All life on Earth comes from a single common ancestor
Recent details about Earth’s earliest ecosystem, shows that life was thriving just a few hundred million years after the planet formed.
This groundbreaking study traces the origins of all modern life back to a single common ancestor, known as LUCA (Last Universal Common Ancestor). (CREDIT: Creative Commons)
A team of international researchers, led by the University of Bristol, has uncovered fascinating details about Earth’s earliest ecosystem, showing that life was thriving just a few hundred million years after the planet formed. This groundbreaking study traces the origins of all modern life back to a single common ancestor, known as LUCA (Last Universal Common Ancestor). The study "‘The nature of the last universal common ancestor and its impact on the early Earth system" is available on Nature Ecology & Evolution.
LUCA is believed to be the progenitor of all cellular life, from bacteria and redwood trees to humans. Representing the root of the tree of life, LUCA existed before the major evolutionary branches of Bacteria, Archaea, and Eukarya diverged. Modern organisms inherited various biological traits from LUCA, such as amino acids for protein building, the energy molecule ATP, cellular machinery like ribosomes, and the use of DNA to store genetic information.
The research team compared the genomes of living species, counting the mutations that have occurred over time since they shared LUCA as a common ancestor. By combining this genetic data with fossil records, they calculated that LUCA existed around 4.2 billion years ago, about 400 million years after Earth and the solar system formed.
Dr. Sandra Álvarez-Carretero from Bristol’s School of Earth Sciences expressed surprise at LUCA's ancient origin, noting that it aligns with current views on early Earth's habitability. The team modeled LUCA’s biological characteristics by tracing back through the genealogy of living species. Dr. Edmund Moody explained that gene exchange between lineages complicates evolutionary history, requiring complex models to align gene evolution with species genealogy.
Dr. Tom Williams from Bristol’s School of Biological Sciences highlighted the advantage of using gene-tree species-tree reconciliation with diverse data representing life’s primary domains, Archaea and Bacteria. This method allowed the team to confidently assess LUCA's characteristics.
Professor Davide Pisani revealed that LUCA was a complex organism, similar to modern prokaryotes, with an early immune system indicating an ancient battle with viruses. Tim Lenton from the University of Exeter added that LUCA was not solitary; its waste likely served as food for other microbes, contributing to a recycling ecosystem.
The study’s findings and methodologies will inform future research on prokaryote evolution, particularly Archaea and their methanogenic representatives. Professor Anja Spang emphasized the significance of these insights for understanding Earth history.
Professor Philip Donoghue noted that this interdisciplinary study offers unique insights into early Earth and life, suggesting that ecosystems were established quickly. This rapid establishment hints that life could thrive on other Earth-like planets in the universe.
Collaborating institutions included University College London (UCL), Utrecht University, Centre for Ecological Research in Budapest, and Okinawa Institute of Science and Technology Graduate University.
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