The search for deep life on Earth… and what it means for Mars

Onstott_Deep LifeThe living inhabitants of the soil and seas are well known to biologists. We have long studied their food chains, charted their migration, and speculated about their evolutionary origins. But a mile down an unused tunnel in the Beatrix mine in South Africa, Tullis C. Onstott, Professor of Geosciences at Princeton and author of Deep Life, is on a quest for mysterious bacteria and microbes that require neither oxygen nor sun to survive. When they open up an old valve, water full of microbes and even little worms flows—a discovery with stunning implications. The New York Times has chronicled Onstott’s research in a feature that asks, was there ever life on Mars? And could it still exist far below the surface? That organisms are nourished by our own earth’s core, thriving in darkness encased in hard rock provides major insights:

The same conditions almost certainly exist on Mars. Drill a hole there, drop these organisms in, and they might happily multiply, fueled by chemical reactions in the rocks and drips of water.

“As long as you can get below the ice, no problems,” Dr. Onstott said. “They just need a little bit of water.”

But if life that arose on the surface of Mars billions of years ago indeed migrated underground, how long could it have survived, and more to the point, how can it be found? Kenneth Chang writes:

If life is deep underground, robotic spacecraft would not find them easily. NASA’s InSight spacecraft, scheduled to launch in 2018, will carry an instrument that can burrow 16 feet into the ground, but it is essentially just a thermometer to measure the flow of heat to the surface. NASA’s next rover, launching in 2020, is largely a clone of Curiosity with different experiments. It will drill rock samples to be returned to Earth by a later mission, but those samples will be from rocks at the surface.

In the meantime, what can we learn deep in Earth’s mines? What do we know now about the energy required to sustain life underground? As Chang notes, if Beatrix is a guide, methane could be the answer:

As NASA’s Curiosity rover drove across Gale Crater a couple of years ago, it too detected a burp of methane that lasted a couple of months. But it has not detected any burps since.

Perhaps an underground population of methanogens and methanotrophs is creating, then destroying methane quickly, accounting for its sudden appearance and disappearance from the atmosphere. If Beatrix is a guide, the methane could be providing the energy for many other microbes.

Conventional wisdom is that Martian life, if it exists, would be limited to microbes. But that too is a guess. In the South African mine, the researchers also discovered a species of tiny worms eating the bacteria.
“It’s like Moby Dick in Lake Ontario,” Dr. Onstott said. “It was a big surprise to find something that big in a tiny fracture of a rock. The fact it would be down there in such a confined space slithering around is pretty amazing.”

A full account of Dr. Onstott’s work appears in the New York Times feature, Visions of Life on Mars in Earth’s Depths.

Read more about Deep Life: The Hunt for the Hidden Biology of Earth, Mars, and Beyond here.

Stephen Heard: Write like a scientist

the scientist's guide to writing heardScientific writing should be as clear and impactful as other styles, but the process of producing such writing has its own unique challenges. Stephen Heard, scientist, graduate advisor, and editor speaks from personal experience in his book The Scientist’s Guide to Writing: How to Write More Easily and Effectively Throughout Your Scientific Career. Heard’s focus on the writing process emphasizes the pursuit of clarity, and his tips on submissions, coauthorship, citations, and peer reviews are crucial for those starting to seek publication. Recently, Heard agreed to answer a few questions about his book.

What made you decide to write a book about scientific writing?

SH: I think the first spark was when I realized I give the same writing advice to all my students, over and over, and caught myself thinking it would be easier to just write it all down once. That was foolish, of course: writing the book wasn’t easy at all! But before long, my rationale shifted. The book became less about stuff I wanted to tell everyone else, and more about stuff I wished somebody had told me. A lot of us get into science without much writing experience, and without thinking much about how important a role scientific writing plays – and when we start doing it, we discover that doing it well isn’t easy. It took me many years to become a reasonably competent scientific writer, and the book includes a lot of the things I discovered along the way. I was surprised to discover that writing the book made me a better writer. I think reading it can help too.

Surely there a bunch of other scientific-writing books out there? What do you do differently?

SH: Yes – and some of them are quite good! But I wanted to write something different. I’m not sure my book says anything that no one else knows about outlining or paragraph structure or citation formatting (for example). But I thought there was a lot of value in a book that pays attention to the writer as much as the writing: to the way writers behave as they write, and to ways in which some deliberate and scientific attention to our behavior might help us write faster and better. I’ve also discovered that knowing a bit about the history and culture of scientific writing can help us understand the way we write (and why). Just as one example: knowing something about the history of the Methods section, and how it’s changed over the last 350 years as scientists have struggled with the question of how scientific studies gain authority, can help us decide how to write our own Methods sections. I also tackle the question of whether there’s a place in scientific writing for beauty or for humor – something that gets discussed so rarely that it seems almost like a taboo.

Finally, I wanted to write a book that was really engaging: to show that thinking about writing (as we all need to) needn’t be dry and pedantic. So readers might be surprised, in a book about scientific writing, to find mentions of Voltaire’s lover, SpongeBob SquarePants, and the etymology of the word fart. But I hope they’ll also find that there are lessons in all those things – and more – for scientists who want to write better and more quickly.

You also go into a lot of depth about the review and publication process. Why are these things important to cover alongside the writing process?

SH: Well, maybe that isn’t “writing”, strictly speaking – but it’s an essential part of getting one’s scientific writing in the hands of readers. All of us want our scientific writing to be read, and to be cited, and to help move our fields forward. So it’s not enough to write a good manuscript; we have to be able to shepherd it through the process of submission, review, revision, and eventual acceptance. Early in my own career I found this process especially mysterious. Since then, I’ve learned a lot about it – by publishing quite a few papers myself, but also by reviewing hundreds of manuscripts and acting as an Associate Editor for hundreds more. So I have a pretty good overview of the publishing process, from both the writer’s and the journal’s perspective. There’s no particular reason that process has to be mysterious, and I thought it would be helpful to draw back the curtain.

Is scientific writing really that different from other kinds of writing?

SH: Both yes and no! Of course, there are technical issues that matter in scientific writing, like ways of handling text dense with numbers, or ways we handle citations. There are also more cultural ways in which scientific writing is its own thing. One of them is that we’ve developed a writing form that efficiently conveys material to other people who are familiar with that form. Our conventional division of papers into Abstract, Introduction, Methods, Results, and Discussion is a piece of that. Our writing (and our publication process) have evolved in many other ways that aren’t quite the same as you’d find in the humanities, or in writing about science for the public. That’s why there are books about scientific writing, not just about writing. But on another level, good scientific writing is like most other good writing: clear, concise, engaging whenever possible, and did I mention clear? Nothing is more important than clarity! As a result of this similarity, people who learn good scientific writing are well positioned for any career that involves writing – which is to say, pretty much any career.

Do you think of yourself as a good writer?

SH: No! And to loop back to the first question, that’s a big part of why I wrote the book. There are a very few natural writers out there – geniuses – for whom good writing just seems to come naturally. But these are rare. I’m like nearly everyone else: writing is hard work for me. It’s a craft I’ve learned over the years by practicing, by thinking deliberately about how I do it, and by reading advice from books that have gone before mine. It’s still hard work, but that’s OK: I’m willing to put in the effort for my writing product to seem pretty good, even if my writing process is laborious. If I’d understood earlier in my career that most writers are just like me, I would have been less crushed by the discovery that my papers didn’t just write themselves! Every scientific writer can do what I’ve done: practice the craft and improve at it. I hope my book can help.

Stephen B. Heard is professor of biology at the University of New Brunswick in Canada and associate editor of the journal American Naturalist. His most recent book is The Scientist’s Guide to Writing: How to Write More Easily and Effectively Throughout Your Scientific Career.

Conversations on Climate: Paul Wignall says climate crisis is nothing new

NEW climate pic

Climate Change: We’ve Been Here Before
by Paul Wignall

The world’s climate is always changing and always has. Even during the past few centuries we have seen substantial variations, but only recently have we begun to blame ourselves for them. But how much natural variability is there, and just how extreme can climate change be? To gain some longer-term perspective on the climate’s variability we can look back through geological time, particularly at catastrophic events known as mass extinctions. In my recent book, The Worst of Times, I focus on an 80 million year interval when life on Earth suffered one disaster after another. These catastrophes included the Permo-Triassic mass extinction, the worst crisis that life has ever faced. It is not very reassuring to find that these extinctions all coincide with intervals of rapid global warming.

rocks from Permian-Triassic boundary in Guizhou

Sedimentary rocks from the Permian-Triassic boundary in Guizhou Province, SW China that record evidence for the greatest of all mass extinctions.

So, are we all going to hell in a hand basket? Well, probably not just yet. The story from the past is much more nuanced than this and I believe there is substantial hope that all is not so bad today. The reason is that the worst 80 million years happened a long time ago and more recently (in the past 100 million years) things have got a lot better. At one time all the world’s continents were joined together into a single supercontinent called Pangea. This seems to have created a global environment that was very fragile. Every time there was a phase of giant volcanic eruptions in Pangea, climates changed rapidly, the oceans stagnated and life began to suffer. The cause seems to be not the actual lava flows themselves, although these were very large, but the gases that bubbled out of them, especially carbon dioxide, everyone’s (not so) favorite greenhouse gas. As I explain in my book the effects of these gases on climate and oceans changed global environments in a disastrous way. Rapid increases in global temperature were part of the story and the results were some of the hottest climates of all time. The results for life were profound; dominant groups went extinct and new groups appeared only to have their brief hegemony terminated by the next disaster. By the time these waves of extinction were over the dinosaurs were the newest kids on the block. They went on to thrive and get very large whilst scurrying around at their feet were a group of small furry creatures. These were the mammals and they would have to wait a long time for their turn.

basalt flows

A landscape entirely made of giant basalt flows from the Permian Period, Yunnan Province, SW China.

Dinosaurs were the dominant animals on Earth for over 140 million years and it is often thought that they were somehow competitively successful but I think they were just very lucky. They appeared at a time when the Earth was rapidly getting better at coping with climatic changes caused by giant volcanism. There were plenty of episodes of large-scale eruptions during the time of the dinosaurs and none caused major extinctions. The key thing was that Pangea was splitting up and separate continents were forming – the familiar continents of today’s world. Such a world seems better able to cope with rapid increases in atmospheric gases because feedback mechanisms are more effective. In particular rainfall is more plentiful when the continents are small and nowhere is too far away from the sea. Rain scrubs the atmosphere and thus alleviates the problems.

However, the $64,000 question is how quickly this feedback can happen. The world seems better at doing this today than it was in deep time but maybe we are adding the carbon dioxide too fast to our atmosphere, maybe we are swamping the system? This is a hard question to answer, we’re not sure how much gas came out during the giant eruptions of the past and so it’s hard to directly compare with the present day pollution rates. What we do know is that past mega-eruptions have been remarkably damage-free. For over 100 million years, our world has been a benign place.

Oh, except for a remarkably large meteorite impact that was bad news for the dinosaurs, but that’s another story.

Wignall jacketPaul B. Wignall is professor of palaeoenvironments at the University of Leeds. He has been investigating mass extinctions for more than twenty-five years, a scientific quest that has taken him to dozens of countries around the world. The coauthor of Mass Extinctions and Their Aftermath, he lives in Leeds.

New Earth Science Catalog

We invite you to scroll through our new Earth Science catalog:


Planet Oliver Morton explores the uses of geoengineering in addressing the problems posed by climate change in The Planet Remade. This is necessary reading for all those concerned with the health of our planet.
Rules In The Serengeti Rules, Sean B. Carroll describes how the rules of regulation apply to all of life, from the number of zebras in the African savanna to the amount of cells in our organs. Read it to understand how life works!
Life Be sure to check out Life’s Engines. Paul G. Falkowski explains how life is supported by microbes, organisms that have existed on Earth for billions of years.

For more information on these and many more new titles in Earth Science, look through our catalog above. If you would like updates on new titles emailed to you, subscribe to our newsletter.

Finally, if you’re going to be at the American Geophysical Union Fall Meeting from December 14 to December 18, visit PUP at booth #920 and/or join the conversation using #AGU15.

New Earth Science Catalog!

Be among the first to browse and download our new earth science catalog!

Of particular interest is Stephen R. Palumbi and Anthony R. Palumbi’s The Extreme Life of the Sea. The ocean teems with life that thrives under difficult situations in unusual environments. The Extreme Life of the Sea takes readers to the absolute limits of the aquatic world—the fastest and deepest, the hottest and oldest creatures of the oceans. It dives into the icy Arctic and boiling hydrothermal vents—and exposes the eternal darkness of the deepest undersea trenches—to show how marine life thrives against the odds. This thrilling book brings to life the sea’s most extreme species, and reveals how they succeed across the wide expanse of the world’s global ocean.

Also be sure to note Donald E. Canfield’s Oxygen: A Four Billion Year History. The air we breathe is twenty-one percent oxygen, an amount higher than on any other known world. While we may take our air for granted, Earth was not always an oxygenated planet. How did it become this way? Oxygen is the most current account of the history of atmospheric oxygen on Earth. Donald Canfield—one of the world’s leading authorities on geochemistry, earth history, and the early oceans—covers this vast history, emphasizing its relationship to the evolution of life and the evolving chemistry of the Earth. With an accessible and colorful first-person narrative, he draws from a variety of fields, including geology, paleontology, geochemistry, biochemistry, animal physiology, and microbiology, to explain why our oxygenated Earth became the ideal place for life.

And don’t miss out on Gillen D’Arcy Wood’s Tambora: The Eruption That Changed the World. When Indonesia’s Mount Tambora erupted in 1815, it unleashed the most destructive wave of extreme weather the world has witnessed in thousands of years. The volcano’s massive sulfate dust cloud enveloped the Earth, cooling temperatures and disrupting major weather systems for more than three years. Amid devastating storms, drought, and floods, communities worldwide endured famine, disease, and civil unrest on a catastrophic scale. On the eve of the bicentenary of the great eruption, Tambora tells the extraordinary story of the weather chaos it wrought, weaving the latest climate science with the social history of this frightening period to offer a cautionary tale about the potential tragic impacts of drastic climate change in our own century.

Even more foremost titles in earth science can be found in the catalog. You may also sign up with ease to be notified of forthcoming titles at Your e-mail address will remain confidential!

If you’re heading to the annual American Geophysical Union meeting in San Francisco, CA December 9th-13th, come visit us at booth 632, and follow #AGU13 and @PrincetonUPress on Twitter for updates and information on our new and forthcoming titles throughout the meeting. See you there!


Bender_Paleoclimate “Michael Bender, a giant in the field, fits the excitement, rigor, and deep insights of paleoclimatology into a succinct text suitable for a semester-long course introducing this indispensable branch of environmental science.”–Richard B. Alley, Pennsylvania State University

Michael L. Bender

In this book, Michael Bender, an internationally recognized authority on paleoclimate, provides a concise, comprehensive, and sophisticated introduction to the subject. After briefly describing the major periods in Earth history to provide geologic context, he discusses controls on climate and how the record of past climate is determined. The heart of the book then proceeds chronologically, introducing the history of climate changes over millions of years–its patterns and major transitions, and why average global temperature has varied so much. The book ends with a discussion of the Holocene (the past 10,000 years) and by putting manmade climate change in the context of paleoclimate.

The most up-to-date overview on the subject, Paleoclimate provides an ideal introduction to undergraduates, nonspecialist scientists, and general readers with a scientific background.


Watch Michael Bender discuss Paleoclimate at the Fundamentals of Climate Science Symposium at Princeton University

Request an examination copy.