ET Rare?

Discovery reports findings by Andrew Watson, who takes a new approach to determining whether or not life in the universe is rare.

I’m sure you remember the Drake Equation, an early formula for how to measure the chances for life evolving. This new research takes a different approach by looking at how long it took for intelligent life to evolve on Earth. Really, if you think about it, it’s a long time.

First off, we know it doesn’t take long for life to develop on a planet: given Earth formed 4.6 billion years ago (bya), the first single-cell organisms date from around 4 bya – only 600mya after formation, which is really rapid.

Second, estimates show that the sun will make the earth uninhabitable in another billion years or so, so our planet will be 5.6 (maybe even 6 billion years old).

Humans only arrived maybe 2.6 million years ago, but only started developing civilizations 3500 ya. This chart is always demonstrated quite well visually by drawing a map of time starting from San Francisco and going to New York City where 3500 years is only about one cinder block outside the Empire State Building.

Now even if we give the allowance that the extinction of the dinosaurs didn’t occur at 65 mya (or 250 mya for the Permian/Tertiary extinction), and suggest that within a few million years something intelligent might have evolved (more likely at 65 mya, really), for all intents and purposes, it still took 4 billion years for life to evolve into something intelligent (3.8-3.9 if you are generous and think foregoing extinction that something intelligent could have evolved sooner). And extinction events seem to happen pretty rapidly, but you also have to remember that animals also recover from extinction fairly quickly.

Still, 1 billion years is a long time and given the rate at which land animals evolved. Given that we’re talking only about 500 million years from the first amphibians to dinosaurs and mammals I’d say that’s a LOT of opportunity for something to evolve. Who knows…there might even be a pattern here similar to Moore’s Law, but we just don’t have enough fossil evidence.

Basically, I don’t think Andrew Watson is giving enough credit to the rate at which species evolve and the speed at which life was formed on earth. The more important question is why it took 3.5 billion years to create an amphibian and why that happened. Watson seems to suggest that it’s a fluke, but given the rate of evolution, I’d say something interesting would have happened sooner or later.


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