Internationalism No. 84, February 2026 Page 1 In the introduction to Dialectics of Nature and in his unfinished essay The Part Played by Labour in the Transition from Ape to Man , Friedrich Engels outlined the evolutionary process that led from Homo Erectus to Homo Sapiens . The text stands out for the conceptual power of its materialist method, and from it we draw five fundamental concepts. First, for Engels, the brain is a product of labour . It is in the dialectical relationship of mutual action and reaction with labour – made possible by the articulation of the hand freed by man's upright posture, the result of hundreds of thousands of years of natural selection – that the brain evolved to perform the most complex functions and develop self-awareness. In turn, labour is an expression of the social relations at the basis of specific socio-economic formations across successive modes of produ...