The Neoarchean, some 2,700 million years before the present day, has hosted some controversy of late in the geobiology community. At stake is something big: when did eukaryotes - the multicellular organisms that we humans are descended from, as opposed to bacteria and archaea - first appear? And when did oxygen-producing photosynthesis begin?
In 1999, a fella named Jochen Brocks, an Australian, now living in Australia, found some old rocks - in Australia - which contained some rather curious fossils. Lipid fossils — hydrocarbons. One set of fossils was indicative of eukaryotes. (This pushed the earliest eukaryote fossil find back about 1 billion years!) An additional set was indicative of cyanobacteria: the oxygen makers!
These were big finds, but one of the tricky things about old molecular fossils is that it can be hard to tell where they came from. In other words, are they as old as their host rock, or did they wander in later? The rocks of this planet have been twisting and turning for years, and much of the early record of life is erased or contaminated during the metamorphoses. On top of that, these are hydrocarbons we’re talking about — so if you’ve got some oil on your drill when you’re digging these things out, it can be hard to tell what’s what.
So nine years later (in 2008), Brocks and a few others questioned their 1999 findings, and today it’s a bit up in the air. Drilling continues - careful drilling, with efforts to manage contaminants - in an attempt to tease out whether or not the lipids are from the same era as the 2.7 billion year-old-rock, or not.
Meanwhile, in Cambridge, our 100 inches of snowfall has slumped into a filthy grey mess. Roadside snow banks are coated in thick films of black hydrocarbons, and Bostonians are flocking to Miami.