New research suggests we may have been mistaken about the origins of life. In a recent peer-reviewed study, scientists have analyzed amino acids both before and after the “last universal common ancestor,” which is believed to be the single life form that gave rise to all life forms thereafter. This study challenges our previous assumptions about the emergence of genes and the order in which amino acids were incorporated into the genetic building blocks.
Researchers at the University of Arizona argue that our current understanding may be biased, particularly when it comes to distinguishing between living and non-living sources. They propose that our model of gene history may not fully appreciate the significance of early protolife, such as RNA and peptides, in comparison to what emerged later with the beginning of life. By revisiting our understanding of these ancient times, we may uncover important insights into our own origins and potentially discover clues about the beginnings of life elsewhere in the universe.
In a new paper published in the journal Proceedings of the National Academy of Science, a team led by Joanna Masel and Sawsan Wehbi reveals that crucial components of proteins, known as amino acids, can be traced back four billion years to the last universal common ancestor. By analyzing protein domains, which are like versatile parts that can be used in various “cars,” the researchers have proposed a reevaluation of the traditional timeline for the emergence of the 20 essential genetic amino acids.
One significant finding of the study is the suggestion to reconsider the order in which amino acids appeared on early Earth. The current model, which prioritizes the most abundant amino acid in early life forms as the first to emerge, may overlook important nuances. The researchers challenge this perspective, pointing out that amino acids could have originated from different regions of the early Earth rather than from a uniform environment.
The study also highlights the surprising prevalence of the amino acid tryptophan before the divergence of all life forms. Despite being traditionally considered as one of the last amino acids to be incorporated into the genetic code, tryptophan was found in higher proportions in the pre-last universal common ancestor data compared to the post-divergence data. This unexpected discrepancy raises questions about the chemical processes that influenced the emergence of amino acids and challenges previous assumptions about the history of genetic building blocks.
Scientists are delving into an even older iteration of genetic concepts. In the realm of evolution, the notion that any singular successful entity must stand alone as the sole representative of its kind or lineage lacks intuitive resonance. The researchers posit that the gradual assembly of the existing genetic code and the competition among ancient codes could have unfolded in parallel. Moreover, they suggest that ancient codes might have engaged noncanonical amino acids in their processes. These unconventional amino acids could have emerged in the vicinity of alkaline hydrothermal vents, recognized as pivotal environments in the genesis of life, despite the transient habitation of resulting life forms in those locales.
Expanding this conjecture beyond terrestrial bounds, the proximity is not vast. The synthesis of aromatic amino acids in the water-rock interface of Enceladus’s subterranean ocean might be achievable through abiotic means, as elucidated by the scientists. This moon of Saturn, within our Solar System, presents a feasible arena for the manifestation of such biochemical processes. Perhaps the notion of a celestial gathering within our celestial neighborhood is more plausible than previously imagined.
