It describes the "strong possibility of intelligent life". Is this such a strong possibility? Life may be common but the universe is such a rough place that intelligent life may either be extremely uncommon or never reach to the level of a civilisation. Mainstream scientific consensus suggests that most of the Earth's biological history has been dominated by microbes. Most of human history appears to have been spent in the paleolithic — hundreds of thousands of years' worth — with very little in the way of technology.