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Thu May 24, 2012
Dr. Michael Gottfried, Michigan State University – Formation of the Great Rift Valley
In today’s Academic Minute, Dr. Michael Gottfried of Michigan State University reveals advances in our understanding of Africa’s Great Rift Valley and the implications for the study of human evolution.
Michael Gottfried is an associate professor of geological sciences at Michigan State University and Curator of Vertebrate Paleontology at the MSU Museum. His research focuses on marine fish evolution in high-latitude southern hemisphere settings, the paleobiology of the giant fossil 'megatoothed' sharks, and the evolution and biogeographical relationships of vertebrate faunas from the ancient southern supercontinent of Gondwana. He holds a Ph.D. from the University of Kansas.
Dr. Michael Gottfried – Formation of the Great Rift Valley
A key section of the Great Rift Valley of East Africa – the birthplace of the human species – likely took longer to develop than previously thought, a conclusion that has some major implications for our understanding of the physical and biological setting in which our direct ancestors evolved.
The East African Rift system is composed of two main segments: the eastern branch that passes through Ethiopia and Kenya, and the western branch, which sweeps from Uganda to Malawi, and includes the famous African rift lakes.
We now believe that the western portion of the rift formed about 25 million years ago, making it equally as old as the eastern part, instead of much younger as other studies have maintained. This nearly doubles the age of the western branch and the timing of uplift in this part of East Africa. We’re interested in this issue because the Rift Valley is the setting for crucial steps in primate and ultimately human evolution, and our study deepens our understanding of how East Africa changed during key stages in that story.
I worked with an international team led by Eric Roberts who said that the findings provide new data for studying deep-time climate change, animal evolution, and the development of Africa’s unique landscape. Key to this study was my colleague, Nancy Stevens’ discovery of approximately 25 million-year-old lake and river deposits in the western rift that preserve volcanic ash, which can be accurately dated, and vertebrate fossils – including some of the earliest primates yet found in the rift.
So, rather than happening just 10-15 million years ago, our research reveals that the uplift of East Africa around 25 million years ago re-arranged the flow of large rivers such as the Congo and the Nile, and started to create the distinct landscapes and climates that mark Africa today and form the environmental backdrop for the origin of our own species.