As far as the fancy aliens (with their lasers and tentacles) that I assume the question is really about: probably. However, stars are far apart (especially around here), and the likelihood of finding intelligent life is really low. In any event, once you get these things right, you just add time (a billion years probably would suffice) and viola, life is born. If is sufficiently small, then there would be almost no chance of any life forming, including our own, and hence we should not exist. Whatever caused natural or sexual selection to select for high levels of mammalian intelligence on earth could lead to intelligent aliens as well.