That may sound at first like a B-movie plot, but it’s actually the latest hypothesis of well-known Arizona State University’s Paul Davies. The physicist told Chicago’s conference of the American Association for the Advancement of Science (see items #4, #5) that our planet may have forms of “weird life” totally unrelated to life as we know it. The symposium Davies addressed was “exploring the possibility that life has evolved on Earth more than once,” or perhaps that life on Mars was transferred to Earth.
Perhaps life on Mars was transferred to Earth.
Where might these “aliens” be found? Davies suggests toxic arsenic lakes, salt lakes, deserts, and extremely hot hydrothermal vents in the deep sea as their likely habitats. He proposes a new “mission to Earth” to find such exotic life, which he calls a “shadow biosphere.”
According to BBC News, Davies asked, “The question is why? The cost is not expensive—it would be a fraction of the money we spend searching for extraterrestrial life.” Davies believes we may have missed these life-forms because our searches are customized for finding “life as we know it.”
More specifically, Davies believes we could find life-forms whose genetic codes use different amino acids, or who are based on elements other than hydrogen, oxygen, nitrogen, carbon, and phosphorous. Davies suggests arsenic could function as an ideal substitute for phosphorous, which is why he proposes looking for life-forms in arsenic-rich lakes.
“Personally, I’m only interested in establishing whether life happened more than once,” Davies said. “If we find it has happened twice from scratch then it’s going to have happened all around the universe.”
As interesting as it would be to find forms of life even more exotic than what we’ve already discovered (such as so-called “extremophiles” that dwell in seemingly inhospitable habitats), Davies’ idea is entirely rooted in evolutionary theory. That’s actually ironic, since the unity of all life (its genetic basis) is an occasional argument given in support of evolution. Whether or not more exotic forms of life are one day found, neither creationists nor evolutionists should have any difficulty incorporating them into their worldview—although if life originating once was a chance event, imagine the likelihood of it evolving twice!
Despite the evolutionary interest in “alien” life on Earth, however, don’t expect the search for extraterrestrial life to disappear. This week scientists further speculated on the possibility of water on Mars; meanwhile, NASA and the ESA are hoping to send a mission to the Jovian moons to look at other places “where life might have evolved.”
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