The Brain of LB1, Homo floresiensis
The brain of Homo floresiensis is 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, Sts 5 (Australopithecus africanus) and WT 17000 (Paranthropus aeithiopicus). Morphometric , allometric and shape data indicate that LB1 is not a microcephalic or pygmy. LB1's brain size versus body size scales like an australopithecine, but its endocast shape resembles that of Homo erectus. LB1
... 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. The type specimen of Homo floresiensis (LB1, female) (1) has a brain size of ~400 cm 3 similar to that of Australopithecus afarensis AL 288-1 (Lucy) (2) that lived approximately 3.0 Ma. Yet its species was associated with big-game stone technology, remains of Stegodon, and charred animal bones that hint at the use of fire and cooking. Its ancestors also had to cross the sea to reach Flores (3). Could a tiny hominin with an ape-sized brain really have engaged in such advanced behaviors? Some workers reject the notion that LB1 represents a new species that was closely tied to Homo erectus (1) and suggest, instead, that it was a pathological human microcephalic (4). To help address this debate, three-dimensional computed tomographic (3DCT) reconstructions of the internal braincase (virtual endocasts) that reproduce details of external brain morphology including sulci, vessels, sinuses, cranial capacity and shape (5-8 ) are compared from LB1, an adult female chimpanzee, an adult female Homo erectus (ZKD XI), a contemporary woman, and a European microcephalic. To broaden taxonomic comparisons and supplement limited sample size, our analysis also includes endocasts of Sts 5 (Australopithecus africanus), KNM-WT 17000 (Paranthropus aethiopicus), 10 humans, 10 gorillas, 18 chimpanzees (9), an adult female pygmy, and five Homo erectus skulls.