Theoretical origin of life; in hot puddles on land (Introduction)

by David Turell , Thursday, July 20, 2017, 21:59 (2683 days ago) @ David Turell

A study of Western Australia stromatolites from 3.5 billion years ago:

https://www.sciencedaily.com/releases/2017/07/170718142900.htm

"what Djokic discovered amid the strangling heat and blood-red rocks of the region was evidence that the stromatolites had not formed in salt water but instead in conditions more like the hot springs of Yellowstone.

"The discovery pushed back the time for the emergence of microbial life on land by 580 million years and also bolstered a paradigm-shifting hypothesis laid out by UC Santa Cruz astrobiologists David Deamer and Bruce Damer: that life began, not in the sea, but on land.

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"In Deamer's vision, ancient Earth consisted of a huge ocean spotted with volcanic land masses. Rain would fall on the land, creating pools of fresh water that would be heated by geothermal energy and then cooled by runoff. Some of the key building blocks of life, created during the formation of our solar system, would have fallen to Earth and gathered in these pools, becoming concentrated enough to form more complex organic compounds.

"The edges of the pools would go through periods of wetting and drying as water levels rose and fell. During these periods of wet and dry, lipid membranes would first help stitch together the organic compounds called polymers and then form compartments that encapsulated different sets of these polymers. The membranes would act like incubators for the functions of life.

"Deamer and his team believe the first life emerged from the natural production of vast numbers of such membrane-encased "protocells."

"While there is still debate about whether life began on land or in the sea, the discovery of ancient microbial fossils in a place like the Pilbara shows that these geothermal areas -- full of energy and rich in the minerals necessary for life -- harbored living microorganisms far earlier than believed.

"For Damer, the new "end-to-end hypothesis" of how life began on land offers something else: that the origin of life was not just a simple story of individual, competing cells. Rather that a plausible new vision of life's start could be a communal unit of protocells that survived and evolved through collaboration and sharing of innovation rather than strict competition."

Comment: how innovation happened is not explained. But it certainly shows how early life appeared on Earth.