Molecular Fossils Shed Light on Ancient Life
Published:06 Mar.2024 Source:University of California - Davis
David Gold, associate professor in the Department of Earth and Planetary Sciences at the University of California, Davis, works in the new field of molecular paleontology, using the tools of both geology and biology to study the evolution of life. With new technology, it’s possible to recover chemical traces of life from ancient rocks, where animal fossils are scarce.
Lipids in particular can survive in rocks for hundreds of millions of years. Traces of sterol lipids, which come from cell membranes, have been found in rocks up to 1.6 billion years old. In the present day, most animals use cholesterol -- sterols with 27 carbon atoms (C27) -- in their cell membranes. In contrast, fungi typically use C28 sterols, while plants and green algae produce C29 sterols. The C28 and C29 sterols are also known as phytosterols.
C27 sterols have been found in rocks 850 million years old, while C28 and C29 traces appear about 200 million years later. This is thought to reflect the increasing diversity of life at this time and the evolution of the first fungi and green algae. Without actual fossils, it's hard to say much about the animals or plants these sterols came from. But a genetic analysis by Gold and colleagues is shedding some light.