Transhumanist blogger George Dvorsky points to a debate between astrophysicist Brandon Carter and a team of Serbian researchers, the core of which revolves around how long complex (and intelligent) life takes to evolve:
Prior to ‘recent times’, universal mechanisms were in place to continually thwart the evolutionary development of intelligence, namely through gamma-ray bursts, super novae and other forms of nastiness. Occasional catastrophic events have been resetting the “astrobiological clock” of regions of the Galaxy causing biospheres to start over. “Earth may be rare in time, not in space,” they say. They also note that the rate of evolution is intimately connected with a planet’s environment, such as the kind of radiation its star emits.
For further discussion of our place in the universe see the Copernican Principle, which exhorts us to avoid assuming that humanity, Earth, and our place in the universe can be assumed to be unique and special.
Further the notion of punctuated equilibrium to describe evolution is interesting: might it be extended to describe other evolutionary phenomena? Eric Beinhocker‘s superb The Origin of Wealth describes both technology and the economy in terms of evolutionary systems, both of which experience a form of punctuated equilibrium.
One of the better known responses to the 
