NASA researchers have found a life form that on the molecular level is unlike all others on Earth, reports The Washington Post. The bacterium, found in Mono Lake in California, is strong evidence that life may not have evolved from a single common ancestor.
A Single Genetic Model Composed Of Six Elements
So far, the idea has been that all life on Earth is based on a single genetic model composed of at least the six elements carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorus. No one has ever found any example that violates this golden rule of biochemistry.
But Arsenic Can Replace One Of Those Elements
But now, NASA researchers at Mono Lake have found a bacterium that has five of these essential elements, but that uses the usually poisonous element arsenic in place of phosphorus, the sixth element.
From The Washington Post:
News of the discovery caused a scientific commotion, including calls to NASA from the White House and Congress asking whether a second line of earthly life has been found.
A NASA press conference Thursday and an accompanying article in the journal Science, gave the answer: No, the discovery does not prove the existence of a “second genesis” on Earth. But the discovery very much opens the door to that possibility and to the related existence of a theorized “shadow biosphere” on Earth – life evolved from a different common ancestor than all that we’ve known so far.
An Alternative Scheme To Life?
The researchers set out precisely to find an alternative scheme to life as we know it. With the hypothesis that there might be life in which the normally poisonous element arsenic could work in place of phosphorus and phosphates, they began to study the bacteria that live in Mono Lake, home to arsenic-rich waters.
They then grew the bacteria in a laboratory, using increasing levels of arsenic, and found to their surprise that the microbes eventually took up the element completely.
Scientists were anxious to state that it is far too early to jump to any conclusions about exactly what this discovery means.
A Weird Branch On The Tree Of Life
“This is just a weird branch on the known tree of life,” said Paul Davies, the Arizona State University and Nasa Astrobiology Institute researcher who co-authored the research. “We’re interested ultimately in finding a different tree of life…that will be the thing that will have massive implications in the search for life in the Universe.”
He continued, “The take-home message is: who knows what else is there? We’ve only scratched the surface of the microbial realm.”
But this find must be significant for what scientists understand about life on earth, whatever it suggests about extraterrestrial life.
And it will surely open the door to some fascinating science fiction possibilities. It also means that those of us who love Mono Lake and the nearby Sierra Nevada mountains, will have a slightly different perspective on the area from now on!
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