East Africa preserves the most complete record of human evolution anywhere in the world, but scientists know little about how long-term biogeographic dynamics in the region affected the diversity and distribution of hominins.
An artist’s earliest human habitation in Tanzania 1.8 million years ago. Image credit: M. López-Herrera / Enrique Bagutano / Olduvai Paleoanthropology and Paleoecology Project.
In the new research, the National Research Center for Human Evolution (CENIEH) Dr. Ignacio Lascapaster and his colleagues focused on the fossil record of mammals from the East African Rift System.
„Late Cenozoic fossil sequences in the East African Rift System provide the richest, longest and most continuous record of human evolution and its environmental context anywhere in the world,” the authors explained.
„Thus, the hominin and faunal records of East Africa play an important role in understanding the factors that shaped human evolutionary history.”
„Our study provides new perspectives on how climate and environmental changes have influenced the evolution of mammals and hominins over the past 6 million years,” said Dr. Lasakapaster.
„It particularly highlights that biotic homogenization, the process by which fauna from different regions become more similar in composition, has been a key factor in the evolution of ecosystems and the development of organisms that inhabit them.”
„Through beta diversity analysis, the relationship between local and regional biodiversity, we can track how vegetation and climate change drive patterns of dispersal and extinction over time.”
They found that the fauna of the Late Miocene and Pliocene (about 3 to 6 million years ago) consisted mainly of endemic species.
The shift toward biological homogeneity or faunal uniformity began about 3 million years ago, driven by the loss of endemic species within functional groups and an increase in the number of grazing species shared between regions.
This important biogeographic shift closely matches the regional expansion of ecosystems dominated by graminoids and type C4 pastures, which grow best in warm and dry climates.
These environmental changes directly affected the feeding and movement patterns of the hominins and primates that shared their habitat.
„Since hominins, like other mammals in East Africa, were certainly influenced by many factors, this work provides a new perspective on the links between environmental and human evolutionary changes, which provides us with a framework for future research and for testing hypotheses about the adaptation of hominins to their environments,” said Dr Lasakapaster.
The study Published in Journal on July 15, 2024 Natural Ecology & Evolution.
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J. Rowan and many others. Long-term biological synchrony in the East African Rift System during the last 6 million years of hominin evolution. Nat Ecole Evol, published online July 15, 2024; doi: 10.1038/s41559-024-02462-0