The origins of life, a few billion years ago, were humble. Fossils early indicated as the earliest evidence of animal life have been believed to be algae. The reinterpretation, declared yesterday in the journal Nature Ecology and Evolution, will force scientists to reconsider early animal evolution.
A team of researchers, led by the University of Bristol, has uncovered that ancient fossils, thought to be some of the world’s earliest examples of animal remains, could in fact belong to other groups such as algae. The oldest fossils ever discovered are stromatolites, the remains of ancient cyanobacteria, or blue-green algae.
They said, “We were able to demonstrate that certain molecules from common algae can be altered by geological processes – leading to molecules which are indistinguishable from those produced by sponge-like animals.” In two new papers in Nature Ecology & Evolution, however, teams of researchers show that we cannot conclusively interpret C30 steranes as faunal in origin, and this would neatly resolve another mystery surrounding that interpretation.
Since it is well known that demo sponges are unable to survive in completely anoxic waters, this posed a challenge to the demo sponge interpretation. So, the two teams set out to see if there might be another organism that could produce C30 steranes.