Early life may have formed between a rock and a wet place.
Floating rafts of lava rock had the right conditions to nurture life as it emerged from the primordial ooze of chemicals in the Earth's early oceans. Researchers from the University of Oxford in England suggest lava rock, or pumice, had four special qualities that may have made it the cradle of life.
1. Only the cruelest of mothers would put her baby in a lava rock cradle. But for Mother Nature, the sharp nooks and crannies of lava rock that torture bare feet also made the rock a great shelter for the chemical reactions that led to life. The many crevices provide a large surface area compared to the volume of the rock.
2. Pumice “is the only known rock type that floats as rafts at the air-water interface and then becomes beached in the tidal zone for long periods of time,” wrote the researchers in the journal Astrobiology.
Wading near the beaches of the early Earth would create a mix of water, solids and air from which the building blocks of life could be drawn. Plus, like a modern day beach-goer, the chemical soup would be soaking up the sun, giving it a dose of UV radiation, which could have caused chemical reaction leading to more complex organic chemicals and eventually life.
3. As they floated on the surface of the sea and bumped into the shore, the lava rock was exposed to a wide variety of conditions, including lightning strikes and dehydration. The changing conditions could have fostered chemical reactions leading to life.
4. “Finally, from rafting to burial, it (pumice) has a remarkable ability to adsorb metals, organics, and phosphates as well as to host organic catalysts such as zeolites and titanium oxides,” wrote the researchers.
Metals, organics, and phosphates are the construction materials for building life. The organic catalysts are the tools and workers that get the job done faster than it would happen randomly.
The researchers' hypothesis is readily testable, they wrote. The first step is to scrutinize rocks formed from what were once floating rafts of pumice for fossilized signs of early life.
The next step is to recreate the conditions of early earth, add lava rocks and see what happens.
The results may reveal that from the very beginning it was a hard rock life for us.
Pumice raft near Tonga Islands, taken by NASA Earth Observatory. (Wikimedia Commons)
Pumice is a term for a volcanic rock that is a solidified frothy lava typically created when super-heated. (Wikimedia Commons)
Diagram showing how some of the key components for abiogenesis could have occurred simultaneously along volcanic shorelines associated with abundant pumice and scoria clasts. (CREDIT: Astrobiology)