Were Acheulean Bifaces Deliberately Made Symmetrical? Archaeological and Experimental Evidence

Acheulean bifaces dominate the archaeological record for 1.5 million years. The meaning behind the often symmetrical forms of these tools is the topic of considerable debate, with explanations ranging from effectiveness as a cutting tool to sexual display. Some, however, question whether the symmetry seen in many Acheulean bifaces is intentional at all, with suggestions that it is merely the result of a bias in hominin perception or an inevitable consequence of bifacial flaking. In this paper we address the issue of intention in biface symmetry. First, we use transmission chain experiments designed to track symmetry trends in the replication of biface outlines. Secondly, we use archaeological data to assess the symmetry of Acheulean bifaces from British, East African and Indian assemblages in relation to reduction intensity; the degree of bifaciality; and the symmetry of four Middle Palaeolithic bifacial core assemblages. Thirdly, we look at specific examples of the reduction sequences that produced symmetrical Acheulean cleavers at the sites of Olorgesailie CL1-1, Isinya, Chirki, Morgaon and Bhimbetka. All three lines of evidence support the notion that symmetry was a deliberately imposed property of Acheulean bifaces and not an epiphenomenon of hominin visual perception or bifacial technology.