Origin & Evolution of Life: February 2009

Bacteria are not usually thought of as having a natural habitat like a mammal or insect, but indirect evidence has suggested that, if anything, most of the early evolution of bacteria was in the marine environment (oceans) and not on land. Surprisingly, NAI researchers from Penn State, Fabia Battistuzzi (now at Arizona State University) and Blair Hedges, found evidence that a large group of bacteria--two-thirds of all ~10,000 described species--trace their ancestry back to a life on land, not in the oceans. These bacteria have many useful adaptations, including the production of oxygen, which now may be tied to their land-loving lifestyle. Their article appeared in the February issue of Molecular Biology and Evolution.

Geological and biological evidence suggests that Earth was warm during most of its early history, despite the fainter young Sun. Upper bounds on the atmospheric CO2 concentration in the Late Archean/Paleoproterozoic (2.82.2 Ga) from paleosol data suggest that additional greenhouse gases must have been present.