Coastal and marine palaeo-environments and human dispersal points across the Africa-Eurasia boundary

摘要

Submarine prehistoric archaeological sites on Mediterranean coasts contribute to understanding human migrations in the last 2 million years. "Out of Africa", "Multi-regional", and "Trellis" models of human origins and dispersal depend on what environments attracted hominid and modern human occupation, and how temporal and spatial variations in environments facilitated or impeded population dispersal and gene flow. A determining factor for migration routes, and possible two-way dispersal across potential boundaries, was the level of the world ocean, and the degree of obstruction presented by straits, channels, estuaries, and semi-enclosed seas. During the last 2 million years, the recurrent high latitude glaciations caused the sea level to fluctuate between -120m and +10m relative to present sea level, changing the potential crossing points. During periods of low sea level hominids and anatomically modern humans could probably cross from Morocco to Spain, from Tunisia to Sicily, and from Djibouti/Eritrea to Yemen, as well as by the land route through Sinai. It is probable that at these points, the process was two-way, with communities on opposite shores in regular cultural communication. The down-stream migrations into north-west Europe, Arabia, India, and SE Asia may also have been profoundly affected by episodic exposure of the continental shelf, and changes in climate and intensity of the monsoons. This paper examines the tectonic changes in the coastal areas, the glacio-eustatic-isostatic factors determining the exposed shelf areas, the regional climate changes, the natures of the exposed shelf, vegetation, and water supply, in the key crossing zpnes and transit areas. It presents a programme for finding submerged archaeological evidence for the crossings.