It’s a little bit dated (as would be expected, the history of life on Earth comes into sharper focus with every new discovery) but check out this video of Carl Sagan taking us through nearly 4 billion years of evolutionary change. Although the animation is fun, the point near the end of the clip strikes me most; humans are but one of many animals that have been produced by evolution, every lifeform we share our planet with has a tale as amazing (if not moreso) than our own.
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Categories : Abiogenesis, Ecology, Education, Evolution, Paleontology
The way Yahoo! news is run often amuses me, with important or interesting stories about science or world events being buried by what Paris Hilton did to her poor little dog this week or about when Elvis met Nixon. I did, however, manage to catch this little tidbit this morning, which is far more interesting than the other featured stories as of 12:17 today (they are “New Years Investing Tips”, “When Elvis Went to the White House”, “Eagles Beat Giants in Closing Seconds”, and “‘Museum’ Extends its Good Box-Office Run”). The story goes a little something like this:
In 1975 Viking 1 and Viking 2, two unmanned probes consisting of an orbiter and a lander, were sent to Mars to take photographs of the surface and to carry out experiments/observations on the surface. While on the surface, the landers conduced experiments in an environmentally controlled compartment in an attempt to determine the biology of the Martian surface, the initial findings suggesting life but with the claims under heavy dispute. There may have been some serious flaws in the experiments, however, the search for alien life at the time being too heavily predicated upon finding life identical (or nearly so) to that one earth. The director of the research, Dirk Schulze-Makuch suggests that life on Mars may have evolved a primary internal fluid based upon water and hydrogen peroxide, whereas the Viking missions were looking for life with internal fluid closer to salt water. How does this make a difference? Well, according to Schulze-Makuch, experiments conducted by NASA like pouring water on the Mars soil and heating the Mars soil would have respectively drowned and baked any life present in that soil, thus resulting in no life being found.
The discovery of various extremophiles has given some hope of finding extraterrestrial “bacteria” or other microbes on places like Mars, although the presence of absence of life elsewhere in our solar system is yet to be conclusively proven. Regardless of whether the new report is right or wrong in its assertion the Martian life would be based on water+hydrogen peroxide, it raises the important point that if we are to go looking for life elsewhere in the universe we can’t assume that it will be identical or familiar in appearance or composition; making the assumption that life elsewhere must be like that on earth only narrows our chances of finding anything. Personally, I can’t help but think that if Mars ever had any life to begin with that there is life still present somewhere, albeit unfamiliar and cryptic. Especially in the case of bacteria and prokaryotes, it is difficult for me to believe that once such things evolve that there is any event short of crashing into the sun that would exterminate all life permanently, evolution sparing at least some life to carry on despite how humble it might be. This is merely blind assertion and does not do anything to help the debate one way or another, but it is difficult for me to believe that if there ever was life on Mars that the planet would be entirely devoid of life today.
What is more interesting, to me anyway, is that fact that amino acids are found on meteors, some Martian in origin. In the great debate about evolution, the question of abiogenesis or the origin of life often arises, creationists claiming that amino acids could never arise on their own under such harsh conditions, much less have the correct orientation to give rise to life. What’s fascinating is that amino acids in relative abundance have been found on meteors, amazingly showing a bias towards the variety of amino acids that give rise to life. I am terrible at microbiology and I am attempting to tutor myself in that area so I can understand more, but the abstracts I’ve seen at PubMed about these meteoritic amino acids have been exceedingly interesting, one paper by Meierhenrich, Munoz, Bredehoft, Jesseberger, and Thiemann on the Murchison meteorite reporting that the diamino acids they found could very well be representative to the precursors of life on the planet. The abstract has this to say:
“Laboratory data indicate that diamino acids support the formation of polypeptide structures under primitive Earth conditions [Brack, A. & Orgel, L. E. (1975) Nature 256, 383-387] and suggest polycondensation reactions of diamino acids into early peptide nucleic acid material as one feasible pathway for the prebiotic evolution of DNA and RNA genomes [Joyce, G. F. (2002) Nature 418, 214-221]. The results obtained in this study favor the assumption that not only amino acids (as the required monomers of proteins) form in interstellar/circumstellar environments, but also the family of diamino monocarboxylic acids, which might have been relevant in prebiotic chemistry.”
After reading about this I was actually a little pissed off no one had told me about this previously. While evolutionary scientists and creationists continue to debate the origin of life, the precursors to life are continually forming on their own in places no one would expect. This even leads me to wonder if amino acids and other elements of the “pre-biotic soup” are not still being formed on earth somewhere, in hot springs or near volcanoes or other places that seem more like earth the way it once was. Has anyone looked? Of course life has already evolved on this planet and the conditions today (especially in terms of oxygen content of the atmosphere) is very different than it was 3.8+ billion years ago, but if amino acids and other organic compounds necessary to life were found to be still forming on earth or elsewhere, such a find would give us a closer look into the origins of life on Earth.
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Categories : Abiogenesis, Astrobiology, Evolution, Idiocy