For the first four billion years of Earth’s history, our planet’s continents would have been devoid of all life except microbes.
All of this changed with the origin of land plants from their pond scum relatives, greening the continents and creating habitats that animals would later invade.
The timing of this episode has previously relied on the oldest fossil plants which are about 420 million years old.
New research, published today in the journal Proceedings of the National Academy of Sciences, indicates that these events actually occurred a hundred million years earlier, changing perceptions of the evolution of the Earth’s biosphere.
The researchers were using molecular clock technology.
Co-lead author Mark Puttick described the team’s approach to produce the timescale. He said: “The fossil record is too sparse and incomplete to be a reliable guide to date the origin of land plants. Instead of relying on the fossil record alone, we used a ‘molecular clock’ approach to compare differences in the make-up of genes of living species — these relative genetic differences were then converted into ages by using the fossil ages as a loose framework. Paper. (public access) – JL Morris, MN Puttick, J Clark, D Edwards, P Kenrick, S Pressel, CH Wellman, Z Yang, H Schneider and PCJ Donoghue. Timescale of early land plant evolution. Proceedings of the National Academy of Sciences, 2018 More.
We’re not particularly surprised by “earlier than thought” origins; those stories are now reported all the time. But how reliable is the molecular clock?
See also: Evolution Makes No Sense on This Molecular Clock Problem (Cornelius Hunter)
Molecular clocks and fossils at odds again
Stasis: Life goes on but evolution does not happen