The Deep Past and the Deep Future

Lindsay Zanno is one of the world’s leading paleontologists focusing on dinosaurs and ancient beasts of the Cretaceous more generally. She is employed by the Department of Biological Sciences at North Carolina State University and the North Carolina Museum of Natural Sciences. In recent years, Lindsay and her students have studied the evolution of the ear bones of crocodiles and their relatives, patterns in bird brain size evolution, the evolution of tail weapons in glyptodonts, the conditions that favor the origin of dinosaur herbivory, the history and ecology of tyrannosaurs and much, much more. In the process, they have discovered more new dinosaur species than all but a tiny handful of living paleontologists.

She is uniquely positioned to speak about major changes in the past, so Rob Dunn decided to seek out her thoughts on the future. 

RRD: What is the period in the past about which you are most fascinated? 

LZ:  Most of my research centers on the Cretaceous Period. I know just enough about what’s going on to be excited about what remains to be discovered.

RRD: Which of your discoveries pleases you the most?

LZ: The latest one. I’d venture to say that most scientists are discovery addicts. It’s the vexing that keeps me up at night; it’s the unrevealed, the unexplored, that I thrive on.  

RRD: In this interview series, we spend most of the time thinking about the future, whether that be a hundred years, a thousand years or ten million years from now. I find that most of the writing about the future, beyond a few hundred years, is by paleontologists, rather than say ecologists (or even the subset of evolutionary biologists that don’t focus on fossils). Do you have sense of why this might be? 

LZ:  For paleontologists, time has a different meaning.  If an event happens in less than a million years, we say it occurred in a “geologic heartbeat.” For us, a 100,000 year interval is touted as high resolution data!  So, yes, there is a definite comfort in that headspace, but more to your question is the matter of scale. One cannot simply scale up the patterns and processes that govern biological evolution on human lifespans and fully explain what happens to life over geologic time. There are emergent properties of evolution, extinction, and biological interaction that must be studied at the scale at which they manifest. The same is true for the scientific study of other complex systems. Given this fact, paleontologists come armed with an exemplary set of skills and perspectives for tackling evidence-based predictions about our long-term future.

RRD: When you imagine the biotic future, ten million years from now, what do you foresee?

LZ: Unfortunately, from studying past mass extinction events and recovery, we know that ten million years is not a sufficient amount of time to get back to pre-extinction conditions. If humans continue to decimate our present cohort of Earth-bound species at the level we are currently, the planet will still be biotically depleted ten million years in the future. Based on what we know from past recoveries, we would predict that ecosystems will be far less complex, faunas more generalized, and life will exist closer to the tipping point. Less diverse ecosystems are often more susceptible to collapse under future duress; think of a Jenga board with only a few blocks remaining.

RRD: Will the Earth ever see terrestrial species as big as the biggest dinosaurs again?

LZ: Oh this is a lovely question. It is certainly possible with the ideal recipe of physiology, atmospheric chemistry, and global climate, and wouldn’t it be wonderful?

RRD: As an ecologist, I experience sorrow in the loss of populations of species that I know and find beautiful or just interesting. I experience sorrow in the loss of species. But I have a sense that paleontologists often find a little more solace in the big picture. What is your emotional response to the species that have already gone extinct?

LZ:  I personally feel the loss of species deeply and I suspect that my colleagues feel the same. True, as paleontologists, we deal in extinct species, but maybe because of it, we have come to accept the harsh reality of extinction. We understand the impact of that loss on human knowledge and sustainability. On the flip side, when I step out of my feelings as a person living on the planet today, when I detach as a member of our current global ecosystem and approach the future with a strictly scientific mind, I get excited about all the as of yet unimagined species that might evolve from the devastation. Mass extinction has shaped and reshaped the characteristic megafauna on our planet so many times, each with fantastical results. If only we could visit the future and see for ourselves what awaits.

RRD: Do you feel differently about extinctions due to say, meteors, compared to those due to human actions?

LZ: Not particularly no. Our behaviors, our struggle to change our short term behavior for long term gains, are the natural result of evolutionary processes. Therefore, the situation we currently find ourselves in is just as “natural” an outcome as an asteroid impact or volcanic eruption. The frustrating thing about it is that evolution has also given us the knowledge, the power, and the foresight to change our future, to act beyond our basic instincts, and thus far have chosen to do little on our own behalf. 

RRD: How about the mysteries of the past compared to the mysteries of the future? Is there something more satisfying about a mystery of the past (about what did evolve rather than what will) in part because, at least in theory, you could uncover it?

LZ: Most definitely. Sure, part of our job as scientists is to model the future and make predictions based on the data we already have. But, the future isn’t directly testable until it is the past.

RRD: I know that when you are going about your day at the university or the museum that you spend a lot of time thinking about ordinary daily things. Faculty meetings. Budgets. Grants. Papers. Space. Students. Faculty meetings. And so on. But when you are in the field, I imagine things are different. When you are in the field, how much of your thinking time is spent imagining the world as it was? 

LZ: Yes and, no. Fieldwork is an intense undertaking. As a PI, I spend most of my time keeping the expedition organized, safe, and on task. It takes months of pre-planning to construct the right team with the right tools, figure out how to access outcrop, planning for basic necessities, and attempting to ensure we meet the goals of the funders. Onsite, you’re just constantly dealing with the chaos of the unexpected. Someone has heat exhaustion, a rainstorm imprisons the team at camp for three days, you expose the “last” bone at the quarry only to uncover a dozen more, a “road” you thought you saw on satellite turns out to be two winding cow paths side by side, your 100lb jacket just engorged to 1,000lbs… there’s no end to the surprises.  But there are quiet times. I love to prospect for new sites. Sure it involves long hikes in rough terrain, but I usually fly solo, giving me time to reflect on all the thoughts I’ve ignored the rest of the year or just think of nothing at all.

RRD: When else do you really get to step back and think?

LZ: Ha, ha, ha! Oh, are you being serious?

RRD: People often ask whether humans would evolve again (or something like humans) once we go extinct. I don’t want to know about that. I’m not very interested in it, to be honest, but I would be interested in what other kinds of organisms you might imagine would be very successful in our wake? What does the past say about that?

LZ:  From past mass extinctions, we know that the simple fact of being widely distributed increases your chances of survival. You can imagine that your chances of surviving somewhere go up substantially if you are present everywhere, or can at least move anywhere. Burrowing seems to be a plus as well (although this has yet to be quantitatively tested). Beyond that there are few uniformly applicable get out of jail free cards for species during mass extinction events. Sometimes fresh water verses salt water needs matter, but it depends on the kill mechanisms involved. In this time of human-induced mass extinction, one of the main catastrophes is habitat loss. Thus it seems likely that organisms that have learned to survive in our urban or disturbed environments are the best candidates.

RRD: If governments spent ten times as much on paleontology as they do today, it would still be very little. Let’s imagine that they increased by a hundred fold the funding for paleontology, what could we know that we don’t already? What is the potential for a really fundamental change in what we know about the past and what it tells us about the future? 

LZ:  The history of life on Earth is our longest natural experiment and it has already been run. Over four billion years of data on how life has responded to climate change, extinction, evolutionary processes, shifting continents, rising seas, changing habitat, and on and on. Paleoscientists are simply attempting to recover it from Earth’s hard drive (admittedly it’s a bit buggy). Recently, I’ve mentally experimented with the value in putting a single label on the scientists who use fossil data in their research (i.e., “paleontologists”). More and more it feels like a detriment to me. All paleontologists can equally be assumed under other sciences, and for many of us, a whole host of other sciences. Paleontologists are anatomists, evolutionary biologists, geo- and biochemists, molecular biologists, ecologists, biogeographers, and even sedimentologists. Sometimes labels matter. The future of humanity depends in large part on making bridges between scientists and it may be high time to ask if paleontology shouldn’t work harder to integrate with other sciences.