GA Cohen’s take here is complete rubbish. And Darwinism got the left into trouble long ago with its confusion of class struggle and natural selection. The realm of Stalinist mass murder among other now forgotten/suppressed marxist tragedies. It is really unhelpful to get stuck in this double theoretical quagmire.
Darwinian evolutionary theory marries a genetic account of the origin of species to a selectionist account of their subsequent fate. The Marxian theory of history is analogous: class struggle provides an account of the origins of new regimes of production and selection pressures explain their subsequent history. The theory is technologically determinist, but there are three distinct doctrines ascribing primacy in different ways to the technological forces of production over the social relations of production. Natural Primacy is probably true but of limited relevance to the debate about historical process. Intentional Primacy, as advocated by G. A. Cohen, is untenable. Competitive Primacy is a genuinely evolutionary doctrine that may even be true.”