I must disagree. Forgetting the stone age slaughters (proven by recent archeology), canibalism and other ancient examples of "human nature", let's face the imperfections of humanity before Christianism (time to think was based on slavery and worse in the greek-roman world, just to mention one improvement in the last millenia), and, during some centuries of Jewish-Christian dominance, to torture and to kill by fire the "herectic infidels" was also considered "normal". So, "human nature" has changed -- and is meant to keep changing. Is not a linear progress, but it will keep happening until the end of times. If not, I would buy at once a ticket to Mars.