The Brain of LB1, Homo floresiensis

Abstract

The brain of Homo floresiensis was assessed by comparing a virtual endocast from the type specimen (LB1) with endocasts from great apes, Homo erectus, Homo sapiens, a human pygmy, a human microcephalic, specimen number Sts 5 (Australopithecus africanus), and specimen number WT 17000 (Paranthropus aethiopicus). Morphometric, allometric, and shape data indicate that LB1 is not a microcephalic or pygmy. LB1's brain/body size ratio scales like that of an australopithecine, but its endocast shape resembles that of Homo erectus. LB1 has derived frontal and temporal lobes and a lunate sulcus in a derived position, which are consistent with capabilities for higher cognitive processing.

Flores hominid: New species or microcephalic dwarf?

“…In fact, the volume of the virtual endocast subsequently reported for LB1 by Falk et al (2005a) is appreciably larger, at 417 cc. The discrepancy of 37 cc between these two reported values for cranial capacity, almost 10%, is disconcertingly large.…”

“…Indeed, because of the small cranial height associated with the small brain size of this individual, stated that their inferred stature of 106 cm was likely to be an overestimation. Despite this very small cranial capacity, a follow-up study of a virtual endocast derived from the LB1 skull concluded that the brain shows a number of similarities to that of Homo and is closest to that of Homo erectus (Falk et al, 2005a).…”

“…Rejection of the possibility of pathological microcephaly in LB1 by was seemingly supported by a subsequent publication by Falk et al (2005a), which compared virtual endocasts of LB1, modern human, Homo erectus, chimpanzee, and ''a European microcephalic.'' It was concluded that the endocast of LB1 was distinctly different from the single microcephalic included in that comparison.…”

“…It was concluded that the endocast of LB1 was distinctly different from the single microcephalic included in that comparison. Later on, however, a study of 19 human microcephalic skulls revealed considerable variation in external brain morphology, with the endocast of one individual seemingly showing overall similarity to that of LB1 (Weber et al, 2005), although that conclusion was questioned (Falk et al, 2005a).…”

Virtual Assessment of the Endocranial Morphology of the Early Modern European Fossil Calvaria From Cioclovina, Romania

“…Cranial endocasts allow the observation of some of the external features of the brain. The information on circulatory and nervous system of the endocranium as well as general shapes and volumes can be inferred from endocasts, and such information has been used to address the paleoneurology of fossil hominins (Connolly, 1950;Holloway, 1974;Holloway, 1983;Holloway and Kimbel, 1986;Bruner et al, 2003;Holloway et al, 2004a;Falk et al, 2005;Bruner and Manzi, 2008). Among the most commonly described features of the brain hemispheres are the petalia asymmetries (protrusions of the hemispheres producing imprints on the inner skull surface); the Yakovlenian torque (a forward ''torquing'' of the structures surrounding the right Sylvian fissure relative to their counterparts on the left); and the asymmetry on the occipital horns of the lateral ventricles (a deeper projection on the left occipital bone is common; Toga and Thompson, 2003).…”