Scientists have made progress in studying Luca, the last universal common ancestor that links all modern life forms on Earth. Luca, an ancient unicellular organism that existed around 4.2 billion years ago, is a crucial figure in the evolutionary chain, although it was not the first living creature. Luca served as the starting point for biological evolution, giving rise to the variety of organisms present today.
A study published in Nature Ecology and Evolution reveals that Luca was more complex than previously thought. This organism utilized hydrogen and carbon dioxide for energy production, allowing it to thrive in environments devoid of oxygen. Additionally, Luca possessed a genome containing approximately 2600 proteins, comparable to modern bacteria genomes. The study also uncovered evidence of a primitive immune system, indicating advanced protective mechanisms at the earliest stages of evolution.
Scientists speculate that Luca existed within a complex ecosystem, interacting with other microbes. It is possible that its habitat was in hydrothermal springs or chemically rich ancient oceans, where interaction with surrounding organisms supported its survival and development.
Researchers at the University of Bristol, led by Edmund Moody, reconstructed the genetic makeup of Luca using data from 350 types of bacteria and 350 types of archaea. By analyzing nearly 10,000 genes, they created evolutionary trees to identify genes likely belonging to Luca. They identified 399 genes in Luca’s genome and calculated probabilities for thousands of other genes to paint the most accurate picture.
Luca’s age is estimated at 4.2 billion years, coinciding with a period of intense asteroid bombardment of Earth. While this time was considered inhospitable for life, Luca and its descendants managed to survive and develop complex biological mechanisms. Some scientists suggest that evolution under such conditions may have been more rapid than previously thought.
However, debates persist regarding Luca’s era and challenges. For instance, Patrick Forterr from the Pasteur Institute argues that more cooling time would be needed for Earth after the formation of the moon to support life. Discrepancies in cell membranes and DNA replication mechanisms between bacteria and archaea are also noted, possibly suggesting that Luca was simpler than indicated in the recent study.
Despite differing opinions