Exoplanets expert thinks intelligent beings rare in galaxy

Here, Space.com's Mike Wall interviews astronomer Geoff Marcy on "Life on other planets?" (2/1/2011):

Leading expert weighs in

Marcy has had a hand in finding more alien planets than anyone else. He helped spot 70 of the first 100. He also found the first multiplanet system around a sun-like star, and he discovered the first planet that transits — or passes in front of — its star from our perspective on Earth

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Space.com: Our solar system is so young, compared to the universe. And the universe is so big. So there's been lots of time and opportunity for advanced civilizations to get started, and to try to contact us. Some people think that the fact that we seemingly haven't been contacted means that we may well bealone in the universe.

Marcy: Well, you have to fold it in. The absence of an intelligent radio or television wave from any advanced civilization represents one indication, not a proof, that maybe habitable planets that sustain Darwinian evolution for a billion years —maybe they're rare. Maybe.

Space.com: What do you reckon? Do you have a gut feeling about this?

Marcy: I do. If I had to bet — and this is now beyond science — I would say that intelligent, technological critters are rare in the Milky Way galaxy. The evidence mounts. We Homo sapiens didn't arise until some quirk of environment on the East African savannah — so quirky that the hominid paleontologists still can't tell us why the australopithecines somehow evolved big brains and had dexterity that could play piano concertos, and things that make no real honest sense in terms of Darwinian evolution.

The whole is worth reading. He thinks $billion should do the trick.