From PhysOrg:
How far will you go to avoid bad luck? Do you avoid walking under ladders, carry lucky charms, or perhaps instead perform special rituals before important meetings or sporting events? If you do any of those things, hold your head up high and be proud, because researchers are finding evidence that superstitions may not be as pointless at all. By adopting a belief that you can — or cannot — do something to affect a desired outcome, you're among the cadre of beings that learn. By the way, that cadre includes pigeons.
Superstition is an evolutionary surprise — it makes no sense for organisms to believe a specific action influences the future when it can't. Yet superstitious behavior can be recognized in many animals, not just humans, and it often persists in the face of evidence against it. Superstitions are not free — rituals and avoidances cost an animal in terms of energy or lost opportunities. The question becomes how can natural selection create, or simply allow for, such inappropriate behavior?
More here.