Studies on the Studies on the
Current Scientific Studies
We begin with a generally accepted time line for the origin of life. A recent discovery apparently pushes the genes of modern life back even further.
Modern origin of life studies were sparked by Stanley Miller's (1953) synthesis of amino acids by discharging electricity through an atmospheric soup of chemicals - much as lightning passing through a primordial Earth's atmosphere might have done. Subsequent investigation of the atmosphere of the early earth suggested a more likely oxidizing atmosphere and that the building block chemicals needed to form amino acids and nucleotides were probably not present in sufficient concentrations in the atmosphere or oceans.
Today, many diverse research groups are engaged in origin of life studies. They range in size from NASA's Astrobiology project to groups within departments of biology, chemistry, and geology and research institutes around the world.
Earth Studies
Thermal Vents
One current approach by Russell, Hall, and co-workers at the University of Glasgow ( Origin of Life Research ) proposes the emergence of life in iron sulfide compartments in a hot acidic early ocean. The Corliss group assumes a hot mildly basic ocean.
The Work of Sidney Fox
In the 60s Sidney Fox, at the University of Miami took Miller's amino
acids (created in the same way) and then, by heating them (to less than 150 degrees F) in
conjunction with aspartic and glutamic acids (also created through simulation experiments)
and was able to polymerize them into proteinoid microspheres. Under a microscope, the
microspheres look like primitive cells. In fact, artificially fossilized microspheres are
indistinguishable from the earliest known microfossils that date back to about 3.5
BYA.
Although hesitant to claim that these were alive Dr. Fox stated that they were undeniably
"protoalive". This is not an evasive answer. As Tim M. Berra says in Evolution
and the Myth of Creationism (1990): "For centuries, science knew
nothing intermediate between non-living and living things, but today the distinction is
not at all clear. Since life evolved from non-living matter, at some point we must
arbitrarily draw a line and say that everything beyond that point is alive. Viruses, for
example, appear to be alive when they infect a host, but seem to be non-living when
outside a host."
Some more recent examples of protocells and protocell aggregates.
Since a single cell would appear to be the smallest unit that can be said to be alive, proteinoid microspheres may quite justifiably be called protocells, or, life. These are just the early stages of these types of experiments. There is every likelihood that within the next couple hundred years man will be able to create self-replicating life of varying forms from purely chemical and natural elements under laboratory conditions. --- Simon Ewins
A former student of Fox comments:
…I will say a bit about [Sidney Fox} from first hand experience. He was one of my
professors at University of Miami. I learned from Sidney Fox himself how to make his
proteinoids and microspheres. I have also discussed with him at length the claims he had
made in the 1960s to have created life. He would not repeat those claims in my presence
(he knew me well enough to know what I believed). He was able to make such claims in an
audience of believers, but not in the presence of an antagonist. It was in this context
that I asked him about the origin of the ribosome, and he told me a fanciful story about
some researcher in France who had discovered a bacterium that assembled proteins right off
the DNA without the aid of a ribosome, a claim that has not yet reached scientific
circles. He never claimed to have created life when he was on campus (and of course, I
think with good reason) or in the classroom, nor could he have to an audience of
biochemists and molecular biologists. Among my peers, he was considered not to be doing
acceptable science, although there was not general disrespect among students. However, our
mentors had nothing good to say about his science. Again, it was not personal. He was a
nice enough person. Two good friends of mine did their Ph.D. work under him. Neither of
them believed he had "created life" by a long shot. One of them switched to
another advisor because he did not believe what he had been doing in his lab was science.
In spite of the many claims that we have heard that he had created life
... or even a "protocell", whatever that is, there is nothing in his work to
suggest this was the case. All of the features he (and others) have claimed for his
microspheres are features explainable in terms of non-living physical and chemical
interactions in a system going to equilibrium. To trivialize life in this context by
saying that such systems are "living" does not make sense. No living system
resembles Fox's proteinoids in any way. All living systems are far from equilibrium, and
remain there until they are no longer living. All known living systems are information
rich, and are capable of passing that information on to progeny in an organized way. To
claim that Fox's proteinoid microspheres are alive is, in short, not to understand what
life is. Sidney Fox either did not understand what life is, or made such claims in his own
self-interest.
Private Communication, 5/13/99
Some articles have appeared in scientific journals claiming to have generated self-replicating peptides or RNA strands, but they fail to provide a natural source for their compounds or an explanation of what fuels them.
Scientists in this field are able to demonstrate that
random sequences of RNA sometimes exhibit useful properties. For example, in 1995, a group
of researchers reported "Structurally Complex and Highly Active RNA Ligases Derived
from Random RNA Sequences" (Ligases are enzymes that splice together other
molecules such as DNA or RNA.) The results are interesting—they suggest that
randomness can produce functionality. The authors interpret the results to mean that,
"the number of distinct complex functional RNA structures is very large indeed."
There is a lot to learn about RNA, and research like this is how we learn it. But these
and other similar findings arrived at in highly orchestrated experiments that start with
biologically produced RNA are very far from proving that the RNA world is the pathway
between nonlife and life. In nature, far from the sterilized laboratory, uncontaminated
RNA strands of any size would be unlikely to form in the first place. "... The direct
synthesis of ... nucleotides from prebiotic precursors in reasonable yield and
unaccompanied by larger amounts of unrelated molecules could not be achieved by presently
known chemical reactions" . At present, the gap from the primal
"soup" to the first RNA system capable of natural selection looks
forbiddingly wide.
Kauffman (1996)
Other Theories
In spite of the intense level of work on the RNA world in the last
decade, there is no true consensus theory for precellular life. Here are a few of the many
theories proposed.
One idea is the "PNA world." Because starting the RNA world is so difficult, there probably needs to be a pre-RNA world. PNA, or peptide nucleic acid, might have some of the properties necessary to constitute that world .This would be pre-precellular life.
Even more basic is the "proteins first" school. Manfred Eigen, of the Max Planck Institute, says, "There is no doubt that proteins, which are more easily formed, were first on the scene". Of course, these first proteins must be much shorter than any used in life today, because of the sheer unlikelihood of forming useful long ones out of a soup of amino acids.
A few scientists still say that DNA could succeed in starting life on its way ( But even the shortest DNA strand needs proteins to help it replicate- the chicken-and-egg problem.
Physicist Freeman Dyson solves the chicken-and-egg problem with a double origin, one for metabolism (proteins) and one for replication (strands of nucleotides)
In Seven Clues to the Origin of Life , A. G. Cairns-Smith says that clay crystals could have served as the scaffolding upon which the first short DNA or RNA genome was constructed. A recent elaboration of this idea prompted one writer to title an article, "Primordial soup or crpes?"
Even more recently another tangent on this path leads to
zeolite. Biologists Harold J. Morowitz David Deamer , and others, advocate a theory
that could be paraphrased as "containers first."
From Brig Klyce, "The RNA World," www.panspermia.com/rnaworld.htm
Why be picky about start-up
conditions? Stuart Kauffman of the Santa Fe Institute, says, "...whenever a
collection of molecules contains enough different kinds of molecules, a metabolism will
crystallize from the broth".
Kauffman, a theoretical biologist at the Sante Fe Institute in New Mexico argues that life
forms may exist that have no need of RNA or DNA or any other “aperiodic solid”.
What is more, he says, the emergence of life wasn’t some chance event, but something
that was bound to happen under the conditions of the primitive Earth.
Kauffman argues that the emergence of life on Earth is not the success story of a single type of molecule, such as RNA, slowly evolving to take on the catalytic burden of self-replication. In his view, the process was far more democratic. According to complexity theory, when a system reaches some critical level of complexity, whether it is made of stocks and shares or molecules, it naturally generates a degree of complex order. Likewise, he says, the mundane mix of nucleotides, lipids and amino acids that made up the primordial soup would in one magic instant have become an integrated system as the natural consequence of being part of a chaotic and complex mess.
Under such conditions, he says, self-replicating, “life-like” order is not a chance occurrence, it’s a dead cert. In Kauffman’ view, the modern mnage trois of protein, RNA and DNA is not a conundrum, but a natural consequence of how life began.
He has demonstrated his theory using a computer model of the primordial stew. This shows that when a group of molecules--computer equivalents of simple organics with a few rudimentary catalytic skills--reach a critical level of diversity they spontaneously form an “autocatalytic set”: a molecular cooperative that replicates as a group and evolves to create ever more complicated members. In other words, an autocatalytic set is a life form. What is more, says Kauffman, any sufficiently diverse mix--whether it is of carbon compounds or particles in an intergalactic dust cloud--will form autocatalytic sets, live, and evolve.
True, says Kauffman, RNA and DNA are part of all life today, but they arose as an accessory to an already flourishing ancestral autocatalytic set. Before genes existed, natural selection exerted its forces on the autocatalytic sets, ensuring that they were not biological dead-ends, but living systems capable of evolving to best suit their environment.
But many bench biologists scorn such ideas as cyberfantasy. “It’s a pretty thought,’’ says Gerald Joyce, who studies test-tube evolution at the Scripps Research Institute in San Diego. “But to be convinced, I need to see this autocatalytic gemish.” And there’s the rub. To prove Kauffman’s theory you would need to analyze the contents of a pot in which percolated billions of different organic molecules, identify the autocatalytic entities and isolate them, and put them through their self-replicating cycles. Such an experiment stretches the bounds of what is technically feasible.
After years of trying to persuade the RNA world enthusiasts of the errors of their ways, however, Kauffman says he has gathered allies in biochemistry (he refuses to name names) who are willing to take on that task. He expects results in two to three years.
But in the short-term at least, most biologists say that the RNA world theory will
prevail. Not unnaturally that worries those in opposition such as Woese, Kauffman, and
Wchtershuser. “RNA chauvinism dominates the textbooks,” says Gary Olsen,
Woese’s colleague at the University of Illinois. And that’s a mistake, he warns,
because the RNA world “as a theory it is only partly proven. The rest is speculative
optimism.”
From Phil Cohen, "Let There Be Life," New Scientist (February 7,
1998)
Extraterrestal Studies
On the other hand, Cosmic Ancestry (or panspermia) claims that life on earth was seeded by spores from space and that the genetic programs needed for the evolution of life came from space. What's New in Cosmic Ancestry provides an update on the latest research. With NASA funding this approach will be much in the headlines in the next few years. The NASA astrobiology website paints a more optimistic picture. A National Space Society site provides broad coverage of the field.
Life via Synthesis
A leading genetics researcher has worked out the process to create a synthetic bacterium. Scientists say it is only a short step to the creation of much more complex life forms. This raises the real possibility of synthesizing new species of plants and animals.
Dr
Craig Venter revealed at a US science conference in January 1999 that he planned to investigate
the possibilities of making bacteria using artificial DNA. The production of a written
blueprint for creating a synthetic organism so rapidly will confound skeptics. His
creative plan is based on the simple, little Mycoplasma genitalia, a parasite, which, as
the name suggests, sets up home in human reproductive organs. The parasite has only four
hundred and seventy genes, all told. Venter wants to see whether he can make something
live out of three hundred of them. It offers the potential to make human beings the
creators of other living forms far sooner than expected, possibly just a few years into
the new millennium. The blueprint is now being submitted to Science.
From Toby Moore and Michael Hanlon, "The New Genesis," The Experess
(microedition), 21 September 1999.
For more background on Dr. Venter
and a picture of the politics of genome
research check-out the links.
The view from the inside....
Origin of life scientists are ambivalent about the direction of their work. Scientists of Darwin's day largely felt that any investigation into the origin of the first life was beyond the bounds of science. Emphasis in the earlier period was on the demonstration of alleged cases of spontaneous generation. Careful investigation demonstrated that the cases offered as evidence were suspect due to contamination or faulty experimental method - yet one could completely not rule out the possibility. Even if such an event could be demonstrated, it could not be proof that the first life occurred in that way. Yet - an adherence to a mechanistic bottom-up view of nature would require such an event(s). Robert Shipiro's Origins: A Skeptic's Guide to the Creation of Life on Earth (New York: Summit Books, 1986) offered a perceptive analysis on the previous work. Arthur Ellington offers good insights as a worker in the field.
Today's workers in the field recognize the limits of their work on origin of life chronology and focus on the 'line' between life and none-life as well as evaluate various chronological scenarios
Be sure to check your favorite science news sites regularly for the latest findings. Investigators are seldom bashful!
Papers and Reviews
Bernstein, Max P.; Scott A. Sandford and Louis J. Allamandola. "Molecules from Space"
Scientific American, 281 ( July 1999):41-49.
Christian de Duve, "The Beginnings of
Life on Earth", The American Scientist (September-October 1995).
Henry Gee, "What is life?" Nature (April 22, 1999)
Stewart A. Kaufman, "Self-replication: Even peptides do it," Nature 382 August 8, 1996.
E. Wilson, "Go Forth and Multiply", Chemical and Engineering News (Dec. 7, 1998).
Books
Older
Christoph Adami. Artificial Life (New York: Springer-Telos,
1998).
Andr Brack. The Molecular Origins of Life: Assembling the
Pieces of the Puzzle (New York: Cambridge University Press,
1998).
Julian Chela-Flores and Francois Raulin. "Chemical Evolution:
Physics of the Origins and Evolution of Life," Proceedings of the
4th Trieste Conference on Chemical Evolution, Trieste, Italy,
4-8 September 1995 (Netherlands: Kluwer Academic
Publishers, 1996).
A. G. Cairns-Smith. Seven Clues to the Origin of Life (New
York: Cambridge University Press, 1985).
David W. Deamer and Gail R. Fleischaker. Origins of Life: The
Central Concepts (Boston: Jones and Bartlett Publishers,
1994).
1.Deepak Publ. Prebiological Self-Organization of Matter (A. Deepak Publishing: Hampton, VA 1990) .
Stuart Kauffman. At Home in the Universe: The Search for the
Laws of Self-Organization and Complexity (New York: Oxford
University Press, 1995).
Bernd-Olaf Kppers. Information and the Origin of Life (Cambridge: MIT Press, 1990) .
Noam Lahav. Biogenesis: Theories of Life's Origin (Oxford
University Press, 1998) .
Lynn Margulis and C. Sagan. What is Life? (London:
Weidenfeld and Nicholson, 1995).
H. J. Morowitz. Beginnings of Cellular Life (New Haven, CT:
Yale University Press, 1992) .
Syozo Osawa, Evolution of the Genetic Code (Oxford: Oxford
University Press, 1995).
Rizzoti (ed.): Defining Life (University Padua Press, 1996) .
Periannan Senapathy. Independent Birth of Organisms (Madison: Genome Press, 1994).
Hubert P. Yockey. Information Theory and Molecular Biology,
(Cambridge: Cambridge University Press, 1992).
Geoffrey Zubay. Origins of Life on the Earth and in the
Cosmos (New York: WCB/McGraw Hill, 1996) .