Human beings possess a stable human nature that has been formed over millions of years of evolutionary history. Through the mechanism of natural selection, phenotypic traits and behaviors have evolved for the sole purpose of ensuring the survival of the organism that carries genetic information. This means that there is interspecific, genetic continuity across evolutionary history. Two types of continuity that will be discussed are aggression and sexual dimorphism, both of which can be understood as stable aspects of human nature that influence how humans behave.
The thesis then discusses the Marxist-humanist appropriation of the term “human nature” as a semantic mystification intended to reconcile Marx with the biological sciences. Marx is much less clear on human nature, and even in his early humanist writings, his conception of human nature is thoroughly social and incompatible with evolutionary theory. The Marxist-humanists attempt to find human nature in biological limitation and human needs, but these conceptions are far too meager to be considered a robust account of human nature.
The thesis then discusses the anti-humanism of the Marxist philosopher Louis Althusser. In opposition to the Marxist-humanists, Althusser believes that the writings of Marx post-1845 are his definitive statement on human nature. Althusser argues that Marx established the science of historical materialism by removing humans from the center of the historical process and instead focusing on the non-human elements of the historical process itself.
Althusser is concerned with the universal applicability of historical materialism, just as the Marxist-humanists are concerned with the universalism of human emancipation. The thesis argues that their universalism, although limited, is an accurate way of perceiving commonalities across the human species, but true universalism can only be understood when applied to human nature in the context of evolutionary history.