Mid-Late Pleistocene species are reported to have sinuses of taxonomic and functional interest. Frontal hyperpneumatisation in Homo heidelbergensis is one of few hypothesized autapomorphies of this controversial taxon and Neanderthal sinuses are also said to be distinctively large, resulting from cold adaptation and explaining diagnostic craniofacial morphology. Variation in sinus size within and between populations of recent H. sapiens has been described, but has not been quantified. Sinus variables in Mid-Late Pleistocene hominins were investigated to illuminate causes of craniofacial variation and clarify alpha taxonomy, whilst evaluating theories of sinus function and advancing the understanding of adaptation in this group. Sinus volumes were measured from CT data and geometric morphometric methods were used to identify associated shape variables in a large sample of fossil and extant hominins. Relationships were investigated between these sinus variables and taxonomic/population, dietary, and climatic variables. The results demonstrate that the sinuses have no detectable direct function in Mid-Late Pleistocene hominins but they do respond to selective pressures, such as diet and climate, indirectly via craniofacial adaptation. There is also a relationship with neutral population differences in craniofacial morphology, for at least the frontal sinus. These effects are of varying strength, and it is likely that stochastic development also plays a part in determining differences in individual volumes. Inter-taxon comparisons support frontal hyperpneumatisation as a distinctive, perhaps derived, trait in H. heidelbergensis, but show that H. sapiens has hypopneumatised maxillary sinuses, rather than H. neanderthalensis being hyperpneumatised. Whilst the causes of extremely large sinuses in H. heidelbergensis remain uncertain, small maxillary sinuses in H. sapiens are suggested to result from their derived craniofacial size and morphology. These conclusions build on previous studies to over-turn long-standing but unfounded theories about the pneumatic influences on Neanderthal morphology and the functional nature of sinuses, whilst opening up exciting questions about relationships between strain, climate, pneumatisation, and intraspecific variation.

In this research, the relationship of climatic changes between 130k to 28k years BP to concurrent morphological variations in Neanderthals was tested. Traditional anthropological studies attribute robust Neanderthal morphological traits as an adaptation to a cold environment. A database of previously completed terrestrial paleoclimatic reconstructions in Europe and the Mediterranean was compiled and used to create a series of GIS-generated timeslice maps. Regional climatic conditions were then related to changes in Neanderthal appearances, morphology and disappearances as evident in the archaeological record. To establish climatic conditions, existing studies were compiled from two regions: Europe and the Mediterranean. The European data are based on pollen assemblage sequences from terrestrial lacustrine cores. The Mediterranean data are based on established ƒÔ18O/16O and ƒÔ13C/12C maximum and minimum events recorded in speleothems. The GIS perspective allows these changes to be viewed at significant time to better correlate regional climatic changes with known Neanderthal morphological variation and to extend the investigation both temporally, including Stage 4 and Stage 5e, and geographically, into the Mediterranean from similarly completed studies.