System biologists are the newest branch on the life-sciences tree. No one is sure who, or what they are, only that some of them are ex-string physicists, others are bioinformatics guys, and the rest are biologists who have spent too much time playing Simcity or Civilization. Systems biologists collect data from all the other disciplines and then build their own fancy computer generated models. When they're done they head over to the pub and show off their fancy flow diagrams to the other biologists. Those systems guys try hard to impress the others, using words like "in silico", but no one pays any attention. If they're really desperate, systems guys will start using words ending with 'omics. Since systems biologists would love to kill, but not sure how to do it, they are mostly harmless.