If we want to find intelligent life elsewhere in the universe, it might be wise to look for stars with asteroid belts similar the one in our own Solar System.
According to the theory of punctuated equilibrium, evolution goes faster and further when life has to make rapid changes to survive new environments — and few things have as dramatic an effect on the environment as an asteroid impact. If humans evolved thanks to asteroid impacts, intelligent life might need an asteroid belt like our own to provide just the right number of periodic hits to spur evolution on. Only a fraction of current exoplanet systems have these characteristics, meaning places like our own Solar System — and intelligent aliens — might be less common than we previously thought.
Source: Wired. Read full article. (link)