Life Histories, Metapopulation Ecology, and Innovation in the Acheulian

Abstract

In the course of the evolution of the genus Homo, the most profound developments in life history parameters seem to have occurred in the Lower Pleistocene. Yet Acheulian industries are widely seen as having remained essential-ly unchanged for some 1.3 million years or more. In reality, however, although the Acheulian did not develop in a cumulative or directional manner over its long history, it nevertheless displayed considerable levels of typological and technological diversity and variability at continental, regional, and local levels. It is at the local level that this variability is at its greatest, with prepared core technologies regarded as characteristic of the succeeding Middle Paleolithic and Middle Stone Age appearing sporadically and ephemerally in the Acheulian. It is our contention that this pattern of local, short term variability combined with global long term stasis cannot be accounted for by models asserting that the hominin makers of the Acheulian lacked the cognitive capabilities of their evolutionary successors. Instead, we argue that Acheulian hominins were cognitively capable of innovative technical behavior and often displayed it; but that, despite structural life history parameters that approached those of living Homo sapiens, relatively short childhood, juvenile, and adolescence phases, combined with small local group size, con-strained the social and developmental scope for innovation. Furthermore, we argue that metapopulation-level so-cial, demographic, and ecological dynamics in the Acheulian, relating to group size, foraging ranges, and levels of individual migration, served to limit the lifespan of local groups and thereby reduced the likelihood of innovative behaviors disseminating through social networks and becoming fixed in cultural repertoires before the origina-tor population became extinct. We explore the idea that the transition from the Acheulian to the ensuing Middle Paleolithic and Middle Stone Age was therefore driven not by evolutionary developments in hominin cognitive capacities, but by changes in life history and metapopulation factors.