In “Evidence of earliest oxygen-breathing life on land found” (MSNBC, October 25, 2011), Wynne Parry reports on those bacteria who process stuff from mine wastewater , “Analysis indicates earliest estimate to date for Great Oxidation Event — 2.48 billion years ago” Of course, it’s probably not the “earliest” evidence, just the earliest we’ve found. From Parry we learn,
For this study, the researchers performed more than 2,000 analyses on samples from more than 100 rock formations, including those called banded iron formations, located around the world, from Canada to South Africa.
Life did exist at the point when chromium levels increased, but it was simple; single cells had yet to come together and begin cooperating as multicellular life forms.
There probably wasn’t much to cooperate about: They were all doing the same thing. Today, we would describe it as eating mine tailings. Great photo of a banded iron formation there.
What we’re learning is that the earliest land life forms didn’t even try finding oxygen; they manufactured it.