Facial morphology features figure prominently in species identification and phylogenetic reconstructions of the human fossil record. However, its use remains controversial, as the evolutionary significance of facial features is not well-understood. An improved knowledge of the development, integration and variation of the human face is necessary in order to assess the value of facial morphology in defining species and its usefulness in phylogenetic reconstructions. Questions addressed in this study include: Are there population-specific changes in facial shape during modern human ontogeny? Are facial traits developmentally integrated in modern humans? How do particular facial traits vary ontogenetically between individuals and populations of modern humans, and among Pleistocene hominins? Is the mid-Pleistocene Homo (H. heidelbergensis s.l.) facial form more variable than that of modern humans? Is the same true for H. neanderthalensis? Is there a phased time-sequential development of Neanderthal-like facial traits among European Pleistocene hominins? Is there a similar trend in Africa?
To answer these questions, this study uses a cutting edge semilandmark geometric morphometric method involving analysis of facial surfaces, rather than just landmarks, to quantify subtle facial features frequently used to define Pleistocene taxa. Patterns of adult and ontogenetic variation and co-variation of these features will be established within recent human geographic samples and used as a framework for interpreting the Pleistocene hominin fossil record. This novel approach for the first time enables the rigorous quantitative analysis of facial morphology and the evaluation of its evolutionary significance. This work has important implications for the use of facial morphology in assessing the human fossil record and helps elucidate the evolutionary processes of the later stages of human evolution and modern human origins.
