Saturday, October 24, 2009

The great arc of dispersal of modern humans: Africa to Australia

Stephen Oppenheimer

School of Anthropology and Museum Ethnography, Oxford University, 51 Banbury Road, Oxford, OX2 6PE, UK

Available online 26 July 2008.

Abstract

During the Late Pleistocene, anatomically modern humans (AMH) dispersed out of Africa across the continents. Their routes obeyed the limitations placed on any large terrestrial mammal dependent on daily drinking water, following certain climate-permissive corridors. AMH first spread north, with game, across the Sahara to the Levant during the Eemian interglacial (c.125 ka), but failed to continue to Europe, then occupied by Neanderthals. The savannah ecosystem in North Africa and the Middle East then dried up, and AMH vanished from the Levantine fossil record, being replaced there by Neanderthals. Later, AMH successfully left Africa as a single group by the southern route to India. The added ability to make short but deliberate open water crossings allowed them first to cross the mouth of the Red Sea from Eritrea, and subsequently Wallace's Line to reach the isolated Sahul continent at least by 48,000 years ago and possibly by 60–50,000 years ago. They only finally arrived in Europe from South Asia around 45–50,000 years ago, probably linked to climatic amelioration during OIS-3.

Article Outline

1. Introduction
2. Regional setting
3. Materials and methods used in review of genetic phylogeography
3.1. Phylogeography
3.2. Complete sequence data: sources, phylogeny and dating
4. Review of out of Africa models
4.1. How many AMH exits from Africa? The genetic evidence
4.1.1. Single exit models
4.1.2. Models with multiple exits: the Cambridge model
4.2. Quo vadis?
4.2.1. Southern rather than northern exit: genetic evidence
4.2.2. Climatic considerations: constraints and imperatives for an exit route
4.3. Dating migrations
4.3.1. Possible dates of exit
4.3.2. Delayed migration to West Eurasia
4.3.3. Dating arrival of AMH in India and Southeast Asia
4.3.4. Dating Pleistocene arrivals of humans in Sahul and near Oceania
5. Conclusions
Acknowledgements
References