Intelligence: A Rare Cosmic Commodity

By John D. Ruley

Astrobiology Magazine

posted: 10 April 2008, 07:00 am ET

Advanced ground and space-based telescopes are discovering new planets around other stars almost daily, but an environmental scientist from England believes that even if some of those planets turn out to be Earth-like, the odds are very low they'll have intelligent inhabitants.

In a recent paper published in the journal Astrobiology, Professor Andrew Watson of the University of East Anglia describes an improved mathematical model for the evolution of intelligent life as the result of a small number of discrete steps.

Evolutionary step models have been used before, but Watson (a Fellow of England's Royal Society who studied under James Lovelock, inventor of the "Gaia hypothesis") sees a limiting factor: The habitability of the Earth (and presumably, other living worlds) will end as the sun brightens. Like most stars, as it progresses along the main sequence, the sun's output increases (it is believed to be about 25 percent brighter now than when the Earth formed). Within at most 1 billion years, this will raise the average temperature of the Earth to 50 degrees C, rendering the planet uninhabitable.

Full article here:

http://www.space.com/scienceastronomy/080410-am-intelligence-model.html