Essentially, human nature is the same as ever: there is the weak and there is the strong. Those who have more power, be it physical, monetary, political, social, etc. rule. Oh, they may cloak their "valuting ambitions" in religious, rhetorical, liberal, or conservative phrases, but the motivation is usually focused on gaining power.
If man has so changed and advanced, why are there still wars, and why is there yet violence and those who exploit others? It is only the controls of a society that reduce "the evil that men do." And, as a society becomes weaker, the evil proliferates. Is there not substantial proof of this condition?
Here's an example: When the British colonial government dissolved and the "oppressors" left, instead of developing a more democratic government, the native people of these countries often began slaughtering one another. Then, when a ruler was put in place, he often was crueler than any colonial governor, persecuting his own people, stealing from them by keeping monies for himself, etc. [e.g. Idi Amin of Uganda and others]