For as long as people have organized themselves into groups with powerful leaders, those leaders have sometimes abused their power. But evolutionary biologists say corruption might actually be holding societies together. Of course, this doesn't have to mean corruption is a good thing, or that the current levels of it are anywhere close to the relatively low levels of corruption people are supposed to find acceptable. But it does seem that a certain amount of corruption is needed to make human society work. That's one of the problems with evolutionary psychology - the basic truths that hold society together aren't always pleasant to hear.