TAG: GS 3: SCIENCE AND TECHNOLOGY
THE CONTEXT: The quest to understand the origin of life on Earth is one of science’s most profound endeavours. Recent studies suggest that the Last Universal Common Ancestor (LUCA) formed just 300 million years after the Earth, offering new insights into how life began and evolved on our planet.
EXPLANATION:
Theories of Life’s Origin
- The Oparin-Haldane Hypothesis
- In early 1920s, Alexander Oparin and J. B. Haldane came up with the information theory that life commenced from amino acids and other ingredients that formed in Earth’s early stage.
- In their view, these molecules began to enter into a process of self-organization and that over time the primitive structures started forming the first living organisms.
- It was a revolutionary idea in its time and is today referred to as the Oparin-Haldane hypothesis and has paved way for other researches.
- The Miller-Urey Experiment
- Stanley Miller and Harold Urey in 1952 at the University of Chicago, give the experimental back-up to the Oparin-Haldane hypothesis.
- To model that early conditions of the earth, they combined methane, ammonia and water, and then applied electricity to the gaseous mixture to create a lightning effect.
- Rather surprisingly, this experiment led to the formation of the so-called amino acids – the basic elements of proteins, which proved that the organic compounds could be produced from inorganic materials.
- While their results later proved to be contingent on the assumption that early Earth’s environment was similar to the conditions in their experiment, the Miller-Urey experiment was a groundbreaking discovery towards the formation of life.
- Many theories regard the existence of other life forms and here we are going to focus on Extraterrestrial Origins of Life.
- Another well-known theory indicates that life began from pieces that arrived on the earth via meteorites.
- There are findings of extraterrestrial organic matter that supports this claim.
- The French and Italian researchers stated that they had successfully locating 3 in August, 2019.
- The N-strewn field meteorite contains an abundance of extraterrestrial organic matter that according to research is said to be 3 billion years old whereas Japan Hayabusa 2 mission to the asteroid Ryugu detected over twenty amino acids. These discoveries put forward in this work indicate that some elements for life may have been delivered from space which can create a new stories on the possibility of origins of life.
LUCA and the Molecular Clock
- The Concept of LUCA
- The Last Universal Common Ancestor (LUCA) is the hypothetical single-cell organism from which all life on Earth descended.
- Although there is no direct fossil evidence of LUCA, the shared features in modern genomes offer valuable insights.
- LUCA is believed to be the common ancestor of all three branches of life: bacteria, archaea, and eukarya.
- The Molecular Clock Theory
- The molecular clock theory, proposed by Emile Zuckerkandl and Linus Pauling in the 1960s and later refined by Motoo Kimura, is a crucial tool for reconstructing the evolutionary history of life.
- This theory posits that genetic mutation rates are relatively constant, allowing scientists to estimate the time between evolutionary events.
- Researchers can create a timeline of life’s evolution by calibrating the molecular clock with known events, such as the emergence of the first mammals or the age of specific fossils.
Recent Discoveries and Their Implications
- Dating LUCA
- In a recent study published in Nature Ecology and Evolution, researchers from the University of Bristol and Exeter used a molecular clock to estimate LUCA’s age.
- By constructing a phylogenetic tree of 350 bacterial and 350 archaeal genomes, they determined that LUCA could have originated around 4.2 billion years ago, just 300 million years after Earth’s formation.
- This finding significantly predates previous estimates of life’s emergence and suggests that life began almost immediately after Earth’s formation.
- Characteristics of LUCA
- The study also revealed that LUCA likely had a small genome, comprising about 2.5 million bases and encoding around 2,600 proteins.
- These genetic components would have been sufficient for LUCA to survive in a unique environmental niche.
- Additionally, LUCA’s metabolites could have created a secondary ecosystem, fostering the emergence of other microbes.
- The presence of genes responsible for immunity suggests that LUCA faced viral threats, indicating a complex and interactive early biosphere.
- Comparison with Fossil Evidence
- The discovery that LUCA may have existed around 4.2 billion years ago challenges previous fossil records.
- Fossils found in the Pilbara Craton in Western Australia, dating back to 3.4 billion years ago, were once considered the earliest evidence of life.
- The new study pushes the timeline back by almost a billion years, aligning the origin of life closely with the birth of our planet.
Broader Implications
- Understanding Evolution
- The study of LUCA provides crucial insights into the early evolution of life on Earth.
- By analyzing modern genomes and applying molecular clock techniques, scientists can better understand how life diversified into the rich array of organisms we see today.
- These findings also underscore the importance of integrating genomic data with paleontological evidence to construct a comprehensive picture of life’s history.
- Search for Extraterrestrial Life
- The insights gained from studying LUCA also have implications for the search for life beyond Earth.
- Understanding the conditions that allowed life to emerge on our planet can guide the search for similar conditions on other planets and moons.
- The discovery of life’s potential building blocks on meteorites further supports the possibility that life could exist elsewhere in the universe.
- Engineering Synthetic Life
- The knowledge gained from studying the origins and evolution of life can also inform efforts to engineer synthetic organisms.
- Understanding the genetic and metabolic pathways that allow early life forms to thrive can help scientists develop new biotechnological applications.
- These could range from industrial processes to creating or moderating ecosystems on other planets, advancing scientific knowledge and practical applications.
