Great Oxidation Event Archives

Prior to ca. 2.32 Ga, during deposition of the upper Rooihoogte and lower Timeball Hill formations, atmospheric pO2

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Gaia Mission, Habitable Zones, Status Report

Onset Of Persistent Surface Ocean Oxygenation During The Great Oxidation Event

by Keith CowingDecember 15, 2025December 15, 2025

Free oxygen (O2) first began accumulating in Earth’s atmosphere shortly after the Archean-Proterozoic transition during the ‘Great Oxidation Event’ (GOE).

South Africa’s exceptionally preserved ancient rocks hold key evidence for the rise ofatmospheric oxygen. Within them, researchers see the disappearance of sulfur mass-independent fractionation, evidence for a GOE. Credit Photo by Daniel Hentz, ©Woods Hole Oceanographic Institution

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Gaia - Planetary Perspectives, Habitable Zones, Press Release

A New Study Reveals How Oxygen First Reached Earth’s Oceans

by Keith CowingDecember 10, 2025December 10, 2025

For roughly two billion years of Earth’s early history, the atmosphere contained no oxygen, the essential ingredient required for complex life. Oxygen began building up during the period known as […]

Tree of life (“species tree”) used for gene reconciliation analyses, showing reconstructed habitats for specific phyla over time. Phyla are color-coded and grouped to match to the larger phylum groups used for habitat reconstructions (see Methods). Outer ring shows habitat designations for all leaves of the species tree. Pie charts superimposed on internal nodes indicate the habitat reconstruction results of all organisms in the phylum (including additional genomes not represented in the species tree), with each wedge representing the probability that the internal node resided in a terrestrial (grey), shallow marine (light blue) or deep marine (dark blue) habitat. Habitat reconstruction results were based on much larger trees within each phylum (beyond those shown on the tree), so habitat reconstruction results were superimposed onto this tree for visualization purposes. -- biorxiv.org

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Gaia - Planetary Perspectives, Genomics, Proteomics, Bioinformatics, Origin & Evolution of Life, Status Report

Time-resolved Phylogenomics Analysis Reveals Patterns In Biosphere Nutrient Limitation Through Earth History

by Keith CowingNovember 18, 2025November 18, 2025

The co-evolution of life and Earth has profoundly transformed global biogeochemical cycles over the past 3.5 billion years.

Conceptual model for the evolution of exoenzymes and the recycling of organic matter across the Great Oxidation Event (GOE). (A) In the Archean Ocean, prior to the GOE, the recycling of organic matter depended entirely on the activity of fermenters. This resulted in low recycling efficiency, elevated carbon burial, and limited regeneration of essential nutrients back into seawater. This scarcity of particulate organic matter (POM) also reduced the availability of niches for microbial colonization, thus limiting the selective pressure for the evolution of exoenzyme systems. (b) Following the GOE, rising oxygen levels increased the availability of high-energy electron acceptors (e.g. O2, nitrate and ferric iron), supporting the expansion of metabolic groups with high exoenzyme capacity, such as aerobic heterotrophs, dissimilatory nitrate reducers and dissimilatory ferric iron reducers. Concurrently, increases in POM abundance and microbial cell densities would have amplified the selective pressure to produce exoenzymes. Collectively, these changes in the Paleoproterozoic promoted more efficient recycling of organic matter and regeneration of nutrients back into the water column, ultimately fueling greater primary productivity and oxygen release. This feedback between exoenzyme evolution, nutrient cycling, and oxygen production would have amplified Earth’s progressive oxygenation. -- biorxiv.org

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Gaia - Planetary Perspectives, Origin & Evolution of Life, Status Report, Water/Hycean Worlds & Oceanography

Microbial Exoenzymes Catalyzed The Transition To An Oxygenated Earth

by Keith CowingOctober 11, 2025October 11, 2025

Microbial exoenzymes—extracellular enzymes secreted to degrade complex organic polymers— are essential for recycling carbon and nutrients, thus sustaining primary productivity in today’s oceans.

The solid curve represents the average dissolved oceanic Ni concentration (nmol L−1). Light blue indicates pO2 (Present Atmospheric Level, PAL). Changes in urea concentration are indicated by a red gradient (darker red represents higher concentrations). The average dissolved oceanic Ni concentration is plotted on data from ref. 26, and the Oxygen evolution curve is from ref. 1. Solar Lyman α flux is from ref. 83. -- Nature

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Gaia - Planetary Perspectives, Habitable Zones, Origin & Evolution of Life, Press Release, Water/Hycean Worlds & Oceanography

Earth’s Oxygen Boom: A Fresh Perspective For A Billion-year-old Problem

by Keith CowingOctober 10, 2025October 10, 2025

The appearance of oxygen in Earth’s atmosphere was a turning point in the history of our planet, forever transforming the environment and setting the stage for complex life. This event, […]

By delving into ancient rock records, scientists have uncovered new clues that sharpen the timeline of Earth’s oxygenation—shedding fresh light on one of the most transformative chapters in our planet’s evolutionary story. Credit Benjamin Uveges

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Fossils & Paleontology, Gaia - Planetary Perspectives, Origin & Evolution of Life, Press Release

Rock Record Illuminates Earth’s Oxygen History

by Keith CowingMay 30, 2025May 29, 2025

Several key moments in Earth’s history help us humans answer the question, “How did we get here?”

Molecular evolution of Kai-protein oscillator over 3 billion years Credit Yoshihiko Furuike & Atsushi Mukaiyama

Biochemistry & Organic Chemistry, Biophysics, Extinction events, Genomics, Proteomics, Bioinformatics, Microbiology & Virology, Origin & Evolution of Life, Press Release

Tracing The Evolutionary History Of Bacterial Circadian Clocks On Ancient Earth

by Keith CowingMay 20, 2025

To better understand the circadian clock in modern-day cyanobacteria, a Japanese research team has studied ancient timekeeping systems. They examined the oscillation of the clock proteins KaiA, KaiB, and KaiC […]

ML tree inferred using IQ-TREE under the LG + C60 + F + G + PMSF model, based on a set of 579 archaeal taxa (411 Asgard archaea, 51 DPANN archaea, 47 Euryarchaea and 70 representatives of TACK archaea). Only Asgard archaeal lineages are shown in the tree. Two cultured Asgard archaeal strains are highlighted with a red star. Newly identified genomes in this study are displayed by coloured bars in the outermost ring. Bootstrap support values of at least 95% are represented by black dots. The scale bar denotes the average expected number of substitutions per site. -- Nature via PubMed

Extremeophiles and Extreme Environments, Genomics, Proteomics, Bioinformatics, Microbiology & Virology, Origin & Evolution of Life, Press Release

Deep Origin Of Eukaryotes Outside Heimdallarchaeia Within Asgardarchaeota

by Keith CowingMay 19, 2025May 19, 2025

Research on the morphology, physiology and genomics of Asgard archaea has provided valuable insights into the evolutionary history of eukaryotes.

Geochemical profiles of the Jeerinah Formation in AIDP2 and AIDP3. Total Fe, highly reactive Fe and pyrite Fe are denoted by FeT, FeHR and FePY, respectively. The solid black lines indicate the thresholds for local anoxia (FeHR/FeT > 0.38) or euxinia (FePY/FeHR > 0.8); the dashed lines in Fe speciation panels represent relaxed thresholds for the same redox conditions (FeHR/FeT > 0.22 for anoxia and FePY/FeHR > 0.7 for euxinia)31. Purple and red symbols are Δ33S and authigenic Tl isotopic compositions (ε205TlA), respectively. Stratigraphy, iron speciation, Mo concentration and Δ33S data were from previous work4,37,60. The vertical blue bands represent the Tl isotopic composition of the bulk upper continental crust (BUCC, ε205Tl = −2.1 ± 0.3, 1 s.d., N = 6)39. All error bars represent two times the s.d. of that sample or the long-term external reproducibility of natural reference materials, whichever is larger. Thallium isotope data are presented as mean values ± 2 s.d. BIF, banded iron formation. -- Nature Geoscience

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Mapping, Geodesy, Cartography, Bathymetry, Status Report, Water/Hycean Worlds & Oceanography

Transient Marine Bottom Water Oxygenation On Continental Shelves By 2.65 Billion Years AgoNature Geoscience

by Keith CowingMay 9, 2025May 9, 2025

A growing body of evidence suggests that molecular oxygen (O2) accumulated in some shallow marine environments beneath the effectively anoxic Archaean atmosphere 4.0 to 2.5 billion years (Ga) ago.