Good question. Alasdair Wilkins asks on io9.com:
Corruption is as old as human history. 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.
That’s the theory put forward by evolutionary biologists Francisco Ubeda and Edgar Duenez. The pair used game theory to figure out why people cooperate to form a society even though the ones in charge are corrupt. The model they developed assumes that government officials and law enforcers — in other words, the individuals responsible for punishing noncooperators — can get away with a certain amount of noncooperation themselves in the form of corruption, and that they can sidestep most punishments when caught being corrupt.
Their findings make a lot of intuitive sense — most people will continue to cooperate to keep their society together, in part because they don’t want to be punished by law enforcers. People will tolerate a certain amount of corruption from their leaders and law enforcers as long as there isn’t too much of it. Above a certain level of corruption, people stop seeing the point of cooperating and society begins to break down.
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