Why did the Acheulean happen? Experimental studies into the manufacture and function of Acheulean artifacts

This chapter will consider the origins, evolution and adaptive significance of the Acheulean Industrial Complex, based upon experimental replicative and functional studies. It is argued here that the Acheulean emerged as a response to large-mammal carcass acquisition and butchery, where larger, heavier and more ergonomic butchery tools with long, sharp, durable edges were desirable. The production of hand axes and cleavers (as well as picks and knives), made either on large flake blanks struck from mega-cores or made on large cobbles, nodules, or tabular pieces, heralded a new technological sophistication and presumably greater cognitive skills. The Acheulean, beginning between approximately 1.76 million years ago (mya) and lasting in some places until around 154,000 years ago, also documented one of the most profound periods of encephalization in hominin evolution and the transition from Homo ergaster/erectus (hereafter referred to as Homo erectus) to Homo heidelbergensis (formerly called archaic Homo sapiens), and even very early Homo sapiens idaltu. Cranial capacity increased from approximately 800 cubic centimeters in H. erectus to about 1250 cubic centimeters in H. heidelbergensis (and presumably a proportional increase in anthropocentric encephalization quotient, or EQ, from approximately 0.5 to 0.85, with modern humans and Homo sapiens idaltu with a cranial capacity of 1450 cc representing an EQ of roughly 1.00). This neural increase is correlated with more refined and standardized biface technologies over time and the rise of prepared core technologies. This increase in absolute and relative brain size is almost certainly also correlated through time with larger mean hominin group sizes, higher quality diets (i.e. more protein and fat food resources, primarily from animal tissue and obtained with an increasing reliance upon more complex technologies) and greater cognitive, social and communicative complexity. (C) 2017 Published by Elsevier Masson SAS.