Riddle unravel reprised: the role of LB1 in inferences about human functional morphology and phylogeny

Abstract

In his paper titled “The unraveled LB1 (Homo floresiensis) riddle? Some critical comments on the morphology of LB1” Alfred Czarnetzki (2014) argued that LB1, incorrectly designated as Homo floresiensis, is actually a specimen of an orangutan (Pongo abelii floresiensis). Although we agree that LB1 is not a member of a new hominin species, we disagree with Dr Czarnetzki’s diagnosis. He bases his conclusion on some poorly observable morphological traits such as the oblique line of the lower jaw and condyle tangent angle of the femur, plus unspecific characters including rounded orbits, and arbitrary conversion of continuously distributed traits into discrete traits. Some of these traits of LB1 clearly differ from those of the orangutan, e.g. wide interorbital region, while some others, such as those of wrist bones, vaguely echo those of Pongo. As hominoid primates, orangutans show some morphological similarities to humans, but these are not borne out by DNA sequence analyses. Bones and teeth of LB1 yielded only DNA fragments compatible with modern humans, though so far they are interpreted as contamination. Morphological traits of LB1 show disharmony that is a sign of abnormal development and thus LB1 is best interpreted as a pathological modern human.