Texas Tech Today reports that Texas Tech University Paleontologist Dr. Sankar Chatterjee is presenting what he calls the “Holy Grail of science” to the 125th Anniversary Annual Meeting of the Geological Society of America in Denver today (October 30/13), addressing the topic of how life began on planet Earth. New research by Dr. Chatterjee suggests that it may have rained from the skies and erupted from the bowels the Earth.
Dr. Chatterjee, who is curator of paleontology at the Museum of Texas Tech University and a Horn professor in the Department of Geosciences in the university’s College of Arts and Sciences, believes he has found the answer by connecting theories on chemical evolution with evidence related to our planet’s early geology. “This is bigger than finding any dinosaur,” Dr. Chatterjee comments in a Texas Tech release. “This is what we’ve all searched for – the Holy Grail of science.”
Dr. Chatterjee suggests that large craters formed by regular and heavy comet and meteorite bombardment of Earth’s surface during its formative stage some 4 billion years ago, not only collected water and the basic chemical building blocks for life, but also became the perfect crucible in which the constituent chemicals that created the first simple organisms could concentrate and mingle.
Dr. Chatterjee discovered the Shiva Meteorite Crater, which was created by a 25-mile-wide meteorite that struck off the coast of India. His research concluded this giant meteorite wreaked havoc simultaneously with the Chicxulub meteorite strike near Mexico, finishing the dinosaurs 65 million years ago.
Dr. Chatterjee conducted a 10-year study using geophysical evidence and core samples collected by oil companies to reconstruct the Shiva Crater – a massive 300-mile-wide pock mark with a 3-mile peak as high as Mount McKinley. Though the actual crater is covered by more than five miles of sediment, Chatterjee says the geological evidence he collected allowed him to map out the crater. He presented his findings at the 2009 Annual Meeting of the Geological Society of America in Portland, Oregon.
However, Dr. Chatterjee’s latest research casts meteorites as givers of life as well as killers. His theory is that that meteor and comet strikes likely brought the ingredients and created the right conditions for life to form on our planet, and by studying three sites containing the world’s oldest fossils, he believes he’s discovered how the first single-celled organisms formed in hydrothermal crater basins.
“When the Earth formed some 4.5 billion years ago, it was a sterile planet inhospitable to living organisms,” Chatterjee is cited noting. “It was a seething cauldron of erupting volcanoes, raining meteors and hot, noxious gasses. One billion years later, it was a placid, watery planet teeming with microbial life – the ancestors to all living things.”
Dr. Chatterjee’s theory suggests that as basins created by meteorite and come strikes filled, volcanically driven geothermal vents heated the water creating convection and constant water movement, stirring a thick primordial soup, and that life began in four steps of increasing complexity – cosmic, geological, chemical and biological.
In the cosmic stage, the still-forming Earth took a daily pounding from rocky asteroids and icy comets between 4.1 to 3.8 billion years ago. While plate tectonics, wind and water have hidden evidence of this early onslaught, ancient craters on the surfaces of Mars, Venus, Mercury and the moon provide evidence of how heavy these meteorite showers once were. The larger meteorites that created impact basins some 350 miles in diameter thus became the perfect crucibles in which life could form, he observes. Some meteorites also penetrated the Earth’s crust, creating volcanically driven geothermal vents and carried the basic building blocks of life that could be concentrated and polymerized in the crater basins.
Based on his study of the environments of the oldest fossil-containing rocks on Earth in Greenland, Australia and South Africa, Dr. Chatterjee concludes that they could be remnants of ancient craters and possibly the very spots where life began in deep, dark and hot environments, and because of the Earth’s particular proximity to the sun, comets that crashed here melted into water, filling these basins with water and other life constituents. Then began the geological stage, with geothermal venting heated the water and created convection, with constant water mixing and constituent stirring.
“The geological stage provides special dark, hot, and isolated environments of the crater basins with the hydrothermal vent systems that served as incubators for life,” Dr. Chatterjee says in the TTU release. “Segregation and concentration of organic molecules by convective currents took place here, something like the kinds we find on the ocean floor, but still very different. It was a bizarre and isolated world that would seem like a vision of hell with the foul smells of hydrogen sulfide, methane, nitric oxide and steam that provided life-sustaining energy.”
The geological stage was followed by the chemical stage, in which the heat-churned water in the craters mixed chemicals together and caused simple compounds to grow into larger, more complex ones. Eventually, the first life forms left the confines of the crater and ventured into the newly formed oceans.
Dr. Chatterjee suggests that most likely, pores and crevices on the crater basins acted as scaffolds for concentrations of simple RNA and protein molecules, contradicting a popular theory maintaining that RNA came first and proteins followed. Dr. Chatterjee believes RNA and proteins emerged simultaneously and were encapsulated and protected from the environment, noting that “The dual origin of the ‘RNA/protein’ world is more plausible in the vent environments than the popular ‘RNA world. RNA molecules are very unstable. In vent environments, they would decompose quickly. Some catalysts, such as simple proteins, were necessary for primitive RNA to replicate and metabolize. On the other hand, amino acids, from which proteins are made, are easier to make than RNA components.”
The question still remains as to how loose RNA and protein material floating in this soup protected itself in a membrane. Dr. Chatterjee refers to University of California professor David Deamer’s hypothesis that membranous material existed in the primordial soup. Deamer isolated fatty acid vesicles from the Murchison meteorite that fell in 1969 in Australia. The cosmic fatty bubbles extracted from the meteorite mimic cell membranes. Dr. Chatterjee suggests that “Meteorites brought this fatty lipid material to early Earth,” where it not only floated on top of the water surface of crater basins but also was moved to the bottom by convection currents. He deduces that: “At some point in this process during the course of millions of years, this fatty membrane could have encapsulated simple RNA and proteins together like a soap bubble. The RNA and protein molecules begin interacting and communicating. Eventually RNA gave way to DNA – a much more stable compound – and with the development of the genetic code, the first cells divided.”
Finally Dr. Chatterjee says, the chemical stage was superseded by the biological stage in which replicating cells began to store, process and transmit genetic information to their daughter cells. Infinite combinations took place, and countless numbers of them must have failed to function before the secret of replication was broken and the proper selection occurred. “These self-sustaining first cells were capable of Darwinian evolution,” he contends. “The emergence of the first cells on the early Earth was the culmination of a long history of prior chemical, geological and cosmic processes.”
Dr. Chatterjee also believes that modern RNA-viruses and protein-rich prions that cause deadly diseases probably represent the evolutionary legacy of primitive RNA and protein molecules, and may be the oldest cellular particles that predated the first cellular life. Once cellular life evolved, RNA-viruses and prions became redundant, but survived as parasites on the living cells.
The problem with theories on the origins of life is that they don’t propose any experiments that lead to the emergence of cells, Chatterjee observes, suggesting an experiment to recreate the ancient prebiotic world and support or refute his theory and noting “If future experiments with membrane-bound RNA viruses and prions result in the creation of a synthetic protocell, it may reflect the plausible pathways for the emergence of life on early Earth.”
Texas Tech Today
Texas Tech Today
Texas Tech University