Unfinished business: Mahalanobis and a clockwork orang

Skulls of orang-utan and chimpanzee were studied by multivariate analysis, keeping the sexes separate. Skulls of Pongo pygmaeus from south-western Borneo were found to be as distinct from skulls from the remainder of Borneo as were those from Sumatra. Although Pan paniscus separated well from other chimpanzees, the conventionally recognised subspecies of Pan troglodytes did not separate well; localised samples within the conventional subspecies proved in some cases to be at least as distinctive. This emphasises that "accepted" taxonomy must in no case be taken as given, but must be subject to continual testing.