By
In the sandstone cliffs of the Scottish Highlands, Earth and Environmental Science Department part-time faculty member Paul Strother and colleagues discovered fossils that show early life forms might have emerged 500 million years earlier than previously established.
The fossils reveal that eukaryotes that evolved on land may have emerged from the sea sooner than scientists have thought, Strother and his colleagues reported this month in the online edition of the journal Nature.
“We tend to think of evolution as originating out of the sea, but it could have come from land,” said Strother. “We can take more seriously the idea that life had occupied terrestrial habitats much earlier than we thought previously and that it was much more a cradle of evolutionary novelty than the oceans were.”
Strother, a researcher in paleobotany at BC’s Weston Observatory, and the rest of the team describe complex microfossils found in billion-year-old rocks from the Torridonian sequence in northwest Scotland.
These diverse microfossils include mostly simple single-celled organisms, but do include some rare multicellular structures with organic walls that measure up to one millimeter long. The team reports that these simple eukaryotes lived in ancient lakes that periodically dried out, exposing life directly to the atmosphere. This discovery places eukaryotes in freshwater settings approximately 500 million years earlier than previously thought.
Life probably originated in the sea more than three billion years ago; however, the first signs of life on land are less well-defined. The identification of eukaryotes in non-marine settings described by Strother’s team indicates that eukaryotic evolution on land may have commenced much earlier than previously thought.
In addition to Strother, other researchers involved in the project include Leila Battison and Martin Brasier of the University of Oxford, and Charles H. Wellman, of the University of Sheffield. Funding from NASA’s Exobiology Program supported the team’s research.
The article co-authored by Strother is available online here.