Issued on: Modified:
Paris (AFP)
Lightning strikes may have supplied the original Earth with enough phosphorus to support the creation of life, according to new research Tuesday that provided an alternative explanation for how living organisms were born.
Phosphorus is a vital building block of life as we know it, forming basic cell structures and the double helix form of DNA and RNA.
Billions of years ago on the early Earth, most of the available phosphorus was locked up in insoluble minerals.
However, one mineral, schreibersite, is highly reactive and produces phosphorus that can form organic molecules.
Since most of the schreibersite on Earth comes from meteorites, the origin of life here has long been thought to be related to the arrival of alien rocks.
But schreibersite is also found in the glassy rock formed by lightning strikes in some types of clay-rich soils.
Researchers in the US and Great Britain used state-of-the-art imaging techniques to analyze the amount of phosphorus mineral formed with each lightning strike.
They then estimated how much schreibersite could have been produced in the eons before and around the time of the origin of life on Earth, about 3.5 billion years ago.
“Early Earth lightning strikes may have produced a significant amount of reduced phosphorus,” Benjamin Hess, lead study author of Yale’s Department of Earth and Planetary Sciences, told AFP.
“And by summarizing the best of our knowledge of early Earth conditions, I think our results confirm this hypothesis.”
In the journal Nature Communications, Hess and his colleagues wrote that lightning strikes could have produced between 110 and 11,000 kilograms of phosphorus per year.
Using simulations of the early Earth’s climate, they said that while meteor strikes began to recede after the moon formed 4.5 billion years ago, lightning strikes surpassed the space rock for phosphorus production about 3.5 billion years ago.
That timing coincides with the origin of life.
Hess said the study did not completely disregard meteorites as another source of life-giving phosphorus.
“Meteor impacts around the time of the onset of life are much less than was thought a decade ago,” he said.
“But I don’t see our work as a competition against meteorites as a source of phosphorus. The more sources the better.”
He said he wanted to know if lightning strikes produce traces of phosphorus on other planets where meteor strikes are rare.
“Meteor impacts diminish over time, while lightning, at least on Earth, is relatively constant over time,” added Hess.
© 2021 AFP