London, March 14 (ANI): By searching for an alternative form of microbial life on Earth, dubbed 'shadow biosphere', scientists are hoping that they can get close to finding life elsewhere in the solar system.
New origins of life are unlikely today, because existing life would gobble up any aggregations of prebiotic molecules before they could edge over the threshold.
However, opportunities for the origin of life may well have existed for long periods on the early Earth.
Some of these origins may have been dead ends, out-competed by other life forms, but others could still be living among us, unnoticed.
"I think if we found a second sample of life on Earth, it would be as big as Darwin's theory of evolution," cosmologist and astrobiologist Paul Davies at Arizona State University in Tempe told New Scientist.
"It would answer the most fundamental question we can imagine, which is: are we alone in the universe?" he added.
Skeptics might scoff at the idea that shadow life could pass unrecognized for so long, but Davies and his collaborators have a simple rejoinder: scientists have never looked properly.
Such life would probably take the form of single-celled microbes, so naturalists should not be expected to spot it casually.
The techniques microbiologists use to detect life, like, staining for DNA, sequencing DNA, and culturing microbes in the lab, assume that the target microbes have the normal biochemistry.
"They couldn't detect an alternative form of microbial life," said Carol Cleland, a philosopher of science and astrobiologist at the University of Colorado in Boulder. iven that fewer than 1 per cent of microbes have been cultured and described, there is plenty of room for shadow life to be living right under our noses, according to scientists.
However, the task of searching for shadow life on Earth is much tougher than looking for life on other planets.
"This planet is heavily contaminated with life as we know it," said Shelley Copley, a biochemist at the University of Colorado.
One promising avenue is to explore extreme environments that are beyond the reach of conventional life, such as ultra-dry deserts, ice sheets, the upper atmosphere or the hottest hydrothermal vents.
According to Davies, more researchers will start looking for shadow life.
Even if they don't find it, the search could turn up previously unknown branches on the familiar tree of life.
"So, it's worth doing anyway, even if you've convinced yourself that we're alone in the universe," he said. (ANI)