Seven Deadly Sins
The world is a place dominated by a clash good and evil; light and dark; sins and virtues. But whatever name you tag them, these are man's two tendencies that define his humanity.
The best thing, however, is that while man maybe bound by these tendencies, he is a rational being capable of logical thinking and distinguishing right from wrong. And this gift is probably how our specie has preserved itself through the ages by heavily relying on the whispers of his divinely-endowed reason called conscience.
And whenever man fails to heed this faculty, or overuses it, sin is born. More than an act committed against the stipulations of moral rule, sin is in fact an act committed by anyone against himself, firstly, and almost always against his co-man. Sin knows no rules; follows no rules. Sin, therefore, is not just everything one commits by stealing, or anything grave against Moses' pieces of advice. Pride, anger, lust, envy, gluttony, sloth, greed these are seven of man's sins that have stood out throughout the ages. Petty in nature, but these sins sometimes provide lee ways to which man learns to commit bigger' mistakes from where he lusts, he learns adultery, to where one greeds, he learns to steal and to where one envies, he learns to kill and many more.
But the task of distinguishing between the sheep and the goat throughout the history has been hindered by man's faculty of emotion which has made it more difficult to resist the temptations all around him. But though other's choose the path of darkness, others still choose to be on the right track where fortitude, temperance, prudence and justice are deemed as 'cardinal virtues' and therefore, of utmost necessity. If there are people who choose to be on the chaos of evil deeds, there are still those who fight to live in light where their reason preserves them planted on the good ground, in the right place, in the right time, in the right situation the people who know how to define emotions and reason without forgetting what the two mean.
The battle sees no end and shall rage on as long as man is man; and even if he evolves into some other sort of specie, these tendencies would more or less, still be the same.