On Aug. 21, 2024, a research team at the University of Texas at Austin reported that the first weapons your body deploys when you get infected with a virus were passed down to us from our microbial ancestors billions of years ago. Specifically, viperins and argonautes, two proteins that are known to play important roles in the immune systems of all complex life — from insects to plants to humans — came from the Asgard archaea.

Versions of these defense proteins are also present in bacteria, but the versions in complex life forms are most closely related to those in Asgard archaea, according to the study results published in the journal Nature Communications. This research bolstered the idea that all complex life, called eukaryotes, arose from a symbiotic relationship between bacteria and Asgard archaea.