WP-2 The impact of AETs on early modern human populations in North Africa

Unlike Europe, all major cultural transitions in North Africa during the period 130-20 ka BP occurred within Homo sapiens populations. The presence of tephras in marine and terrestrial palaeoenvironmental archives allow the timing of these key cultural changes to be tested against known abrupt environmental transitions (AETs) within this timespan. The key hypothesis to be tested in this work package is whether the arrival of early modern humans in NW Africa and subsequent cultural transitions were all strongly determined by AETs.

Aims and Research Objectives

North Africa is a key to understanding the emergence and dispersal of anatomically modern humans (AMH). Not only does this region form an important bridging point for population movements into the Near East and Europe but it has now produced amongst the earliest anatomically modern human fossils outside East Africa, dating to around 160,000 years (Smith et al. 2007). Some of the oldest evidence for symbolically modern behaviour also derives from this region. The recent discovery of Nassarius shell beads (right) from Taforalt in Morocco, dating to about 82,000 years ago, suggests that humans living in this area had already developed a capacity for cultural modernity at a very early stage (Bouzouggar et al. 2007).

When Middle Palaeolithic modern populations first arrived in North Africa and whether subsequent cultural transitions developed in situ or were the result of further migrations are core questions in this research. The test-bed for this study is northern Morocco which forms part of the Maghreb, a semi-arid upland zone that lies on the northern edge of the Sahara. Here, the Mousterian and Aterian (illustrated below) represent early examples of Middle Palaeolithic presence yet the dating of their first appearance in this region is unclear. Currently, the earliest dates for the Aterian are around 82 ka BP (82,000 years ago) from Grotte des Pigeons at Taforalt (Bouzouggar et al. 2007) but part of this project will be to date other occurrences in Morocco and to see whether these coincided with periods of rapid climatic change.

A further major cultural transition is believed to have occurred at around 20 ka BP with the appearance of the Iberomaurusian technology. This epipalaeolithic tradition is very different from preceding Middle Palaeolithic ones yet there is still a great deal of controversy surrounding its evolution and development in this region. For example, it is uncertain what processes led to its apparently sudden appearance in the Maghreb and whether these were connected with climatic events (Barton et al. 2007) or other factors. A second feature that has not been widely commented upon is the sudden and potentially synchronous occurrence of large scale midden deposits in caves across the western Maghreb at 13 ka BP which seem to mark a change in emphasis in the use of caves. For example, it is from about this time that such locations become extensively used as cemeteries (Barton et al. 2008, Bouzouggar et al. 2008). The midden horizons recognisable in many caves in Morocco may mark a significant change in subsistence activities and in a diversification in the exploitation of resources which again could have been influenced by climatic change.

A major element of this project will therefore be to refine the chronology of these periods through the application of tephrostratigraphy and by improving the accuracy of radiocarbon, luminescence and U-series dating of archaeological cave deposits at sites such as Taforalt. Broader comparisons will involve the modelling of marine cooling in the Atlantic and Mediterranean to provide a framework for understanding the nature and timing of aridification phases on the adjacent landmasses. Palaeoenvironmental proxies (small mammals, reptiles, amphibians, birds, charcoal, phytoliths etc) from within the stratified cave sequences will also provide important subsidiary information on periodicity of these processes.

The aim of this work package is to establish whether critical transitions, such as the appearance of early modern humans in North Africa and innovations in Middle and Upper Palaeolithic technologies, can be explained by major environmental disruption. To achieve this the following research objectives will be pursued:

• To model marine cooling in the Atlantic and Mediterranean to assess how this affected the adjacent landmasses, particularly in relation to phases of increased aridity
• To refine, through tephrostratigraphy, the accuracy of radiocarbon, luminescence and U-series dating for the archaeological record (130-20 ka BP)
• To assess the relationship between changes in the archaeology and AETs

Geographical focus

The primary geographical focus of this work package includes the littoral zones of Mediterranean and Atlantic Morocco, including the North African coastal dispersal corridor. Caves of interest to this work package include Grotte des Pigeons at Taforalt (right), Rhafas Cave and Dar es-Soltane I. In selecting these sites this study builds on the earlier investigations of Nick Barton and Abdeljalil Bouzouggar within the NERC funded EFCHED programme, more details of which can be found here.

References

Barton, R.N.E., Bouzouggar, A., Bronk-Ramsey, C., Collcutt, S.N., Higham, T.F.G., Humphrey, L.T., Parfitt, S., Rhodes, E.J., Schwenninger, J.L., Stringer, C.B., Turner, E. & Ward, S. 2007. Abrupt climatic change and chronology of the Upper Palaeolithic in northern and eastern Morocco. In P. Mellars, K. Boyle, O. Bar-Yosef & C. Stringer (eds), Rethinking the human revolution: new behavioural and biological perspectives on the origin and dispersal of modern humans. Research Monographs of the McDonald Institute, Cambridge, p. 177-186.

Barton, R.N.E., Bouzouggar, A., Humphrey, L.T., Berridge, P., Collcutt, S.N., Gale, R., Parfitt, S., Parker, A.G., Rhodes, E.J. & Schwenninger, J.L. 2008. Human burial evidence from Hattab II Cave (Oued Laou-Tétuoan, Morocco) and the question of continuity in Late Pleistocene-Holocene mortuary practices in Northwest Africa. Cambridge Archaeological Journal 18 (2), 195-214.

Bouzouggar, A., Barton, N., Vanhaeren, M., D'errico, F., Collcutt, S.N., Higham, T.F.G., Hodge, E., Parfitt, S.A., Rhodes, E.J., Schwenninger, J.-L., Stringer, C.B., Turner, E., Ward, S.C., Moutmir, A. & Stambouli, A. 2007. 82,000 year-old shell beads from North Africa and implications for the origins of modern human behavior.Proceedings of the National Academy of Sciences USA 104, 9964-9969.

Bouzouggar, A., Barton, R.N.E., Blockley, S., Bronk-Ramsey, C., Collcutt, S.N., Gale, R., Higham, T.F.G., Humphrey, L.T., Parfitt, S., Turner, E. & Ward, S. 2008. Re-evaluating the age of the Iberomaurusian in Morocco. African Archaeological Review 25, 3-19.

Smith, T.M., Tafforeau, P., Reid, D.J., Grün, R., Eggins, S., Boutakiout, M. & Hublin, J-J. 2007. Earliest evidence of modern human life history in North African early Homo sapiens. Proceedings of the National Academy of Sciences USA 104, 6128-6133.

Stringer, C.B. and Barton, R.N.E. 2008. Putting North Africa on the map of modern human origins. Evolutionary Anthropology 17, 5-7.