We analyse million-year-old DNA to predict the effects of climate change

Love Dalén is a biologist and evolutionary genomicist. Together with his research team at the Centre for Palaeogenetics (CPG) at Stockholm University, he analyses DNA from prehistoric wild animals to understand how evolution works. "The goal is to use prehistoric changes to gain a better understanding of today's climate change and species extinction.

"We are looking at the consequences of various prehistoric, so-called abiotic or non-biological, environmental changes. This could be climate change, sea level change, or human progress. That is, how they have affected the evolution of wild animals. For example, leading to the extinction of a species."

Researchers in the DNA lab at the Centre for Palaeogenetics. Photo: Björn Terring/Stockholm University

What can ancient DNA tell us?

"One of the great mysteries of the extinction of the so-called megafauna, the large prehistoric animals, has been the question: was it caused by the climate or by humans? There are those who believe that humans were the main reason for the disappearance of the mammoths. Here we have a different perspective. We don't think there's a clear evidence that humans were responsible for the extinction. By studying ancient DNA, we can see exactly how things evolved and thus determine what caused what."

Are you fully focused on mammoths?

"Not only. We are currently starting two major research projects focusing on really old DNA. In addition to mammoths, we will examine samples from a dozen different species, including prehistoric bears, bison, voles and lemmings. Small, more common animals such as voles and lemmings may not sound very exciting, but in fact they are. Lemmings have a very fast generation time, which makes them respond more quickly to changes in the external environment in evolutionary terms. They have also not been hunted by humans, so we can rule out humans as the cause of the extinction of a particular species."

Love Dalén Photo: Beth Shapiro

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What is the main difference from previous projects?

"Previously, we have mostly worked on the last ice age. Now we are broadening the time span and looking at several ice ages. This means that there have been much greater changes during the time we are studying. It is more about the origin of species than before."

You come into Darwin's realm ...

"Well, the fact is that Darwin had a pretty good idea, even though he didn't have the same access to technology as we do today. Back then, it wasn't even in the human worldview that species could change, yet he was able to draw the conclusions he did about evolution. He was a great thinker."

The students come into the lab and start sequencing real bones from Siberia and Canada. This is the most popular part, when they put on their protective suits and realise that they have found mammoth DNA.

What is the strength of the Centre for Palaeogenetics?

"One of the great advantages we have at the Centre for Palaeogenetics is our multidisciplinary approach. We have archaeologists, geologists, biologists, zoologists and museum staff [from the Museum of Natural History]. It's a great advantage that they all belong to an institution that has an interest in making sure the different approaches are reflected in the research."

"It's nice that we use the same materials and methods, but we try to understand different things by starting from different questions. The archaeologists might ask whether there are any diseases that spread from animals to humans. Instead, I ask if there were any diseases that spread from humans to animals, causing them to die out."

Are students allowed in the lab?

"Yes, I am one of the course leaders for the Master's course in palaeogenetics. We go through DNA analysis from scratch. The students can come into the lab and start sequencing real bone remains from Siberia and Canada. This is the most popular part, when they put on their protective suits and realise that they have found mammoth DNA."

"Another part of the job I also find very fun and meaningful is training young researchers. Research training is an important interface between teaching and research. It's not a matter of either teaching or researching, but they are intertwined. You don't do research on your own, but in large teams that include doctoral students and postdocs. Then it's teaching at the same time as research."

Why is it important to have an international environment?

"The aim is not to have many nationalities. We simply want to have the best. At the CPG we therefore have 18 different nationalities among 40 people. This has positive consequences for research, such as bringing many different perspectives to the research work. This gives rise to many new ideas on how to work well in the lab."

It is important to constantly find new mountains to climb, to think in new ways.

What is most fun, the field work or the lab?

"When I'm in the office, I think the field work is the most fun. When we are in the field and you are in the middle of a swarm of mosquitoes, I want to go to the lab...

No, jokes aside. What's most fun is probably the variety. But it is clear that I like the field work. Very few people do their own fieldwork. Most people do research on material they get from museums. As someone who also works in the field, I understand how much work goes into the actual fieldwork. That was also the part that drove me to my research choice in the first place. I guess I find it quite difficult to sit still."

What drives you?

"It is important to constantly find new mountains to climb, to think in new ways. If you don't, there's a risk that you get comfortable and start doing the same studies you've always done. In research there are many such moments all the time, big and small. Actually, every study you do offers some surprise. Basically, that's what research is all about - exploration. Instead of being the first to set foot somewhere, you are the first to discover something that no one else knows."