The potential for insular dwarfism in Homo floresiensis

Abstract

About a decade ago, members of the paleoanthropological community first announced the unique discovery of what appeared to be a new species of Homo. Unearthed in the Liang Bua caves of the island of Flores, Indonesia (see Fig. 1), the assemblage consisted of remains from an estimated nine to 14 individual hominins, as well as associated faunal remains and stone tools (Aiello 2010). Designated since their discovery as the new taxon Homo floresiensis, the hominins are represented by the type specimen Liang Bua 1 (LB1; see Fig. 2). LB1 is extremely small, with an endocranial volume of roughly 380 to 426 cc and an estimated height of 106 cm (Brown et al 2004). Given the relatively recent dates for the skeletal remains (spanning between roughly 95 and 18 kya, with LB1 dated to the more recent time) (Brown et al 2004), the diminutive form of these creatures has caused debate over their evolutionary origins. At present, there are two primary hypotheses that have been proposed toexplain Homo floresiensis' origins. The first theory was initially mentioned by the discovery team, and proposes that H. floresiensis represents an insularly dwarfed population (Brown et al 2004). Scholars who share this view can sometimes be subdivided between those who believe H. floresiensis descended from Homo erectus (Brown et al 2004, Kaifu et al 2011, Lyras et al 2008) and those who support a pre-Homo erectus lineage (Argue et al 2009, Baab and McNulty 2009, Martinez and Hamsici 2008). The second hypothesis suggests that H. floresiensis exemplifies a population of dwarfed, pathological modern Homo sapiens (Aiello 2010). This hypothesis has seen numerous pathologies proposed over the years, including microcephaly, Laron syndrome, and myxoedematous (ME) endemic cretinism (Hershkovitz et al 2007, Obendorf et al 2008, Vannucci et al 2011). Palaeoanthropologists continue to debate their positions.