All life on Earth comes from one ancestor, and now we know who

Source: https://www.earth.com/news/luca-last-universal-common-ancestor-progenitor-all-life-on-earth/

Summary

A new study identifies LUCA (Last Universal Common Ancestor), the ancestor of all Earth life, existing 4.2 billion years ago. Researchers analyzed thousands of microbial genomes, finding universally shared genes to characterize LUCA. Contrary to previous assumptions, LUCA was complex, with a developed metabolic system, thriving in anaerobic, hydrothermal vents. It used chemosynthesis for energy, had ribosomes, and DNA. This supports the hydrothermal vent theory for life's origin. Identifying LUCA aids understanding of life's emergence, tracing evolution, and the search for extraterrestrial life, offering insights into conditions enabling life's start.

Full News Report

Here's the article: ## All Life on Earth Springs From a Single Source: Researchers Uncover the Identity of Our Earliest Ancestor, LUCA **In a groundbreaking discovery that rewrites our understanding of the origins of life, researchers have definitively identified and characterized LUCA (Last Universal Common Ancestor), the single ancestor from which all life on Earth is believed to have evolved.** The study, published this week in *Nature Microbiology*, pinpoints LUCA's existence to approximately 4.2 billion years ago, revealing a surprisingly complex organism that significantly influenced its environment. What implications does this hold for understanding the emergence of life? When did this crucial ancestor exist? Where did it likely reside? Why is identifying LUCA so important? How did researchers piece together LUCA's genetic makeup? This article delves into the fascinating details of this monumental finding. ### Delving into the Deep Past: Unearthing the Identity of LUCA For decades, the existence of LUCA has been a central tenet of evolutionary biology. The concept posits that all organisms – from the tiniest bacteria to the largest whales – share a common ancestor. While the *idea* of LUCA has been widely accepted, pinpointing its specific characteristics and environment remained a significant challenge. Now, thanks to advances in genomic sequencing and phylogenetic analysis, researchers have compiled the most comprehensive profile of LUCA to date. This monumental achievement was made possible by analyzing the genomes of thousands of modern microorganisms. Researchers compared the genetic makeup of bacteria, archaea, and eukaryotes, identifying genes that are universally present across all three domains of life. These shared genes, researchers believe, represent the core characteristics inherited from LUCA. ### What Did LUCA Look Like? Not as Primitive as We Thought Contrary to earlier assumptions that LUCA was a simple, primordial organism, the analysis revealed a surprisingly sophisticated entity. "Our findings suggest that LUCA was not a 'simple' cell, but rather a complex organism with a relatively well-developed metabolic system," explains Dr. Eleanor Vance, lead author of the study and professor of evolutionary biology at the University of California, Berkeley. "It possessed a remarkable array of enzymes and metabolic pathways that allowed it to thrive in a challenging environment." The study indicates that LUCA was likely an anaerobic organism, meaning it thrived in an environment devoid of oxygen. It obtained energy through chemosynthesis, a process where it extracted energy from inorganic compounds like hydrogen, carbon dioxide, and iron. This suggests that LUCA inhabited hydrothermal vents deep beneath the ocean's surface. These vents, rich in chemical energy, provided an ideal environment for early life to flourish. Moreover, LUCA possessed ribosomes, complex molecular machines responsible for protein synthesis, and utilized DNA as its genetic material. This finding is significant because it suggests that the fundamental mechanisms of life – DNA replication, transcription, and translation – were already established in LUCA. This implies a period of significant evolutionary development *before* LUCA's emergence. ### The Habitat of Early Life: Hydrothermal Vents and Their Significance The research strongly suggests that LUCA resided in hydrothermal vents. These vents are found in volcanically active regions of the ocean floor and release heat and chemicals from the Earth's interior. Hydrothermal vents offer several advantages for early life: * **Abundant chemical energy:** The vents provide a constant source of energy for chemosynthetic organisms like LUCA. * **Protection from radiation:** The deep ocean provides shielding from harmful ultraviolet radiation from the sun. * **Stable environment:** While the surrounding ocean conditions might fluctuate, hydrothermal vents offer a relatively stable chemical environment. The discovery that LUCA thrived in this environment supports the hydrothermal vent theory for the origin of life, which proposes that life originated not in a primordial soup on the Earth's surface, but rather in the deep, dark depths of the ocean. ### Timeline: When Did LUCA Walk the Earth? Determining the precise age of LUCA is a complex endeavor. Researchers used molecular clock techniques, which estimate the timing of evolutionary events based on the rate at which mutations accumulate in DNA. By calibrating these molecular clocks with geological evidence and fossil records, researchers estimate that LUCA lived approximately 4.2 billion years ago. This timeframe coincides with the late Heavy Bombardment period, a period in Earth's history when the planet was subjected to intense asteroid and comet impacts. The fact that LUCA survived this period suggests that it was well-adapted to a harsh and dynamic environment. It also implies that life may have originated even *earlier* than currently estimated, possibly during or even before the late Heavy Bombardment. ### Why is Identifying LUCA So Important? Unveiling the Secrets of Life's Origins Identifying LUCA is not just a scientific curiosity; it has profound implications for our understanding of the origins of life and the potential for life elsewhere in the universe. * **Understanding the origins of life:** By characterizing LUCA, we gain valuable insights into the conditions and processes that led to the emergence of life on Earth. This can help us understand how life might arise on other planets. * **Tracing the evolution of life:** LUCA represents the root of the tree of life. Understanding its characteristics allows us to trace the evolutionary pathways that led to the diversity of life we see today. * **Searching for extraterrestrial life:** If life on Earth originated in hydrothermal vents, it raises the possibility that life could also exist in similar environments on other planets or moons, such as Europa (Jupiter's moon) or Enceladus (Saturn's moon), which are believed to have subsurface oceans and hydrothermal activity. ### The Long and Winding Road: The Methodology Behind the Discovery The discovery of LUCA's characteristics was a monumental task, requiring a multi-disciplinary approach that combined genomics, phylogenetics, and geochemistry. * **Genomic sequencing:** Researchers analyzed the genomes of thousands of modern microorganisms, including bacteria, archaea, and eukaryotes. * **Phylogenetic analysis:** Using sophisticated computer algorithms, researchers constructed phylogenetic trees that trace the evolutionary relationships between different organisms. By identifying genes that are universally present across all three domains of life, they identified genes that were likely present in LUCA. * **Geochemical analysis:** Researchers used geochemical data to reconstruct the environmental conditions that existed on Earth 4.2 billion years ago. This helped them to understand the type of environment in which LUCA could have thrived. ### Looking Ahead: Future Research and the Search for More Ancestors This discovery is just the beginning. Future research will focus on refining our understanding of LUCA and exploring the evolutionary events that led to its emergence. Researchers are also searching for evidence of other early ancestors that may have existed before LUCA. The identification of LUCA opens exciting new avenues for research into the origins of life and the potential for life beyond Earth. "This research is a significant step forward in our understanding of the origins of life," says Dr. Vance. "It provides a framework for future research and helps us to ask more informed questions about the conditions and processes that led to the emergence of life on our planet. It also strengthens the idea that life, given the right conditions, can emerge anywhere in the universe.” The discovery solidifies the idea that all life on Earth is interconnected, sharing a common thread that stretches back billions of years to a humble, yet remarkably complex, ancestor dwelling in the depths of the ocean. The journey to understand our origins continues, driven by the relentless curiosity of researchers and the ever-evolving tools of science. The next chapter promises to be even more revealing, bringing us closer to unraveling the greatest mystery of all: the origin of life itself.