By Didier Descouens – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=15944367
A new study may turn the answer of where did life begin upside down. Previous studies and experimentation have suggested simple organic molecules are the building blocks of life and could have been synthesized in the atmosphere of early Earth and rained down into the oceans. A new study paper by Tara Djokic, a Ph.D. student at the University of New South Wales Sydney, focuses on stromatolites that were discovered there in the 1970s and represent the oldest evidence that there were living organisms on Earth 3.5 billion years ago. Stromatolites are sheet-like sedimentary rocks, that were originally formed by the growth of layer upon layer of cyanobacteria. Cyanobacteria are the simplest form of modern carbon-based life and were one of the only forms of life on Earth for the first 2 billion years.
Scientists who subscribe to the “life began in the ocean” theory thought Stromatolites had formed in shallow, salty seawater. But what Djokic discovered in 3 years of exploring the Pilbara region of Western Australia, was evidence that the stromatolites first formed in conditions more like the hot fresh water springs of Yellowstone.
While the debate will likely still continue about whether life began on land or in the sea, this new discovery sets time back for the emergence of microbial life on land by 580 million years. The study also supports the paradigm-shifting assertion spelled out by UC Santa Cruz astrobiologists David Deamer and Bruce Damer, in the paper: A Field Trip to the Archaean in Search of Darwin’s Warm Little Pond. The UC Santa Cruz team hypothesized that life began, not in the sea, but on land in geothermal areas. According to Deamer and his colleagues, this discovery by Djokic, combined with their own research should change our focus on the search for life on other planets to land. Specifically using Mars as an example, which is known to have a 3.65-billion-year-old hot spring deposit similar to geothermal areas on Earth, would be a good place to start exploring first.
