What was the direct cause of job specialization in early human civilizations?

The direct cause of job specialization in early human civilizations was the development of agriculture, which allowed for surplus food production. This surplus enabled a portion of the population to move away from food procurement and engage in various other tasks, such as crafting, trade, and governance. As communities grew and became more complex, this division of labor led to increased efficiency and the emergence of distinct professions, fostering the advancement of society.