In a paper published recently in PNAS, ACA scientists and colleagues describe an ancient deep-sea mud-inhabiting 1800-million-year-old sulfur-cycling microbial community from Western Australia that is essentially identical both to a fossil community 500 million years older and to modern microbial biotas discovered off the coast of South America in 2007. 


The fossils are interpreted to document the impact of the mid-Precambrian increase of atmospheric oxygen, a world-changing event that altered the history of life.  Although the apparent two-billion-year-long stasis of such sulfur-cycling ecosystems is consistent with the null hypothesis required of Darwinian evolution -- if there is no change in the physical-biological environment of a well-adapted ecosystem its biotic components should similarly remain unchanged -- additional evidence will be needed to establish this aspect of evolutionary theory.

Read the full paper here