Posted on 01/10/2004 8:05:30 AM PST by PatrickHenry
GAINESVILLE, Fla. --- Researchers at the University of Florida say they have shown that minerals were key to some of the initial processes that formed life on Earth. Specifically, a borax-containing mineral known as colemanite helps convert organic molecules found in interstellar dust clouds into a sugar, known as ribose, central to the genetic material called RNA. This announcement provides a key step toward solving the 3-billion-year-old mystery of how life on Earth began. The findings will appear in Friday's issue of the journal Science. Steven Benner, Alonso Ricardo, Matthew Carrigan and Alison Olcott built on a famous experiment done 50 years earlier by Stanley Miller that is found in many textbooks. In 1953, Miller showed that electric sparks in a primitive atmosphere made amino acids, the building blocks of proteins.
Miller's experiment failed to identify sugars that were needed for genetic material, however. "The sugar ribose can be formed from interstellar precursors under prebiotic conditions," said Benner, who led the research funded by NASA, the National Science Foundation and The Agouron Institute in Pasadena, Calif. "But ribose is too unstable to survive under Miller's conditions." Ribose, like most sugars, turns into tar if not handled carefully. "It is like baking a cake too long," said Benner, a UF distinguished professor of chemistry and anatomy and cell biology. In 1995, Miller gave up trying to make ribose prebiotically, writing: "The first genetic material could not have contained ribose or other sugars because of their instability."
Benner, who also is a member of NASA's Astrobiology Institute, did the first experiments as an instructor at an international geobiology course last summer funded by the Agouron Institute and held at the University of Southern California Wrigley Institute for Environmental Studies. "We asked two questions. First, what simple organic molecules might have been present on early Earth as starting materials to form ribose? Then, what might have been present on early Earth to capture ribose and keep it from burning up like overcooked cake?" Benner said.
To identify simple organic molecules that might be the starting materials, Benner turned to compounds known to exist in interstellar dust, such as formaldehyde, used to preserve tissue. "Formaldehyde may not seem to be a good starting point for the life that we know," he said. "But it is simple. With only one carbon atom, one oxygen atom and two hydrogen atoms, there is a lot of formaldehyde to work with in the cosmos."
Benner and his team showed that formaldehyde, with other interstellar compounds, could form ribose and other sugars when treated in the presence of base materials such as lime, a material used to adjust the pH level of lawns, among other things. Lime was effective, but the ribose decomposed soon after it was formed.
Recognizing that ribose had a particular chemical structure that allowed it to bind to minerals containing the element boron, they turned to another substance called colemanite. "Colemanite is a mineral containing borate found in Death Valley," he said. "Without it, ribose turns into a brown tar. With it, ribose and other sugars emerge as clean products." Benner then showed similar reactions with other borate minerals, including ulexite and kernite, which is more commonly known as borax.
Benner and his team are the first researchers to succeed in making significant amounts of ribose under these early conditions.
Joseph Piccirilli, a biological chemist at the Howard Hughes Medical Institute and the University of Chicago, said Benner's work "has simplicity and brilliance."
"Organic chemists have long known that borate complexes with compounds like ribose," Piccirilli said, "and prebiotic scientists have long believed that minerals on the early Earth played an important role in the origin of life." Until now, "no one has put the two ideas together," he said.
"We are not claiming that this is how life started," Benner stressed. "We are saying that we have demonstrated a recipe to make a key part of life without any biochemical machinery. The more recipes of this type that can be found, the more clues we have about how life could have actually gotten started on the primitive Earth."
While best classified as basic science, the work has practical biological and medical value. "Curiously, thinking about how life originated and what form it might take on other planets helps us design new tools for disease diagnostics and therapy," Benner said. Diagnostic tools enabled by Benner's work seeking alternative life forms are used today in the clinic to monitor the load of the viruses that cause AIDS and hepatitis C.
The work also complements other research Benner is conducting that focuses on ancient forms of life on Earth. In a September report in Nature, Benner and his collaborators deduced the structure of a protein found in a bacterium that lived several billion years ago and resurrected the ancient protein. By studying it in the laboratory, the group inferred the ancient bacteria lived in a hot spring at about 150 degrees Fahrenheit.
With the prebiotic experiments, Benner said, "we are working forward in time, from the origin of the planet to the first life. With experiments with ancient proteins, we work backwards in time, from the modern world to the most primitive of bacteria." The group's goal, he said, is to have the two meet in the middle.
I see your knowledge of the prophets and the writings is extensive. I have often wondered about those rascals myself. Could you elaborate on the manipulative behavior of Elijah, Daniel, Isaiah, Ezekiel, Jeremiah and John the Baptist for me?
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The scientific method requires that a hypothesis be refutable, not circular. "Survival of the fittest" is circular, because essentially "fittest" is defined by its own survival.
Evolution is circular? The process of adapting to changing environments leading to natural selection is a linear process that leads to divergent forms over many generations.
Circular reasoning is main pillar of theology. I seem to recall the " I think, therefore I am" philosopher Descartes deduced the existence of God because only God could put that idea in his head.
Aw come on. Have you ever seen an urban riot in the middle of winter during a frigid spell? Heat drives people mad. Look what it'd doing to the Arabs, Persians, Javanese, and the rest of the lunatics living in the sun drenched mid east.
I see. Have you shared this concern with the editors of "Science" and "Nature" and the directors of the Franklin Institute, as yet?
The scientific method requires that a hypothesis be refutable, not circular.
These are not polar opposites. What does it mean for a scientific argument to be "circular"?
"Survival of the fittest" is circular, because essentially "fittest" is defined by its own survival.
Much as "tuned" is defined by a Tv set being in legible adjustment. I fail to understand what is circular here. Are you suggesting that because humans have survived, and humans invented, or discovered, the concept of Darwinian evolution, that there is a circular argument here? If Darwin had been a dodo bird, would that resolve the difficulty for you?
On the other hand, at least it can be confirmed or refuted whether particular catalysts can aid in the formation of biological materials, although it's still a big leap of faith to the larger hypothesis.
However, it's not such a great leap of faith to realize that if biological materials can be produced abiologically, than natural abiogensis has to remain on the table as a possibility.
That's really very funny. But Reagan would have been the first to admit that he was probably that old.
The two most famous cases of church repression and murder for holding scientific beliefs are those of Galileo [which I presume I won't need to cite], and Giordano Bruno, I couldn't even hazard a guess as to the net body count.
Was it really that bad or is it worse than any of us realize?
How many people have to be burned at the stake for their heretical opinions, for it to be "really that bad?"
Well then, it's a good thing that proof has nothing whatever to do with natural science. It's a viable theory, like all scientific theories.
How do we know that the fittest survive? We don't. We assume that whatever survives must be the defacto fittest, because we believe in and to some extent see evidence that it's a dog eat dog world. Logic would say that only the fittest survive. But what if they don't?
We know the fittest survive because that is how we define "fittest" for scientific purposes. Noodling around about the actual, transcendental meaning of the word "fittest" is about as silly a ploy as I've seen anytime lately.
Likewise, the fact that there is little significant selection pressure on humans in the 21st century [as yet] is hardly a signficant refutation of darwinian evolutionary theory. It is, in fact, just about totally irrelevant.
Yes, but there are so many other variables that play into survival. I agree the principle exists to an extent. Certain animals may be better suited to survive an unusual cold spell or change in environment.
But will that always strenghen the species? That I don't know. It might lead to extinction.
When I was about 4-5 I was with a group of kids playing Daniel Boone in the woods next door when my brother hatcheted a vine that just happened to be a yellow jacket nest. The older kids took off for the house yelling "bees" and I trailed behind. However the bees went after the fastest kids, slownest was a survival trait. I was stung less than anybody because I was younger and slower.
Apparently I was more fit than the older faster kids for an environment with bees that tend to attack the fastest kids.
Which illustrates the point about how many variables there are. Fitness for a "given environment" does not always lead to survival of the "best" specimens. There are senarios where natural selection can have a negative potentially devastating impact on a species. The protective behavior of herds may allow faulty genes to be replicated.
Then again perhaps it was randomness or providence that the bees went after the older kids. Survival of the Fittest is logical but is it even significant relative to luck or providence or other external environmental issues?
Even if it is significant, it's still doubtful in my mind that even given millions or billions of years, it would lead to the development of new functioning organs or transition between species, especially in those species whose gene pools are stabelized by male/female mating.
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