The rise of the earth’s first living organisms billions of years ago may have been facilitated by a bolt out of the blue – or perhaps a quintillion of it.
Researchers said on Tuesday that lightning strikes released the phosphorus needed for the formation of biomolecules essential for life during the first billion years after the planet’s formation about 4.5 billion years ago.
The study provides insight into the origins of the Earth’s earliest microbial life – and potential extraterrestrial life on similar rocky planets. Phosphorus is an important part of the recipe for life. It forms the phosphate backbone of DNA and RNA, hereditary material in living organisms, and represents an important component of cell membranes.
In the early earth, this chemical element was trapped in insoluble minerals. Until now, it was generally thought that meteorites that bombed the early Earth were primarily responsible for the presence of ‘bioavailable’ phosphorus. Some meteorites contain the phosphorineral called schreibersite, which is soluble in water, where life is thought to form.
When a lightning bolt hits the ground, it can become glassy rocks called fulgurites by superheating and sometimes evaporating surface rock, which releases phosphorus trapped in it. As a result, these fulgurites may contain schreibersite.
The researchers estimate the number of lightning strikes that range between 4.5 and 3.5 billion years ago, based on the atmospheric composition at the time, and calculate how many schreibersite can cause. The upper range was about a quintillion lightning regions and the formation of more than 1 billion fulgurites annually.
Phosphorinerals due to lightning strikes eventually exceeded the amount of meteorites about 3.5 billion years ago, about the age of the earliest fossils commonly accepted as those of microbes, they found.
“Lightning strikes may therefore have been an important part of the rise of life on Earth,” said Benjamin Hess, a graduate student at Yale University in Earth and Planetary Sciences and lead author of the study, published in the journal Nature Communications. , said.
‘Unlike meteorite impacts that decrease exponentially over time, lightning strikes can occur at a sustained rate throughout the history of a planet. This means that lightning strikes can be a very important mechanism to provide the phosphorus needed for the emergence of life on other Earth-like planets after meteorite impact became scarce, ‘Hess added.
The researchers examined an unusually large and pristine fulgurite sample formed when lightning struck the backyard of a home in Glen Ellyn, Illinois, outside Chicago. This sample illustrates that fulgurites contain significant amounts of schreibersite.
“Our research shows that the production of bioavailable phosphorus by lightning bolts may have been underestimated and that this mechanism provides a continuous supply of material that can supply phosphorus in a form suitable for the introduction of life,” said Jason Harvey, co-author of the study, said. an associate professor of geochemistry at the University of Leeds.
Among the ingredients needed for life are water, carbon, hydrogen, nitrogen, oxygen, sulfur and phosphorus, along with an energy source.
Scientists believe that the earliest bacterial-like organisms originated in the original waters of the earth, but there is a debate about when it occurred and whether it unfolded in warm and shallow water or in deeper waters at hydrothermal vents.
“This model,” Hess said, referring to phosphorus unlocked by lightning, “applies only to the terrestrial formation of life as in shallow waters. Phosphorus added to the ocean due to lightning strikes is likely to be negligible, given its size. ”