i think the most essential and simple way to counter this argument is to explain how biology is a fundamentally insufficent explanation for the development of society

the biology and genome of today's human and the humans of ~20,000 years ago are functionally the same, if not identical. and yet, all of modern history has occurred within that period. how do we explain the explosion of population associated with the development of capitalism, the extreme advancement of technology etc with a biological reasoning? it just doesn't make sense

then you have separated biological and social darwinism. there is some truth to the latter in that the superior or more efficient survive, whereas the weak will eventually fall to the wayside. the catch is that this applies to social systems, and not individuals. and, what determines social systems if not biology? the production of what sustains us, what satisfies human need. this would be a good time to demonstrate how things like the development of the factory system and the socialization of production explain the rise of capitalism and the overthrow of feudalism. i think this is a good start