Work in political communication has discussed the ongoing predominance of negative news, but has offered few convincing accounts for this focus. A growing body of literature shows that humans regularly pay more attention to negative information than to positive information, however. This paper argues that we should view the nature of news content in part as a consequence of this asymmetry bias observed in human behavior. A psychophysiological experiment capturing viewers' reactions to actual news content shows that negative news elicits stronger and more sustained reactions than does positive news. Results are discussed as they pertain to political behavior and communication, and to politics and political institutions more generally.