Thursday, June 04, 2015

Recalibrating the First Eukaryotes

Reappraisal of hydrocarbon biomarkers in Archean rocks. 2015. PNAS

Contaminated samples have evidently created some confusion in the timetable of life.

On the basis of ultra-clean analyses, an international team, including scientists from the Max Planck Institute for Biogeochemistry, has disproved supposed evidence that eukaryotes originated 2.5 to 2.8 billion years ago.

In contrast to prokaryotes such as bacteria, eukaryotes have a nucleus. Some researchers thought they had discovered molecular remnants of living organisms in rock samples up to 2.8 billion years old. However, as the current study shows, these molecular traces were introduced by contamination. The oldest evidence for the existence of eukaryotes is now provided by microfossils that are ca. 1.5 billion years old.