Lightning Strikes Played Role in Creating Prebiotic Phosphorus on Early Earth, Study Suggests
Phosphorus is one of the key elements for life, involved in biomolecules such as DNA, RNA, phospholipids, and adenosine triphosphate. Phosphide minerals — such as the mineral schreibersite — delivered to early Earth in meteorites have been advocated as a main source of prebiotic phosphorus. Planetary scientists believed minimal amounts of these minerals were also brought to our planet through billions of lightning strikes. But now a team of researchers from the University of Leeds and Yale University has established that lightning strikes were just as significant as meteorites in performing this essential function.
An illustration of early Earth, as it would have looked around 4 billion years ago. Image credit: Lucy Entwisle.
In the study, Yale University Ph.D. student Benjamin Hess and colleagues examined an exceptionally large and pristine sample of fulgurite.
The sample was formed when lightning struck a property in Glen Ellyn, Illinois, the United States, in 2016.
The scientists were initially interested in how fulgurite is formed but were fascinated to discover in their sample a large amount of schreibersite.
The phosphorous present on early Earth’s surface was contained in minerals that cannot dissolve in water, but schreibersite can.
“Many have suggested that life on Earth originated in shallow surface waters, following Darwin’s famous ‘warm little pond’ concept,” Hess said.
“Most models for how life may have formed on Earth’s surface invoke meteorites which carry small amounts of schreibersite.”
“Our work finds a relatively large amount of schreibersite in the studied fulgurite.”
“Lightning strikes Earth frequently, implying that the phosphorus needed for the origin of life on Earth’s surface does not rely solely on meteorite hits.”
“Perhaps more importantly, this also means that the formation of life on other Earth-like planets remains possible long after meteorite impacts have become rare.”
The authors estimate that phosphorus minerals made by lightning strikes surpassed those from meteorites when the Earth was around 3.5 billion years old, which is about the age of the earliest known microfossils, making lightning strikes significant in the emergence of life on the planet.
Furthermore, lightning strikes are far less destructive than meteor hits, meaning they were much less likely to interfere with the delicate evolutionary pathways in which life could develop.
“The early bombardment is a once in a solar system event,” said Dr. Jason Harvey, a researcher in the School of Earth and Environment at the University of Leeds.
“As planets reach their mass, the delivery of more phosphorus from meteors becomes negligible.”
“Lightning, on the other hand, is not such a one-off event. If atmospheric conditions are favorable for the generation of lightning, elements essential to the formation of life can be delivered to the surface of a planet.”
“This could mean that life could emerge on Earth-like planets at any point in time.”
“Our exciting research opens the door to several future avenues of investigation, including search for and in-depth analysis of fresh fulgurite in early Earth-like environment; in-depth analysis of the effect of flash heating on other minerals to recognize such features in the rock record, and further analysis of this exceptionally well-preserved fulgurite to identify the range of physical and chemical processes within,” said Professor Sandra Piazolo, a researcher in the School of Earth and Environment at the University of Leeds.
“All these studies will help up to increase our understanding of the importance of fulgurite in changing the chemical environment of Earth through time.”
The research is described in a paper in the journal Nature Communications.
B.L. Hess et al. 2021. Lightning strikes as a major facilitator of prebiotic phosphorus reduction on early Earth. Nat Commun 12, 1535; doi: 10.1038/s41467-021-21849-2
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