A study of gut microbiomes finds that a common DNA sequencing technique overlooks 90 percent of the diversity in archaea, which are single-celled microbes more closely related to humans than bacteria. Archaea are difficult to study, so not much is known about the organisms. This can lead to bias in the archaea knowledge base, says the DOE Joint Genome Institute’s Tanja Woyke, who was quoted in this recent article in The Atlantic.