Part 2: The search for shadow life
Gallery: What might shadow life be like?
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WHEN the Nobel prizewinning physicist Richard Feynman died in 1988, his blackboard carried the inscription, 鈥淲hat I cannot create, I do not understand.鈥� By that measure, biologists still have a lot to learn, because no one has yet succeeded in turning a chemical soup into a living, reproducing, evolving life form. We鈥檙e still stuck with Life 1.0, the stuff that first quickened at least 3.5 billion years ago. There鈥檚 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. David Deamer, a biochemist at the University of California, Santa Cruz, has been saying that scientists would create synthetic life in 鈥渇ive or 10 years鈥� for three decades, but finally he might actually be right. 鈥淭he momentum is building,鈥� he says. 鈥淲e鈥檙e knocking at the door.鈥�
Meanwhile, a no-less profound search is on for a 鈥渟hadow biosphere鈥� 鈥� life forms that are unrelated to the life we know because they are descendants of an independent origin of life. We know for sure that life got going on Earth once, so why couldn鈥檛 it have happened twice? Many scientists argue that there is no reason why a second genesis might not have taken place, and no reason why its descendants should not still be living among us.
So the appearance of an 鈥渁lien鈥� organism seems imminent 鈥� we may find one that arose naturally, or engineer one in the lab. Either way, it鈥檚 a momentous step. Until now, biologists have had to base their understanding of life on the plants, animals and microbes that surround us, which all share a common ancestor. That doesn鈥檛 give much perspective.
鈥淲hen you have a single example, it鈥檚 very hard to know whether it鈥檚 representative,鈥� says Carol Cleland, a philosopher of science and astrobiologist at the University of Colorado in Boulder. 鈥淚f you were an alien biologist who鈥檚 interested in understanding what a mammal was, and all you had was zebras, it鈥檚 very unlikely that you would focus on their mammary glands, because only half the specimens have them. You鈥檇 probably focus on the stripes, which are ubiquitous.鈥�
Discovering 鈥� or engineering 鈥� a second genesis wouldn鈥檛 just broaden our view of life. Alternative life forms could supply biotechnologists with fresh molecules and new functions that they could apply to practical problems. A synthetic, made-to-order living system might even serve as a self-maintaining, self-improving, adaptable assembly line for producing everything from pharmaceuticals to petrochemicals. Over the next four pages we first report on rapid progress in the lab, and then bring news from the field, as researchers race to make what could be one of science鈥檚 most far-reaching breakthroughs.
