The Origins of Life on Earth May Have Been Terrestrial After All

For much of modern science's existence, the question of how life originated on Earth has vexed researchers and scientists alike. One of the most followed theories has been extraterrestrial in nature and has been placed at point in time some 3.9 billion years ago. That was when the orbital patterns of the gas giant planets of the solar system (Saturn and Jupiter) changed and allowed a swarm of comets, asteroids and other small celestial bodies to plunge into the gravitational attraction of the sun.

As these chunks of solar system debris fall toward the sun, they collided with the inner planets and moons that were in their path causing violent collisions that left huge craters in their wake, and in regards to the Earth; the impacts had a devastating effect. The Earth lost its primordial oceans as the surface of our planet was turned into a moltant cauldron of liquefied rock and debris.

With the cessation of the celestial impacts, the Earth cooled and rocks formed a global crust of silicic rocks embedded in a basaltic crustal layer. Oceans quickly formed and weathering produced the first sedimentary rocks worldwide. Protocontenents took early shape from a process of metamorphosis and the melting of accumulated debris. Plate tectonics began to shift the early continental structures and an atmosphere made up mostly of nitrogen, with some carbon dioxide, ammonia, methane, and water took shape.

The combination of all of these materials and ingredients could have possibly resulted in the formation of organic molecues. And amazingly life began to stir some 3.85 billion years ago when primitive single-celled bacteria appeared. This startling development has lead intrigued observers of the Earth's past in deep time to question how and why life was able to develop so quickly.

Although scientists feel comfortable with the time frame for the development of life outlined above, they have been unable or unwilling to agree on the source of the organic molecules that came together to form life. Leading the proponents that suggest that life had extraterrestrial origins has been such noteworthy scientists such as Francis Crick who is credited with discovering the structure of DNA. These theories have developed because there has yet to exist a plausible explanation that links the formation of life on Earth to terrestrial sources.

Among those who have worked to discover a terrestrial origin to life; recent developments have surfaced that give plausible reasons why Earth is where the origin of life occurred and break down into four component parts.

The first part of this terrestrial theory concerns the existence of fatty chemicals available on our primordial world and their relationship to the co-development of a 'genetic system' and a 'cell membrane.' Researcher Jack W. Szostak, according to the New York Times, discovered that "(s)imple fatty acids, of the sort likely to have been around on the primitive Earth, will spontaneously form double-layered spheres, much like the double-layered membrane of today’s living cells. These protocells will incorporate new fatty acids fed into the water, and eventually divide. Living cells are generally impermeable and have elaborate mechanisms for admitting only the nutrients they need. But Dr. Szostak and his colleagues have shown that small molecules can easily enter the protocells. If they combine into larger molecules, however, they cannot get out, just the arrangement a primitive cell would need. If a protocell is made to encapsulate a short piece of DNA and is then fed with nucleotides, the building blocks of DNA, the nucleotides will spontaneously enter the cell and link into another DNA molecule."

David P. Bartel and P. Luigi Luisi, the other two main researchers along with Jack W. Szostak according the New York Times explained "that the way to make a synthetic cell was to get a protocell and a genetic molecule to grow and divide in parallel, with the molecules being encapsulated in the cell. If the molecules gave the cell a survival advantage over other cells, the outcome would be" as they described in a Nature article of 2001 “a sustainable, autonomously replicating system, capable of Darwinian evolution.” The researchers went on to say: “It would be truly alive.”

The New York Times explains that: "Dr. Szostak’s experiments have come close to creating a spontaneously dividing cell from chemicals assumed to have existed on the primitive Earth. But some of his ingredients, like the nucleotide building blocks of nucleic acids, are quite complex. Prebiotic chemists, who study the prelife chemistry of the primitive Earth, have long been close to despair over how nucleotides could ever have arisen spontaneously.

"Nucleotides consist of a sugar molecule, like ribose or deoxyribose, joined to a base at one end and a phosphate group at the other. Prebiotic chemists discovered with delight that bases like adenine will easily form from simple chemicals like hydrogen cyanide. But years of disappointment followed when the adenine proved incapable of linking naturally to the ribose.

"Last month, John Sutherland, a chemist at the University of Manchester in England, reported in Nature his discovery of a quite unexpected route for synthesizing nucleotides from prebiotic chemicals. Instead of making the base and sugar separately from chemicals likely to have existed on the primitive Earth, Dr. Sutherland showed how under the right conditions the base and sugar could be built up as a single unit, and so did not need to be linked.

"Once a self-replicating system develops from chemicals, this is the beginning of genetic history, since each molecule carries the imprint of its ancestor. Dr. Crick, who was interested in the chemistry that preceded replication, once observed, “After this point, the rest is just history.”"

Another step in the process of understanding of how terrestrial life developed from earthly origins has been made by Gerald F. Joyce of the Scripps Research Institute in La Jolla, California who stands as a preeminent expert life's origin on Earth. Among a number of accomplishments, Dr. Joyce has most recently worked with RNA; investigating it's capacity for reproduction. In a major article in Science, Joyce announced his development of two RNA molecules that assisted each other's synthesis from the four neucleotides that constitute RNA. Joyce reacted to his acomplishment by exclaming that: “We finally have a molecule that’s immortal,” since the information has an indefinite timeframe for indefinitely passing on instructions. And even though his synthetic system is not alive it can mimic life functions such as self replication and adapting to the environment.

The New York Times explains: "Another striking advance has come from new studies of the handedness of molecules. Some chemicals, like the amino acids of which proteins are made, exist in two mirror-image forms, much like the left and right hand. In most naturally occurring conditions they are found in roughly equal mixtures of the two forms. But in a living cell all amino acids are left-handed, and all sugars and nucleotides are right-handed.

"Prebiotic chemists have long been at a loss to explain how the first living systems could have extracted just one kind of the handed chemicals from the mixtures on the early Earth. Left-handed nucleotides are a poison because they prevent right-handed nucleotides linking up in a chain to form nucleic acids like RNA or DNA. Researchers such as: "Donna Blackmond of Imperial College London have discovered that a mixture of left-handed and right-handed molecules can be converted to just one form by cycles of freezing and melting.

The New York Times explains: "With these four recent advances — Dr. Szostak’s protocells, self-replicating RNA, the natural synthesis of nucleotides, and an explanation for handedness — those who study the origin of life have much to be pleased about, despite the distance yet to go. “At some point some of these threads will start joining together,” Dr. Sutherland said. “I think all of us are far more optimistic now than we were five or 10 years ago.”

"One measure of the difficulties ahead, however, is that so far there is little agreement on the kind of environment in which life originated. Some chemists, like Günther Wächtershäuser, argue that life began in volcanic conditions, like those of the deep sea vents. These have the gases and metallic catalysts in which, he argues, the first metabolic processes were likely to have arisen.

"But many biologists believe that in the oceans, the necessary constituents of life would always be too diluted. They favor a warm freshwater pond for the origin of life, as did Darwin, where cycles of wetting and evaporation around the edges could produce useful concentrations and chemical processes."

The origin of life on Earth may forever remain an inexact proposition spread across millions of years. The most ancient evidence of fossilized bacteria has been found in the Gunflint Formation of Ontario and is estimated to be some 1.9billion years old. There also exist rock formations in Greenland that contain evidence of carbon isotopes related to 3.830 billion years old biological processes. Researchers are convinced that the 'late heavy bombardment' of celestial bodies could have left some life untouched and that is what accounts for the wide span of time across which evidence of life has been found.

The new York Times reports: "Recent evidence from very ancient rocks known as zircons suggests that stable oceans and continental crust had emerged as long as 4.404 billion years ago, a mere 150 million years after the Earth’s formation. So life might have had half a billion years to get started before the cataclysmic bombardment."

The conclusion drawn by the New York Times is that: "Chemists and biologists are thus pretty much on their own in figuring out how life started. For lack of fossil evidence, they have no guide as to when, where or how the first forms of life emerged. So they will figure life out only by reinventing it in the laboratory."

Dangerous levels of E. Coli Found in 500 Mile Stretch of the Ohio River

Bob Driehaus reports from Cincinnati for the New York Times that: "Six states bordering the Ohio River are joining the Environmental Protection Agency in the largest study of its kind to identify and reduce dangerous levels of bacteria that plague the waterway. Unsafe levels of fecal coliform, or E. coli, have been identified in about 500 miles of the 981-mile river, which stretches from Pittsburgh to the Mississippi River at Cairo, Ill.

The E. coli, or fecal coliform is a bacteria that provides indications for researchers that human and or animal sewage contaminants have entered the waterway and often indicates the presence of other possible disease causing bacteria or viruses that exist in the fecal material. The fecal material can enter the water by one of several methods; by the direct release from birds or mammals, from farm runoffs and or as a result of precipitation from heavy storms, and or from possible overflows caused by home owner's septic systems. Diseases caused by the water propagated bacteria and viruses can comprise outbreaks of dysentery, infections of the ear, stomach flu or bacterial gastroenteritis, typhoid fever, viral and hepatitis A and generally affects humans more often than aquatic life.

Mr. Driehaus reports that: "The pathogens can sicken swimmers and others who come in close contact with the water. The river also provides about five million people with drinking water, including residents of Cincinnati, Louisville, Ky., and the suburbs of Pittsburgh, though typical bacteria levels do not pose a threat to safely treating the water."

The E.P.A. "analysis, which officials plan to finish next year, will identify how much bacteria sewage treatment plants, factories and farms, among others, can discharge into the river without exceeding safety standards," Mr. Driehaus reports. The states that are facing possible pathogenic pollution risks, are "Kentucky, Illinois, Indiana, Ohio, Pennsylvania and West Virginia ..., as well as the Ohio River Valley Water Sanitation Commission, which has collected weekly water samples during the recreational season, May through October, since 1992," according to the Times. Mr. Driehaus continues his reporting by explaining that: "According to the E.P.A., carrying out the recommendations of a similar study led to the restoration of healthy oxygen levels in the Middle Cuyahoga River in northeastern Ohio through the removal of one dam and modification of another. After another study, oyster harvesting was revived in Lynnhaven Bay in Virginia after bacteria pollution caused by boaters, sewer systems, farms and pet waste was reduced. But cleaning up the Ohio poses a much bigger challenge because its watershed spans seven states and covers 204,000 square miles."

Mr. Driehaus reports that it is common knowledge that: "In 49 cities and towns, combined sewer and storm water systems release untreated sewage directly into the river during heavy rains. Upgrading those systems will cost billions of dollars, officials said, and federal regulations require sewage treatment plant operators to assemble long-term improvement plans, which will be taken into consideration in the new study."

Mr. Driehaus adds: "Runoff of manure used as fertilizer and waste from animal farms, referred to as nonpoint-source pollution, are also major bacteria contributors. The E.P.A. and the states have little authority to force farmers to change their practices, and the study cannot mandate changes to farms." E.P.A. coordinator for West Virginia, David Montali remarked that: "Everybody recognizes the need to reduce the bacteria levels," adding his inability to guarantee if the proposed report will “be a driving force to make things happen.”

The Times includes the opinion of "Kevin Kratt, a project manager with Tetratech, a private firm that was hired as a consultant, (who) said he hoped the study’s wealth of new information on pollution sources would enable the E.P.A. and the states to better focus money on projects that yield the biggest improvements in water quality." Mr. Kratt added: “The publicity generated may drive some nonpoint-source improvements as well.”

Also adding her opinion, as reported by Mr. Driehaus was: "Jennifer Clark, an environmental protection specialist in Illinois, (who) said the study’s intention was “to get people on board and aware that it needs to be dealt with.” Ms. Clark concluded by stating her belief that: “A lot of people want to choose a smaller watershed because it would be easier,... but we need to hit this on the head and find out our biggest problems and where we can make a difference.” With rising population levels in the six state region added to the increasing possibility for greater fecal coliform contamination, the E.P.A. study should yield valuable information that can help local, state and federal officials make decisions that will effect millions of people. The question remains, however, how such a massive cleanup will be funded?