Fossil records stretch back over a billion years, but new research says that complex life may have inhabited Earth even earlier.
Complex life could have existed on Earth at least once before
“It’s generally thought that the evolution of complex life was a rare, once-in-4.5-billion-years event. But new research suggests that conditions were right for complex cells to evolve and die off at least once – or perhaps several times – before our lineage even got started.”
Conditions right for complex life may have come and gone in Earth’s distant past
“Conditions suitable to support complex life may have developed in Earth’s oceans – and then faded – more than a billion years before life truly took hold, a new University of Washington-led study has found. The findings, based on using the element selenium as a tool to measure oxygen in the distant past, may also benefit the search for signs of life beyond Earth.”
Selenium isotopes record extensive marine suboxia during the Great Oxidation Event
“Oxygen is essential for eukaryotic life. The geologic record of early Earth contains abundant evidence of low oxygen levels, and accordingly, a lack of eukaryote fossils. The rise of oxygen to near-modern levels at the end of the Proterozoic Era is thus often cited as the trigger for the evolutionary radiation of complex life forms at this same time.”
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Written By: Amy Shira Teitel