A groundbreaking investigation might have unearthed a crucial component that elucidates Earth’s distinctive oxygen-rich atmosphere and the consequent evolution of animal life on our planet.
Led by a distinguished Fellow of the Forrest Research Foundation at The University of Western Australia and recently published in the prestigious Nature journal, the study potentially unlocks the mystery of why oxygen levels on Earth were insufficient for animal life for almost 90% of our planet's history.
The inaugural significant evolutionary event of animal life transpired during an incident named the Shuram Excursion, which occurred between 570 and 550 million years ago. This episode is thought to symbolize a colossal discharge of carbon dioxide and oxygen into the ecosystem and seas, triggered by a surge in oceanic phosphorus levels.
To validate this hypothesis, the research team employed a novel tool to monitor the prevalence of phosphorus in the seas hundreds of millions of years ago, using data recorded in six locations across Australia, China, Mexico, and the US.
The gathered data and an Earth chemistry model exposed that the escalation of ocean phosphorus levels could not justify the rise of oxygen. This effect was only simulated by the model when vast quantities of sulfate rock weathered, liberating sulfate into the oceans, thereby generating copious amounts of oxygen.
The study's primary author and Forrest Fellow, Dr. Matthew Dodd, from the UWA School of Earth Sciences, emphasized that the results implied sulfate, rather than phosphorus, was pivotal in oxygenating the planet during the earliest major evolution of intricate life.
Dr. Dodd stated, "Our research may elucidate the extended periods of low oxygen levels throughout Earth’s history and, as a result, the delayed evolution of animal life on our planet. Crucially, we observed that ocean phosphorus was predominantly low when oxygen levels were low throughout the Shuram Excursion. This would have confined the early oceans and atmosphere into an oxygen-deprived state."
The study's data also carry implications concerning the potential for intelligent life on other planets. "Our findings suggest that potentially habitable planets could foster complex intelligent life, given sufficient incubation times," said Dr. Dodd. "This may imply that planets around stars larger than the Sun might not develop complex intelligent life due to the comparatively short lifespan of these larger stars."
Reference: “Uncovering the Ediacaran phosphorus cycle” by Matthew S. Dodd, Wei Shi, Chao Li, Zihu Zhang, Meng Cheng, Haodong Gu, Dalton S. Hardisty, Sean J. Loyd, Malcolm W. Wallace, Ashleigh vS. Hood, Kelsey Lamothe, Benjamin J. W. Mills, Simon W. Poulton and Timothy W. Lyons, 31 May 2023, Nature.
DOI: 10.1038/s41586-023-06077-6
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