Granite white quartz veins on the northeastern United States coast
Richard Berube / Alamy Stock Photo
Earthquakes and other geological processes may have enabled the oxygen-producing reactions that shaped the evolution of some of Earth’s earliest life forms.
Today oxygen makes up about one-fifth of the earth’s atmosphere and is mostly produced by plants and microorganisms. It didn’t start out that way. Oxygen in the atmosphere was almost nonexistent until levels spiked during the Great Oxidation Event 2.4 to 2.3 billion years ago, thanks to the rapid diffusion of microbes that release oxygen through photosynthesis.
However, the widespread presence of antioxidant enzymes throughout the phylogenetic tree of life suggests that the common ancestor that existed prior to the Great Oxidative Event was exposed to some degree of oxygen.
Marc Siemens and his colleagues at the University of California, San Diego ground quartzite and exposed it to water under chemical conditions similar to Earth’s before high levels of oxygen developed. Researchers used quartz because it is the simplest and most common silicate mineral.
They found that broken crystals on the surface of quartz can react with water to form molecular oxygen and other reactive oxygen species such as hydrogen peroxide. These molecules, also known as free radicals, were important for early evolution because they can damage a cell’s DNA and other components, said his Timothy Lyons of the University of California, Riverside. I’m here. He was not involved in this research.
“Life was able to develop enzymatic abilities very early on to deal with the harmful effects of these species,” he says.
In nature, quartz and other silicate minerals can similarly be worn away by earthquakes, erosion and moving ice. It can then interact with water to produce the same oxygen molecule. The researchers estimated that the seismic process alone could have produced 100 billion times more hydrogen peroxide than the reaction in the atmosphere.
Adaptation to the quake’s oxygen source may have helped some organisms survive the abrupt changes in geochemistry that accompanied the Great Oxidation Event hundreds of millions of years later, says Lyons.
The researchers believe that similar geological processes on other planetary bodies, such as dust storms on Mars and tidal fluctuations on Saturn’s moon Enceladus, could also produce oxygen, making it important for detecting life on these planets. added that it could be a significant factor.
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