modern variation and evolutionary change in the hominin eye orbit

structural and functional components interacting during morphogenesis (Moss & Young,1960). These cranial constituents are interrelated by way of tensions and pressuresbetween connective tissues, muscles, sutures, the remodeling and displacement of bone,and perhaps most importantly, expansion of organs such as the brain (Bruner, 2007).Encephalization within the hominin lineage has resulted in a number of changesin the cranial vault, cranial base, and face, which comprise the major structuralcomponents of the skull. Relative increase in brain size during human evolution hasresulted in changes to underlying structures, and can be understood in the framework ofheterochrony (changes in the timing or rate of growth and development), modularity(relationship among structural units in which variation in each component is dependentupon variation in others), and allometry (shape change in relation to size) (ibid.).It is also important to consider that adaptive features do not always result fromthese processes, but rather “during evolution, a selective pressure determining changes inone of these components (size or shape) involves secondary changes in the other. Suchsecondary changes are not necessarily adaptive but may be merely consequences of theadjustment within the structural system.” (Bruner, 2007 p. 1360). Selection favoringindividuals with greater cognitive ability resulting from the expansion of underlyingcerebral components could result in a consequent diminishment of the structurallyintegrated visual matrix.Change in neighboring features that are part of the functional and structuralmatrix of the skull interact during ontogeny and are viewed in association with thecounterpart principle of craniofacial growth, which states that “the growth of any givenfacial or cranial part relates specifically to other structural and geometric “counterparts”5