Meet the menagerie of life-forms that dig, crunch, bore, and otherwise reshape our planet. Did you know that elephants dig ballroom-sized caves alongside volcanoes? Or that our planet once hosted a five-ton dinosaur-crunching alligator cousin? In fact, almost since its fascinating start, life was boring. More than a billion years ago, bacteria, algae, and fungi began breaking down rocks in oceans, a role they still perform today. About a half billion years ago, animal ancestors began drilling, scraping, gnawing, and breaking rocky seascapes. In turn, their descendants crunched through the materials of life itself—shells, wood, and bones. Today, such “bioeroders” continue to shape our planet—from the bacteria that devour our teeth to the mighty moon snail, always hunting for food, as evidenced by tiny snail-made boreholes in clams and in other moon snails.
There is no better guide to these lifeforms than Anthony J. Martin, a popular science author, paleontologist, and co-discoverer of the first known burrowing dinosaur. Following the crumbs of lichens, sponges, worms, clams, snails, octopi, barnacles, sea urchins, termites, beetles, fishes, dinosaurs, crocodilians, birds, elephants, and (of course) humans, Life Sculpted reveals how bioerosion expanded with the tree of life, becoming an essential part of ecosystem functioning while reshaping the face of our planet. With vast knowledge and no small amount of whimsy, Martin uses paleontology, biology, and geology to reveal the awesome power of life’s chewing force. He provokes us to think deeply about the past and present of bioerosion while also considering how knowledge of this history might aid us in mitigating and adapting to climate change in the future. Yes, Martin concedes, sometimes life can be hard—but life also makes everything less hard every day.
In this post, we chat with Tony—fresh off a great review in the Wall Street Journal and a profile in the Atlanta Journal-Constitution—about his research and the important lessons to be learned from the study of bioerosion.
How did you wind up in your field, and what do you love about it?
How I became a geologist and paleontologist seems almost accidental. When I was a kid, I didn’t plan to be either of those, and I didn’t have geosciences in mind when leaving home for college. But while growing up in Indiana during the 1960s, I enjoyed watching Mutual of Omaha’s Wild Kingdom and Jacque Cousteau specials on TV, and I spent a lot of time exploring my backyard by studying insects and their behaviors. I also was a bibliophile, devouring every book about insects, dinosaurs, and wildlife past and present that I could find at our public library. So I knew that natural history would be an important part of my future, I just wasn’t sure how.
Fast forward to my freshman year of college, when I took two semesters of geology alongside biology. That’s when I got a glimmer of how the Earth worked, and how life interacted with the Earth and vice versa. Then, after going on to graduate studies in geology, I learned about ichnology, the study of fossil and modern traces, which eventually became my research (and writing) specialty.
What I love about the geosciences in general, and paleontology specifically, is how they require a synthetic sort of thinking that integrates knowledge and concepts from many disciplines, including the humanities and social sciences. But the geosciences also fed my childhood dreams of exploration and discovery. For me, nothing beats the feeling of going into the field, looking for and finding trace fossils, and then trying to figure out the various ways an animal could have made them.
You’re funny, and we love it: you’ve written the least boring book imaginable about “The Biggest and Most Boring of Animals” (pun intended) and Earth’s many other bioeroding organisms. Yet Life Sculpted also has serious lessons, showing how the study of trace fossils and bioerosion can teach us a great deal about periods of rapid climate change. Can you tell us a bit about that?
Thank you for your compliments about my writing and the book. My previous books have light-hearted banter and whimsy woven throughout them, so now I suspect my readers approve of it. But while writing a major work about “boring” topics, I also knew the pressure was on to make it a fun-to-read and lively popular science book.
So yes, there’s a time for fun, but there’s also a time for getting serious, and nothing is more serious than climate change. Because climate change is the most important global challenge now for us and the rest of the biosphere well into the twenty-first century, we need to look at the geologic past and study how life adapted (or not). And trace fossils, such as burrows and borings, give us direct evidence of how animals were behaving in their original environments. In this sense, the past may be the key to the future.
A mild spoiler for those who haven’t yet read Life Sculpted is that when I get to humans and their bioerosion toward the book’s end, I point out that nearly all human-caused climate change is related to our bioerosion that’s happened in just the past few hundred years. Drilling for oil and gas, strip mining for coal and mineral resources, deforestation, and breaking apart rocky landscapes and seascapes: all of this bioerosion has changed earth ecosystems in ways we do not yet understand, nor can we predict. Sorry, I guess that qualifies as a double spoiler.
It’s summertime, and we’d like to think of Life Sculpted as the ideal beach read. In that vein, can you share how parrotfishes help make beautiful sandy beaches in tropical areas and even help build islands?
This is one of those “Maybe I didn’t need to know that” moments readers will experience with the book. Anyway, most of the sediments in those beautiful white-sand beaches of the Bahamas, Caribbean, and South Pacific islands traveled through the guts of parrotfishes and came out their rear ends. Think of parrotfishes like underwater sheep grazing on algae growing on corals, except they sometimes chomp corals or other reef rocks, and then reduce them to sand-sized particles in their guts, which are dumped into their all-natural toilets. Multiply this process by the millions and over many generations, and parrotfishes supply enough sand to ensure those beaches keep on beaching. Amazingly, parrotfishes also produce enough sand in shallow-water areas around atolls in the Pacific Ocean that they’re helping prevent these islands from vanishing under rising sea levels. So a big message of that chapter is, save the parrotfishes, and you also may be saving your favorite beaches.
While you were working on this project, what did you learn that surprised you the most?
One of the main reasons why I wrote this book was so I would learn more about the role of bioerosion in the history of life and Earth systems. Life Sculpted covers the last billion years or so of bioerosion history and explains how life of the past broke down rocks, shells, wood, and bones, while also spotlighting how life today makes these solids less solid. In that sense, then, I wasn’t so much surprised by the “big picture” of the book, but a few of the details of how life broke down hard stuff still blew me away.
For instance, I learned how a lineage of marine clams that first bored into rock more than 400 million years ago evolved into clams that drilled into driftwood about 250 million years later, but then descendants of those wood-boring clams just recently evolved to drill into rock in freshwater environments! And did you know the evolutionary history of woodpeckers is reflected by the sound patterns they make from drumming wood with their beaks? I also learned that huge Pleistocene mammals got itchy from parasites, so they wallowed in mud and rubbed their bodies against former sea stacks of coastal California, leaving polished surfaces more than 3 meters (10 feet) off the ground.
But the one subject that left me slack-jawed with wonder was the bone-eating Osedax worms that live in the deep sea, covered in Chapter 9 (Bone Eaters of the Deep). For one, these worms weren’t even known to scientists until they accidentally discovered them in 2002, when they were living in a gray whale skeleton about 2,900 meters (9,500 feet) deep. Then their biology sounds like something straight out of science fiction. For one, they lack eyes, mouths, stomachs, and anuses. They’re also mostly represented by females who are thousands of times larger than the males. They secrete mucous and acids, with the acids breaking down bones and allowing worms to take root in them. Then, with the help of bacteria living in their cells, they digest marrow in the bones. And thanks to the distinctive trace fossils these worms leave in bones, we know their ancestors have existed since the Mesozoic Era. Today they use whale skeletons as their main food source, but in the geologic past, they used the bones of big marine reptiles and fishes. These worms taught me that sometimes the unknown has been there all along and for tens of millions of years.
Where will your research and writing take you next?
My research right now is focused on two places, one close to home and dealing with modern environments, and the other in Australia and Cretaceous environments. For the home front, I’m part of a research team with the Center for Digital Scholarship at Emory University that’s creating a digital atlas about the Georgia coast, appropriately titled the Georgia Coast Atlas. This atlas is a public resource that teaches about the environmental and human histories of the Georgia barrier islands and other nearby coastal environments, with its content free and available to anyone with an online connection.
As for the Australia research, I’m working with colleagues in Victoria, Australia to document trace fossils made by Cretaceous animals that lived there about 125-105 million years ago. This research is absolutely fascinating to me because the trace fossils are preserved in sedimentary rocks that formed in polar environments when that part of Australia was still connected to Antarctica. The trace fossils are non-avian dinosaur and bird tracks, as well as burrows made by insects, crayfishes, and other animals. These trace fossils reflect animals’ adaptations and behaviors in those polar environments when the global climate was warmer than today, so they give us insights on how polar animals adapted to those conditions.
Because I somehow managed to publish five books in 10 years, with Life Sculpted the fifth of that quintet, I’m taking a break before writing another book. With that said, I’ve already outlined my next ichnology-related book, which will be about the natural history of animal nests through time. But I’m also keenly interested in writing fiction. My non-fiction books—including Life Sculpted—already have science-based fictional stories folded into them, so it might be fun to write a book-length version of such stories, whether as an anthology or a novel.
What’s the best book you’ve read lately?
The best book I’ve read in the past year is Sabrina Imbler’s How Far the Light Reaches: A Life in Ten Sea Creatures (2022, Little, Brown and Company). It’s the most marvelous combination of science communication and introspective memoir I’ve had the pleasure of reading, all expressed with Imbler’s lovely and heartfelt prose. But I’m also very happy to have read Imbler’s book after I’d finished writing Life Sculpted, as one of the “ten sea creatures” they picked was on Osedax, the deep-sea whale-bone-eating worms. What was nice about this biological-literary coincidence is that Imbler expressed their own personal wonder about these worms, and I expressed mine, demonstrating the value of multiple voices writing about scientific topics, and from different perspectives.
Other stand-out science books I’ve read recently were Ed Yong’s An Immense World: How Animal Senses Reveal the Hidden Realms Around Us (2022), and David George Haskell’s Sounds Wild and Broken: Sonic Marvels, Evolution’s Creativity, and the Crisis of Sensory Extinction (2022). As for fiction, I finally read Cloud Atlas (2012) by David Mitchell earlier this year, followed by Monica Byrne’s The Actual Star (2021) and Nnedi Okorafor’s African-futurism novella Remote Control (2021). Reading well-written and original speculative fiction helps me hone both my writing skills and my imagination.
Anthony J. Martin is teaching professor in the Department of Environmental Sciences at Emory University, where he has taught classes in geology, paleontology, and environmental sciences for more than thirty years. He has a PhD in geology, and his research specialty is ichnology, the study of modern and ancient traces caused by animal behavior, such as tracks, burrows, and borings. He is the author of numerous books, including Dinosaurs without Bones, The Evolution Underground, and Tracking the Golden Isles.