Posted: Sat, April 20, 2013 | By: Miscellaneous
by Walter Farah Calderón, translated from Spanish by Samir Farah
Since last March 12th when NASA announced that Mars was able to foster microbial life, earthlings have lost their innocence, facing doubts that they were not the only ones, nor were they the first. Quite possibly, from now on, a certain unavoidable anguish will run across the blue planet, where its inhabitants are used to the absolute privilege of life.
Earth is 4.5 billion years old. The earliest evidence comes from fossilized carpets of cyanobacteria called stromatolites found in Australia. These unicellular organisms still exist after 3.4 billion years. Hence, some scientists point to the origin of life 3.8 billion years ago: a rapid beginning with a slow development.
Everything points towards the RNA World Hypothesis, today considered the quid molecule of primitive life. Under this hypothesis RNA appeared on Earth serving as a storage container for genetic material, which caused chemical reactions and evolved as DNA and its proteins, i.e., self-sustaining systems.
Obviously, we also needed water, energy, the techtonic plates, the slight variation of our solar radiation, protection of our magnetic field, the stabilization of the planet’s axis, the connection with our Moon, the influence of Jupiter and who knows how many other things! That’s why some debate whether life is tiny or less probable, but in such terms this debate is unnecessary; research will continue and will resolve the issue.
Life on Earth has proven to be persistent and flourishing in the most diverse environments—many of them extreme. Perhaps, here on Earth, there was not a single origin, but many—in as many environments as possible, through chemosynthesis.
But, the question of the origin of RNA itself continues given that it is a molecule composed of smaller molecules called neucleotides. In other words, carbon—nitrogen based, and of the phosphate group. At this point, we are not talking biology, but rather chemistry—prebiotic chemistry, and with NASA’s announcement we are no longer referring only to life on Earth, but beyond. This is something that addresses astrobiology, a newly developing science that studies the origin, evolution, distribution and future of life in the universe.
And with this a classic theory, Panspermia, takes on a new momentum, one that affirms that the simple life forms—at least those derived from carbon—are everywhere throughout the universe and that, according to the ancient Anaxagoras, they travel like seeds in comets, but mostly in organic meteorites. We then speak of the ‘litopanspermia theory’ (from the Greek: lithos=rock, pan=all, eperma=origin): models in which primitive organisms were able to resist the speed and radiation of their voyages. With all of this the old theory of Leucippus and Democritus, that of the innumerable worlds, is also reborn.
Meanwhile, as all of this is taking definitive form the small, grand things of Curiosity accumulate, as exemplified in the March 12th pronouncements. While perforating a rock some of the basic chemical components of life were found, including sulfur, nitrogen, hydrogen, oxygen, phosphorous, carbon and clay minerals. The place where this was found was wet, a river or a lake—some say knee-deep—a type of wet bed, different from other environments on Mars. It was not extremely acidic or saline, partially oxidized, moderately alkaline, with sulfites that could have provided a chemical energy and favorable conditions for the microbes.
It is not that this is all new. On the contrary, Mars is the most studied planet (see ‘Gods, humans, extraterrestrials and robots’), and it will continue to be. Since Curiosity landed on Mars, over eight months ago, many other discoveries have been made: the best evidence of carbon dioxide snows, frozen carbonic snow or dry ice—the only case known in the solar system; a meteorite found in the Sahara—origin Mars— with a proportionate concentration of water ten times that of any of the at least 90 meteorites of Martian origin known. And, from some optimists—who never are lacking—comes the announcement of the Extraterrestrial Genome Search project to send a life genome sequencer out to whatever life forms might be found on that planet.
If not today, it will be tomorrow. But, sooner or later we will discover life beyond our planet. And then the current angst—as yet imperceptible—will turn into a real torrent that will take with it our privileged place in the cosmos, uselessly lamenting its loss. Although, perhaps there will be some of us who will celebrate the marvelous history that has been ours to live, finding answers to problems of the last 2,500 years, by opening doors to the unknown into a universe that ever awaits us, toward the transhuman.