Soylant Green, Mass Effect and Human Nature

I watched Soylant Green hoping to get a good reflective sci-fi and I am aware of its theme and plot and how it is heavily to do with our culture and the encroaching overpopulation issue and brings it to a rather frightening logical conclusion if we continue treating the world and ourselves the way we currently do, or currently did in the 70's at least (its an old film)

While the film had a lot to do with culture (which is one of the many appendages of human nature is not exactly what im focusing on) it didnt have massive amounts to do with human nature as a topic, actually. There is a main character who is our way into the world, he is an old man who was alive when people still ate meat and real food and not just products from the Soylant company. His son (who is the main character) says to him at one point about how he said people where better back in the old days, and he replies "I never said people were better, people have always been dirtbags. The world sure was prettier though" I'm paraphrasing by the way i dont remember exactly what he said but it was along that jist. What he said there is an interesting stab at human nature, because no matter how advanced we get human nature is always the nature of an animal that needs to fight for survival and unfortunatly fighting for survival involves being rather mean to others and caring for your own survival so dosnt make for the nicest people.

Thinking of it most sci-fi's (particularly the ones with alien races) are mostly personified parts of human nature and our battle against it to be civilised. For instance in almost all alien sci-fi's there is the big tough strong alien, usually savage, warlike and tribal representing the animalistic part of human nature and then to juxtapose them the enlightened, civilised and usually sceintific aliens who represent our new civilised ideals that fight to control the anamalistic part of our nature, and this is just a wild stab in the dark but i bet usually those two species are at war or are at least unfreindly towards each other.

In one sci-fi game specifically called Mass Effect the tribal, warlike, violent species the Krogans where almost completely wiped out by the civilized scientific race called the Salariens, which now i realize is a pure representation of us trying to supress and hide our violent animalistic side with our new more civilized selves... also i just realised that even though the Salariens used a biological weapon to try and get rid of the Krogan the animelistic Krogan still managed to survive even if in reduced numbers showing how the more civilized side of us can never truly oust our nature.