A microbe found in a Californian lake is alive but its DNA includes a different material to everything else living on Earth: Arsenic. It's proof positive, says NASA, that E.T. is out there -- and already here with us.
The location for the find is Mono Lake in Calfornia--one of the places on Earth that you can find the highest levels of naturally-occurring concentrated arsenic. Arsenic, of course, is a poison to many forms of life, and frequently used to murder unsuspecting victims throughout history (check out this old text  on arsenic eating for fun facts).
But biologists discovered bacteria living in this lake, where everything should be dead. The discovery was made years ago, prompting many to talk of "re-writing the book of evolution," since the existence of an extremophile life form on Earth informs all sorts of theories about life on other planets  (or even other places in our solar system, as Arthur C. Clarke suggested in his novel 2010, highlighting the clouds of Jupiter and the moon Europa as possible places for life).
It also implies important things about the evolution of early life on Earth, and affects some of the more unusual theories like cosmic seeding, or panspermia --where the chemistry of life arrived on our planet courtesy of meteorites.
The new research explains how this organism substitutes arsenic for one of the major elements that make up everything else living on Earth--carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur. The science team took mud from Mono lake, added in other chemicals like sugar and subjected the resulting soup to heat, and they found that one particular type of microbe grew like crazy, in an environment in which no life really should. By harvesting the microbe, and then cracking open its cells, the team found that it actually substitues arsenic for phosphorous in the phosphate backbone of its DNA molecules.
This news should excite you because it means that at least one lifeform here on Earth is very different from all the rest. Different enough that its very DNA includes an element in place of one that you and I couldn't live without. It means that alien life could easily exist in an environment that is radically different to ours.
This week other extraterrestrial research , the result of observations of remote red dwarf suns made using the huge Keck telescope on Hawaii, suggests that our models of the cosmos may be wrong in another respect. There may be as many as three times as many stars in the universe than we thought.
The chances of life existing on other planets, therefore, just got a boost because there are so many more suns for planets to orbit.
Meanwhile analysis of the first atmosphere of an exoplanet (orbiting a star in another solar system) has just been announced , and suggests the "super Earth" has a thick atmosphere of mainly steam, or a mix of hydrogen and hazy vapors. And new images of Enceladus , a tiny, scarred moon of Saturn, have revealed in unprecedented detail the plumes of water vapor and ice particles that we know spray forth from cracks in its icy skin, revealing active hotspots inside the moon.
In short, the odds that E.T. is out there, somewhere, just got trillions of times better.
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