Today, oxygen fuels much of life on Earth, but it wasn’t always that way. Three billion years ago, this gas was scarce in the atmosphere and oceans.

‘Totally new’ idea suggests longer days on early Earth set stage for complex life

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2021-08-02 18:00:05

Today, oxygen fuels much of life on Earth, but it wasn’t always that way. Three billion years ago, this gas was scarce in the atmosphere and oceans. Knowing why oxygen became plentiful could illuminate the evolution of our planet’s flora and fauna, but scientists have struggled to find an explanation satisfying to all. Now a research team has proposed a novel link between how fast our planet spun on its axis, which defines the length of a day, and the ancient production of additional oxygen. Their modeling of Earth’s early days, which incorporates evidence from microbial mats coating the bottom of a shallow, sunlit sinkhole in Lake Huron, produced a surprising conclusion: as Earth’s spin slowed, the resulting longer days could have triggered more photosynthesis from similar mats, allowing oxygen to build up in ancient seas and diffuse up into the atmosphere.

That proposal, described today in Nature Geoscience, has intrigued some scientists. “The rise of oxygen [on Earth] is easily the most substantial environmental change in the history of our planet,” says Woodward Fischer, a geobiologist at the California Institute of Technology who was not involved with the work. This study offers “a totally new flavor of an idea. It’s making a connection that people haven’t made before.”

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