Scientists at the University of Arizona propose that the order of amino acid incorporation into the genetic code differs from traditional models. New research challenges previous theories on the origins of life, suggesting a revised understanding of how genes and amino acids emerged. Their findings, published in Proceedings of the National Academy of Sciences, suggest early genetic codes may have been more complex and diverse, revealing insights into the evolutionary history of life on Earth.

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New Evidence Challenges Traditional Theories on Life’s Origins

Scientists have uncovered fresh evidence that challenges previous ideas about the origins of life. A new peer-reviewed analysis suggests that our understanding of how genes first emerged—specifically, when amino acids began playing a role—needs significant revision. The research was conducted by genetic scientists at the University of Arizona, who have raised questions about the conventional theories surrounding the development of the genetic code.

New Study Suggests a Different Evolution of the Genetic Code

The genetic code, which is shared by all living organisms, is a fundamental aspect of life on Earth. However, the exact processes and timeline for how this code evolved have been subjects of ongoing debate among researchers. According to Scientists the new study, the sequence in which amino acids—the essential building blocks of the genetic code—emerged may have been very different from what has been widely accepted in the scientific community.

New Theory Proposes a Different Sequence for Amino Acid Evolution

In their study published in the Proceedings of the National Academy of Sciences, researchers Sawsan Wehbi and senior author Joanna Masel presented a novel theory. They argue that the order in which amino acids became part of the genetic code differs significantly from previous models. Masel explained that the genetic code is an intricate system where sequences of three nucleotides, called codons, in DNA or RNA are translated into protein sequences using 20 distinct amino acids. This process is extraordinarily complex, and the current genetic code is incredibly efficient, optimized for various functions, suggesting it evolved in stages.

Study Challenges LUCA Concept and Reassesses Early Life Experiments

The study revisits the concept of the “last universal common ancestor” (LUCA), the single life form from which all life on Earth is believed to have descended. The researchers contend that many earlier models were based on outdated or flawed assumptions, particularly those that relied on laboratory experiments rather than the actual process of evolution. One such example is the 1952 Urey-Miller experiment, which tried to simulate early Earth conditions to replicate the origins of life. Despite its significance, this experiment failed to detect sulfur-containing amino acids, even though sulfur was abundant on early Earth.

Research Challenges Sulfur Theory, Reveals Older Genetic Codes with Aromatic Structures

This discrepancy led the researchers to question whether sulfur-containing amino acids were added to the genetic code at a later stage, a theory that may no longer hold. Using modern data and advanced tools from the National Center for Biotechnology Information, the team reconstructed a tree of protein domains dating back to LUCA. They identified over 400 families of protein sequences that predate LUCA, with more than 100 of them having already evolved before LUCA appeared. Some of these sequences contained amino acids with aromatic ring structures, which the researchers believe might indicate a more complex genetic code existed earlier than previously thought.

Wehbi further elaborated on their findings by comparing protein domains to wheels in cars. “A domain is like a wheel,” she explained. “It’s a component that can be used in many different contexts, and these components have been around far longer than the vehicles themselves.”