Malay Peninsula, or the Andamanese at also for adult women. LB1's body mass is estimated to have been . LB1 and LB8 are also somewhat smaller than the australopithecines, such as Lucy, from three million years ago, not previously thought to have expanded beyond Africa. Thus, LB1 and LB8 may be the shortest and smallest members of the extended human group discovered thus far. Their short stature was likely due to insular dwarfism, where size decreases as a response to fewer resources in an island ecosystem. In 2006, Indonesian palaeoanthropologist Teuku Jacob and colleagues said that LB1 has a similar stature to the Rampasasa pygmies who inhabit the island, and that size can vary substantially in pygmy populations. The Rampasasa pygmies are completely unrelated to H. floresiensis. Aside from smaller body size, the specimens seem to otherwise resemble H. erectus, a species known to have been living in Southeast Asia at times coincident with earlier finds purported to be of H. floresiensis. Brain In addition to a small body size, H. floresiensis had a remarkably small brain size. LB1's brain is estimated to have had a volume of , placing it at the range of chimpanzees or the extinct australopithecines. LB1's brain size is half that of its presumed immediate ancestor, H. erectus (). The brain-to-body mass ratio of LB1 lies between that of H. erectus and the great apes. Such a reduction is likely due to insular dwarfism, and a 2009 study found that the reduction in brain size of extinct pygmy hippopotamuses in Madagascar compared with their living relatives is proportionally greater than the reduction in body size, and similar to the reduction in brain size of H. floresiensis compared with H. erectus. Smaller size does not appear to have affected mental faculties, as Brodmann area 10 on the prefrontal cortex, which is associated with cognition, is about the same size as that of modern humans. H. floresiensis is also associated with evidence for advanced behaviours, such as the use of fire, butchering, and stone tool manufacturing. Limbs The angle of humeral torsion is much less than in modern humans. The humeral head of modern humans is twisted between 145 and 165 degrees to the plane of the elbow joint, whereas it is 120 degrees in H. floresiensis. This may have provided an advantage when arm-swinging, and, in tandem with the unusual morphology of the shoulder girdle and