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Every living organism traces its lineage to a common ancestor that lived about four billion years ago. Scientists call this organism the “last universal common ancestor” and it represents the oldest life form that can currently be studied using established evolutionary methods.
Studies of this ancient ancestor show that many characteristics of modern life were already present at that time. Cells already had membranes and genetic facts was stored in DNA. Once these basic characteristics have been established, scientists seeking to understand how life arose must look even further back to the evolutionary events that occurred before this common ancestor existed.
Studying life before the first common ancestor
In a study published in the journal Cellular genomicsresearchers Aaron Goldman (oberlin College), Greg Fournier (MIT), and Bethul Cachar (University of Wisconsin-Madison) describe a way to study this earlier period of evolution. “Although the last universal common ancestor is the oldest organism we can study using evolutionary methods,” Goldman saeid, “some of the genes in its genome were much older.” The team focuses on a special group of genes called “universal paralogs,” which preserve evidence of biological changes that occurred before the last universal common ancestor.
A paralog is a group of related genes that appear multiple times in the same genome. people set a good example. Our DNA contains eight different hemoglobin genes, all of which produce proteins that carry oxygen through the blood. all of these genes evolved from a single ancestral globin gene that existed about 800 million years ago. Over long periods of time, repeated copying errors created additional versions of the gene, and each copy gradually developed its specialized role.
What makes universal Paralogs unique
Universal paralogues are much less common. These gene families are present in at least two copies in the genomes of almost all living organisms. Their widespread presence suggests that initial gene duplication occurred before the appearance of the last universal common ancestor. These duplicated genes have been passed down through countless generations and remain alive today.
Because of this deep evolutionary coverage, the authors argue that universal paralogues are an vital but often overlooked resource for studying the earliest history of life on Earth. this approach is becoming more practical as new AI-based techniques and AI-optimized hardware facilitate detailed analysis of ancient genetic patterns.
“Although there are very few universal paralogues that we know of,” says Goldman, “they can give us a lot of information about what life was like before the time of the last universal common ancestor.” Fournier adds: “The history of these universal paralogs is the only information we will have about these oldest cell lineages, and thus we need to carefully extract as much knowledge from them as possible.”
Clues to early cellular functions
In their analysis, Goldman, Fournier and Cachar considered all known universal paralogues. Each of these genes plays a role in building proteins or moving molecules across cell membranes. This discovery suggests that protein production and membrane transport were among the first biological functions to evolve.
The researchers also emphasize the importance of reconstructing the ancient forms of these genes. In a study from Goldman’s lab at Oberlin, scientists investigated a universal family of paralogs involved in inserting enzymes and othre proteins into cell membranes. Using standard techniques in evolutionary biology and computational biology, they reconstructed the protein produced by the original ancestral gene.
Their results showed that this ancient and simpler protein can still attach to cell membranes and interact with the machinery that produces proteins.It probably helped the first proteins become incorporated into primitive membranes,giving an idea of how the first cells might have worked.
A new window into the early history of life
The authors hope that new advances in computational tools will allow scientists to identify additional universal families of paralogs.
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