Project Will Delve Into How Climate and Tectonics Shaped Human Ancestors Over 25 Million Years

September 25, 2020

A newly funded project will investigate the forces that shaped the environments in which the ancestors of humans evolved, by exploring the relationships between tectonics, climate and mammal evolution in Kenya’s Turkana Basin.

The possible evolutionary roles of climate and tectonics have been longstanding questions, and the East African Rift, along which the Turkana Basin is situated, is among the best places to study this. The rift system is considered the cradle of humankind. Here, the region’s geologic and climate histories, including the formation of the rift itself, are uniquely preserved in sedimentary rocks. The team will investigate the sediments, and the fossils they contain, to gain insights into the emergence of humans’ primate ancestors and other African mammals between 5 million and 25 million years ago, a period known as the Miocene.

Researchers from Stony Brook University’s Turkana Basin Institute, Columbia University’s Lamont-Doherty Earth Observatory and other institutions will carry out the work over four years, funded by a $2.7 million grant from the U.S. National Science Foundation.

man holding up a fossil femur

Francis Ekai Ikai, a fossil finder at the Turkana Basin Institute, holds up a fossil hippo femur from the Lothagam geologic formation, near Kenya’s Lake Turkana. Looking on, his colleague Julius Kerio. (Sophia Lee)

Chimpanzees, gorillas, and orangutans are our closest precursors. It is estimated that the human-chimpanzee common ancestor evolved approximately 6 million to 7 million years ago, having diverged from the common ancestor with the gorilla about 8 million to 10 million years ago. The common ancestor of the African great apes and humans is estimated to have diverged from the ancestor of the orangutans approximately 14 million to18 million years ago.

The project “will allow our team to dive deep into a critical period of Africa’s biotic, climatic and geologic history,” said Lamont paleoclimatologist Kevin Uno. “This will be the first major multidisciplinary project to work on many of the Miocene age deposits which dot the landscape in Turkana. Our goal is to connect up these dots to understand the role of climate and tectonics in human and mammalian evolution.”

Uno will head a group analyzing carbon and oxygen isotopes in fossil teeth to reconstruct mammal diets, and plant remains to assess vegetation, rainfall, and the role of fire in ecosystems. Lamont geochemists Sidney Hemming and Stephen Cox will generate new, high-precision radioisotope dates for study sites.

The investigators will combine new and existing data to study the links between rift development and climate change, and their respective roles in vegetation and mammal evolution. As part of this, they will produce a tectonic model that reconstructs rift evolution for the past 25 million years. The tectonic model will then be integrated with climate-vegetation models of equal or better resolution.

The expertise of team members includes tectonics, sedimentology, geochronology, isotope geochemistry, paleoecology, climate modeling and paleontology. In addition to Lamont-Doherty and Stony Brook (which is leading the project), participants will include Rutgers University, Hamilton College, the University of Michigan, the National Museums of Kenya and the University of Helsinki, Finland.

Adapted from a press release by the Turkana Basin Institute, Stony Brook University.

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