the old greek root of that bring us oyster also brings us ostracize--  
i heard the story--(and other can say whether its true or not) that voting greek cities was done by counting the number of voters, and then at election time,  a man would toss a  small sea shell into a baskets  (they had problems counting the shards, not chads.)  for yea /nae, dem/rep, whig/tory what ever..
when some one had offened public sensability-- a vote would be called and if lost-- the man could be banished... shells used for voting led to some one being ostracized..