Arizona State University geochemist Lynda Williams and her colleagues have discovered that certain clay minerals under conditions at the bottom of the ocean may have acted as incubators for the first organic molecules on Earth.
Williams' research suggests how some of the fundamental materials necessary for life might have come into existence deep in the sea. The results of Williams' experiments were published in the article, "Organic Molecules Formed in a Primordial Womb," in the November issue of Geology.
Williams and her team mimicked the conditions found in hydrothermal vents along the lines where tectonic plates converge on the ocean floor. The vents are fissures in the seafloor that spew out super-hot water much like an underwater volcano.
From earlier work, the researchers knew that with high enough temperatures and pressure, volcanic emanations could produce the chemical compound methanol. What scientists did not know was how the methanol could survive intense temperatures of 300 to 400 C.
"When I first heard that, I thought, 'that's strange,'" Williams said of the methanol formation. "Methanol is supposed to break down at those temperatures. I asked myself, 'what can protect it?' The answer is common clay minerals."
Williams hypothesized that the expandable clay surrounding the hydrothermal vents might have served as a "primordial womb" for infant molecules, sheltering them within its mineral layers. She devised an experiment that would test whether the organic compound methanol would be protected between the clay layers.
Williams and her team simulated the intense heat and pressure of the ocean floor within a pressurized vessel. The reaction of the clay and methanol was monitored over six weeks. The team found that the expandable clay not only protected the methanol, but also promoted reactions that formed even more complex organic compounds. The mineralogical reaction between the clay and methanol was facilitating the production of new organic material.
Scientists theorize that the diverse organic molecules protected within the clay might eventually be expelled into an environment more hospitable to life, leading to an "organic soup." What makes the finding so exciting is that the experimental conditions reflect scientists' best estimations of the simplest conditions that likely existed when life began, Williams said.
"This research tells us that as long as there is water and the right chemical ingredients, common clay minerals can help produce the ingredients for biomolecules (chemical components used by living organisms)," Williams said.
Because the reactions simulated in these experiments can be found anywhere volcanic activity exists, Williams added, it is likely that similar organic compounds could be produced on other volcanically active planets that have water. Additional experiments are planned to find out what chemical conditions would be required to form the building blocks of life.
"We have only started investigating the influence of clays on the origin of life," Williams said.
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