Ancient duplicated genes are giving scientists their first real clues about what life was like before all life on Earth shared a common ancestor.
Every living organism on Earth can be traced back to a single shared ancestor that existed about four billion years ago. Scientists call this organism the “last universal common ancestor,” and it marks the oldest point in evolutionary history that researchers can reliably study using current methods.
Studies of this ancient ancestor show that many features common to life today were already in place, including a protective cell membrane and a genome made of DNA. Because these core traits were already established by that time, scientists who want to understand how life first developed must look even further back, to evolutionary events that happened before this shared ancestor existed.
Genes That Predate All Known Life
In a new study published today (February 5) in the journal Cell Genomics, scientists Aaron Goldman (Oberlin College), Greg Fournier (MIT), and Betül Kaçar (University of Wisconsin-Madison) outline an approach for investigating this earlier chapter of life’s history. “While the last universal common ancestor is the most ancient organism we can study with evolutionary methods,” said Goldman, “some of the genes in its genome were much older.” The team focuses on a special category of genes called “universal paralogs,” which preserve evidence of biological changes that occurred before the last universal common ancestor.
A paralog refers to a group of related genes that appear multiple times within the same genome. In humans, for instance, there are eight different hemoglobin genes, all of which produce proteins that transport oxygen through the bloodstream. These genes originated from a single ancestral globin gene that existed around 800 million years ago. Over time, copying errors during DNA replication created extra versions of the gene, and each copy gradually evolved unique characteristics.
What Makes Universal Paralogs Special
Universal paralogs are far more unusual. They are gene families that appear in at least two copies in nearly every living organism on Earth. This widespread distribution strongly suggests that the original gene duplication happened before the last universal common ancestor appeared. Both copies were then passed down through countless generations, surviving across billions of years of evolution.
Because of this, the authors argue that universal paralogs offer a powerful yet largely overlooked way to study the earliest stages of life on Earth. This opportunity is becoming more important as advances in artificial intelligence and specialized computing hardware make it possible to analyze ancient genetic patterns with greater precision.
“While there are precious few universal paralogs that we know,” 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 ever have about these earliest cellular lineages, and so we need to carefully extract as much knowledge as we can from them.”
Clues About the First Cells
In their study, Goldman, Fournier, and Kaçar reviewed every known universal paralog identified so far. All of these genes are involved either in building proteins or in transporting molecules across cell membranes. This finding suggests that protein production and membrane transport were among the very first biological functions to evolve.
The researchers also emphasize the importance of reconstructing the original forms of these ancient genes. In one example, Goldman’s lab at Oberlin examined a universal paralog family that helps insert enzymes and other proteins into cell membranes. Using established methods from evolutionary biology and computational biology, the team rebuilt the protein produced by the original ancestral gene.
Their analysis showed that this simpler, ancient protein could still attach to cell membranes and interact with the machinery that builds proteins. It likely helped early, basic proteins become embedded in primitive cell membranes, offering insight into how early cells may have functioned.
A New Path Toward Life’s Origins
The authors hope that continued improvements in computational tools will allow scientists to identify additional universal paralog families and study their ancient ancestors in even more detail. “By following universal paralogs,” says Kaçar, “we can connect the earliest steps of life on Earth to the tools of modern science. They provide us a chance to transform the deepest unknowns of evolution and biology into discoveries we can actually test.”
Their goal is to build a clearer picture of evolution before the last universal common ancestor, shedding light on the moment when life as we know it first began to take shape.
Reference: “Universal paralogs provide a window into evolution before the last universal common ancestor” by Aaron D. Goldman, Gregory P. Fournier and Betül Kaçar, 5 February 2026, Cell Genomics.
DOI: 10.1016/j.xgen.2026.101140
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