New Evidence for a 67,000-Year-Old Human Presence at Callao Cave, Luzon, Philippines
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Journal of Human Evolution 59 (2010) 123e132 Contents lists available at ScienceDirect Journal of Human Evolution journal homepage: www.elsevier.com/locate/jhevol New evidence for a 67,000-year-old human presence at Callao Cave, Luzon, Philippines Armand Salvador Mijares a,*, Florent Détroit b, Philip Piper a, Rainer Grün c, Peter Bellwood d, Maxime Aubert c, Guillaume Champion b, Nida Cuevas e, Alexandra De Leon e, Eusebio Dizon e a Archaeological Studies Program, Palma Hall, University of the Philippines, Diliman, Quezon City 1101, Philippines b UMR 7194, CNRS, Département de Préhistoire du Muséum national d’histoire naturelle, 57, rue Cuvier, 75005 Paris, France c Research School of Earth Sciences, Bldg 61 Mills Road The Australian National University, Canberra ACT 0200, Australia d School of Archaeology and Anthropology, AD Hope Building, The Australian National University, Canberra ACT 0200, Australia e Archaeology Division, National Museum of the Philippines, P Burgos Ave., Manila, Philippines article info abstract Article history: Documentation of early human migrations through Island Southeast Asia and Wallacea en route to Received 24 August 2009 Australia has always been problematic due to a lack of well-dated human skeletal remains. The best Accepted 22 April 2010 known modern humans are from Niah Cave in Borneo (40e42 ka), and from Tabon Cave on the island of Palawan, southwest Philippines (47 Æ 11 ka). The discovery of Homo floresiensis on the island of Flores in Keywords: eastern Indonesia has also highlighted the possibilities of identifying new hominin species on islands in Cave faunas the region. Here, we report the discovery of a human third metatarsal from Callao Cave in northern Hominin dispersal Luzon. Direct dating of the specimen using U-series ablation has provided a minimum age estimate of Southeast Asia Æ U-series dating 66.7 1 ka, making it the oldest known human fossil in the Philippines. Its morphological features, as well as size and shape characteristics, indicate that the Callao metatarsal definitely belongs to the genus Homo. Morphometric analysis of the Callao metatarsal indicates that it has a gracile structure, close to that observed in other small-bodied Homo sapiens. Interestingly, the Callao metatarsal also falls within the morphological and size ranges of Homo habilis and H. floresiensis. Identifying whether the metatarsal represents the earliest record of H. sapiens so far recorded anywhere east of Wallace’s Line requires further archaeological research, but its presence on the isolated island of Luzon over 65,000 years ago further demonstrates the abilities of humans to make open ocean crossings in the Late Pleistocene. Ó 2010 Elsevier Ltd. All rights reserved. Introduction sea levels reached their minima during the most extreme climatic phases. Thus, migrating human populations could have reached Hominin movement into Island Southeast Asia has always been both islands without necessarily requiring a sea crossing. To reach problematic due to the lack of well-dated human remains. The the rest of the Philippine archipelago and other islands in the humid tropical environment of Island Southeast Asia contributes to Wallacean group (e.g., Sulawesi, Flores, Timor) that were never the problems of bone preservation. Early modern human remains attached to either mainland Asia or Australasia (Sahul), open sea have, however, been recovered in Niah Cave in Sarawak, Malaysian crossings were required. The Lake Mungo remains from Australia Borneo (Harrisson, 1975; Barker et al., 2002), dating to 42 ka dating to 40 Æ 2ka(Bowler et al., 2003) are evidence that modern (Barker et al., 2007), and from Tabon Cave in Palawan (Fox, 1970; humans were capable of making very early sea crossings. Homo Dizon et al., 2002), dating to 47 Æ 10/11 ka (Détroit et al., 2004). floresiensis, discovered on the islands of Flores, Indonesia, is another Borneo is located on the Sunda shelf and was possibly joined by dry hominin that managed to cross the Wallace line. While its remains land to Sumatra, Java and Peninsular Malaysia during periods of are only dated to 18e38 ka (Morwood et al., 2004), Flores also has lowered sea level in the Pleistocene. The island of Palawan may stone artifact assemblages suggesting that a hominin of unknown have been intermittently attached to northeastern Borneo when affinity reached the island more than 800 ka years ago (Brumm et al., 2006). Our recent excavations (2007) in Callao Cave (Fig. 1) have produced what is probably one of the earliest hominin fossils ’ * Corresponding author. east of Wallace s Line, from the island of Luzon, northern E-mail address: [email protected] (A.S. Mijares). Philippines. 0047-2484/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jhevol.2010.04.008 124 A.S. Mijares et al. / Journal of Human Evolution 59 (2010) 123e132 Figure 1. The Location of Callao Cave and the 2003 excavation. Materials and methods In Layer 13 (255e265 cm BS), the bones and teeth of deer became more abundant, and in Layer 14 (270e295 cm BS), the team The excavation of Callao Cave encountered cemented sediment (carbonized breccia) containing a relatively dense concentration of animal bone. In this layer, at In 2003, archaeological excavations under the direction of a depth of 275 cm below the cave surface, we found the human A. Mijares at Callao Cave in Peñablanca, Cagayan Valley, northern third metatarsal (MT3) bone, which is the subject of this paper. Luzon (Fig. 1), were designed to investigate the regional transition Beyond 300 cm depth, the excavation unit became too confined from Paleolithic hunting and gathering to the introduction of between the cave wall and a large stalagmite for excavation to farming during the MideLate Holocene. At the commencement, continue. there was no intention of exploring the earlier history of the cave, but the excavations exposed an Upper Pleistocene layer 130 cm below present ground level that contained chert flake tools, burnt animal bones and a hearth feature. A radiocarbon determination of 25 968 Æ 374 (uncalibrated) BP (Mijares, 2005, 2007) made this the oldest known human occupation in the main Philippine archi- pelago (excluding Palawan) and demonstrated that there was Paleolithic occupation in the cave entrance. To investigate this further, a joint partnership between the University of the Philippines Archaeological Studies Program, the National Museum of the Philippines, and the Australian National University was established to continue excavation in Callao Cave in 2007. The 2007 excavations started at 130 cm below surface, the level at which the 2003 excavation had ended (Fig. 2). Procedures followed the 2003 system of excavating in 5 cm spits and recording each archaeological find three dimensionally by spit and strati- graphic layer. The excavation was reduced in size from the 2003 excavations, and only Square 1 in the north (2 Â 2 m) and the northern portion of Square 2 (2 Â 1 m) were excavated below 130 cm. Since water for wet sieving was not available in the cave, most sediment was dry sieved through a 4 mm mesh. In addition, samples were also collected for flotation. At a depth of 160 cm below the surface (BS), the excavation area was further reduced and only the southern end of Square 1 and the northern end of Square 2 were excavated. Between 160 cm and 250 cm, BS archaeological remains were scarce, with just a flake tool, chert core and deer bones recovered from Layer 11, and several poorly preserved deer bones, including a scapula, the proximal end of a humerus and several fragments of antler identified in Layer 12. There was no evidence of human occupation similar to that Figure 2. Stratigraphic profile of Square 2, Callao Cave. Layer 14 is the breccia that observed in the Upper Pleistocene Layer 8. contained the human metatarsal (Callao MT3). A.S. Mijares et al. / Journal of Human Evolution 59 (2010) 123e132 125 Dating almost perpendicular to the long axis of the shaft, resulted from the post depositional fracture of already dry bone (Lyman, 1994). The Three osseous samples from the breccia were selected for two parts of the metatarsal join almost perfectly at the fracture, and dating. Two cervid teeth (Callao 1 and Callao 2) recovered from 275 only the presence of a thin layer of concretion inhibits a perfect to 295 cm below present ground surface were dated by Electron refitting. Spin Resonance (ESR) and Uranium Series (U-series) analysis. Laser Before cleaning the bone, a complete set of photographs, a 3D ablation U and U-series analysis was carried out at by R. Grün at the surface scan and a mCT-scan were made for archival records and Australian National University (see Eggins et al., 2003, 2005 for the future analysis. The object of cleaning the bone was to remove the experimental set-up and Grün et al., 2005, 2006, 2008 for previous thickest patches of sediment in order to observe its shape and applications). The ESR dating of the teeth followed procedures morphological features. Whenever possible, the thin carbonated routinely applied in the ANU ESR dating laboratory (Grün et al., coating was kept intact to avoid damaging the underlying surface, 2001). For ESR dose analysis, the enamel was powdered and which was cleaned using dental tools under a stereo-microscope. aliquots were successively irradiated in ten steps to 372 Gy. Only purified water and a 50e50 mix of purified water and alcohol Radiation doses were monitored with alanine dosimeters and were used to soften the compact sediment. evaluated against a calibrated dosimeter set provided by A. Wieser, Except where noted, all descriptions and comparisons were Messtechnik, München. Dose values were determined by partial made after cleaning. Observations and measurements were made spectrum fitting (Grün, 2002). The external dose rate was deter- directly on the original specimen and on the 3D surface scan, after mined from a single representative sample from the breccia.