Final Report Summary - IN-AFRICA (IN AFRICA: THE ROLE OF EAST AFRICA IN THE EVOLUTION OF HUMAN DIVERSITY)
That our species, Homo sapiens, evolved in Africa has become the paradigm of human evolutionary studies, supported by multiple lines of evidence. This paradigm has become known as the “Out of Africa” Model, a name that reveals the emphasis on the dispersals into Eurasia arising from the African origins of Homo sapiens. The overarching aim of the IN-AFRICA Project was to focus on the patterns and processes of modern human evolution within the African continent, both before and after the major dispersals. Africa remains the place where the fundamental nature of the human species was established, and where its diversity developed. Where, when, why and how remain major research questions. The IN-AFRICA Project set out to carry out major, methodologically-innovative and theoretically-driven fieldwork in different lake basins of the East African Rift System as a means of tackling these questions. This field exploration aimed at expanding the evidence of modern human evolution in East Africa, and assess the role played by the lake basins of the Rift Valley in shaping the ecology of population refugia in the later Quaternary.
Field research was carried out in four lake basins – Turkana, Nakuru-Naivasha, Edward and Albert in both the Eastern and Western Rift Valleys. Discoveries and finds have contributed to a greater understanding of two main periods in the evolution of our species in Africa – the origins and context for the evolution of Homo sapiens during the later Middle/early Upper Pleistocene, and the diversity and adaptations of modern humans in the region during the African Humid Period prior to the establishment of food producing communities. Eleven new Middle and early Upper Pleistocene sites and 28 later Quaternary ones were discovered in Southwest Turkana, Kenya, as well as two major Upper Pleistocene and Holocene sites in the Albertine Rift, Uganda, leading to excavations and major surveys. The project also re-excavated the famous prehistoric site of Prospect Farm in the Nakuru-Naivasha basin, where a stratigraphic sequence spanning the transition from the Middle to the Later Stone Age was exposed, thus offering new insights into this critical period in the history of modern humans in Africa.
The most significant finds of the project result from the work in Turkana, where three new Middle Pleistocene hominin crania, as well as numerous hominin cranial and post-cranial fragments were discovered in association with rich Middle Stone Age archaeological industries and animal fossils that include multiple extinct taxa. The former add significantly to the fossil record of human origins and early diversity in Homo sapiens and its immediate ancestors, while the extensive fauna recovered, often associated with lithics and bone tools, map the ecology and extinction of African vertebrates in the late Quaternary. The work on the younger, later Quaternary sediments, revealed an extraordinary record of the fisher-forager populations that occupied the Turkana Basin during the African Humid Period that now stands as the largest collection African prehistorical human remains from this time. The ecological and archaeological context of this human palaeontological record, which includes more than 600 barbed bone harpoons, offer unique insights into how humans responded to climate change and demographic pressure both in periods of adversity and plenty.
Five main conclusions emerge from the project:
1. that early modern humans, their close relatives and African descendants were extremely diverse, varying in ways and to extents not observed today;
2. that variation in East African Middle and Later Stone Age industries, particularly when studied in the context of inter-basin comparisons, is spatially and temporally patterned, and together with the an increased hominin and human fossil record, throws light into the human dispersals and demographic contractions in Africa before and after the permanent colonisation of Eurasia by our species;
3. that the conditions leading to inter-group conflict occurred among African Humid Period hunter-gatherers, as revealed by the earliest evidence for lethal inter-group conflict at Nataruk;
4. that mammals and other vertebrates survived in the East African Rift System longer than previously thought, highlighting the role of the Turkana Rift as a refugium, and offering insights into the possible role of hominins in African mammalian extinction;
5. That humans responded behaviourally, morphologically and demographically to the dynamic history of late Quaternary climate change in the Turkana Basin at long and short time scales, which would have shaped human adaptation, diversity and the ecosystem.
The corpus of data collected during the IN-AFRICA Project will continue to be a source of information, insight and further study into the evolution of modern humans and their diversity for years to come, as well as provide the basis for methodological developments. The project’s biggest and most lasting contribution is empirical, with significant numbers of new East African hominin and human fossils from different time periods, along with their palaeontological, archaeological and environmental context. This will be an enduring contribution, taking the state of the art of the field into an empirically richer phase.
Field research was carried out in four lake basins – Turkana, Nakuru-Naivasha, Edward and Albert in both the Eastern and Western Rift Valleys. Discoveries and finds have contributed to a greater understanding of two main periods in the evolution of our species in Africa – the origins and context for the evolution of Homo sapiens during the later Middle/early Upper Pleistocene, and the diversity and adaptations of modern humans in the region during the African Humid Period prior to the establishment of food producing communities. Eleven new Middle and early Upper Pleistocene sites and 28 later Quaternary ones were discovered in Southwest Turkana, Kenya, as well as two major Upper Pleistocene and Holocene sites in the Albertine Rift, Uganda, leading to excavations and major surveys. The project also re-excavated the famous prehistoric site of Prospect Farm in the Nakuru-Naivasha basin, where a stratigraphic sequence spanning the transition from the Middle to the Later Stone Age was exposed, thus offering new insights into this critical period in the history of modern humans in Africa.
The most significant finds of the project result from the work in Turkana, where three new Middle Pleistocene hominin crania, as well as numerous hominin cranial and post-cranial fragments were discovered in association with rich Middle Stone Age archaeological industries and animal fossils that include multiple extinct taxa. The former add significantly to the fossil record of human origins and early diversity in Homo sapiens and its immediate ancestors, while the extensive fauna recovered, often associated with lithics and bone tools, map the ecology and extinction of African vertebrates in the late Quaternary. The work on the younger, later Quaternary sediments, revealed an extraordinary record of the fisher-forager populations that occupied the Turkana Basin during the African Humid Period that now stands as the largest collection African prehistorical human remains from this time. The ecological and archaeological context of this human palaeontological record, which includes more than 600 barbed bone harpoons, offer unique insights into how humans responded to climate change and demographic pressure both in periods of adversity and plenty.
Five main conclusions emerge from the project:
1. that early modern humans, their close relatives and African descendants were extremely diverse, varying in ways and to extents not observed today;
2. that variation in East African Middle and Later Stone Age industries, particularly when studied in the context of inter-basin comparisons, is spatially and temporally patterned, and together with the an increased hominin and human fossil record, throws light into the human dispersals and demographic contractions in Africa before and after the permanent colonisation of Eurasia by our species;
3. that the conditions leading to inter-group conflict occurred among African Humid Period hunter-gatherers, as revealed by the earliest evidence for lethal inter-group conflict at Nataruk;
4. that mammals and other vertebrates survived in the East African Rift System longer than previously thought, highlighting the role of the Turkana Rift as a refugium, and offering insights into the possible role of hominins in African mammalian extinction;
5. That humans responded behaviourally, morphologically and demographically to the dynamic history of late Quaternary climate change in the Turkana Basin at long and short time scales, which would have shaped human adaptation, diversity and the ecosystem.
The corpus of data collected during the IN-AFRICA Project will continue to be a source of information, insight and further study into the evolution of modern humans and their diversity for years to come, as well as provide the basis for methodological developments. The project’s biggest and most lasting contribution is empirical, with significant numbers of new East African hominin and human fossils from different time periods, along with their palaeontological, archaeological and environmental context. This will be an enduring contribution, taking the state of the art of the field into an empirically richer phase.