Methane-eating microbes can use iron and manganese oxides to ‘breathe’

http://www.spaceref.com/news/viewpr.html?pid=28688

“Iron and manganese compounds, in addition to sulfate, may play an important role
in converting methane to carbon dioxide and eventually carbonates in the Earth’s
oceans, according to a team of researchers looking at anaerobic sediments. These
same compounds may have been key to methane reduction in the early, oxygenless
days of the planet’s atmosphere.”

Explosive growth of life on Earth fueled by early greening of planet

http://www.spaceref.com/news/viewpr.html?pid=28687

“Earth’s 4.5-billion-year history is filled with several turning points when
temperatures changed dramatically, asteroids bombarded the planet and life forms
came and disappeared. But one of the biggest moments in Earth’s lifetime is the
Cambrian explosion of life, roughly 540 million years ago, when complex, multi-
cellular life burst out all over the planet.”