Afro-Eurasian mammalian dispersal routes of the Late Pliocene and Early Pleistocene, and their bearing on earliest hominin movements

Mammalian migrations provide an excellent context for the dispersal of hominins in the Plio-Pleistocene. Here we present a discussion of a variety of different techniques that can be used to elucidate migration patterns in the fossil record, focussing on the Gibraltar Straits as an example. There are three main mechanisms for studying such patterns - 1) recent mitochondrial DNA analyses on a variety of taxa, 2) modern circum-Mediterranean biogeography and 3) the biogeography of fossil taxa. The advantages and disadvantages of each are considered, and the circum-Mediterranean palaeobiogeography of three genera: Theropithecus, Hippopotamus and Homo are discussed. We consider that, with the exception of a few small bodied animals, there is little evidence of across Gibraltan dispersal since the Messinian, making this an unlikely route for Hominin migration. The most likely route of dispersal for both fossil and modern large mammal migrations appears to be the Levantine corridor. We then conclude this paper with a discussion of the wider theoretical context for such large-scale palaeobiogeographic studies.