4. Organic evolution, "Life from rocks."
We do not know exactly how life originated on Earth. We do know that it happened at least once at the end of the Hadean era, or about 3.9 billion years ago.* But, recall that the creationists like Jack Chick insist that there is no evidence that this could have occurred at all. There is just a glimpse at the available evidence in my A Short Outline of the Origin of Life. The appropriate goal for a critique of "Big Daddy" is merely to show that there are no apparently insurmountable barriers to a natural origin of life as Jack Chick, and his pal Kent Hovind have set out that there is no observable evidence for any "kind of evolution," other than their mischaracterized "micro evolution."
There are bacteria which "spring from inanimate matter" all the time. At least in the sense that they require absolutely no organic form of nutrition. And we know that "organic" molecules have no particular magic. There was once the thought that the organic "stuff" of life was completely different from "inorganic" or mineral matter. This seems still to be the thought of the ignorant. Known as vitalism, this concept was shown to be false by F. Wöhler, in his 1828 synthesis of urea, a "live" compound, from inorganic stock chemicals ("ON THE ARTIFICIAL PRODUCTION OF UREA" Annalen der Physik und Chemie, 88, Leipzig).
Charles R. Darwin in a letter to the botanist Joseph Hooker wrote, "It is mere rubbish thinking at present of the origin of life; one might as well think of the origin of matter." A few years later in 1871, he had observed, "It is often said that all the conditions for the first production of a living organism are present, which could ever have been present. But if (and Oh! what a big if!) we could conceive in some warm little pond, with all sorts of ammonia and phosphoric salts, light, heat, electricity, etc., present, that a protein compound was chemically formed ready to undergo still more complex changes, at the present day such matter would be instantly devoured or absorbed, which would not have been the case before living creatures were formed. "
The study of the origin of life is properly called abiogenesis. As Darwin noted, it was nothing but speculation until the 1950s. Then, in 1953 a short paper by Stanley Miller published in Science magazine brought origin of life studies into actual experimental research (“A Production of Amino Acids Under Possible Primitive Earth Conditions” Science vol. 117:528-529). What Miller had shown was that a very simple set of starting conditions, common gasses, hot water, and an electric spark would produce many of the chemicals essential to the origin of life. There were many critics, especially creationists. Miller and others repeated his experiment with different gasses, and energy sources. It was so simple to set up even high school chemistry labs could manage. Miller's last paper was published posthumously 55 years later, "A Reassessment of Prebiotic Organic Synthesis in Neutral Planetary Atmospheres" (H. James Cleaves & John H. Chalmers & Antonio Lazcano & Stanley L. Miller & Jeffrey L. Bada 2008 Orig Life Evol Biosph 38:105-115). This group at the University of California's Scripp's Institute demonstrated that under a neutral atmosphere, or even with a trace of free oxygen, ample amino acids could form in the presence of common minerals such as borax, or calcite.
A recent book reviewing the last 58 years of abiogenesis research, and pointing out several still large gaps in our knowledge is;
Deamer, David W.
2011 “First Life: Discovering the Connections between Stars, Cells, and How Life Began” University of California Press
A bit more technical is;
Schopf, William (editor)
2002 "Life's Origin: The Beginnings of Biological Evolution" University of California Press
For some really up-to-the-minute research see;
NASA's Astrobiology Institute website
http://astrobiology.nasa.gov/
* Rosing, Minik T. and Robert Frei 2004 U-rich Archaean sea-floor sediments from Greenland – indications of >3700 Ma oxygenic photosynthesis" Earth and Planetary Science Letters, 217 237-244 (online 6 December 03), Oleg Abramov, Stephen J. Mojzsis 2009 “Microbial habitability of the Hadean Earth during the late heavy bombardment” Nature 459, 419-422 (21 May) | doi:10.1038/nature08015;
No comments:
Post a Comment