Hunting extreme microbes that redefine the limits of life

Summary

Intraterrestrials: Discovering the Strangest Life on Earth Karen G. Lloyd Princeton University Press (2025)Is there such a thing as a ‘beach read on microbial thermodynamics’? That was how Karen Lloyd, the author of Intraterrestrials, informally billed her book when talking to her friends in science (including myself) — and at a beach-bag-friendly 200 pages or so, this lively and compulsively engaging book is an unusual page-turner. Lloyd, a geomicrobiologist, expertly guides readers who have a taste for biological adventures to ‘intraterrestrial’ life: microorganisms that survive under the most extreme environmental conditions, such as in Earth’s deep sediments, deep ocean crust, volcanoes and permafrost soil.Glaciers are not just blocks of ice — plans to save them mustn’t overlook their hidden lifeThe encounters include microbes that have never been cultured before, or that can live on extremely limited energy supplies, or that persist in states of suspended animation, their biological functions slowed or paused for thousands of years. The intraterrestrials in the title echo the extraterrestrials that might populate other planets and moons. But there’s no need to search far for alien-like life: surprising microbes thrive here on Earth. Lloyd reports on this research frontier and its big-picture implications from a front-row seat, as a seasoned geomicrobiologist who has made major contributions to the unfolding story of intraterrestrials.Far-flung placesSampling and studying these micro-organisms is difficult — and sometimes dangerous. Dealing with the challenges and keeping reasonably safe requires teamwork, portrayed here with the right balance of light-hearted banter and ominous foreboding. Lloyd brings the reader along as she collects gas-rich sediments and microbial mats aboard a deep-sea submersible in the Gulf of Mexico; samples sulfurous gas fumaroles in Andean volcanoes; resurrects microbes by drilling Arctic permafrost soil on the Norwegian Arctic archipe...