GROUNDBREAKING research has given new insights into the evolution of life on Earth.
The Great Oxidation Event took place 2.3 billion years ago, introducing the gas into the atmosphere in free form and paving the way towards the world we know now, including the development of O2-breathing animals.
Now St Andrews University researchers have led new work examining the changes this caused. Their findings fill a 400 million year gap in the geochemical records of a "dramatic" change that struck halfway through the planet's history.
Dr Aubrey Zerkle, who headed the work, says the findings could help humanity respond to catastrophic changes in the future and even aid the search for a planet which could serve as an alternative Earth.
She said: "The Great Oxidation Event was arguably the most dramatic environmental change in Earth history. It was critical to the development of the hospitable environment that we inhabit today, as it was a prerequisite for the evolution of animals that universally require O2 to live.
"Catastrophic upheavals in past surface conditions such as these provide a critical window for Earth scientists to study how the biosphere responds to environmental change. Understanding how life on this planet responded to geochemical changes in the past will help us to more clearly predict the response to future changes, including Earth’s warming climate. It will also inform our search for habitable planets in other solar systems."
Zerkle and her team studied rock cores taken from the National Core Library in South Africa and captured the response of the nitrogen cycle to this major transition for the first time.
Nitrogen is needed by all living organisms and used in the formation of proteins, amino acids and DNA components. The key "nutrient" helps control elements regulating climate, weather and levels of oxygen at the Earth's surface.
The experts produced high-resolution records of nitrogen isotopes in the rocks, revealing the immediate onset of a modern-style nitrate-driven ecosystem appeared at the same time as the first evidence of atmospheric oxygen.
The results were published in the scientific journal Nature.
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