Intraterrestrials: Discovering the Strangest Life on Earth

by Karen G. Lloyd

Overview

A biologist’s firsthand account of the hunt for life beneath earth’s surface—and how new discoveries are challenging our most basic assumptions about the nature of life on Earth

Life thrives in the deepest, darkest recesses of Earth’s crust—from methane seeps in the ocean floor to the highest reaches of Arctic permafrost—and it is unlike anything seen on the surface. Intraterrestrials shares what scientists are learning about these strange types of microbial life—and how research expeditions to some of the most extreme locales on the planet are broadening our understanding of what life is and how its earliest forms may have evolved.

Drawing on her experiences and those of her fellow scientists working in challenging and often dangerous conditions, Karen Lloyd takes readers on an adventure from the bottom of the ocean through the jungles of Central America to the high-altitude volcanoes of the Andes. Only discovered in recent decades, “intraterrestrials”—subsurface beings that are truly alien—are demonstrating how life can exist in boiling water, pure acid, and bleach. They enable us to peer back to the very dawn of life on Earth, disclosing deep branches on the tree of life that push the limits of what we thought possible. Some can “breathe” rocks or even electrons. Others may live for hundreds of thousands of years or longer. All of them are living in ways that are totally foreign to us surface dwellers.

Blending captivating storytelling with the latest science, Intraterrestrials reveals what microbes in Earth’s deep subsurface biosphere can tell us about the prospects for finding life on other planets—and the future of life on our own.

Product Details

ISBN-13:	9780691236117
Publisher:	Princeton University Press
Publication date:	05/13/2025
Pages:	248
Product dimensions:	5.80(w) x 8.80(h) x 1.00(d)

About the Author

Karen G. Lloyd is the Wrigley Chair in Environmental Studies and Professor of Earth Sciences at the University of Southern California. Her work has appeared in leading publications such as Nature and Science.

What People are Saying About This

From the Publisher

“Intraterrestrials is an astonishing, exhilarating, mind-bending journey into the hidden living world deep beneath our planet’s sunlit surface. Lloyd is a master storyteller and unrivaled expert in sharing the thrills and challenges of diving to the ocean floor, sampling near active volcanoes, and dodging polar bears on rapidly thawing permafrost. Read this book and prepare to enter a living realm beyond your wildest imagination.”—Robert M. Hazen, author of The Story of Earth

“Forget Ewoks, tribbles, and Daleks. Fictional extraterrestrials seem quite ordinary compared with the truly bizarre organisms living beneath our feet: microbes that thrive in physical and chemical extremes, ‘breathe’ rocks—and outlive humans. Karen Lloyd’s Intraterrestrials will forever change your understanding of what it means to be alive on Earth.”—Marcia Bjornerud, author of Timefulness and Turning to Stone

“Karen Lloyd’s innovative research will change the way that readers think about life on Earth. She tells extraordinary stories about hidden ‘intraterrestrials’ that live in the rocks beneath our feet and transports us from volcanic jets to deep ocean vents to Arctic permafrost. I have long defined my own research on the unexplored rainforest canopy as the eighth continent, but Lloyd’s world ranks far beyond that, perhaps as a tenth planet. I loved reading every page!”—Meg Lowman, author of The Arbornaut

“In Intraterrestrials, Karen Lloyd takes readers on the exciting quest to understand biodiversity’s last frontier: microbial life within the earth. Part Indiana Jones, part Louis Pasteur, Lloyd engagingly explains the challenging fieldwork and sophisticated lab research that together are revealing the subterranean biota and showing why it matters.”—Andrew H. Knoll, author of A Brief History of Earth: Four Billion Years in Eight Chapters

“As we search for life elsewhere in the universe, there is much still to learn about the life beneath our feet. In a narrative that combines the principles of thermodynamics with breathtaking, all-action adventure, Lloyd ventures from the high Arctic to deep-sea hydrothermal vents in pursuit of the limits of life. This is one of the most exciting books I have read in ages.”—Henry Gee, author of A (Very) Short History of Life on Earth

Editorial Reviews

"The central question Lloyd poses in her fascinating exploration of underground microbial ecology—are there life-forms hiding inside Earth that are so strange that they change our conception of life itself?—is easily answered. Yes!"—-Tony Miksanek, Booklist

"The author gives us a completely new appreciation of how deep life is embedded in our own planet."—-Bruce Dorminey, Forbes

"[A] must-read."—-Mark Martin, Matters Microbial

"[This] book is so fascinating."—-Mia Funk, One Planet Podcast

"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. . . . Thanks to Intraterrestrials, the general reader can now peek into the work of this network of experts and hopefully leave with a changed perspective as regards microbial life on and within this planet, and of its antiquity, evolutionary pace, adaptability and extraordinary tenacity."—-Andreas Teske, Nature

"Intraterrestrials: Discovering the Strangest Life on Earth by Karen G. Lloyd is a much-needed field guide to Earth’s subterranean life. . . . Through witty prose, she brings us along on some of her own adventures chasing microbes from the high desert of the Andes to the perilous summit of a Costa Rican volcano. These are scenes out of an action movie: careful not to slip on the shards of volcanic glass, lest you fall into the lake of acid! . . . All this makes for fun and evocative reading about biogeochemistry."—-James Dineen, New Scientist

"Fascinating."—-Brian Clegg, Popular Science

From the Publisher

"Lloyd is one of those rare gifted writers who can be as broadly profound as she is precise, able to make science both come raucously alive and resonate with meaning. She does this via perfect metaphors, an effortless wit, and a massively infectious enthusiasm for the outsize significance of her very small subjects. This science book is, furthermore, part adventure story, as she travels to the ends of the earth to pursue her small subjects, and generally bears witness to 'the shocking enormity of what we have been missing about life on Earth."

starred review Kirkus Reviews

"Lloyd, an environmental studies professor at the University of Southern California, debuts with an astonishing study of the remarkable microorganisms that thrive in the 'subsurface biosphere.' . . . Filled with mind-blowing trivia that will change how readers think about life on Earth, this captivates."

starred review Publishers Weekly

★ 2025-03-08
Confronting the “shocking enormity” of all we don’t know.

In recent years we have discovered that most earthly life-forms do not derive their energy from the sun (photosynthesis). Most earthly life-forms are single-celled creatures dwellingbelow ground, where they derive chemical energy from inorganic compounds found there (chemosynthesis). Lloyd, a microbial biogeochemist, joyously notes that these preternaturally subsurface critters, which seem barely alive but can live for eons, are giving us hints as to how life first developed, leading us to change basic assumptions about life’s rules. The most hardy intraterrestrials, which dwell in extreme places like arctic ice or volcanoes, are upending our understanding of what life is—here and, perhaps, on other planets. Furthermore, intraterrestrials may even help us clean up our planet, given that one of the inorganic compounds that they can generate energy from is carbon, the main driver of climate change. Lloyd is one of those rare gifted writers who can be as broadly profound as she is precise, able to make science both come raucously alive and resonate with meaning. She does this via perfect metaphors, an effortless wit, and a massively infectious enthusiasm for the outsize significance of her very small subjects. This science book is, furthermore, part adventure story, as she travels to the ends of the earth to pursue her small subjects, and generally bears witness to “the shocking enormity of what we have been missing about life on Earth.”

A glorious gallop through one of the last, and possibly most important, frontiers of science.

Kirkus Reviews