It's the human nature of empathy, socialisation and collaboration that allowed us to survive as a species as we know it; including the passing on and development of knowledge and technology within a generation, and from one generation to the next so we don't start from scratch each time. We survived despite our selfishness (as defined limited to the ingratiation of self at the expense of society) not soley because of it.

Capitalism itself tends towards the socialisation of labour, socialism takes it the next step forward and socialises the surplus value.

That's the science of human nature, anthropology and politcal economy in a nutshell. (If you want to go further I would suggest the Dialectical Biologist by Lewis and Lewontin).

Capitalism promotes sociopathy to be the axiom of governance whereas a scientific socialist society harnesses any spectrum of sociopathy towards the overall good of the proleteriat. They can't fathom it in the same way sufficiently advanced science is indistinguishable from magic, even when you see it before your very eyes (eg there's a litany of youtube videos of liberals glazing China but unable to relay that it is because of marxism-leninism).

So they misconstrue what surivival of fitness is, what evolution is, and draw metaphysical parallels with biological "competition" to their fantasy of a free market and then dare to say you're the unscientific one.

It is human nature to force the fascist to face the wall. It is also human nature for that fascist to exist. We are only demonstrating which nature of human will win in the end.

Dialectical and historical materialism - Stalin https://en.prolewiki.org/wiki/Library:Dialectical_and_historical_materialism