Age and context of the oldest known hominin fossils from Flores

Abstract

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.

New fossil remains of Homo naledi from the Lesedi Chamber, South Africa

“…Skeletal remains of H. floresiensis are known from ~100–60-ka-old sediments at Liang Bua, Flores (Brown et al, 2004; Sutikna et al, 2016), and possibly also in Mata Menge, Flores sediments from the early Middle Pleistocene (van den Bergh et al, 2016; Brumm et al, 2016). The features shared by H. naledi and H. floresiensis are nearly all inferred to be primitive features shared with australopiths and/or in some cases with early Homo (Figures 35 and 36).…”

Aspects of human physical and behavioural evolution during the last 1 million years

“…The presence of a succeeding population of modern humans may be indicated by teeth dated to~46 ka (Sutikna et al, 2016b). Moreover, additional excavations at open-air sites in the So'a Basin on Flores have revealed archaeology stretching back to at least 1 million years, and the presence of a small fragmentary jawbone and isolated teeth at~700 ka, perhaps documenting an ancestral population for H. floresiensis (Brumm et al, 2010;Brumm et al, 2016;van den Bergh et al, 2016).…”

Tropical forests and the genus Homo

“…0.7 Ma) may indicate a later expansion of Homo east of Wallace's line into more isolated tropical forest settings. However, stable isotope analysis of faunal remains, as well as faunal profiles and both pollen and phytolith analysis indicate that the fossils at Mata Menge are associated with dry climates and open grassland, perhaps representing a continuation of Homo erectus' ecological preferences in the region …”

“…However, stable isotope analysis of faunal remains, as well as faunal profiles and both pollen and phytolith analysis indicate that the fossils at Mata Menge are associated with dry climates and open grassland, perhaps representing a continuation of Homo erectus' ecological preferences in the region. 96 The expansion of hominins into Flores from c. 0.8 Ma seems best associated with sea-level regression and forest cover declines rather than the evolution of specialized tropical forest adaptations (Box 1). 36 During this early phase of hominin expansion and the ongoing presence of Homo erectus on Sulawesi and Java until c. 200-100 ka, Early-Middle Pleistocene hominin species appear to be part of a grasslandwoodland mosaic fauna that became extinct during the shift toward modern rainforest conditions c. 125 ka.…”