The ancestors of eukaryotic cells contained a mix of genes from various microbes

The ancestral gene repertoire of eukaryotic cells reveals traces of extensive interactions with diverse microorganisms and viruses, according to research published online in Nature on June 17, 2026. This reconstruction challenges the long-held theory that eukaryotic cells originated from a straightforward fusion of only two organisms. Instead, the findings suggest a more complex evolutionary history involving a series of close, long-term relationships with various microbial partners. The study indicates that viruses played a significant role in facilitating gene exchange between these ancient cellular entities. This new understanding provides a more nuanced perspective on the origins of eukaryotes, highlighting a dynamic process of gene acquisition and integration from a broad spectrum of microbial life. The research involved analyzing gene sequences to infer the genetic makeup of these early cellular ancestors, uncovering evidence of multiple evolutionary events rather than a single, simple merger.