Steranes in ancient rocks have been used as ‘molecular fossils’, but the very earliest records of steranes have been shown to be contaminants; here, the presence of two key sterol biosynthesis enzymes in eukaryotes and bacteria suggests at least one gene transfer between bacteria and the earliest eukaryotes occurred some 2.3 billion years ago.
- David A. Gold
- Abigail Caron
- Roger E. Summons
