Sunsets in a Pre-Cambrian World: the likelihood of life on other planets

If one were to look at the geological history of the earth in terms of potential earth-like analogues for other planetary systems in our galaxy, the probability of finding intelligent life at a similar technological level as we currently have is pretty small.

A random selection of a small period in earth history, would more often than not select a period with single cell life forms. This is based on the geological record and presence of macro and microfossils in that geological record. It is possible to use the history of the Earth as a representation of other planets at different stages of geological and biological evolution. This assumes that the planet would at least have liquid water as the dominant liquid, and a temperature range within the limits reflected by the Earth's orbit and distance from the sun.