This is a symmetric handaxe from Meung sur Loire (a charming small town, home to 6388
residents and located at the heart of the Loire Valley) of unknown age. Although it is generally suggested, that symmetry of handaxes is increasing during time, this assumption is far from been proven and may have been generated from biased primary data. Material from modern excavations (Benot Ya´aqov) shows a high level of sophistication and symmetry in biface -manufacture approximately 800 k.a. BP. Naama Goren-Inbar, regarding the operational sequence at this site showed that “The diverse methods of production observed on the site clearly demonstrate flexibility in decision-making as well as creativity in order to achieve the desired goal. In contrast to the view of the lithic reduction sequence as “repetition and rhythm”, the evaluation processes of each individual blow and the flexibility shown in selecting a particular method out of a varied repertoire, tailored to the specific circumstances at hand, are clearly indicative of advanced cognitive abilities” (Phil. Trans. R. Soc. B 2011 366, 1038-1049).
Exhibiting external bilateral symmetry about a vertical midline, the animal and human body consists of two enantiomorphs — the right and left sides. The overwhelming preponderance of bilateral symmetry in animals suggests that it provides an evolutionary advantage.
A large body of experimental evidence supports the hypothesis that many species of animals including all primates have a preference for symmetry. For example Rensch demonstrated that monkeys, raccoons, and birds prefer symmetry to asymmetry and irregularity. Humans, including infants, find the symmetrical faces and bodies more beautiful, than asymmetrical ones. There is also a significant degree of cross-cultural agreement between tests of ratings of facial attractiveness conducted in populations of different ethnic backgrounds Taken together this evidence falsifies the argument that criteria of physical attractiveness are determined solely by cultural conventions.
Some biologists and psychologists suggest that symmetry preferences across species are simply a by-product of symmetrical organization of neuronal connections in the brain. An adaptive explanation seems to be more reasonable, since many important environmental elements are symmetrical and sensitivity to symmetry may have evolved because it is important for discriminating living organisms from inanimate objects.
Many retinal images correspond to rotations, translations and reflections of each other, so that even for an asymmetrical display, there will be symmetries hidden among the images of the signal. Thus, symmetry preferences may arise as a by-product of the need to recognize objects irrespective of their position and orientation in the visual field.
A monocausal theory suggests that symmetry may be an effective and easily perceived measure of “genetic quality” and may play a role in mate selection (Mithen 2005). In addition proponents of this theory, argue that the symmetrical shape of many Acheulean handaxes was a product of sexual selection. Nowel and Chang have convincingly refuted this odd theoretical construct www.paleoanthro.org/journal/content/PA20090077.pdf
Many Authors from a variety of disciplines argue that symmetrical tools function more efficiently than asymmetrical ones. Experimental data did not really substantiate this assumption. A feature of both the natural and cultural realms is that symmetry of form is frequently over-determined in relation to functional necessities. This means that bifacial artifacts often appear to be more symmetrical than is strictly necessary for the purposes of efficient mechanical design. This observation may indicate that symmetry may have constituted an instrument for the generalization and abstraction of a perceptual imperative into the world of artificial objects. In this sense handaxes may be an early example, how people modified and manipulated their environment.
Gowlett found, that averaged sized handaxes from many Acheulean sites exhibit a Breadth/Length Ratio (B/L) approximated closely to Golden Section (expressed as 0.61: 1, or inversely as around 1:1.64), showing that 1 myr ago, people had already a sense for “proportions”. http://www.paleoanthro.org/journal/content/PA20110106.pdf
Derek Hodgson described neurobiological pathways and networks that are involved in the perception on symmetry. More interesting, areas of the brain that were associated with symmetric perception also overlap with areas implied in aesthetic judgment. Therefore the production of symmetric handaxes seems to be related to first manifestations of an aesthetic sense. http://www.mdpi.com/2073-8994/3/1/37/