The late Archaean to early Proterozoic origin and evolution of anaerobic methane-oxidizing archaea.

Microorganisms, called anaerobic methane-oxidizing archaea (ANME), can reduce a large amount of greenhouse gas methane and therefore have the potential to cool the Earth. We collected nearly all ANMEs genomes in public databases and performed a comprehensive comparative genomic analysis and molecular dating. Our results show that ANMEs originated in the late Archaean to early Proterozoic eon. During this period of time, our planet Earth was experiencing the Great Oxygenation Event and Huronian Glaciation, a dramatic drop in the Earth's surface temperature. This suggests that the emergence of ANMEs may contribute to the reduction of methane at that time, which is an unappreciated potential cause that led to the Huronian Glaciation.