Billions of years ago, the emergence of the first living organisms on Earth may have been made possible by a bolt of thunder from a clear sky – or perhaps a trillion of them.
Researchers said Tuesday that during the first billion years after the planet’s formation, about 4.5 billion years ago, lightning strikes may have released phosphorus needed for the formation of biomolecules essential for life.
The study may provide insight into the origins of Earth’s earliest microbial life – and possibly extraterrestrial life on similar rocky planets. Phosphorus is a vital part of the recipe for life. It forms the phosphate backbone of DNA and RNA, hereditary material in living organisms, and is an important part of cell membranes.
In the early Earth, this chemical element was trapped in insoluble minerals. Until now, it was widely believed that meteorites that bombarded the early Earth were primarily responsible for the presence of “biologically available” phosphorus. Some meteorites contain a phosphoric mineral called schreibersite, which is soluble in water, where life is believed to have formed.
When a bolt of lightning strikes the ground, it can create glassy rocks called fulgurites by overheating and sometimes evaporating surface rock, releasing phosphorus trapped inside. As a result, these fulgurites can contain schreibersite.
The researchers estimated the number of lightning strikes between 4.5 billion and 3.5 billion years ago based on the atmospheric composition of that time and calculated how much schreibersite could result. The upper range was about a trillion lightning strikes and the formation of more than 1 billion fulgurites per year.
Phosphorals released by lightning strikes eventually surpassed the amount of meteorites by about 3.5 billion years ago, about the age of the earliest known fossils widely believed to be those of microbes, they found.
“Lightning strikes, therefore, may have been an important part of the creation of life on Earth,” said Benjamin Hess, a Yale University graduate in earth and planetary sciences and lead author of the study published in the journal Nature Communications.
“Unlike meteorite strikes that decline exponentially over time, lightning strikes can occur at a sustained speed throughout a planet’s history. This means that lightning strikes can also be a very important mechanism to provide the phosphorus needed for life to form on other Earth-like planets after meteorite strikes become rare, ”added Hess.
The researchers examined an unusually large and pristine fulgurite specimen formed when lightning struck the backyard of a house in Glen Ellyn, Illinois, outside of Chicago. This sample illustrated that fulgurites harbor significant amounts of schreiberite.
“Our research shows that the production of bioavailable phosphorus by lightning strikes may be underestimated and that this mechanism provides a continuous supply of material that can provide phosphorus in a form suitable for early life,” said study co-author Jason Harvey. , an associate professor of geochemistry at the University of Leeds.
Among the ingredients considered necessary for life are water, carbon, hydrogen, nitrogen, oxygen, sulfur and phosphorus, along with an energy source.
Scientists believe the earliest bacterial-like organisms originated in Earth’s primal waters, but there is some debate as to when this occurred and whether it unfolded in warm and shallow waters or in deeper waters at hydrothermal vents.
“This model,” Hess said, referring to phosphorus released by lightning, “applies only to the terrestrial formation of life, such as in shallow waters. Phosphorus added to the ocean by lightning strikes would likely be negligible given its size. “