An illustration of the early earth, as it would have looked 4 billion years ago. Credit: Lucy Entwisle
Lightning strikes were just as important as meteorites to create the perfect living conditions on earth, geologists say.
Minerals that were delivered to Earth more than 4 billion years ago in meteorites have long been touted as key ingredients for the evolution of life on our planet.
Scientists believe that minimal amounts of these minerals were brought into the earth early by billions of lightning strikes.
But now researchers from the University of Leeds have determined that lightning strikes were just as important as meteorites in performing this vital function and making life manifest.
They say it shows that life can evolve on Earth planets at any time by the same mechanism as atmospheric conditions are right. The research was led by Benjamin Hess during his undergraduate studies at the University of Leeds at the School of Earth and Environment.
Mr. Hess and his mentors studied an extraordinary and pristine sample of fulgurite, a rock that forms when lightning falls to the ground. The sample was formed when lightning struck a property in Glen Ellyn, Illinois, USA, in 2016 and donated it to the geological department at Wheaton College nearby.
The fulgurite monster excavated in Glen Ellyn, Illinois. Credit: Benjamin Hess
The Leeds researchers were initially interested in how fulgurite is formed, but were fascinated to discover in the Glen Ellyn sample a large amount of a very unusual phosphorus mineral called schreibersite.
Phosphorus is essential for life and plays a key role in all life processes, from movement to growth and reproduction. The phosphorus present on the early earth’s surface was in minerals that could not dissolve in water, but on schreibersite.
Mr. Hess, now a PhD student Yale University, Connecticut, USA, said: ‘Many have suggested that life on earth originated in shallow surface water, according to Darwin’s famous’ hot little pond’ concept.
‘Most models for how life on earth can originate evoke meteorites that contain small amounts of schreibersite. Our work finds a relatively large amount of schreibersite in the fulgurite studied.
‘Lightning strikes the earth frequently, implying that the phosphorus needed for the origin of life on the earth’s surface does not rely solely on meteorite hits.
“More importantly, it also means that the formation of life on other Earth-like planets will likely remain long after meteorite impact became scarce.”
The fulgurite monster excavated in Glen Ellyn, Illinois. Credit: Benjamin Hess
The team estimates that phosphorinerals produced by lightning strikes surpassed the meteorites when the earth was about 3.5 billion years old, that is about the age of the earliest known microfossils, which cause lightning strikes in the origin of life on the planet make significant.
Furthermore, lightning strikes are far less destructive than meteorite hits, meaning they are much less likely to interfere with the delicate evolutionary paths in which life can evolve.
The research, entitled Lightning strikes as a major facilitator of early earth prebiotic phosphorus reduction, was published on March 16, 2021 in Nature communication.
The School of Earth and Environment has funded the project under a scheme that enables undergraduate research using high-quality analytical facilities.
Dr. Jason Harvey, associate professor of geochemistry at Leeds’ School of Earth and Environment, and Sandra Piazolo, professor of structural geology and tectonics at the School of Earth and Environment, Hess mentored in the research project.
Dr Harvey said: ‘The early bombing is an event in the solar system. 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 for the formation of life on the surface of a planet can be delivered.
“It could mean that life could form on Earth-like planets at any time.”
Professor Piazolo said: “Our exciting research opens the door to several future ways of research, including the search for and in-depth analysis of fresh fulgurite in an early Earth-like environment; in-depth analysis of the effect of flash heating on other minerals to recognize such features in the rock survey, and further analysis of this exceptionally well-preserved fulgurite to identify the extent of physical and chemical processes within.
“All of these studies will help increase our understanding of the importance of fulgurite in changing the earth’s chemical environment over time.”
Read the lightning regions – perhaps 1,000,000,000,000,000,000,000,000 of them – may have sparked life on earth for more information on this research.
Reference: “Lightning Strikes as a Major Facilitator of Early Earth Prebiotic Phosphorus Reduction” by Benjamin L. Hess, Sandra Piazolo, and Jason Harvey, March 16, 2021, Nature communication. |
DOI: 10.1038 / s41467-021-21849-2