We reconsider the classic puzzle of why election turnouts are persistently so high even though formal analysis strongly suggests that rational agents should not vote. If we assume that voters are not making systematic mistakes, the most plausible explanation seems to be that agents receive benefits from the act of voting itself. This is very close to assuming the answer, however, and immediately begs the question of why agents feel a warm glow from participating in the electoral process. In this paper, we approach the question from an evolutionary standpoint. We show for a range of situations, that public-spirited agents have an evolutionary advantage over those who are not as public-spirited. We also explore conditions under which this kind of altruistic behavior is disadvantageous to agents. The details depend on the costs of voting, the degree to which different types of agents have different preferences over public policies and the relative proportions of various preference types in the population, but we conclude that evolution may often be a force that causes agents to internalize the benefits their actions confer on others.