LB1 and LB6 'Homo floresiensis' are not modern human ('Homo sapiens') cretins

Abstract

Excavations in the late Pleistocene deposits at Liang Bua cave, Flores, have uncovered the skeletal remains of several small-bodied and small-brained hominins in association with stone artefacts and the bones of Stegodon. Due to their combination of plesiomorphic, unique and derived traits, they were ascribed to a new species, 'Homo floresiensis', which, along with Stegodon, appears to have become extinct ~17 ka (thousand years ago). However, recently it has been argued that several characteristics of 'H. floresiensis' were consistent with dwarfism and evidence of delayed development in modern human ('Homo sapiens') myxoedematous endemic (ME) cretins. This research compares the skeletal and dental morphology in 'H. floresiensis' with the clinical and osteological indicators of cretinism, and the traits that have been argued to be associated with ME cretinism in LB1 and LB6. Contrary to published claims, morphological and statistical comparisons did not identify the distinctive skeletal and dental indicators of cretinism in LB1 or LB6 'H. floresiensis'. Brain mass, skeletal proportions, epiphyseal union, orofacial morphology, dental development, size of the pituitary fossa and development of the paranasal sinuses, vault bone thickness and dimensions of the hands and feet all distinguish 'H. floresiensis' from modern humans with ME cretinism. The research team responsible for the diagnosis of ME cretinism had not examined the original 'H. floresiensis' skeletal materials, and perhaps, as a result, their research confused taphonomic damage with evidence of disease, and thus contained critical errors of fact and interpretation. Behavioural scenarios attempting to explain the presence of cretinous 'H. sapiens' in the Liang Bua Pleistocene deposits, but not unaffected 'H. sapiens', are both unnecessary and not supported by the available archaeological and geochronological evidence from Flores.