modern variation and evolutionary change in the hominin eye orbit

differences in measurement technique will not confound the investigation of populationaffinities. Though these two techniques yield consistent results, because a differentresearcher collected these orbital volume data as part of a separate study, the degree ofinterobserver error cannot be known.In addition to this orbital volume measurement recorded in milliliters, a separateindicator of orbital size is used in the analysis of evolutionary change in orbitalmorphology since the Upper Paleolithic investigated in chapter 4. This provides anadditional estimate that enables the inclusion of more individuals that would otherwise beexcluded due to poor preservation of the thin bones that make up the interior orbit.This orbital size variable is derived from the geometric mean of orbital height,orbital breadth, and orbital depth (Height * Width * Depth)·³³³³³ following the methods ofGonzález-José et al. (2005). The geometric mean of these three variables provides anestimate of volume, which is the same as that of a rectangular prism with side lengthsequal to each measure of orbital depth, width, and height. Though the orbit is more pearshapedthan cuboid, this provides an estimate of its volume when damage to the fragilebone of its internal structure prohibits accurate measure in milliliters.In addition to these continuous traits of the face and cranium, other quantitativeand categorical variables such as age, sex, ancestry, species, and time are used foraddressing questions and testing hypotheses relating to orbital development, interspecificvariation, sex differences, and how much change is characteristic of this feature throughtime. In most cases sex was listed in the museum database or written on individualskulls, though when not available it was estimated using different skeletal indicators afterBurns (1999), and was marked indeterminate if a clear distinction could not be made. In33