This winter, biology professor Mark Laidre received a grant from National Geographic to study the behavioral ecology of coconut crabs in the Chagos Archipelago, located in the Indian Ocean south of the Maldives. Laidre’s specialty is the study of behavioral evolution, and the coconut crab is a particularly unexplored animal — Charles Darwin was one of the first and last scientists to study the organism. Laidre focuses on how animal behavior, ecology and evolution interact and studies how individual organisms shape their physical and social environments, influencing natural selection. He conducts field and laboratory experiments in addition to theoretical modeling and computer simulations. He plans to release papers on the animals over the course of the next several years, and hopes to return to the archipelago soon to conduct continue his research.
After graduating from Cornell University in 2004, Laidre went on to pursue a masters in philosophy at the University of Cambridge, and then a doctorate at Princeton University. He joined Dartmouth as a Neukom Fellow in 2013, a position that encourages interdisciplinary research with a computational component. Laidre’s research on hermit crabs and monkeys has been published in National Geographic, NPR and BBC. At the College, he has taught the course “Organisms that Change their World,” which looks at evolutionary consequences of animal behavior, and “The Evolution of Cooperation and Gossip,” focusing on how organisms work together towards a common goal. He will start his position as an assistant professor of biology in July 2016. The Dartmouth sat down with Laidre after his lecture on his time in the Chagos to discuss his findings and observations.
How did you get involved in this field of research, and what motivated you to study coconut crabs?
ML: I’ve always been interested in the evolution of behavior, and have spent a lot of time studying all sorts of animals in remote locations. Lately, I’ve been especially interested in hermit crabs, in particular, coconut crabs, which are the largest of all terrestrial vertebrates. What’s particularly interesting is that they start off living in shells, the way hermit crabs do, and then get so big that they outgrow their shell. I’m interested in this transition that they make from living in a housing market, where they have to fight for shells, and need to do so to grow, to ultimately when that’s no longer necessary, which lends itself to this prediction that they should become less social. What’s also very interesting is that despite their name, no one had ever bothered to study whether and how these animals opened the coconuts they’re named after. I’ve wanted to study them for many, many years now.
What inspired you to conduct your observations in the Chagos Archipelago?
ML: You’d think there’d be a lot of places to study these animals, but it turns out, that’s not the case. Although they once had a vast range all throughout the Indo-Pacific, their population has been greatly decimated as people use them for nutrition, and due to other factors such as global warming. However, the Chagos Archipelago is an especially interesting place. As a byproduct of what once was a U.S. Naval Base, the entire archipelago has been created as this amazing marine preserve. In a day and age where humans have an impact on everything, the Chagos is as close as you can get to approximating a pristine environment devoid of human interaction. This is critical if you want to learn about natural behavior and how animals evolve without the influence of humans.
What do you think this research will reveal?
ML: So little had been previously known about these animals. You can go back and carve out a lot of quotes from Darwin’s Eagle Voyage, and that’s basically all the research that had existed on coconut crabs before my observations, simply because no one else had studied them. There was a lot to learn about coconut crabs, from how they actually open up coconuts, to their social interactions, to their incredibly strong claws that allow them to scale trees. Because it was such an unexplored field, I was trying to study as much of these details as possible and get as much data on each of these topics as I could.
What’s the most prevalent problem that coconut crabs face?
ML: It’s hitting them on all angles right now. Take, for example, climate change: all the glacial melt from global warming is hitting these atolls — their habitat — which are barely above sea level. That means that we are all responsible for what ultimately could drown these animals. Another concern is the atoll itself — as discovered by Darwin, these atolls are made up of miles of dead coral created from ancient geological activities. We as humans continue to do things that undermine the integrity of that coral, and the foundations of where these coconut crabs live are being obliterated. And if that isn’t bad enough, people eat them. In some areas, they’ve been driven to local extinction based on that fact alone.
How do you plan on bringing this research back to Dartmouth?
ML: Ultimately, whatever research I do, I find a way to somehow weave it into my classes. I have specimens of these animals that I hope to bring out in lectures. It’s inspiring to see this kind of unique evolutionary experiment, and understanding the process of how these animals evolved is so propelling. Next spring, I’ll be teaching a class called Animal Minds and I’m sure I’ll be bringing my research into that. I also have some students starting to get involved in research, and over the long haul, I’m sure there will be a lot of opportunities for students to analyze data and observe video, if I can’t actually bring them with me to the Chagos.
What is one thing that you hope Dartmouth students could take away from your experience ?
ML: What’s amazing is to step foot on an area where it’s just nature, and everything is so remote from human activities and impacts. It makes you pretty awed by the things that are out there, and you can really sense the importance and urgency of actually doing something to preserve these places while we can, and to ensure that we allow these environments to last.
This article has been edited and condensed for length and clarity.
