The mirror cracked: Symmetry and refinement in the Acheulean handaxe

Abstract

The Acheulean is a stone tool industry that originates in Africa over 1.7mya. It is characterised by the bifacially shaped handaxe as part of a group of tools commonly referred to as LCTs — large cutting tools. Traditionally, the Lower Palaeolithic/Early Stone Age Acheulean is seen as continuing throughout much of the Old World until c. 0.25mya and the advent of the Middle Palaeolithic, though handaxe usage continues well after this. At least two different hominin species are responsible for making handaxes across this time span,Homo ergaster/erectusandHomo heidelbergensis. It is possible that the earliestHomo sapiensin Africa also made and used handaxes. A long running debate concerns whether or not there is an evolution in Acheulean material culture. This involves the belief that handaxes and other LCTs become more refined and sophisticated as time goes by. There are two schools of thought on this. The first argues that advances in Acheulean material culture march in lockstep with brain and cognitive evolution, whilst the second sees a mismatch between them. In this latter scenario material culture falls behind cognitive evolution. We argue that the key to understanding Acheulean material culture is variability and that symmetry and refinement in handaxes are likely to be situational/local. No long-term trends are visible in the archaeological record which show an increase in refinement or handaxe symmetry. We suggest a ‘variable equilibrium’ model to explain the patterns seen and show how the archaeology maps onto similar biological interpretations

From side to side: Symmetry in handaxes in the British Lower and Middle Palaeolithic

“…Despite an enthusiastic defence of evolution in handaxe form, appearance and symmetry over time by Hodgson (2015), most of the instances he cites do not really support his arguments (McNabb and Cole, 2015). The use of powerful 3D recording methods by Grosman et al (2011) and Couzens (2012) certainly involve robust methodologies that would be ideal for the assessment of handaxe symmetry.…”

“…This hominin evolutionary trajectory is often portrayed as a single upward cline, a slope of gradual development as for example in the iconic Social Brain graph (Dunbar et al, 2014;Gowlett et al, 2012), although a more punctuated interpretation is possible (McNabb and Cole, 2015;Shultz et al, 2012).…”

“…However, two of us (JM and JC) have elsewhere noted the difficulties in finding appropriate data in which to study longterm changes in handaxe symmetry over time (McNabb and Cole, 2015). Ideally, long sequences with large assemblages from single sites are necessary, and lots of them; but they are scarce.…”

“…In addition, there have been a number of theoretical stances that have sought to extract behavioural meaning from Acheulean handaxes. We will give a brief summary for some of the main positions here, but recently Hodgson (2015) and McNabb and Cole (2015) provide useful additional references and critiques. Saragusti and Sharon (1998) applied their Continuous Symmetry Measure to three Lower Palaeolithic handaxe assemblages from Israel.…”

“…In the former case the use of surface finds renders concepts of progression difficult to accept, and in the latter case only two sites are involved, and Couzens himself believed that function rather than progression explained the differences between the two chronologically distinct South African Acheulean assemblages he studied. Likewise Shipton (2013) presented a sophisticated methodology well suited to the assessment of shape and symmetry, but small sample sizes and undated or surface assemblages made identification of evolution and progression in symmetry premature (Hodgson, 2015;McNabb and Cole, 2015). Another paper quoted by Hodgson (2015) is Shipton, et al (2013).…”