Summary: Hundreds of astronomers yesterday learned that life in outer space is likely to lack green eyes and be far more prosaic, tiny and, quite possibly, completely unlike life as we know it. This blunt appraisal came from the University of Washington's Center for Astrobiology and Early Evolution, one of the first programs in the country to give an advanced degree in astrobiology.
By Eric Sorensen
The hands-down best freebie at this week's American Astronomical Society meeting in Seattle is the Los Alamos National Laboratory alien pen, a fat chrome-plastic alien with a bulbous head and, naturally, green eyes.
But two floors up from the Washington State Convention and Trade Center exhibition hall, hundreds of astronomers yesterday learned that life in outer space is likely to lack green eyes and be far more prosaic, tiny and, quite possibly, completely unlike life as we know it.
This blunt appraisal came from the University of Washington's Center for Astrobiology and Early Evolution, one of the first programs in the country to give an advanced degree in astrobiology. The program, space missions looking for clues of life in space and the capacity crowd at the discussion all point to boundless interest in how life might have begun here and how it might exist on other planets.
But even defining what life is can be tricky, with various interpreters bouncing around notions of replication, growth, metabolism, evolution and the presence of water and carbon. No universal definition exists, said John Baross, a UW professor of oceanography.
Moreover, life elsewhere might be unlike life we have seen here, which would make it hard to know it if we see it, he said.
"I also don't think that a carbon-based life found on solar bodies will resemble Earth life at the molecular level," he said. "We expect to see something quite a bit different, and we have to be prepared for that."
Roger Buick, an associate UW professor of Earth and space sciences and astrobiology, warned that some planets we look at may have once had life but became inhospitable as their sun's intensity increased.
Like many astrobiologists, he suggested looking to the Earth's fossil record for analogies for the rest of the universe. That is difficult as some of the oldest fossils are destroyed as the planet's crust is subducted and recycled.
Still, the evidence so far suggests that even if we find microbial life as can be found in fossils here going back 3 billion years, it is a far cry from the intelligent life sought by the likes of SETI, the Search for Extraterrestrial Intelligence.
"It's taken us at least 2 ¾ billion years for intelligent life to arise on this planet," said Buick, "and there's no reason to suppose that on any other planet that has complex organisms that they need necessarily become intelligent very fast."
David Stahl, a UW microbiologist, agreed: "Visitors to the Earth during any average point in its history would have been greeted only by microorganisms," he said.
And even today, most living stuff on the planet is small, even if the life we tend to identify is big, he said. Of the 1.4 million species identified so far, the majority are plants, insects and other animals. Yet, most of the tree of life is unicellular and prokaryotic, or lacking a nucleus. The microscopic life in a single tablespoon of seawater contains more genetic information than the human genome, he noted.
"If we're even going to begin to approach this question of origins of cellular life on Earth or other planetary bodies... it's essential that we begin to understand the fundamental biology of this planet, this planet of the microbes," Stahl said. "They are the glue that binds together the macroscopic world.
"You can scrape all the big stuff off this planet and the biosphere wouldn't mind very much. It would go on clicking as it did for 3-plus billion years before the big stuff made its presence known."