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Other origins of life theories:

A survey of the major theories

Sulphur compounds: The chemical evolution leading to cellular life on earth almost four billion years ago likely passed through a stage where RNA alone performed all of the functions of the modern macromolecules RNA, DNA and protein. However the so-called RNA world was itself too complex to evolve directly from organic molecules found on the prebiotic earth. More likely, the RNA world emerged from and was supported by a primitive sort of metabolism fueled by the bonds in sulfur-containing compounds called thioesters.

Watson-Crick pairs and RNA: Whether RNA arose spontaneously or replaced some earlier genetic system, its development was probably the watershed event in the development of life. It very likely led to the synthesis of proteins, the formation of DNA and the emergence of a cell that became life’s last common ancestor. The precise events giving rise to the RNA world remain unclear.

Amino acids and RNA: Yale scientists report they have synthesized molecules like those that probably gave rise to the earliest life forms on Earth nearly 4 billion years ago, thus creating a biochemist’s version of “Jurassic Park” populated by exotic molecular “fossils” that have long since become extinct. In the May 26 issue of the Proceedings of the National Academy of Sciences, the Yale biologists report the creation of one of these “fossils,” an unusual hybrid molecule made up of a scaffold from deoxyribonucleic acid (DNA) with chemical “scissors” attached to it. Ronald R. Breaker, who created the first DNA enzymes in 1994 with colleagues at The Scripps Research Institute, said he “looted the tool box of proteins” to get the amino acid “scissors,” which destroy messenger ribonucleic acid (RNA) in humans and many other organisms. The feat was accomplished using a technique known as test-tube evolution. Breaker’s tailor-made enzyme is the first known nucleic acid enzyme that uses an amino acid to trigger chemical activity, and it brings scientists a step closer to finding the precursor of all life — a single molecule containing both genetic code and an enzyme capable of triggering self-replication.
Extraterrestrial influences may have helped shape the origin of life on Earth billions of years ago.

Amino acids from outer space: That’s the potentially far-reaching conclusion of two scientists studying chemical compounds that reached Earth aboard a meteorite – the detritus from a passing comet. The focus of the researchers’ study was a set of amino acids borne by a meteorite that struck Australia in 1969. Amino acids form proteins, the biological workhorses of living organisms. They were part of the chemical stew that enveloped the early Earth. Like mittens, amino acids come in left-handed and right-handed varieties – designations they received after scientists saw how polarized light twisted as it passed by sample compounds. Other amino acids show no “handedness” at all, but are symmetrical.

Interstallar dust: Hoyle and Wickramsinge on our cosmic ancestry. Cosmic Ancestry is a new theory of evolution and the origin of life on Earth. It holds that life on Earth was seeded from space, and that life’s evolution to higher forms depends on genetic programs that come from space. It is a wholly scientific, testable theory for which evidence is accumulating.

Primeval soup and sulphur: Although Charles Darwin speculated that life originated in a warm, nourishing broth, new evidence suggests that the cradle of life could have been more like a Puritan minister’s version of hell–a sulfurous swirl of superheated water and oozing lava. In today’s issue of Science, two chemists report that they have re-created a crucial step in assembling the ingredients of living cells–the linking together of amino acids into short, proteinlike chains called peptides–under just such harsh conditions.

Geology: This is an explanation of how life might have originated. It is written for non-specialists. A detailed account was published in 1997 in the Journal of the Geological Society of London, an appropriate journal because we consider that a major geological process, the cooling by seawater of rocks under the floor of the ocean, played an important role in the origin of life. Such a process might seem remote from our everyday knowledge of life but it has now been known for more than twenty years that genetically primitive micro-organisms are to be found living at warm springs on the ocean floor.

Chemical evolution and Haldane: How did life begin, and how did it derive from nonlife? Our contemporary ideas on the evolution of life began in 1924, when the Russian biochemist Alexander Oparin (b. 1894) introduced chemical evolution as a necessary forerunner to biological evolution. In 1928, the English biologist J.B.S. Haldane (1892-1964) independently suggested an outline for chemical evolution, which is still the basis of our current understanding.

Autocatalytic sets of proteins: “We’re turning a kind of corner” says Kauffman, SFI faculty member and project coordinator. “For thirty-five or forty years-in fact, since we’ve known about the structure of DNA-the symmetry of the DNA or the RNA double helix has been such a commanding image of how a reproducing molecule might occur, that it has dominated almost everybody’s imagination. On the other hand, the idea that you might have autocatalytic sets or collectively autocatalytic sets of proteins goes back at least to the late 1960s in a book by Melvin Calvin on chemical evolution. That’s the theme that several of us have picked up, more or less independently at about that time. And here Reza has made the first peptide that is able to catalyze its own formation by catalyzing a ligation reaction.”

Creationism: In the beginning when God created the heavens and the earth, the earth was a formless void and darkness covered the face of the deep, while a wind from God swept over the face of the waters. Then God said, “Let there be light”; and there was light. And God saw that the light was good; and God separated the light from the darkness. And there was evening and there was morning, the first day.

Creation Science: Creationism is not “against” modern science! In fact, the Biblical mandate to “subdue” the earth (Genesis 1:28) requires us to understand it, which is what science is all about. “Creation Science” is simply the practice of science with the assumption and acknowledgement that there is a creator God, versus the now standard operating assumption of naturalism (that nature is “all there is”).