Lightning strikes have played a part in theories on the origin of life since Darwin. Discover how a new study sheds more light on the role of lightning in bringing life to our planet.
We had just finished dinner, and we were relaxing in the living room of the cottage. Before we even had time to be frightened by it, lightning struck a tree in the front yard, incinerating it.
It was all over before anyone realized what had happened. The tree was about twenty feet from the house and now looked like a burnt matchstick.
That’s the tremendous power of lightning, and thankfully, we rarely see it from that close. Lightning can destroy and create.
LIGHTNING CAN DESTROY AND CREATE
Charles Darwin had this in mind when he wrote his famous passage to his friend, J.D. Hooker. “If (and oh what a big if) we could conceive in some warm little pond with all sorts of ammonia & phosphoric salts—light, heat, electricity etc. present, that a protein compound was chemically formed, ready to undergo still more complex changes…”
Electricity was one of the critical elements that Darwin imagined for the origin of life. No doubt, he thought of lightning as the natural source of that chemical-changing energy.
Stanley Miller and his University of Chicago supervisor Harold Urey tried to test this hypothesis in 1952. They combined water, methane, ammonia and hydrogen in a sealed 5-litre flask.
FIVE AMINO ACIDS FORMED IN THE MIXTURE
They added water vapour to the solution and fired continuous electric sparks through it to simulate lightning. Miller found that five amino acids had formed in the mixture after it sat for a week.
The University of Chicago preserved some of the vials from the experiment. After Miller had passed away, scientists examined them in 2007. They could identify more than twenty amino acids, which is more than we find in the genetic code.
Biologists agree that electricity in the form of lightning was necessary for life to originate on Earth. Its force synthesizes the amino acids from which all living things form.
RARE MINERAL ESSENTIAL TO LIFE’S FORMATION
A study published two weeks ago in the journal Nature Communications shows that lightning strikes were also essential in forming a rare mineral critical to life’s formation. The conventional wisdom had been that these minerals were carried to Earth by meteorites.
This vital mineral is a rare form of phosphorous that chemists call schreibersite. It’s essential for life formation because, unlike other types of phosphorous, it’s water-soluble.
Ph.D. candidate Benjamin Hess led the research. The University of Leeds team was looking at a sample of the rock called fulgurite that forms when lightning strikes.
SAMPLE OF ROCK THAT FORMS WHEN LIGHTNING STRIKES
Property owners discovered it in Glen Ellyn, Illinois, in 2016 and donated it to nearby Wheaton College. It was a sizable and pure fulgurite sample.
The plan had been to learn more about fulgurite and lightning. However, the investigators were soon fascinated by the quantity of schreibersite the sample contained.
Hess explains, “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.”
PHOSPHOROUS DIDN’T HAVE TO COME FROM METEORITES
This finding has led the investigators to conclude that the required water-soluble phosphorous didn’t have to come from meteorites. They now believe that at least as much schreibersite was formed by lightning strikes as from meteor impacts.
“Lightning strikes Earth frequently,” Hess continued, “the phosphorus needed for the origin of life on Earth’s surface does not rely solely on meteorite hits.”
This debate between lightning and meteorites matters. Earth was heavily bombarded by meteorites in its formative years, during a period called “the early bombardment.”
EARTH WAS HEAVILY BOMBARDED BY METEORITES
If meteors were the only source of water-soluble phosphorous, it would mean that life had to arise due to that primordial barrage. However, if at least as much of the mineral forms from lightning strikes, life’s timing to emerge becomes much more flexible.
One of Hess’s mentors was Dr. Jason Harvey, an Associate Professor of Geochemistry at the University of Leeds’ School of Earth and Environment. He explained that “The early bombardment is a once in a solar system event. 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 favourable 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.”
“LIFE COULD EMERGE ON EARTH-LIKE PLANETS”
Darwin explained evolution by discovering the processes of descent with variation and natural selection. However, he merely speculated on how life could arise from non-living matter.
This new study sheds light on that process and takes away one of the obstacles that scientists had difficulty explaining. It also adds answers to the question we all ask ourselves from time to time, “Are we alone in the Universe?”
Increasingly, we’re learning that if the same conditions prevailed on another planet, life would arise there in the same way it came to be here on Earth. If a commonplace event like a lightning strike can provide one of the minerals needed for life to form, this supports that point of view.
WITH SAME CONDITIONS ON ANOTHER PLANET, LIFE WOULD ARISE
Hess’ other mentor, Professor Sandra Piazolo, wrapped up this discussion by saying, “Our exciting research opens the door to several future avenues of investigation. All these studies will help up to increase our understanding of the importance of fulgurite in changing the chemical environment of Earth through time.”
We always have more to learn if we dare to know.
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