Search

The Wallacean archipelago between the Indian and Pacific Oceans is a critical biogeographic boundary for all kinds of animals, from butterflies to birds. Humans are no exception, and in this paper we offer a three stage model for how our genus overcame this boundary. We review how Lower Palaeolithic hominins were able to colonize the larger islands of western Wallacea through incidental seagoing, and subsistence on the megaherbivores that also made these crossings. However, Lower Palaeolithic hominins were not able to maintain geneflow between islands, nor cross into eastern Wallacea and beyond into Sahul. This biogeographic threshold persisted for hundreds of thousands of years until the arrival of our own species, whose cognitive capacities for planning and abstraction likely allowed for the construction of composite material rafts, interdependent paddles, and multiple-day seafaring. With the sea-level rise of the terminal Pleistocene and early Holocene a greater connectivity is seen in the form obsidian exchange networks, inter-island bead and fishhook traditions, and the colonization of very small islands entirely depauperate in terrestrial fauna. We suggest that the appearance of shell adzes at this time reflects the production of dugout canoes to facilitate regular inter-island voyaging. Wallacea presents a key case study both in the limits of Lower Palaeolithic hominin dispersal and the capacities that allowed Homo sapiens to go beyond these, as well as the intensification response of our species to rapid benign environmental change. [ABSTRACT FROM AUTHOR]

Over the 1.5-million-year duration of the Acheulean, there is considerable variation in biface finesse. It is not clear, however, if there is an improvement in biface knapping ability over time, or if variation between sites is largely unrelated to their age. The diversity and duration of the East African Acheulean presents an opportunity to examine this issue. Variables that reflect difficult aspects of biface knapping, and which were likely important goals for Acheulean hominins, were measured in order to assess skill. These variables—refinement (thinness), edge straightness, and symmetry—were compared across four East African Acheulean sites: Olduvai Gorge, Olorgesailie, Kariandusi, and Isinya. The influence of rock type, blank type, reduction intensity, aberrant scar terminations, and invasive flaking on these variables was assessed. Over relatively short timescales, confounding factors, including ones not possible to control for, tend to obscure any temporal signature in biface knapping skill. However, over the vast timespan of the Acheulean at Olduvai Gorge, a temporal trend was indeed apparent. Possible factors influencing this trend include the invention of new knapping techniques, the addition of adolescence as a life history stage, and evolving hominin cognition. [ABSTRACT FROM AUTHOR]