Possible causes and significance of cranial robusticity among Pleistocene–Early Holocene Australians

An analysis of possible developmental-functional causes of cranial form suggests that the morphology of ‘robust’ Pleistocene/Early Holocene Australians such as Willandra Lakes Human 50 might best be explained by four underlying factors: possession of a (1) large neurocranium, (2) narrow cranial base, (3) viscerocranium with considerable midfacial projection, and (4) large dentition, especially the cheek teeth, with their associated large jaws and high volume masticatory muscles. Some of these features are likely to be highly heritable, while others are caused/exaggerated by influences from ageing processes, diet, and a hunter-gatherer lifestyle in an arid environment. These underlying ‘causes’ are either apomorphies of Homo sapiens (1 and 2) and thus absent from pre-modern specimens such as from Ngandong, or represent plesiomorphic features of latter Homo (3 and 4). It is concluded that combining current knowledge of cranial development-function with genetic studies of the population history of Aboriginal Australians provides the most parsimonious solution to understanding their origins.