"Parasites are among the world's most successful and sophisticated organisms. They can transform the insides of other creatures into hospitable homes. They can evade the onslaught of the immune system and even make it serve them. They can even control the minds of their hosts and force them to do their bidding. And thanks to these skills, parasites may make up the majority of all species ... parasites can control the fate of entire ecosystems and even steer the course of evolution."
--carl zimmer