Astrobiologists Ponder Possibility of Early 'Alien' Microbes
One of the great unsolved mysteries of science is the origin of life. How did it happen?
If we were able to click on Google Earth and visit the Earth during the Archean Eon, we would likely not recognize it is the same planet we inhabit today. The atmosphere was a reducing atmosphere of methane, ammonia, and other gases which would be toxic to most life. Also during this time, the Earth's crust cooled enough that rocks and continental plates began to form.
It was early in the Archean that life first appeared on Earth. Our oldest fossils date to roughly 3.5 billion years ago, and consist of bacteria microfossils. In fact, all life during the more than one billion years of the Archean was bacterial.
We also know that the long period of Earth history prior to the advent of skeletons was punctuated by enormous mass extinction catastrophes that decimated the biota of our planet without a record. The early mass bombardment period 4.6 to 3.8 billion years ago is believed to have sterilized Earth's surface at least several times. The rise of oxygen 2.4 to 2.2 billion years ago also certainly doomed most anaerobic bacterial species.
Through most of the 20th century, scientists thought that life began with a stupendous chemical fluke, unique in the observable universe.
Today, as physicist and astrobiologist Paul Davies of Arizona State
University, points out it is fashionable to say that "life is written
into the laws of nature - easy to get started and therefore likely to
be widespread in the universe. The truth is, nobody has a clue. It
could be either extreme, or somewhere in the middle."
We may
soon find the key in the discovery of a second genesis on another
planet such as Mars, Davies goes on to say. There is an easier and
more startling possibility, however, that is the thesis of Davies
research paper Second Genesis, co-authored with Dr Charley Lineweaver of the Planetary Science Institute, Research School of Astronomy and Astrophysics, at Australia's Mount Stromlo Observatory :
"If life really does form readily then we might expect it to have started many times over on Earth. There could be alien microbes right here, under our noses. Most life is microbial, and you can't tell just by looking whether a microbe is "our" life or alien. You need to analyze the chemical innards. The search for terrestrial aliens has only just begun. If they are here, they could be identified soon. And the discovery that all life on Earth did not, after all, have a common origin would virtually prove that we are not alone in the universe."
Posted by Casey Kazan. Image Credit: Joe Tucciarone.
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I read in a previous article that one of the imposibilities of intelligent life on young stars is the time that took us to reach our tchnologic development, what would be the time for young stars to develop a technological civilization like ours if they were lucky or relatively lucky to don't have mass extinctions, for my point I would take the "Ring World" reference of 300,000 years the hominids took to advance from monkey to humans, if the dinosaurs wouldn't finished as they did, Would they be now a, let's say 60 million civilization old?
Posted by: jer35mx | May 03, 2008 at 04:58 PM
I sure hope you arent the only ones in this universe... because if we are the only thing this 'infinite' universe can offer... well... i'll be damned, we are truly screwed--- bringin me to another thought... how can the universe be infinite... what is really infinite??? how can there be so much space... that makes it inifinite... is it constantly expanding?? what happens if one was to move quicker than it expanded... whats surrounding the universe... how big is its surrounding... if we reach the end... do we find another dimension?? that we cant enter??--- is that what could possible make something infinite?? interesting thought...
Posted by: Cameron | August 13, 2008 at 10:55 AM