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 a role for viruses in gene exchange, according to research published online in Nature on June 17, 2026. This reconstruction challenges the long-held view that eukaryotic cells originated from a straightforward merger of only two organisms. Instead, the findings suggest a more complex evolutionary history involving a series of close, long-term relationships with a variety of microbial life forms. The study's analysis indicates that viruses played a significant part in facilitating the transfer of genetic material between these ancient entities. This new perspective offers a deeper understanding of the foundational genetic makeup of all eukaryotic life, including plants, animals, fungi, and protists. The research utilized advanced computational methods to infer the gene content of the last eukaryotic common ancestor, providing a molecular basis for understanding early cellular evolution. The implications extend to understanding the origins of complex cellular structures and functions unique to eukaryotes.