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The Archive of Humanization - Geoscientists read human evolution from sediment drill cores

The drilling camp in Kenia. Photo: Annett Junginger.

The drilling camp in Kenia. Photo: Annett Junginger.

East Africa is the “cradle of humanity,” where our ancestors lived some 60,000 years ago and where they began spreading throughout the world. In the Great Rift Valley, geoscientists are researching turning points in human evolution and how climatic changes affected them.

It sounds like a thrilling adventure set in a romantic landscape: In 2014, researchers set up camp in the wilderness of the East African Rift amidst an arid salt pan, the Chew Bahir basin in southern Ethiopia. Here researchers spent several weeks on a geological mega-project, drilling 280 meters into the ground and extracting two sediment cores that will provide deep insight into the earth’s history. In reality, though, the work is mostly arduous and exhausting. “The weather is blazing hot; there is no shade; you work day and night in shifts, and – despite the heat – you have to wear thick clothing at night to protect yourself from billions of mosquitoes.” Martin Trauth, apl. Professor of Paleoclimate Dynamics, knows what he is talking about. He has been involved in many projects in East Africa and South America. Despite not being personally onsite for this project – he was a young father at the time – he coordinated the project from afar.

But field research in Africa had more surprises and challenges in store – flash floods, all sorts of poisonous animals, and a tribal conflict that led to the camp’s evacuation. They also faced obstacles at a very different level. “The University’s administration is not fully equipped to support international projects of this dimension and complexity,” Trauth explains. This is why it took a full year for the administration to release the research funds for drilling in Ethiopia. 

Today, the two sediment drill cores extracted by the geoscientists three years ago are in cold storage at a U.S. laboratory. They are now part of a collection of cores contributed by 120 researchers throughout the world – paleoanthropologists, geochronologists, geologists, and biologists – for the “Hominin Sites and Paleolakes Drilling Project.” The researchers are going back to the “cradle of humanity” to find out how our ancestors adapted to environmental changes. Scientists can use the data obtained from the cores to reconstruct climate changes over time. They can spot droughts, humid phases or floods, how the vegetation and thus the nutritional basis of prehistoric humans developed, steadily and continuously. As a result, the researchers hope to gain new insight into the evolution of humanity.

Homo sapiens is the only extant human species 

The history of the early hominid commonly referred to as Nutcracker Man is a good example. A reconstructed replica of the skull of this close relative to our ancestors sits on Martin Trauth’s desk. Paranthropus boisei is the scientific name of the hominid, who was only 1.30 meters tall and not a representative of our genus Homo. It lived in East Africa some two million years ago but went extinct about one million years ago. “We are not sure what the reasons were,” Martin Trauth says, “but it might well have been a worsening of the climate.” The hominid was named for its sturdy jaws and mastication muscles. “They had their own, in-built toolbox with them at all times,” Trauth says with a wink. Despite what the name might suggest, Paranthropus boisei ate grasses and grass seed, not nuts. Climate changes may have destroyed this species’ basic food resource.

Another hominid was living in the same region at the same time: Homo. And it survived these environmental changes. After all, our immediate ancestors used tools such as the hand axe that seem to have enabled them to rapidly adapt – whereas the Nutcracker Man could not. Have climate changes triggered milestones in human evolution? And why is Homo sapiens the only one of 10 known human species to have survived?

Looking three million years into the past 

Pursuing these questions requires the investment of a lot of time and effort in analyzing the core samples. Researchers in specialized laboratories in the U.S., France, Great Britain, Ethiopia, Kenya, and Germany are extracting a wide variety of substances – remnants of algae, shells, rotifers, pollen, volcanic ash, or minerals. They establish the thickness of the various sediment layers as well as their physical properties and age, identify key chemical elements, and extract thousands of samples for many more analyses. In a process called a sampling party, the core samples are cut lengthwise and samples are then taken for various analyses. Half of the core sample is available for research; the other is archived. In the end, an enormous amount of data arrives on Trauth’s desk, and he processes them statistically. He is a specialist in time-series analysis and looks for different types of climate transition, some of which affected human evolution, some of which did not. 

The oldest layers of the core from the Chew Bahir basin are about 550,000 years old. Core samples from other drillings even originate from three-million-year-old layers. Homo sapiens has been around for about 300,000 years, so the researchers have a comprehensive data basis that covers the environment of modern humanity and spans back to its immediate ancestors – an invaluable archive. The ambitious project hopes to combine the results of many individual analyses into an overall picture. Trauth estimates that it may well take 10 or even 15 years to analyze all of the samples and interpret the data. But they will undoubtedly provide important clues about the link between environmental changes and the development of humanity.

The Project

The “Hominin Sites and Paleolakes Drilling Project” (HSPDP) is chaired by Prof. Andrew Cohen of the University of Arizona, together with 19 principal investigators including Martin Trauth, the project researches human evolution with regard to environmental changes and climatic influences. The “Chew Bahir Drilling Project” is a HSPDP sub-project chaired by apl. Prof. Martin H. Trauth (University of Potsdam), Prof. Frank Schäbitz (University of Cologne), Prof. Henry Lamb (Aberystwyth University, UK), and Prof. Asfawossen Asrat (Addis Ababa University, Ethiopia)

Participants: 120 researchers from all over the world Funding: U.S. National Science Foundation (NSF), International Continental Scientific Drilling Program (ICDP), German Research Foundation (DFG), National Environmental Research Council (NERC)https://hspdp.asu.edu/

 

The Researcher

Apl. Prof. Dr. Martin Trauth studied geophysics and geology at the University of Karlsruhe. Since 2011, he has been apl. Professor of Paleo-Climate Dynamics at the University of Potsdam and researches climate changes using statistical methods.

Universität Potsdam
Institut für Erd- und Umweltwissenschaften
Karl-Liebknecht-Str. 24–25
14476 Potsdam
trauth@geo.uni-potsdam.nomorespam.de

Text: Heike Kampe
Translation: Monika Wilke
Online published by: Marieke Bäumer
Contact for the online editorial office: onlineredaktion@uni-potsdam.nomorespam.de