The Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), working jointly with a multidisciplinary group of researchers from the United States, Kenya, and Portugal, is leading the paleontological investigation of Lothagam, an array of sites on the western shore of Lake Turkana (Kenya), where over 600 fossils of terrestrial vertebrates were recovered in the 2022 and 2023 excavation campaigns.

Lothagam, with one of the chronologically longest fossil sequences on the African continent, offers key information about the fauna and paleoenvironment of East Africa between the Upper Miocene, some seven million years ago, and the Lower Pleistocene, about two million years ago. 

Ignacio A. Lazagabaster, a Ramón y Cajal researcher on the CENIEH Paleobiology program, is the codirector, with John Rowan, of the Department of Anthropology of the University of Albany (USA) , of this research project funded by the Turkana Basin Institute (Kenya), whose main objective is to reconstruct how the ecosystems of East Africa evolved during a period that is key to understanding the earliest steps of the human lineage.

“The Late Miocene is a period little represented in Africa, so that we know hardly anything about human evolution in its first stages, close to the separation from the line of the chimpanzees some seven million years ago”, explains Lazagabaster, adding, “Lothagam opens a window for us onto this period of such importance, by helping us to understand what the ecosystems and landscapes of that time were like”.

Martian landscape

From a geological point of view, Lothagam is one of the most spectacular spots on the west side of Lake Turkana, and is well-known for its distinctive beds of reddish sediments. Due to tectonic activity in the basin over millions of years, these beds have become inclined, deformed and eroded. Some of the iron-rich sediments have been chiseled away slowly by the rain, leaving winding gullies and gorges. 

The juxtaposition of white, red, and violet strata. and the black basalts, make up a unique landscape that evokes the surface of Mars. “Due to the lack of vegetation and shade, a day's work at Lothagam is very challenging, with high temperatures that reach 40℃. Nonetheless, the fossils we find mean that the experience is worthwhile”, says Lazagabaster.

There also exist at Lothagam Holocene sites where thousands of archaeological remains from 9000 to 7000 years old have been found, with highlights being the harpoons worked in bone and the North Pillar Site, an assemblage of stones aligned in a formation reminiscent of Stonehenge.

Excavations since 1970

Numerous paleontological expeditions to Lothagam in the 1970s, and especially in the 1990s, retrieved a large number of Pliocene and Miocene fossils, including partial skeletons and skulls of primates, carnivores, tortoises, hippopotamuses, suids, and elephants, as well as gastropods, crustaceans, plants, and birds. 

Although isolated remains of ancient hominins were found in different strata at Lothagam, their scarcity has traditionally been interpreted as reflecting environmental conditions unfavorable to them. However, these deposits have not been prospected systematically in the last 30 years. Today's researchers hope to find clues to our most ancient ancestors. 

“Although the project has only been running for two years, it promises many surprises. Lothagam is a very special site because of the exceptionally long sequence of sediments at a single place. You can literally walk a couple of kilometers east-west and go through several million years of evolution in East Africa”, he concludes.