Scientists have found clues in ancient rocks that suggest life on Earth became more complex at the same time oxygen levels increased in the atmosphere and oceans.

The rocks contain tiny fossils called microfossils that are over 2.4 billion years old. By studying these microfossils, researchers learned that complex life may have evolved earlier than we thought.

The microfossils were discovered in old rocky formations in Western Australia. When scientists looked closely at the fossils under microscopes, they saw that the ancient microbes resembled more advanced algae instead of the simpler bacteria and microbes that existed before oxygen levels rose. Algae, like plants and animals, have cells with nuclei – this makes them more complex than bacteria.

The Hamersley Ranges, a mountainous region of Western Australia, where the researchers carried out their work | photo Erica Barlow

This is an important discovery because it shows that as Earth’s air and water began to contain more oxygen, life itself may have become more complex too. Scientists have thought this was possible, but didn’t have proof until now. These fossils provide direct evidence linking environmental changes to the evolution of more advanced microscopic life.

The fossils look a lot like modern algae groups called Volvocaceae. This suggests they were early complex cells called eukaryotes. Eukaryotes have nuclei and are more advanced than bacteria.

If confirmed, it would push back the earliest known complex fossils by over 750 million years. More research is needed, but it raises exciting questions about early life on our planet.

Microfossil black chert nodules scattered on a rocky outcrop | photo Erica Barlow

The researcher who found the rocks studied them for years as a student in Australia and recently as part of her work in the United States. The fossils are well-preserved, allowing scientists to learn about the ancient microbes by looking at their shape, what they were made of, and how their cells were arranged. Comparison to older fossils without oxygen showed these were more complex.

This discovery helps us better understand how long it took complex life to first evolve on Earth and could also help in the search for life elsewhere in our solar system.

Finding such early complex microbes suggests that if any other life is discovered, it may not just be simple bacteria—more intricate microscopic life is also possible. These ancient microfossils provide new clues about the major event that marked the rise of oxygen and complexity in life on our planet long ago.

Sources

The Pennsylvania State University | Barlow, E. V., House, C. H., Liu, M.-C., Wetherington, M. T., & Van Kranendonk, M. J. (2023). Distinctive microfossil supports early Paleoproterozoic rise in complex cellular organisation. Geobiology, 00, 1–23. doi.org/10.1111/gbi.12576

  • Share this article:
Depositphotos_102731280_L-2
Dinosaurs could exist on other planets, which scientists believe would be easier to detect than modern Earth Using historical Earth models, Cornell University scientists suggest that dinosaurs or large, complex life could exist on exoplanets with high oxygen levels, guided by identifiable "sunlight fingerprints".
24661308922_3eb66388f6_o-1200×800-c-default-2
Iron-Driven Memory: Bacteria Crafting and Transmitting Generational Knowledge A team of researchers from the University of Texas at Austin has made a fascinating discovery that could revolutionize our understanding of how bacteria develop strategies to cause dangerous infections…
Co-author Athena Eyster in front of a large exposure of the banded iron formation, the iron-rich deposit from which ancient magnetic field signals were extracted
Researchers find the Oldest Undisputed Proof of Earth's Magnetic Field: 3,7 Billion Years Old Researchers from the University of Oxford and the Massachusetts Institute of Technology (MIT) have made an important discovery about the history of Earth's magnetic field. They found the oldest clear…
Artistic reconstruction of the Cabrières Biota
A Site with more than 400 Fossils from the Ordovician with Remarkably Preserved Digestive Apparatuses, Discovered in France Two amateur paleontologists have uncovered an important fossil site in southern France. The site contains around 400 fossils from around 470 million years ago. Scientists from the University of Lausanne…
red-zeppelin-YgNAZgcQ3hc-unsplash-2
Levels of Deoxygenation Similar to Current Ones Played a Key Role in Past Marine Extinctions A new study warns that the current stability of marine ecosystems is likely more fragile than it appears. Ocean deoxygenation is expected to significantly increase in response to global warming…
Artists impression of 'Snowball Earth'
Scientists Find Out What Turned the Earth Into a Giant Snowball 700 Million Years Ago Scientists in Australia have figured out what most likely caused a period of extreme cold on Earth over 700 million years ago. By using models of how the continents move…

Something went wrong. Please refresh the page and/or try again.