Friday, July 24, 2009

Origin of life: Current efforts to create life, or else find alternative life

In "Second Genesis: Life, but not as we know it," Bob Holmes (New Scientist, March 11, 2009) provides a summary of attempts to create artificial life (paywall).
We're still stuck with Life 1.0, the stuff that first quickened at least 3.5 billion years ago. There's been nothing new under the sun since then, as far as we know.

That looks likely to change. Around the world, several labs are drawing close to the threshold of a second genesis, an achievement that some would call one of the most profound scientific breakthroughs of all time.
Venter's team at the J. Craig Venter Institute in Rockville, Maryland, plans to remove the genome from an existing bacterial cell and replace it with one of their own design. If successful, this will indeed result in a novel life form, but it is a far cry from the ultimate goal of a second genesis, as Venter would be the first to admit.

Other teams, however, are striving directly for that ultimate goal. The most ambitious of them do not even rely on the standard set of molecular parts, but seek to redesign a living system from first principles. If successful, they would provide an entirely new form ...
Meanwhile, others look for a shadow biosphere, an independent type of life sharing the planet with us.

My sense is that the people who use existing manufactured parts will have the best luck with their work.

Here's University of Colorado (Boulder) philosophy prof Carol Cleland'sargument in Astrobiology Magazine (12/01/06) for looking for a shadow biosphere:
The discovery of a shadow microbial biosphere would be philosophically and scientifically important. It is clear that familiar Earth life has a common origin, and hence represents a single example of life. Logically speaking, one cannot generalize on the basis of a single example. If we are to achieve a satisfactory understanding of the general nature of life, we need examples of unfamiliar forms of life.
Also, Holly Hight asks ("Does Earth harbour a shadow biosphere of alien life," Cosmos: The Science of Everything, 16 February, 2009 ):
Finding life that doesn't fit with the types we already know would be a strong indication that life developed more than one time here on Earth, increasing the chances of finding it elsewhere, said Paul Davies, an astrophysicist at Arizona State University in Tempe.

But nobody has ever seriously searched for microorganisms - or any form of life - different from the carbon-based, DNA-centred type of life about which we have long known.

If we do look, Davies said, "It's entirely feasible that we'll find a shadow biosphere," he told reporters at the annual meeting of the American Association for the Advancement of Science (AAAS) in Chicago.

"Our search for life [has been] based on our assumptions of life as we know it. Weird life and normal life could be intermingled, and filtering out the things we understand about life as we know it from the things we don't understand is tricky."
It must be hard to write science fiction these days.