PNAS Archives

The Variability Of Evolvability: Properties Of Dynamic Fitness Landscapes Determine How Phenotypic Variability Evolves

by Keith CowingSeptember 21, 2026September 21, 2026

[PNAS] The magnitude and shape of phenotypic variation depends on properties of the genotype-to-phenotype (GP) map, which itself can evolve over time. The evolution of GP maps is particularly interesting […]

Origin & Evolution of Life

The History Of Enzyme Evolution Embedded In Metabolism

by Keith CowingSeptember 11, 2026September 11, 2026

[PNAS]. Whereas phylogenetic reconstructions are a primary record of protein evolution, it is unknown whether the deep history of enzymes is encoded at higher levels of biological organization.

Impact of continental chemical weathering and oceanic redox processes on sedimentary Fe speciation. (A) Compilation of Fe speciation data for different rock types (37), the modern terrestrial Earth’s surface (37), tropical soils (this study), and suspended particles (SPM) from 22 rivers in the United States (25), as well as from eight additional rivers worldwide (26), including the Amazon River (Amz), Brahmaputra River (Brp), Magdalena River (Mgd), and Nile River. -- PNAS

Water/Hycean Worlds & Oceanography

Iron Helped Scientists Trace Earth’s Oxygen. Now It’s Telling A Bigger Story

by Keith CowingSeptember 3, 2026September 3, 2026

[Michigan State University] For decades, scientists have studied iron preserved in ancient rocks to reconstruct how Earth’s oceans and atmosphere became rich in oxygen. A new study suggests iron has […]

Submarine alkaline vents are areas on the ocean floor where hydrothermal vents release hot, mineral-rich fluids. (credit: D. Kelley/ M. Elend/UW/URI-IAO/NOAA/The Lost City Science Team)

Extremeophiles and Extreme Environments

Rethinking The Origin Of Life At Seafloor Hydrothermal Vents

by Keith CowingAugust 31, 2026August 31, 2026

[PNAS] Alkaline vents have dominated a class of hypotheses for the origins of life since their discovery a quarter of century ago, but advances in understanding the nature of these […]

Schematic overview of deploying MA as an agnostic biosignature. Proposed life detection missions in the Solar System can collect samples in situ and predict MA scores directly from MS data without the need for structural elucidation, which may be difficult for unknown molecules in extraterrestrial environments. Space missions that use MSn can estimate MA scores with the RecursiveMA algorithm (30). In the current paper, we show that space missions that use MS1 (and optionally MSn) can infer MA scores with ML. -- PNAS

Biosignatures & Paleobiology

Molecular Assembly As A Universal Biosignature Measurable By Mass Spectrometry

by Keith CowingAugust 13, 2026August 13, 2026

[PNAS] Detecting life beyond Earth requires biosignatures that do not depend on the chemistry of known organisms.

Manganese oxides, thought to form almost exclusively through reactions between Mn2+ and O2, catalyze oxidative transformations among redox-sensitive metals. -- PNAS

Analog Studies, Astrogeology, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Mars, Status Report

Anoxic Photo-oxidation Of Mn(II)-bearing Carbonates On Mars And Early Earth

by Keith CowingJune 14, 2026June 14, 2026

Manganese oxides, thought to form almost exclusively through reactions between Mn2+ and O2, catalyze oxidative transformations among redox-sensitive metals. Thus, the occurrence of Mn oxides, either observed or inferred from […]

Schematic of the selection step in the doped in emulsio selection.

Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Genomics, Proteomics, Bioinformatics, Origin & Evolution of Life, Press Release

What Powered the Earth’s Earliest Life?

by Keith CowingJune 12, 2026June 12, 2026

Early biological systems likely relied on RNA molecules to copy themselves and drive simple chemical reactions.

[LEFT] Nano-FTIR measurement of Region 1 (belonging to the aliphatic-rich cluster). Color-coded nano-FTIR spectra (A) of spots shown in the SNOM topography (B), optical amplitude (C), and mechanical amplitude (D) images. [RIGHT] Region 2 (also belonging to the aliphatic-rich cluster). -- PNAS

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Imaging & Spectroscopy, Meteorites & Asteroids, Missions & Hardware, Planetary Protection & Biosafety, Sample Return, Status Report

Nanoscale Infrared Spectroscopy Reveals Complex Organic–mineral Assemblages In Asteroid Bennu

by Keith CowingApril 14, 2026April 14, 2026

Asteroid Bennu preserves primitive material from the early solar system, and returned samples allow direct examination of how organics and minerals were assembled and altered. We applied nanoscale infrared spectroscopy […]

Energetics associated with the occupancy of the K1 site and the position of the M2 ion. (A) Free energy surface of the concerted motions of Prp11 Lys10 and M2, with the initial PDB conformation marked by a yellow star. (B–D) Representative structures of three metastable states from metadynamics simulations. State 1 (B) represents a PDB-like arrangement where Lys10 (slate blue sticks) remains at the K1 site, and M2 (yellow sphere) is properly positioned at the U6 snRNA triple-helix (yellow cartoon). State 2 (C): Lys10 leaves the K1 site, allowing a K+ ion to occupy it and stabilize M2 in place. State 3 (D): M2 directly coordinates G52, losing its catalytic position and partially occupying the K1 site. -- PNAS

Astropharmacy / Biotechnology, Biochemistry & Organic Chemistry, Biophysics, Genomics, Proteomics, Bioinformatics, Nanotechnology & SynBio, Status Report

Computational Chemistry And Supercomputers To Help Understand The Mechanisms Of Life

by Keith CowingApril 13, 2026April 13, 2026

A new study from the Italian Institute of Technology (IIT), in collaboration with Uppsala University (Sweden) and AstraZeneca, shows how computational chemistry and supercomputers can help scientists better understand the […]

(A) Predicted pO2 (red line) and (B) pCO2 (purple line) values are compared for a range of possible assumed pN2. Vertical dashed lines and colored bands reflect pN2 estimates for 1.44 Ga. from existing models (22–26). For O2, the green and yellow bands reflect the thresholds for early animal respiration and full O3 shielding, respectively (31, 32). The pO2 safely exceeds these thresholds (0.01 PAL) if pN2 exceeded 0.2 bar. For CO2, horizontal dashed lines reflect estimated CO2 contents necessary to achieve the specified temperature (33–35). The diagonal line extrapolates from Archean atmospheric models that account for the effect of total atmospheric pressure on the required CO2 to keep the planet warm (35). Based on these points, our data suggests modern-like climates were possible if pN2 exceeded 0.5 bar. -- PNAS

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Gaia - Planetary Perspectives, Status Report

Direct Constraints From 1.4 Ga Fluid Inclusions Reveal A Fair Climate And Oxygenated Atmosphere

by Keith CowingJanuary 8, 2026January 8, 2026

The Mesoproterozoic eon, often regarded as mundane and static, lays the foundation for dramatic transformations in Earth’s physical and biological evolution during the subsequent Neoproterozoic.