Scientist who studies climate change…finds unique survival strategy of hominins.

Humans evolved during the last 3 million years. During this time, earth’s climate cooled and around 1 million years ago ice-age cycles with periods of about 20-120 thousand years began to dominate global climate, rainfall and vegetation patterns. How early humans reacted to these large fluctuations remained one of the largest mysteries in anthropology. I met Elke Zeller, a researcher at the IBS Center for Climate Physics, who ran new supercomputer model simulations to resolve this mystery. In her work, published in the journal Science, she found that as climatic stress increased, our human ancestors developed a unique survival strategy - they adapted to mosaic landscapes.

Q. Please introduce yourself.

I'm Elke Zeller, a PhD student affiliated with the IBS Center for Climate Physics and Pusan National University. My academic journey began with a Bachelor of Applied Science in Chemistry from HAN University in the Netherlands, after which I did a master's degree in financial engineering at the University of Hawaiʻi at Mānoa. Following my master's, I gained valuable experience as a risk analyst at First Hawaiian Bank.

In 2019, I started my PhD in the Department of Climate System, under the mentorship of Axel Timmermann. With the use of my diverse educational background, I possess a unique perspective that aids me in comprehending problems from various angles. Moreover, I have acquired a wide range of skills and techniques throughout my studies, which I am now applying to different aspects of my research.

Q. Please introduce about your research center, the Center for Climate Physics.

In our center, directed by Axel Timmermann, we engage in extensive research encompassing a brought range of climate-related questions. Numerous specialized groups research different aspects of the climate system. Using a combination of models and empirical data, our investigations span the realms of historical, present, and future climate dynamics.

Our group, the Hominin team, primarily focuses on past climate and the effects on early humans. Specifically, we investigate the climatic preferences of early humans and analyze how their spatial and temporal evolution influenced migration patterns and various other factors.
*hominin: those species regarded as human, directly ancestral to humans

Q. What is the major field of your research.

My research revolves around exploring the preferences and adaptability of Hominins to different types of vegetation. Throughout the span of the last 3 million years, the climate has undergone significant transformations, exerting a profound influence on the distribution and composition of vegetation. Consequently, these changes have shaped the utilization of plant resources by early humans.

Through the utilization of our powerful supercomputer, Aleph, we have successfully reconstructed the global climate patterns and various vegetation types spanning the past 3 million years. By integrating this vegetation data with anthropological information, we were able to investigate the environmental preferences of early hominins.

This enables us to uncover how our ancestors interacted with their surroundings, shedding light on their preferred habitats and the interactions between climate, vegetation, and early humans.

Q. What kind of results did you get?

When examining the vegetation patterns at hominin sites across different periods, we found interesting patterns. For instance, we saw that early African hominins predominantly inhabited grassland regions, whereas H. erectus, the first species to venture into Eurasia, marked a shift towards forested areas.

This transition from unimodal to bimodal preference in dominant vegetation types signifies the genus Homo’s adaptability to forest environments. While local studies have hinted at similar findings, our research presents, for the first time, a global-scale analysis that substantiates these trends and reveals statistically significant differences in vegetation preferences between species and between continents.

Furthermore, our analysis shows a distinctive inclination among hominins to live in areas characterized by diverse vegetation types in their proximity.
These mosaic landscapes provided our ancestors with advantageous access to multiple environments within their immediate vicinity. Until now, illustrating this preference was challenging due to the lack of comprehensive global data. By examining the precise locations where hominin remains were discovered and contrasting them with the surrounding environmental conditions, we were able to demonstrate a statistically significant preference for hominins to inhabit mosaic landscapes.

Q. Which place can be a mosaic landscape?

In our model simulation, we see many different areas that are mosaic landscapes. For instance, around Lake Malawi, we see that there is tropical forest, temperate forest, savanna, and grassland around the lake. This would be a perfect place to settle to take advantage of the diverse environment. Below you can see the lake and the different vegetation types that we see in our model on the left and an artistic illustration of how this might have looked on the right side.

Example of a mosaic landscape

Left: Most dominant biome type around Lake Malawi in Tanzania between 1.5 and 1.25 million years ago. The different colors show different biome types creating a mosaic landscape. Right: Artist illustration of hominins arriving in a multi-biome mosaic scenery. Such environments were greatly preferred by early humans, according to a new study published in the journal Science by a team of scientists from South Korea and Italy (Copyright, IBS Center for Climate Physics)

Q. What is the reason or backgrounds of starting this research.

In our group, our primary focus is studying human migration. Initially, our research predominantly centered around climatic factors like temperature and precipitation. We recognized the significance of climate in influencing preferred human habitats. However, we soon realized that the environment, specifically vegetation, played a crucial role in determining whether hominins could inhabit certain areas.

Vegetation, in particular, can present significant barriers, with distinct boundaries between different types of environments. Living in grasslands, for instance, is generally easier compared to surviving in desert regions. By incorporating vegetation analysis into our studies, we hope to gain a more holistic understanding of how changes in climate shaped human habitat preferences, migration end(and)) dispersal.

Q. If you had any difficulties while researching, can you share about it? How did you figure it out?

One of the main challenges I faced during my research was how unfamiliar everything was to me. Coming from a different background, there were many unfamiliar concepts and terminology for me. Fortunately, with the support and guidance from my co-authors, I was able to navigate this area of study. My co-authors played a vital role in my learning process, answering all my questions and providing valuable feedback on my findings. This was instrumental in helping me grasp and assimilate the new ideas associated with my research. I'm grateful for their support in guiding me through the research process.

Q. When, especially in your school days, did you become interested in your major? Was there a special occasion?

I’ve always been interested in unraveling complex problems and understanding phenomena on a broader conceptual scale. This curiosity initially steered me towards studying chemistry and now guides me in getting a better understanding of our human past. The environment of where early humans lived and the path that led us to our present state is still unknown. By exploring the role of past vegetation changes within this problem I and hoping to discover new insights and to contribute to the broader narrative of our human history.

Q. How is your life in Korea? What is the most hard and exciting part?

I have developed a deep fondness for Korea. Coming from a country known for its flat terrain, the Netherlands, I’m still mesmerized by the landscape even after living here for several years. The backdrop of Korea is so beautiful, especially the contrast between the ocean and the mountains. I have been very fortunate to make many friends within and outside my lab. They have introduced me to various parts of Korean culture, including the food, the tradition of 온천, making kimchi, and the importance of 눈치.

Q. How do you spend your time out of the lab? Do you have any hobbies?

I'm a big fan of outdoor activities, and I regularly go sailing, cycling, or hiking. Sailing is my main hobby, although the weather doesn't always cooperate. Through participating in yacht races, I've made many friends in Korea and joined a sailing team. Last year, our team got the opportunity to represent Korea in an international race held in Italy. It was an unforgettable experience that made me really proud.

Q. You have changed your careers through chemistry, financial engineering and climate system.

Yes, during my undergrad, I went to Hawaii for an internship and heard about the master’s in financial engineering program. Even though the topic was new to me, I could use my statistical skills and had always been interested in programming, so I decided to apply for the program. One year in Hawaii can never be a bad thing. One year became five, and Hawaii was an amazing place to live. However, when the chance came to go to Korea, I could not resist living in a new place. Switching topics again was not as daunting as it was at the first time since I knew I could still use many of the skills I learned during my undergrad and master's. There were no big life events but rather opportunities that came, and I was happy to take them. Therefore, I would encourage everyone to look around and, when new things come, welcome them with open arms.

Q. When is the most memorable time living as a scientist.

As a starting scientist, my journey has just begun. I’m very fortunate to be part of our research center. The research atmosphere at our center is outstanding, and I feel incredibly fortunate to be a part of such an extraordinary team. I’m sure that starting my research career at ICCP will be one of the most memorable times.

Q. We wonder if you have further research plans in the future.

After completing my PhD degree, I would like to pursue a Postdoc position as I believe it to be the best next step for my career. My career path has been rather unique, spanning various fields of study and work. This diverse experience has made me able to think outside the box and has given me a valuable set of skills. For me, the most important part of a lab is to work in an enjoyable environment alongside people that are interested in interesting ideas and problems. While I hope to continue my research on Hominin dispersal with a specific focus on vegetation and climate's impact, I am also open to broadening my horizons and exploring other aspects of the climate system.