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+--- Thread: Research Scientists describe a window into evolution before the tree of life (/thread-19750.html)
Scientists describe a window into evolution before the tree of life - C C - Feb 8, 2026
https://www.eurekalert.org/news-releases/1115050
INTRO: All life on Earth shares a common ancestor that lived roughly four billion years ago. This so-called “last universal common ancestor” represents the most ancient organism that researchers can study.
Previous research on the last universal common ancestor has found that all the characteristics we see in organisms today, like having a cell membrane and a DNA genome, were already present by the time of this ancestor. So, if we want to understand how these foundational characteristics of life first emerged, then we need to be able to study evolutionary history prior to the last universal common ancestor.
In a new article published in the journal Cell Genomics, scientists Aaron Goldman (Oberlin College), Greg Fournier (MIT), and Betül Kaçar (University of Wisconsin-Madison) describe a method to do just that. “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 authors describe a type of gene family known as a “universal paralog,” which provides evidence of evolutionary events that occurred before the last universal common ancestor.
A paralog is a gene family that has multiple members in the same genome. For example, in our own genome, we have eight versions of hemoglobin genes, which encode proteins that bind to oxygen and carry it through the blood. All of these paralog genes descended from an ancient globin gene that existed as a single copy about 800 million years ago. The paralogs were created by repeated duplications of that gene through DNA copying errors, with each copy then evolving its own distinct features over millions of years.
Universal paralogs are a rare, special type of paralog that have at least two copies in the genomes of all or nearly all organisms alive today. This broad presence indicates that the duplication of an original gene must have taken place before the last universal common ancestor, with multiple copies inherited by its descendants, all the way to the present day.
For this reason, the authors argue that universal paralogs provide an indispensable, but underutilized, target for understanding the earliest history of life on Earth, especially as tools for such research improve with the arrival of new AI-based techniques and AI-optimized hardware... (MORE - details, no ads)