Scientists have long been fascinated by the idea of a Last Universal Common Ancestor (LUCA) – the organism that gave rise to all life on Earth. Recent research suggests that LUCA may have emerged much earlier than previously thought, just a few hundred million years after the formation of the planet. This challenges previous assumptions about the sophistication of LUCA and its place in evolutionary history.
A study led by Philip Donoghue at the University of Bristol took a multidisciplinary approach to understanding LUCA. By analyzing genes present in all major branches of life today, the researchers were able to trace back 2600 protein-coding genes to LUCA. This is a significant increase from previous estimates, which were as low as 80 genes. The team’s model suggests that LUCA existed around 4.2 billion years ago, closer to the formation of Earth than other estimates.
One of the key findings of the study is that LUCA may have had genes for UV protection and fed on hydrogen, indicating that it likely lived at the surface of the ocean. The researchers speculate that LUCA was part of a larger ecosystem of primitive cells that eventually died out. The discovery of a primitive version of the CRISPR bacterial defence system in LUCA suggests that even billions of years ago, organisms were fighting off viruses.
While the research provides valuable insights into the early evolution of life on Earth, Donoghue acknowledges that there is still much uncertainty and room for error in their findings. He views this study as a starting point for further exploration and refinement of our understanding of LUCA and early life forms.
Greg Fournier from the Massachusetts Institute of Technology sees LUCA as a pivotal point in the evolutionary story, rather than the beginning. He emphasizes the importance of genome data in tracing back to LUCA and understanding the shared ancestor state of all life on Earth.
Overall, the study challenges previous notions about the timing and complexity of LUCA, offering a new perspective on the early emergence of life on Earth. While there may be differing opinions and uncertainties in the scientific community, the research represents a significant step towards unraveling the mysteries of our evolutionary history.
