Evolution: very early oxygen use (Evolution)

by David Turell , Friday, April 04, 2025, 16:50 (11 hours, 2 minutes ago) @ David Turell

A new study supporting the early appearance of oxygen before the Big Oxygen Event:

https://www.sciencealert.com/oxygen-metabolism-emerged-on-earth-before-the-great-oxidat...

https://www.science.org/doi/10.1126/science.adp1853

"The Great Oxidation Event (GOE) some 2.4 billion years ago established the oxygen-rich atmosphere that many living things depend on today.

"Curiously, when it came to evolving ways to actively use the element for respiration, some strains of bacteria had a head start.

"Using a combination of bacterial genome data, geological markers, and machine learning techniques designed to spot genetic patterns, an international team of researchers searched for evidence describing the earliest aerobic (oxygen-breathing) bacteria.

"While most strains took up the ability to tolerate and use oxygen after the GOE, the researchers did spot some outliers – certain bacteria that were aerobic approximately 900 million years before oxygen levels rapidly rose in Earth's atmosphere.

"Among 1007 species of related bacteria, the researchers identified more than 80 genetic transitions from metabolisms that couldn't use oxygen to metabolisms that could. Estimates based on the rate at which mutations accumulate suggest at least a few of these happened before oxygen levels rose to significant levels in Earth's atmosphere.

"'At least three transitions predated [the GOE], suggesting that aerobic respiration evolved before widespread atmospheric oxygenation and may have facilitated the evolution of oxygenic photosynthesis in cyanobacteria," write the researchers in their published paper.

"In other words, these early oxygen-breathers may have laid the foundations for their descendents to use water and carbon dioxide to capture sunlight, freeing up stored oxygen in what would become the Great Oxidation Event.

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"There are some assumptions being made here, about how genes in modern bacteria might link back to genes in ancient bacteria – and do the same oxygen processing job – but the researchers are confident that they included enough bacteria species and corroborating evidence to confirm the link.

"'This allowed us to calibrate bacterial evolution to the record of biospheric oxygenation, greatly augmenting the limited fossil record of early life and bringing a new level of resolution to the study of evolution in deep time," write the researchers.

"As well as validating the idea that aerobic bacteria have a history that goes way, way back, these findings also give us more evidence that cyanobacteria evolution happened relatively slowly, with its roots streching back far before the GOE.

Comment: as I noted before, oxygen is a dangerous substance and requires antioxidants to control it. This advance required increasing complexity and infers the need for design. Evolution seems to know what is coming next, as if someone is planning its advance. Noted in yesterday's entry: Thursday, April 03, 2025, 20:58