire for material progress.2

For Spencer, the increasing complexity of the social organism mirrored biological development, with the division of labour functioning as a sustaining system analogous to the specialized organs in an animal. He maintained that this evolution toward industrial specialization was inherently linked to the rise of individualism, which he considered the hallmark of a civilized and moral society.1