The Asgard archaea, named after the mythological city of Asgard, are a group of microbes that have been found in deep sea sediments and hot springs around the world. They are believed to have evolved more than 2 billion years ago, and their descendants are still living today. However, only two strains of Asgard archaea have been successfully grown in the lab, making them difficult to study directly.
Researchers analyzed the genomes of hundreds of different microbes called archaea to identify the closest microbial relative to all complex life forms on the tree of life. They discovered that eukaryotes, which include all complex life forms such as plants, animals, insects, and fungi, trace their roots to a common Asgard archaean ancestor. This means that eukaryotes are a “well-nested clade” within Asgard archaea, similar to how birds are one of several groups within a larger group called dinosaurs, sharing a common ancestor.