[Little Ray]

Actually there is some question as to whether or not "billions and billions" are relevant. In Alchemy of the Heavens ( http://www.amazon.com/exec/obidos/ASIN/0385472145/qid=1067894396/sr=2-1/ref=sr_2_1/104-8385362-0586309 ) the authors suggest that the conditions that gave rise to (allegedly) intelligent life on Earth may be vanishingly rare. Basically the gas giants of the Solar System and the Moon act as a giant broom reducing the frequency of environment-altering impacts.
Intellgent life may be vary rare indeed.

[justanotherfreeper]

Intellgent life may be vary rare indeed.

God knows it's rare here!

[Moonman62]

Basically the gas giants of the Solar System and the Moon act as a giant broom reducing the frequency of environment-altering impacts.

The Moon also stabilizes the Earth's tilt, and may have been necessary in allowing the Earth to have a crust that would yeild and support life for billions of years. If the astronomers found distant planets like venus or mars, with a planet like jupiter orbiting outside them, they would be jumping up and down, yet there would be no discovery of life.

[from occupied ga]

Intellgent life may be vary rare indeed.

Absolutely true, in fact so rare as to be completely absent with the majority of voters in NY, CA, MD, MA, NJ, CT, RI, IL , and DE.