Interview #2: Dr Kenneth Rijsdijk

This was the second interview as part of my project for my Master’s degree. Dr Rijsdijk was a phenomenal person to talk to – he was kind and open, he was funny and smart, and more importantly, he likes speculative fiction. There is a part of the interview (not included here) where we talk about Sci-Fi and The Expanse. We met in his office and talked for over an hour (our appointment was scheduled only for an hour). I got so taken with his knowledge and the interview that I just kept asking question after question after question.

So, here is the interview with Dr. Kenneth Rijsdijk, a computational geo-ecologist.

So, you’re a computational geo-ecologist – what is that? Could you break down what that entails?

That’s right! So, Geo-Ecology is the field that looks at the interface between landscape change and ecological or biological purposes, and ‘computational’ implies we try to quantify how these landscapes change over time. Nowadays we have a lot of knowledge about how the whole planet has evolved through millions of years or hundreds of thousands of years (we have different resolutions that we look at), so we look back in time, we go back in time – so to speak – in our analysis, and we are able to, based on reconstructions of how the planet looked like in the past, make motion pictures on how these surfaces change over time. We can use that to understand how fast landscape change affects evolutionary processes in plants and animals. So, we quantify how fast the earth changes.

What you’re currently working on?

Well, let’s start with the last one. Currently, I’m working at trying to relate how evolution of plants and animal species is related to the evolution of landscapes and islands. So you have to imagine that you have volcanic islands, for instance, in the ocean, and these islands grow as a result of volcanic effusion – you get lava piling on top of each other and you get this island forming in the middle of the ocean. The island then becomes colonized by species because they are isolated – their gene pools are isolated from the original parent pools and these species change, they evolve and I am very interested in trying to relate the rates of how the shape of the island changes and the active process on the island – volcanism and processes mitigated by climate change and how that affects these speciation rates.

So, how do you carry out this research and analyses?

The interesting thing is that the biologists, based on genetics, can reconstruct how species evolve and split and speciated over time–

 Is that molecular phylogenetics?

Absolutely, yes. Nowadays we can really put these molecular phylogenies next to what they looked like a hundred thousand years ago, few million years ago or even further back in time to hundreds of million years ago. So all the landscape we see are the product of the processes of the past – like you astronomers keep looking into the past. We can reconstruct them reasonably well and align them with these molecular phylogenies. Then we can see, hey, some islands did change a lot due to continental or earth surface processes, or hotspots – radioactivity in the mantle that leads to a very active area – we can compare that island to an island that was relatively tranquil. Then how did that affect, in both cases, for instance, the evolution in snails? Why are snails on exactly the same kind of island, but with different processes, very dynamic versus very static, why are these snails actually so different, in terms of the legacy of the past processes that they experienced?

What drove you to this field in the first place? Was it coincidental or an intentional move? 

Coincidental discovery, actually. In 2005, I went to Mauritius, and that was very coincidental – just to help a friend, because we dutch have, from a history of colonial times, “discovered” or re-discovered the island. We occupied it and lived on that island for a while, and during this time we had also a lot of  [native] island species. One of them became very famous, the Dodo, but we also had two kinds of giant tortoises and a giant skink – a big lizard type of animal. So we had very interesting and specific island species, and I discovered a mass grave, a bone bed, of dodos and giant tortoises. Then I started to get intrigued because I was an Earth Scientist and I knew a lot about the layers of the crust, and the sediments and how they were formed, but I didn’t know anything about life. At that moment [I was] intrigued by [..] how landscape change affects animal life and evolution. It was through this discovery that I got into interdisciplinary research.

Compilation of the Gelderland sketches from 1601 of live and recently killed dodos, attributed to Joris Laerle
Compilation of the Gelderland sketches from 1601 of live and recently killed dodos, attributed to Joris Laerle.

Is that when you started the Dodo research project?

Yes, I became the leader of that program. And, I should update my website, because it ended a few years ago. I worked, since 2005, for more than 10 years and even now I’m still working on final research items from this discovery. The bone bed was so rich that it took years to excavate to do enormous multidisciplinary research – working with bone specialists, palaeontologists, microfossil specialists, working with geologists and cave specialists – all kinds of different disciplines to reconstruct what kind of conditions led to such a  sudden death of dodos four thousand years ago. What kind of conditions were in place and why those species survived these mass mortality events, because there were a few of them, and then they finally became extinct when the humans came into the picture.

What conclusions did you come to about the mass grave? Did you figure out the reason for it?

 Yeah, absolutely. In this period there were hundreds of scientists, students and colleagues waiting to find out what happened.  The reasons were: first, climate change. Four thousand years ago, the onset was a kind of disturbance in the El Niño system, as a result, you get an instability period of about a small century, that in the western Indian ocean – places like Africa, Madagascar – this whole region became extremely dry. This event was so intense that the first Egyptian kingdom, it’s demise was related to this event. Even in India, and the rest of Asia, there was a collapse corresponding to four thousand years ago. A major collapse in civilizations as a result of this extreme dry event. In east Africa, lakes became dry.

We found evidence that this even affected Mauritius. So we found evidence that lakes there became dry. Then we found out that lakes nearby the coast were used by animals to drink freshwater, and these, too, became dry or the water level became lowered. As a result, it became more saline, due to the pressure effect. You have light freshwater on top of heavy saline seawater in the soil, in the ground near the coast, which is very permeable, and if you have a lot of evaporation, then the effect of the intrusion of the saline water becomes more pronounced and the water table becomes more saline. In combination with the water becoming more shallow, and tortoises along with the other animals being attracted to these smaller pools who leave their excrement in these pools leads to hyper eutrophication, we found evidence of special fungi spores that grow when you have the shit of these tortoises. Then we found pigments of the cyanobacteria that flourish when the water is shallow, warm and hypereutrophic. These cyanobacteria might change the water into a poisonous mixture leading to mass mortalities.

This process is known in several spots in Australia, even Charles Darwin observed it in South America, as a result of a drought the water quality changes and the animals started to die, and we found the evidence of the same in Mauritius. You really have to imagine, that everytime there is a dry season in Mauritius, these animals came together to these aquifers to drink water and then they all died. But still, [the species] survived, the whole population survived up until the humans came to Mauritius, and within a century most animals died. This was the impact of the humans.

So I started to get intrigued, wondering how does it happen in nature and how does it compare to humans. If we can quantify these processes of the past, then we know how strong ecosystems are and we can compare what humans are doing ti ecosystems and we can say, we are a large factor compared to natural processes. This is the core of my research.

Before we move on, I wanted to talk about De-extinction. Do you know about that and what do you think of it? 

I have been involved with people who are important in that field. I have worked with [Beth] Shapiro, and she’s quite critical about it and I think she is right to be so critical.

What I’ve seen of it is, it’s like you have a machine that is very complex and now you as a layman want to re-wire it to get it working again. I believe it is still beyond our possibilities to do this because the genetic chemistry and interactions are very complex and the only evidence of success, a publication, is of recently extinct animals from the Pyrenees, a type of goat [the Pyrenean Ibex]. That species became extinct in [the 2000s] and there were still chunks of the animal in freezers, or the animal itself. So they extracted the genetic information, inserted this into a female of a species that is very close to that family. There was only one success, but it was with fused organs. So, I think we are still way beyond reaching that stage. This experiment was very recent, and if we can’t do that, then we are very far away. It’s very complex because we have so many feedbacks that we don’t understand. I’m sceptical, we are far away from it being feasible. But in the far future, maybe.

Then, we must also think of what may happen. If we can do this, then animals going extinct will not matter anymore. 

You also work on things related to climate change, is that so? It is such an important subject nowadays, so what does your research tell you about the effect of human dynamics on climate change? 

Here things get interdisciplinary. I work with people who work on Paleoclimate – how the climate changed in the past. So you can study this very simply – imagine you have a lake on an island in the middle of the ocean. In the lake, all the pollen from the plants that grow in the wet conditions, end up in the lake forming the lake floor, and the lake floor overtime becomes filled with organic sediments. So you can get a layering. So, within a one-meter depth of this mud you can find the pollen from a thousand years ago, and they indicate wet conditions, then underneath them, similarly, you find different plant pollen indicating dry conditions. Then you can say there was a discreet moment in time in the existence of this lake, say four thousand years ago, that all plant species become dry adapted species, and all wet species are gone. This is how Paleoclimatologists can work. They also look at Oxygen isotopes. So, there are many ways to find independent ways to see that the climate dried up. And obviously, that is why we have some insight into what is an anomaly in time, climate change due to the Milankovitch cycle. If you have to understand what the humans are doing with respect to the natural perturbations, we need to understand what are the natural perturbations. We are now so far that we can actually, due to the Milkankivitch cycle, compare the human-induced warming with the natural warming effects, and what we see now is that it is exceeding the natural. For the past 2.6 million years, the humans are already exceeding the hottest periods in terms of the C02 outputs. Which is good for coldblooded reptiles and dinosaurs and not so good for us.

What’re the other methods that you use? Do you bring them in from different disciplines?

That is interdisciplinary research, I don’t do the research, but I collaborate with a colleague who works on stalagmite growth. They grow very slowly with the accretion of calcium, magnesium, they have rings as well and they also have isotopes. The concentration of these isotopes is also related to mean temperatures in the surface, the composition changes with the change in the composition of isotopes in the air or the change in temperature and then you get anomalies.

You can look at the flowstones of Rodrigues, an island nearby Mauritius, few hundred kilometres away but in the same climate-zone. Even those isotopes indicated a relatively dry period at the same time.

There are a lot of possibilities, to cross-correlate and to work with. The key to interdisciplinary research is to have independent evidence, from various disciplines, for your theories. Through this, you can generate a lot of independent streams of information that converge to one point or solution. The amount of independent data sources reduce the number of possible solutions that we potentially have to come up with for a scenario that is realistic.

What, do you think, is the importance and value of interdisciplinary research?

In general, I think it opens up new avenues of thinking and new and especially innovative solutions to old problems. I have actually seen how incredibly valuable it can be to understand something so complex, because I have also seen, working with many disciplines, how they have their own blindsides from their own fields. Like, I work with bone specialists, and they find it very difficult to think of the environment the animals lived in because they have no knowledge of the landscapes. Me, I have no knowledge of bones, so if you give them to me I can’t do anything with them. But if we combine it we can make a reasonable reconstruction of an ecosystem from four thousand years ago. One of our colleagues make a virtual reality of it, reconstructing the plants that might’ve grown at that time, and we can obtain a higher understanding when you collaborate across disciplines.

So, then, is the future of the science tending towards interdisciplinary or can there be anything that is isolated?

 The future is definitely in interdisciplinary research. In the past, we have developed disciplinary studies and these studies have branched into sub-disciplines that have become separated, and now we are in the synergy phase where we start to integrate these fields. It is not a problem to be monodisciplinary, but it is good to integrate other disciplines.

Finally, just a few light questions:  What is the thing you hate most about your job?

The administration. Because I am a lecturer I have a lot of administration, and it is not inspiring to do. I find that boring.

On a happier note, what is the thing that you like most about your work?

The nice thing is to collaborate or brainstorm with other people. It gives you a thrill. You can see a solution that you can never have seen on your own and get the whole team gearing up to resolve a problem.

Finally, what do you do to wind down, when you’re not working?

Haha, I watch a lot of science fiction films! I like to play board games that are strategic. Just things that can put you in a different mindset.

Thank you so much Dr. Rijsdijk for your time!

Additonal Links:

Bringing Them Back To Life [Nat Geo, April 2013.]


Image of the Dodo:

Nationaal Archief, Den Haag, Archieven van de Compagnieën op Oost-Indië 1.04.01 inventorynumber 136

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