Is the Origin of Life in Soil?
with Greg Retallack, PhD, professor of geology at the University of Oregon
The oldest theory for the origin of life, recorded in 4,000 year-old Sumerian cuneiform, is that life was created from soil. Theories of life’s origin in the ocean have also long been popular, including Charles Darwin’s “warm little pond” and Alexander Oparin’s “primeval soup”. Discovery of deep-sea black smokers and their extraordinary life forms has also encouraged the view of hot springs as cradles of life. So what was it: soil, soup or spa?
Soil origins have seemed unlikely because of a lack of evidence for life on land of the early Earth. Newly discovered evidence for life in ancient soils by Greg Retallack of the University of Oregon now opens the possibility that we are after all just soils grown tall. Oceans and hot springs present unlimited supplies of the universal solvent, which dissolves complex organic molecules. Soils however offer a metered supply of nutrients and water, as well as clay and organic colloids which are naturally selected to resist erosion, and steep redox gradients and metals for complex molecular assembly.
Greg Retallack is a professor in the department of geological sciences at the University of Oregon. His doctoral degree was from the University of New England in Australia, and he completed a post-doc at Indiana University before coming to Oregon. His research is dedicated to the study of paleosols: ancient soils buried with fossils in sedimentary and volcanic sequences of the geological past. Paleosols provide new insights into major events in the history of life on land, such as early human evolution in East Africa, major extinctions of life, and evolution of the first forests. In recent years he has found evidence of life in many paleosols predating the Cambrian explosion of life, especially in very ancient rocks of South Africa and Western Australia.
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