Previous projects
The evolution and dispersal of modern humans: the Hofmeyr skull
Many of the interesting ‘why’ and ‘how’ questions in archaeology and physical anthropology can be re-phrased in terms of ‘when’ questions. A number of genetic studies of living people indicate that modern humans evolved in Africa 150-200,000 yrs ago and that a relatively small group of these moved out of Africa to colonize Europe and Asia between 65 000 and 25 000 years ago. However, some other DNA evidence argues against this Africa origin and exodus model, suggesting that archaic, non-African people, such as the Neanderthals of Europe, made significant contributions to the genomes of modern humans in Europe and Asia. The "out of Africa" genetic theory predicts that humans similar to those who lived in Europe and Asia should also be found in sub-Saharan Africa during this colonization period (25-60,000 yrs ago). However, the lack of fossil evidence from sub-Saharan Africa meant that these two competing genetic models of human evolution could not be tested by palaeontological evidence. The Hofmeyr skull (found at the southern tip of South Africa - see map to the right) has a very close affinity with the fossil skulls of Europeans of the Upper Palaeolithic (the colonization period) and was dated, using a combination of optical and uranium-series methods, to approximately 36,000. The Hofmeyr skull, therefore, provides the first sub-Saharan fossil evidence against which the competing genetic theories can be tested and provides strong support to the ‘Out of Africa’ model.
These results were covered extensively by the world press (examples: New York Times, Science Magazine news, National Geographic) and made Time Magazine’s Top Ten Scientific Discoveries of 2007 (#8).
F.E. Grine, R.M. Bailey, K. Harvati, R.P. Nathan, A.G. Morris, G.M. Henderson, I. Ribot, A.W.G. Pike (2007) Late Pleistocene human skull from Hofmeyr, South Africa, and modern human origins. Science 315, 226-229.
Many of the interesting ‘why’ and ‘how’ questions in archaeology and physical anthropology can be re-phrased in terms of ‘when’ questions. A number of genetic studies of living people indicate that modern humans evolved in Africa 150-200,000 yrs ago and that a relatively small group of these moved out of Africa to colonize Europe and Asia between 65 000 and 25 000 years ago. However, some other DNA evidence argues against this Africa origin and exodus model, suggesting that archaic, non-African people, such as the Neanderthals of Europe, made significant contributions to the genomes of modern humans in Europe and Asia. The "out of Africa" genetic theory predicts that humans similar to those who lived in Europe and Asia should also be found in sub-Saharan Africa during this colonization period (25-60,000 yrs ago). However, the lack of fossil evidence from sub-Saharan Africa meant that these two competing genetic models of human evolution could not be tested by palaeontological evidence. The Hofmeyr skull (found at the southern tip of South Africa - see map to the right) has a very close affinity with the fossil skulls of Europeans of the Upper Palaeolithic (the colonization period) and was dated, using a combination of optical and uranium-series methods, to approximately 36,000. The Hofmeyr skull, therefore, provides the first sub-Saharan fossil evidence against which the competing genetic theories can be tested and provides strong support to the ‘Out of Africa’ model.
These results were covered extensively by the world press (examples: New York Times, Science Magazine news, National Geographic) and made Time Magazine’s Top Ten Scientific Discoveries of 2007 (#8).
F.E. Grine, R.M. Bailey, K. Harvati, R.P. Nathan, A.G. Morris, G.M. Henderson, I. Ribot, A.W.G. Pike (2007) Late Pleistocene human skull from Hofmeyr, South Africa, and modern human origins. Science 315, 226-229.
The location of the find site and photo of the skull.
Artist’s reconstruction (credit to Luci Betti-Nash)
Ancient environments: African lakes
The common theme in these projects is the use of OSL dating to define the relative and absolute timing of events linked to specific environmental / geomorphic response to changes in climate. This allows the development of environmental histories and the testing of relevant hypotheses concerning the operation of the climatic and environmental systems.
Samples were taken from ancient beach ridges surrounding the northern shore of Lake Chilwa (Malawi) and Lakes Ngami & Makgadikadi (Botswana), and dated using OSL methods. The purpose of these projects was to document the hydrological history in these regions by assessing the depositional age of geomorphological features (e.g. beache ridges) which are directly related to the presence of former lake highstands. Results show many distinct periods of deposition, and interestingly not paced by precision-forcing of monsoons. In Chilwa, highstands matched well with dates for N. Hemisphere Heinrich events and modelling using HadCM3 confirmed the existence of relevant physical mechanisms operating through ocean-atmosphere connections. The picture in Ngami & Makgadikadi is more complicated, with tropical signals imported from the Angolan highlands, mixed with local lake-climate feedbacks.
David S.G. Thomas, Richard Bailey, Paul A. Shaw, Julie A. Durcan, Joy S. Singarayer (2009) Late Quaternary highstands at Lake Chilwa, Malawi: Frequency, timing and possible forcing mechanisms in the last 44 ka. Quaternary Science Reviews 28, 526–539.
Burrough, S.L. Thomas, D.S.G., Shaw, P.A., Bailey, R.M. Multiphase Quaternary highstands at Lake Ngami, Kalahari, northern Botswana. Palaeogeography, Palaeoclimatology, Palaeoecology 253 (2007) 280–299.
Burrough, S.L, Thomas, D.S.G. Bailey, R.M. Mega-Lake in the Kalahari: A Late Pleistocene record of the Palaeolake Makgadikgadi system. Quaternary Science Reviews 28, 1392-1411.
Lake Chilwa (Malawi), Lakes Ngami & Makgadikadi (Botswana)
...more information to follow
The common theme in these projects is the use of OSL dating to define the relative and absolute timing of events linked to specific environmental / geomorphic response to changes in climate. This allows the development of environmental histories and the testing of relevant hypotheses concerning the operation of the climatic and environmental systems.
Samples were taken from ancient beach ridges surrounding the northern shore of Lake Chilwa (Malawi) and Lakes Ngami & Makgadikadi (Botswana), and dated using OSL methods. The purpose of these projects was to document the hydrological history in these regions by assessing the depositional age of geomorphological features (e.g. beache ridges) which are directly related to the presence of former lake highstands. Results show many distinct periods of deposition, and interestingly not paced by precision-forcing of monsoons. In Chilwa, highstands matched well with dates for N. Hemisphere Heinrich events and modelling using HadCM3 confirmed the existence of relevant physical mechanisms operating through ocean-atmosphere connections. The picture in Ngami & Makgadikadi is more complicated, with tropical signals imported from the Angolan highlands, mixed with local lake-climate feedbacks.
David S.G. Thomas, Richard Bailey, Paul A. Shaw, Julie A. Durcan, Joy S. Singarayer (2009) Late Quaternary highstands at Lake Chilwa, Malawi: Frequency, timing and possible forcing mechanisms in the last 44 ka. Quaternary Science Reviews 28, 526–539.
Burrough, S.L. Thomas, D.S.G., Shaw, P.A., Bailey, R.M. Multiphase Quaternary highstands at Lake Ngami, Kalahari, northern Botswana. Palaeogeography, Palaeoclimatology, Palaeoecology 253 (2007) 280–299.
Burrough, S.L, Thomas, D.S.G. Bailey, R.M. Mega-Lake in the Kalahari: A Late Pleistocene record of the Palaeolake Makgadikgadi system. Quaternary Science Reviews 28, 1392-1411.
Lake Chilwa (Malawi), Lakes Ngami & Makgadikadi (Botswana)
...more information to follow