Evolution: very early oxygen use (Evolution)

by David Turell , Friday, February 26, 2021, 15:12 (1364 days ago) @ David Turell

Before the great oxidation event:

https://www.sciencemag.org/news/2021/02/first-organism-use-oxygen-may-have-appeared-sur...

"The first organisms to “breathe” oxygen—or at least use it—appeared 3.1 billion years ago, according to a new genetic analysis of dozens of families of microbes. The find is surprising because the Great Oxidation Event, which filled Earth’s atmosphere with the precious gas, didn’t occur until some 500 million years later.

"The advent of proteins that can use oxygen, Shih and others say, marks a key step in the emergence of aerobic microbes, which are those able to harness oxygen. “The transition from a world that was mostly anaerobic to one that was mostly aerobic was one of the major innovations in life,” says Tim Lyons, a biogeochemist at UC Riverside.

"Scientists broadly agree that Earth’s early atmosphere and oceans were all but devoid of oxygen gas. But there are signs that there was some oxygen around. Geochemists, for example, have found mineral deposits dated to about 3 billion years ago that they argue could only have formed in the presence of oxygen. And some evidence suggests cyanobacteria, the earliest photosynthetic organisms to release oxygen gas as a waste product—although not use it—may have arisen as early as 3.5 billion years ago.

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"...they turned to a long-used approach that tracks the likely mutation rate of proteins to construct a “molecular clock.” The clock enabled them to pin down when each of these enzymes likely evolved. Of the 130 families of organisms they studied, Jabłońska and Tawfik were able to date 36 with high confidence.

“'We saw something quite striking,” Tawfik says: a “clear burst” of microbes using oxygen between 3 billion and 3.1 billion years ago. Twenty-two of the 36 families appear to have emerged at that time, while 12 came later, and only two seemed to come before, the team reports today in Nature Ecology & Evolution.

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"Overall, the analysis suggests that about 3.1 billion years ago, an organism they dub the last universal oxygen ancestor emerged, Tawfik says. That ancestor in turn gave rise to aerobes that were able to take advantage of the increased energy output that oxygen use enabled. Eventually, this led to multicellular organisms, animals, and us.

"If that transition did occur about 3 billion years ago, it suggests oxygen-using organisms didn’t immediately sweep across the planet. Rather, the ability to use oxygen likely evolved in small pockets that slowly spread over hundreds of millions of years. And only when they became abundant enough did these organisms modify Earth’s environment enough to produce enough oxygen to lead to the Great Oxidation Event."

Comment: The best way to use energy is by burning it with oxygen. But oxygen is so dangerous a full compliment of anti-oxidants must be developed to control its use. This has to be designed because oxygen is so difficult to handle