Photosynthesis and early Earth

Photosynthesis in Hydrogen-Dominated Atmospheres

The diversity of extrasolar planets discovered in the last decade shows that we should not be constrained to look for life in environments similar to early or present-day Earth. Super-Earth exoplanets are being discovered with increasing frequency, and some will be able to retain a stable, hydrogen-dominated atmosphere. We explore the possibilities for photosynthesis on a rocky planet with a th...

Evolution. When did photosynthesis emerge on Earth?

Life began early in Earth's history, but it was the emergence of photosynthesis that allowed its proliferation across the planet, because it freed life from its sole dependence on abiotic chemical sources of reducing power. Des Marais discusses recent geological and molecular biological evidence, such as the paper by Xiong et al., that photosynthesis emerged at least 2,800 million years ago.

Detectability of life and photosynthesis on exoplanets

‘Is there life on exoplanets?’. We refer to exoplanets as planets in other solar systems than our own. This often asked question can be further refined by asking ‘is there life on exoplanets which is so extensive that it may impact on its atmosphere, its biosphere and its optical properties?’. And if such a life exists, at astronomical distances from us, can we detect it with instruments on Ear...

ON THE DISSIPATION OF THERMAL AND CHEMICAL ENERGIES ON THE EARLY EARTH The onsets of hydrothermal convection, chemiosmosis, genetically regulated metabolism and oxygenic photosynthesis

The evolution of photosynthesis...again?

'Replaying the tape' is an intriguing 'would it happen again?' exercise. With respect to broad evolutionary innovations, such as photosynthesis, the answers are central to our search for life elsewhere. Photosynthesis permits a large planetary biomass on Earth. Specifically, oxygenic photosynthesis has allowed an oxygenated atmosphere and the evolution of large metabolically demanding creatures...

Tracking the record of early life

Life may have been present on Earth from about 3.8 Ga or earlier. Based on a combination of geochemical, morphological and sedimentological evidence, the early biosphere included a wide diversity of prokaryotes exhibiting modern metabolisms that thrived in various marine and possibly terrestrial habitats. Among early microorganisms, cyanobacteria played a major role, inventing oxygenic photosyn...