The islands of Wallacea, located between the Southeast Asian (Sunda) and Australian (Sahul) continental areas, offer unique potential for the study of evolution and cultural change. Located east of Java and Bali, which were periodically connected to the Asian mainland, the Wallacean islands could only be reached by

GUIDING LIGHT IN QUANTUM NETWORKS Tiny antennas could direct photons on a chip. go.nature.com/ruNCbv When the remains of tiny hominins-nicknamed hobbits-were found on the isolated Indonesian island of Flores in 2003, it sparked an epic hunt to understand the origins of these diminutive cousins of modern humans. Now, discoveries of stone flakes used as primitive tools on the island suggest that the hobbit's ancestors were there a million years ago, at least 120,000 years earlier than previously thought (A. Brumm et al. Nature doi:10.1038/nature08844; 2010). "Whatever species made it to the island 1 million years ago, it was probably an ancestor of Homo floresiensis," says William Jungers, an anthropologist at Stony Brook University in New York. The metre-high H. floresiensis lived on the island until at least 17,000 years ago, and its small stature probably evolved in response to the island's sparse resources. The simple stone tools demonstrate the skills of its ancestors-people who must have hopscotched across islands from mainland Asia, traversing deep and swift ocean channels, before arriving on Flores. In 2005, Adam Brumm, an archaeologist at the University of Wollongong in Australia, found the first of about 45 stone tools while exploring a bowl-shaped gully on the island that was like "a hot, steamy wok". Three years later, researchers at Roskilde University in Denmark analysed the ratio of two isotopes of argon trapped in volcanic ash overlaying the tools to determine their age. Previous tool discoveries showed that hominins had arrived on Flores by 880,000 years ago, suggesting that the hobbit's ancestors might have wiped out some of the island's peculiar indigenous animals, such as the pygmy elephant-like Stegodon sondaari and giant tortoises (Geochelone spp.), which both disappeared at around the same time. The new finds imply that the hobbit's ancestors coexisted with the creatures for much longer, raising the possibility that a natural disaster was behind the disappearance of the animals. The team will return to Flores this summer, hoping to find older sediments that could hold earlier evidence of the island's first hominins.

Recent excavations at the early Middle Pleistocene site of Mata Menge in the So'a Basin of central Flores, Indonesia, have yielded hominin fossils attributed to a population ancestral to Late Pleistocene Homo floresiensis. Here we describe the age and context of the Mata Menge hominin specimens and associated archaeological findings. The fluvial sandstone layer from which the in situ fossils were excavated in 2014 was deposited in a small valley stream around 700 thousand years ago, as indicated by (40)Ar/(39)Ar and fission track dates on stratigraphically bracketing volcanic ash and pyroclastic density current deposits, in combination with coupled uranium-series and electron spin resonance dating of fossil teeth. Palaeoenvironmental data indicate a relatively dry climate in the So'a Basin during the early Middle Pleistocene, while various lines of evidence suggest the hominins inhabited a savannah-like open grassland habitat with a wetland component. The hominin fossils occur alongside the remains of an insular fauna and a simple stone technology that is markedly similar to that associated with Late Pleistocene H. floresiensis.

Temporal changes, within-group variation, and phylogenetic positions of the Early Pleistocene Javanese hominids remain unclear. Recent debate focused on the age of the oldest Javanese hominids, but the argument so far includes little morphological basis for the fossils. To approach these questions, we analyzed a comprehensive dentognathic sample from Sangiran, which includes most of the existing hominid mandibles and teeth from the Early Pleistocene of Java. The sample was divided into chronologically younger and older groups. We examined morphological differences between these chronological groups, and investigated their affinities with other hominid groups from Africa and Eurasia. The results indicated that 1) there are remarkable morphological differences between the chronologically younger and older groups of Java, 2) the chronologically younger group is morphologically advanced, showing a similar degree of dentognathic reduction to that of Middle Pleistocene Chinese H. erectus, and 3) the chronologically older group exhibits some features that are equally primitive as or more primitive than early H. erectus of Africa. These findings suggest that the evolutionary history of early Javanese H. erectus was more dynamic than previously thought. Coupled with recent discoveries of the earliest form of H. erectus from Dmanisi, Georgia, the primitive aspects of the oldest Javanese hominid remains suggest that hominid groups prior to the grade of ca. 1.8-1.5 Ma African early H. erectus dispersed into eastern Eurasia during the earlier Early Pleistocene, although the age of the Javanese hominids themselves is yet to be resolved. Subsequent periods of the Early Pleistocene witnessed remarkable changes in the Javanese hominid record, which are ascribed either to significant in situ evolution or replacement of populations.

geochronology ͉ human evolution ͉ Homo erectus ͉ Southeast Asia ͉ tephrostratigraphy