What’s the origin of life on Earth? It’s an incredibly old mystery we still don’t have the answer to. What we do know is that life began on this planet sometime between 4.5 billion years ago — the age of the Earth — and 3.4 billion years ago, which is the age of the oldest fossils we’ve found, according to New Scientist.
Previously, scientists had been unsure of whether the chemical process that got life started occurred all at once as a sort of Big Bang or happened more gradually. But now, a study recently published in Nature is introducing a new story of what started life on Earth. According to the scientists who authored this paper, lightning strikes may have been the literal spark that got life started on our planet.
The Prevailing Theory: Meteorites
As Space.com points out, phosphorous is one of the building blocks of life and may have been the fuel that propelled the chemical reactions that lead to the development of life. But this element is a solid at room temperature and mostly found in rocks. How, then, was it released in order to propel the formation of life?
Until now, the prevailing theory has been that phosphorous may have arrived on early Earth through meteorite impacts, according to a study from the University of South Florida. This theory says that these space rocks contained schreibersite, which dissolves in water. If these meteorites crashed into the ocean, the phosphorous would have been released, spurring the creation of life.
However, there’s a problem with this theory: Researchers have posited that there weren’t enough meteorite impacts during this period in Earth’s history to create enough phosphorous to jump-start the chemical reaction for life. As a result, scientists have been looking for alternative explanations for the origins of life on this planet.
Lightning Strikes as a Source of Phosphorous
There’s an abundance of phosphorous within Earth’s rocks — more than enough to jump-start life — but outside of meteorites, these components are not soluble in water. Therefore, there’s no way for the phosphorous to escape. Fulgurite, which is created when lightning strikes Earth, contains phosphorous that is taken from surrounding rocks. And it does, in fact, dissolve in water, as MIT Technology Review explains.
The Earth had volatile weather during this period of its history, and lightning impacted the Earth’s surface trillions of times. The authors of the new Nature study determined that there would have been more than enough phosphorous released to be key to the origin of life on Earth — forming 10-1000 kg of phosphide and 100-10,000 kg of phosphite and hypophosphite per year.
Not only could lightning strikes have been a major source of phosphorous for the creation of early life, but these storms occurred regularly, primarily in tropical regions of the Earth. That means there was a continual supply of phosphorous to ensure that chemical reactions had enough fuel to progress.
Life on Other Planets
This discovery is especially important because understanding what started life on Earth can help us understand how it might develop on other worlds. We’ve already used phosphorous as a key factor when it comes to looking for life on other planets. For example, a well-publicized study in 2020 announced the discovery of phosphine gas in Venus’s atmosphere, as the New York Times reports. This revelation led many to pronounce that we were well on our way to discovering life on our sister planet.
But since then, many have cast doubt on the claim, as three separate studies have since failed to come to the same conclusion and did not find phosphine in Venus’s atmosphere, according to National Geographic. Even if Venus does not harbor life, it’s important to understand the source of the phosphorous that jump-started life on this world, so we can look at other planets with heavy lightning activity as possible candidates for the development of life.
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