Drilling in the cradle of mankind
This summer, archaeologist José Joordens is in the Kenyan Turkana basin, collaborating on a unique international drilling project. The aim: to find out more about the relation between climate change and human evolution.
This project, called Climate Impact on Human Evolution: Age Calibration of Hominid Sites and Paleolakes Drilling, subsidised by NWO, is a collaborative effort of researchers from Leiden and Utrecht. It forms part of the International Continental Scientific Drilling Program (ICDP). Mark Sier, a Leiden postdoc, is working with José Joordens in the project.
Great Rift Valley
The drilling will take place in ancient lake sediments in the East African Rift System, known as the Great Rift Valley. A rift valley forms when a block of the earth’s crust drops down along a fault line, forming a ‘graben’. A rift is made up of a series of these grabens, alternating with raised sections called ‘horsts’. The floor of the valley can rise again in the course of time as a result of accumulating sediment from adjacent areas.
The Great Rift Valley is a remarkable area known as the ‘cradle of mankind’ because so many ancient human remains have been found there, some up to 4.5 million years old. ‘We now want to understand the course of human evolution throughout these millions of years,’ explains Joordens. ‘We suspect that climate played an important determining role in this context. Imagine, for instance, the effect of a period of great drought, which would result in hominid populations being isolated from each other and having to learn to survive in new circumstances; this led to the evolution of new species.’
An enormous drill (known as an ‘apple core’ model) is used to excavate ten-metre long cylinders, up to 400 metres deep. This depth is equivalent to going approximately 4.5 million years back in time. By analysing the various layers of soil, a complete climate archive emerges. Joordens: ‘Normally, we are limited to studying the old sediments that are unearthed accidentally, so we always have a kind of sub-optimal, loose-leaf archive. Now, for the first time, it's possible to have a complete climate overview, and we can combine this information with the insights gained from studying fossils. This really is a once-in-a-lifetime opportunity.’
It is not only the past that can be mapped in this way. Paleoclimatology, as this type of soil research is called, also helps to predict how the climate may develop in the future, and it plays an important role in validating climate models. Joordens: ‘After all, you can only develop ideas about the future once you know what happened in the past. Given the current concerns about our climate, this project also has a clear social impact.’
A lot of effort is being put into embedding the project in Kenyan society. The project runs in collaboration with a Kenyan drilling company and Kenyan researchers. Joordens also hopes that the local population will get involved. ‘We are guests on their territory; it is important that they agree with what we are doing.’ For this reason a professional documentary maker has been called in to film the entire project. This will allow the Kenyans (and later the rest of the world) to see what is happening and why it is so important. ‘Most people are actually already interested,’ says Joordens. ‘No wonder, with this whole circus descending on their village... And they are proud of the fact that their region is seen as the cradle of humanity.’
(23 July 2013)
- Project website
- Facebook page with updates
- Great Rift Valley (Wikipedia)
- ICDP website
- Faculty of Archaeology: Human Origins Group