Human Origins in Mozambique and Malawi Environments (2019-2020)
An archaeological fieldwork project
The Human Origins in Mozambique and Malawi Environments mission is funded by the CNRS as part of the 80-Prime Transversal and Interdisciplinary Initiatives project. In addition to UMR TRACES researchers, it benefits from a solid network of interdisciplinary collaborations involving geologists, geomorphologists, paleontologists, archaeologists, geophysicists, geochemists and geomaticians.
This project, built on ongoing work in South Africa and Mozambique, aims to identify features that could help to locate potential fossil sites, in the context of ancient karsts.
The project is based on recent results from the study of the fossiliferous sites of the Cradle of Humankind in South Africa, where researchers have been working for more than 10 years, and an almost virgin zone for this type of research, northern Mozambique, which constitutes a link between the two main fossiliferous areas. It appears that the hominin fossils of this area and those of East Africa have experienced a comparable evolution even though they are preserved in two distinct regions, separated by more than 4000 km. The only commonality is that in both cases they are kept in geological traps: the rift in East Africa and the karst in South Africa. No other site is known between these two regions. It is difficult to imagine that during the millions of years that this evolution lasted, this large area was not also occupied by hominins, as is certainly the case in a large part of Africa.
The region studied has a unique position at the crossroads between three major geological, geomorphological and bioclimatic domains: the southernmost part of the East African rift, the large areas of erosion that characterize a large part of Africa and the vast coastal plain along the Indian Ocean. It is the only place in Africa where fluvio-lacustrine rift fills (Malawi) are near karstic massifs. There is therefore a possibility of establishing correlations between the faunal and floristic processions, in particular by avoiding taphonomy issues, which are very different between the two domains.
The objective is to identify new fossil traps between these two regions, focusing in particular on the karst, the best geomorphological environment for the preservation of these ancient remains. In order to find these traps, comparative studies will be made with a well-controlled area, the “Cradle of Humankind” in South Africa.
The mission is led by Laurent Bruxelles. As a geologist/karstologist, he has worked on many Southern African archaeological sites, and other projects such as Human Origins in Namibia, which endowed him with a comprehensive view of the region’s geological and geomorphological history, as well as wide recognition from South African and French researchers.
Various specialists are working on this mission, such as geologists (Philippe Vernant and Pierre Camps), geomorphologists (Laurent Bruxelles, Dominic Stratford and Gregory Dandurand) and remote sensing specialists (Nicolas Poirier, François Baleux and Benjamin Lans).
To date, two main regions in Africa can claim to be the cradle of humankind, where fossiliferous sites highlight the appearance of the genus Homo: the Great East African Rift and the South African karsts.
The Great East African rift is a large rift related to the processes of the Nubian and Somali tectonic plates splitting. As the rift floor collapsed, an important thickness of terrigenous sediments have accumulated. This sedimentary sequence is an exceptional record of the paleoenvironmental evolution of this region from East Africa for the Tertiary and the Quaternary. Fauna and flora remains are preserved in these deposits, including those of ancient hominins: Australopithecus, Paranthropus and Homo, covering the period of appearance of the genus Homo. The rifting mechanism has been accompanied throughout its history by volcanic activity related to the decompression of the Earth’s mantle and thus by the production of volcanic deposits.
The second region that can be considered today as a cradle of humankind is located in South Africa in a very different geological and geomorphological context: the karst. Here it is the caves that have played the role of sedimentary trap and, according to the age of their formation and their overlap by the topographic surface, deposits of varying ages have accumulated there. Nevertheless, until very recently, South African fossils were considered to be too recent, because of datings that were poorly constrained by the complex stratigraphies of the caves. The dating of the Little Foot Australopithecus fossil, almost complete and found in anatomical connection, has questioned these datings. Indeed, with a date of 3.67 Ma, this fossil demonstrates, according to geological and biochronological data, that southern Africa has recorded a history of hominins at least as long and complex as the one known for several decades in the East African rift. These two regions show a parallel but complementary recording of this long evolutionary process.
It now appears that South Africa, like East Africa, could potentially be the “Cradle of Humankind”. But it might be better to say one of the cradles of Humanity. Indeed, if we find remains of old Hominids in both East and South Africa, it is mainly because the conditions of preservation are very favorable. It is likely that there were originally many other “cradles”, or even certainly that a very large part of Africa is the cradle. The search for new vestiges must now go through the search for geological traps. The HOMME research program proposes to answer this question, by looking for other geological traps that may have preserved other pieces of the “Cradle of Humankind”.
The discovery of new fossil sites in this region would be a major advancement in the knowledge of human evolution by removing several important scientific obstacles. These fossils would provide the opportunity to better understand the distribution of Australopithecus and paranthropic species and provide an additional milestone for the appearance of the genus Homo. In addition, it is not excluded that new species are present in this region and that they will come to enrich the fossil record of the human line. Such discoveries could help answer a crucial and still unresolved question about monophyly or paraphyly in the evolution of these ancient hominin species, either by showing their coexistence in this intermediate zone, or by highlighting the passage from one zone to another. The Great Rift is a natural corridor that has inevitably oriented migration and the sector we propose to study is exactly at its outlet.