Archaea

This episode of In Our Time explores the groundbreaking discovery of archaea—microorganisms that, despite their bacterial-like appearance, represent a fundamentally distinct branch of life. Hosted by Melvyn Bragg, the discussion features experts Christia Schleper, Thorsten Allis, and Buzz Baum, who trace the revolutionary work of Carl Woese in the 1970s, who used ribosomal RNA to reveal a third domain of life, separate from bacteria and eukaryotes. The episode delves into how archaea, once mistaken for bacteria, are now known to share deep evolutionary ties with complex life, particularly through their information-processing machinery. The discovery of Asgard archaea—named after Norse gods and possessing genes previously unseen in prokaryotes—has provided compelling evidence that eukaryotic cells may have evolved from archaeal ancestors through a symbiotic merger with bacteria, possibly via a 'inside-out' model of cellular evolution. The conversation also covers the ecological importance of archaea, including their roles in methane production, nitrogen cycling, and survival in extreme environments such as hydrothermal vents and salt flats. Despite their importance, archaea remain understudied due to their challenging cultivation requirements, yet their study is reshaping our understanding of life’s origins and evolution.