Journal of Human Evolution 59 (2010) 123e132

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Journal of Human Evolution

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New evidence for a 67,000-year-old human presence at Callao , ,

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, c Research School of Earth Sciences, Bldg 61 Mills Road The Australian National University, Canberra ACT 0200, d School of 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 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 11 ka). The discovery of Homo floresiensis on the island of Flores in Keywords: eastern 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 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 . 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 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 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 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, 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 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 25 968 374 (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 2 m) and the northern portion of Square 2 (2 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. The virtual refitting of the proximal and distal portions of the bone at U-concentration in the dentine of the two cervid teeth had only the mid-shaft fracture. small variations along the laser track, 71.6 8.2 ppm U for Callao 1 and 100 5 ppm U for Callao 2, as usually observed in dentine. Results In order to obtain an age estimate for the hominin metatarsal, the Callao MT3 was also directly analyzed. A diamond wire saw was Faunal remains used to cut the bone 2 mm away from the break described below. Four laser ablation scans were then recorded on the cross-section From the 2007 field season, the Callao Cave excavations (Fig. 3). produced a late Pleistocene vertebrate assemblage of 807 frag- ments of bone. In Layer 11, just a few isolated and potentially Preservation, conservation and cleaning of the Callao MT3 re-worked fragments of animal bone, including several skeletal elements of deer, were recovered. There was no evidence of The Callao specimen with National Museum of the Philippines anything that could be considered an in situ human-derived bone accession number II-77-J3-7691 is a right third metatarsal (Fig. 4). It accumulation and no evidence of butchery or lithics. Humans, is broken in two parts around the mid-shaft, but with the exception however, appear to have been present during this period of depo- of the distal head, which is broken, the bone is almost complete. sition, given the discovery of a terminal foot phalanx in Spit 36 The missing head has not been identified among the other bones (180 cm BS), with an interpolated date of 30 ka. recovered from the same layer. The overall state of preservation of Bone concentrations increased below Spit 47 (Layer 12). Down the bone is rather good, most being preserved under a thin to Spit 53 (265 cm BS), all of the bone fragments were recovered yellowish coat of calcium carbonate concretions. Several small from clayey silt sediments and were very poorly preserved. Spit 54 patches of hard and compact sediment are also attached to the contained numerous mid-dark brown skeletal elements, similar in bone. Smaller scratches (which occurred presumably during exca- appearance to those recovered throughout the clayey silt deposits vation) are visible on the medial and lateral surfaces of the shaft above, as well as a few weathered and eroded fragments with where the white cortex of the bone is exposed. a creamy appearance, similar to those from the underlying breccia Both surfaces (proximal and distal) of the transverse break (Layer 14). It is likely that, after the Layer 14 breccia had formed, around mid-shaft are covered by a very thin layer of carbonate erosional processes caused some bones to be redistributed into the concretions, which indicates that the fracture is ancient. However, accumulating clayey silt sediments above. Alternatively, it is it is neither oblique nor spiral, and has no helicoidal morphology. possible that the boundary between clayey silt and breccia has No scars or peeling around the fracture are visible. This indicates migrated downwards as the breccia has decalcified, and that Spit 54 that breakage did not occur on fresh bone. This transverse break, (270 cm BS) forms a transitional zone between breccia and clay.

Figure 3. Cross-section of the Callao metatarsal showing the scanned transects. 126 A.S. Mijares et al. / Journal of Human Evolution 59 (2010) 123e132

Figure 4. The Callao right metatarsal III (II-77-J3-7691).

The breccia contains by far the greatest number of bone frag- while Callao 2 did not yield a result (the closed system ESR age ments (66%, or 533 fragments), indicating that bone survival was estimate was younger than the U-series result). The discrepant good within the calcium carbonate precipitate. As a result, bones combined ESR/U-series results point to some reworking, as from the breccia are in much better physical condition than the confirmed by taphonomic examination of the bones from the pieces of bone recovered from the overlying clayey silts. breccia. Surface modifications consistent with subsurface weathering, It can be seen that the U-concentration varies greatly along the erosion and water-transport suggest that the bones were derived profiles (Fig. 6). We carried out U-series age estimates for all from elsewhere in the cave system and were redeposited against concentration features to check whether delayed uptake or leach- the wall, where they were incorporated into a carbonate-cemented ing has taken place, such as peaks and troughs (Fig. 6). We found sandy silt loam breccia. The complete absence of any evidence only a small number of results (seven of 69) where the 1 s for bone-accumulating large carnivores and porcupines in the weighted means did not overlap. This is somewhat less than Philippines (excluding Palawan), in addition to the presence of expected from a normal statistical distribution and points to the three parallel cut-marks caused by a sharp implement on the fact that our error bars are probably somewhat too large. medial surface of a deer tibia shaft fragment (Fig. 5), indicates that On the whole, there is no relationship between U-concentration the bone assemblage was almost certainly derived from human and age estimate (Fig. 7). This points to a rapid uptake and excludes activity (Piper and Mijares, 2007). The lack of any lithics from the leaching along pores. Instead, as an indication for U-leaching, the 1980 (Cuevas, 1980) and present excavations at the depth of the drops in U-concentration are probably caused by heterogeneities in breccias in Callao Cave could imply the use of organic tools. Alter- the bone structure, which had little influence on the mode of natively, the differential transport of bones has caused spatial U-mobilization. separation of archaeological materials in the cave entrance. Single age estimates may be affected by a number of processes Three large species of mammal were recorded in the Callao Cave rendering them inaccurate, and for this reason the U-series results breccia: the native brown deer (Cervus mariannus), the Philippine must be considered minimum estimates. This alone precludes any warty pig (Sus philippensis), and an extinct bovid evidenced by two claim for accuracy. In this regard, the interpretation of APNIAH1 in small tooth fragments (Piper and Mijares, 2007). Brown deer Barker et al. (2007) has been used to cast doubt on the results of constitute more than 90% of the identifiable bone fragments. The U-Series dating at Niah. Barker et al. (2007, p. 253) write “.a articular ends of long bones and metapodials are relatively common in the assemblage. Loose maxillary and mandibular teeth indicate that crania were originally present, and scapula, pelvic and vertebral fragments indicate the deposition of axial elements as well. This suggests that whole, or different skeletal elements of various deer carcasses were possibly once brought into the cave on occasion.

Age determination

The cervid two teeth yielded U-series ages of 52 1.4 ka (Callao 1) and 54.3 1.9 ka (Callao 2). Sub-sampling of small peaks and troughs in the U-concentration had yielded U-series age esti- mates that were in the same statistical population as the mean values. We could not identify any regions that may indicate delayed U-uptake or leaching, compared with the average values. Thus, the U-uptake must have taken place over a relatively short period of time (Pike et al., 2002). However, as U-accumulation in bones may be delayed after burial, any U-series age estimates have to be considered minimum age estimates. ESR dating yielded a combined ESR/U-series result (Grün et al., 1988) for Callao 1 of 66 þ 11/9 ka, Figure 5. Cut marks on the surface of a cervid bone. A.S. Mijares et al. / Journal of Human Evolution 59 (2010) 123e132 127

Figure 6. Comparative diagrams of the four laser ablation scans on the Callao metatarsal. uniform date profile [of APNIAH1] may also be reached after further estimates. The question is whether our results could seriously uptake or leaching of uranium, which would give an erroneous result, overestimate the correct age of the sample. Under normal so on its own the date should only be taken as provisional.”. In the circumstances, leaching would start at the surface and be accom- context of MT3, we do not have to consider further U-uptake, panied by lower U-concentrations. While some of the profiles show because this would only lower the calculated apparent U-series significantly lower U-concentrations at or close to the surface, these 128 A.S. Mijares et al. / Journal of Human Evolution 59 (2010) 123e132

100 Several diagnostic features of the Callao metatarsal can be underlined from this comparison (Fig. 8). In the comparative 80 sample, the global size of the Callao metatarsal is medium: it is smaller than Pongo, larger than Hylobates and Macaca, and fits 60 within the genus Homo. In medial view, the dorsal face of the shaft of the Callao specimen is straight, as seen in the two representa- 40 tives of the genus Homo, and not convex as in Pongo, Hylobates,orto a lesser extent Macaca. In dorsal view, the proportions of the Callao 20 MT3 shaft, the shape of the base, and the oblique orientation of the U-series age estimate (ka) proximal articular facet for the lateral cuneiform are close in shape 0 to those observed in other Homo specimens. In this view, the 020406080100 medial and lateral borders of the shaft of the Callao MT3 are slightly U concentration (ppm) and regularly convergent from the proximal portion to the distal Figure 7. Apparent U-series age versus U-concentration (error bars omitted for end of the shaft, which is a condition also encountered in OH8 and clarity). Homo sapiens in general. A different morphology is observed in the other genera: the medial and lateral borders of the shaft appear sections do not show any significantly older apparent U-series age sub-parallel in Pongo, and they are slightly divergent anteriorly in estimates. The only region where leaching could perhaps be iden- Hylobates and Macaca. The proximal view shows an outline of the tified is in the centre of the fourth track between cycles 2190 and base of the Callao MT3, which is definitely closer to Homo than to 2310 (lower diagram, Fig. 6). The U-concentrations drop by 50%, any other primates included in the comparison. Its elongated while the average apparent U-series results are around 15% older triangular outline is completely different from the outline found in than the surrounding data without being statistically significantly Pongo, Hylobates and Macaca. In those genera, the medial and different. lateral borders of the base have very different sizes and shapes, If the bone was younger than 40 ka, the minimum average with articular facets for MT2 and MT4, which are organized and amount of uranium leached from it must have been at least 35%, orientated differently. In this comparison, the base of the Callao and the leaching must have happened relatively recently. On top of MT3, which is proportionally shorter in the dorso-plantar direction, this, it must have affected the whole bone in the same manner, i.e., tends to be closer in shape to OH8 than to the Philippine Negrito parts with high U-concentrations lost 35% of their total uranium, specimen used for comparison. However, variability in this feature and the same would have to be lost from parts with low is rather common in H. sapiens. U-concentrations. Any such process must be regarded as purely Altogether, these features indicate that the Callao MT3 belongs hypothetical, and the above discussion reinforces the need for to the genus Homo. It is especially close to small-bodied Homo, such developing combined mass spectrometric Pa/UeTh/U analysis of as African H. habilis and present-day Philippine Negritos, the latter bones to address questions of U-mobilization (Grün et al., in press). being much closer chronologically and geographically. However, To summarize, it cannot be excluded that some leaching may some differences, such as the reduced proportions of the base, were have taken place in the past, causing an increase in the average observed. They will be discussed further in the morphological and apparent U-series results by some unknown amount. However, we metrical descriptions that follow. do not find any clear evidence for leaching, nor could it have been on a scale sufficient to reduce the minimum age of MT3 to 40 ka or Age at death younger. On balance, we regard the U-age estimate of 66.7 1 ka, derived from the weighted mean of all data points, as a minimum During individual growth, the head is the last anatomical part to age estimate for the MT3. This agrees with the ESR age estimate of fuse on metatarsals, between the ages of 12 and 16 years on average Callao 1, although this may be purely coincidental due to the nature in anatomically modern H. sapiens (Scheuer and Black, 2000). The of the deposit. absence of the head could thus indicate a non-adult individual (i.e., with the distal head being unfused at the time of death) or, alter- Taxonomic identification of the Callao MT3 natively, a broken, fully developed and fused adult metatarsal. The distal extremity of the Callao metatarsal has a fracture, which The general morphology, shape and size of the Callao right MT3 occurred at the level of the dorsal tubercles and is obliquely oriented indicate the bone belongs to a primate. For taxonomic identifica- with respect to the long axis of the shaft. The broken distal tion, morphological comparisons were first undertaken with extremity is slightly eroded and partly covered by sediment, which primates of medium to large body size presently living in Island makes it difficult to ascertain the presence or absence of a meta- Southeast Asia (Fig. 8). Even though Macaca and Homo are the only physeal surface. Such a surface can also not be detected from anal- two extant genera of catarrhines in the Philippines (Fooden, 1991; ysis of CT-scan data through close-up observation of the CT slices at Brandon-Jones et al., 2004; Harrison et al., 2006), representatives the distal extremity (Fig. 9). On the other hand, the morphology and of the genera Pongo and Hylobates are added to this comparison. size of the preserved portion of the medial tubercle seem to be Indeed, their present geographic extension reaches the neighboring rather large and fully developed. This would better correspond to an island of Borneo, and the morphology of their metatarsals is advanced stage of growth, with a distal head that was about to fuse, potentially close to the morphology of the Callao specimen. For or was already fused at the time of death. These observations point comparison from a palaeontological perspective, the left MT3 of more to an adult or young adult metatarsal, which was broken Homo habilis, OH8, is included in the comparative sample. This distally after burial. However, it is impossible to discard entirely the specimen (whose 3D model is mirrored in Fig. 8 for easiest direct possibility that the specimen is from a juvenile or adolescent. comparison) is part of one of the oldest groups of foot bones attributed to the genus Homo, and related to a partly or fully bipedal Morphological and metrical features: comparisons with H. sapiens locomotion (Day and Napier, 1964; Archibald et al., 1972; Kidd et al., 1996; Berillon, 2000; Susman, 2008; see Wood, 1974; and Gebo and As seen in the anatomical comparisons, the general morphology Schwartz, 2006 for a different taxonomic attribution of OH8). of the Callao metatarsal matches those observed in the genus Homo A.S. Mijares et al. / Journal of Human Evolution 59 (2010) 123e132 129

Figure 8. Comparison of (A) the Callao MT3 in proximal, dorsal and medial views with right third metatarsals of (B) Homo sapiens, male Negrito; (C) Homo habilis,OH8e mirrored 3D model of a cast of the left MT3; (D) Macaca, (E) Hylobates; and (F) Pongo. 3D models obtained by surface scanning with a NextEngine Desktop 3D Scanner. and appear close to H. sapiens. Some morphological particularities facet for the fourth metatarsal is clearly visible; it is well developed also diverge to some extent from the general morphology and slightly elongated. A bulging tubercle is also present, distal to encountered in anatomically modern H. sapiens (see Fig. 4 for the the lateral articular facet. On the medial side, only one articular morphological features discussed, and Fig. 8 for comparison with facet for the second metatarsal is visible and located on the dorsal the MT3 of a male Philippine Negrito). corner of the base. After cleaning the attached sediment, the In proximal view, the shape of the base is typically human. It plantar portion of the medial side of the base appears to be rather shows a triangular contour with slightly depressed medial and flat, but no delimited facet is visible. It remains possible that lateral sides, the latter being more depressed just under the artic- insufficient cleaning prevents us from observing the plantar facet, ular facet for the fourth metatarsal. However, the medial facet for but it is not uncommon in the H. sapiens MT3 for the second facet the second metatarsal appears to be more plantarly oriented than for MT2 to be reduced in size or even totally absent. In a study of generally encountered in H. sapiens. In lateral view, the proportions 100 MT3, Singh (1960) found 41 specimens without this plantar and especially the dorso-plantar development of the proximal part facet. are reduced compared with the size and development of the shaft. The shape of the shaft is also unusual, especially when seen in The proximal articular facet for the lateral cuneiform shows lateral view. The dorsal face of the shaft is very slightly convex, a marked dorso-plantar convexity where it is usually flat or slightly almost straight and horizontal, and with a longitudinal ridge concave in anatomically modern H. sapiens. More precisely, the running along the dorsal surface. In H. sapiens, the plantar surface convexity of the facet in lateral view is mainly due to the orienta- of the shaft generally tapers gradually from the base to the head. tion of the plantar portion of the base that is clearly oblique to the Accordingly, the plantar surface around the mid-shaft has a slight main axis of the bone and thus marks an angle with the dorsal longitudinal concavity, with more marked and abrupt concavities portion of the base. On the lateral side of the base, the articular located just anterior to the base and posterior to the distal head. 130 A.S. Mijares et al. / Journal of Human Evolution 59 (2010) 123e132

Figure 9. CT-scan views of the Callao MT3. A: midsagittal CT slice; B: 3D model with transparency (lateral view); C: close-up view of a sagittal CT slice of the distal extremity (the slice is parallel to A but more medially located). Images A and C show the distal extremity of the MT3, which is broken and partially filled-up by sediment. No transverse metaphyseal surface is visible.

The Callao metatarsal shows a marked concavity just anterior to the male and female Negritos. However, the dimensions of the base of base and then a more regular and pronounced concavity of the the bone and the section of the shaft are smaller, indicating peculiar plantar surface of the shaft from the first third of its length to proportions for the Callao metatarsal. At the mid-shaft, the shaft the most distally preserved portion. No clear and marked change in appears to be considerably smaller in the dorso-plantar direction the angle towards the head is visible. Consequently, the cross- than in the Negrito comparative sample. As shown by the reduced section at the mid-shaft is almost circular, flattened medio-laterally dimensions obtained for the dorso-plantar height and medio- and enlarged in the dorso-plantar direction for the distal-most lateral breadth of the proximal facet for the lateral cuneiform, the third of the shaft. base is very small. It is the smallest of our sample, confirming the While not formally developed in this paper, general metrical particular shape and proportions of the bone as seen from lateral comparisons with H. sapiens samples were undertaken with data and superior views. from the literature (for instance Volkov, 1903e1904; Gabunia et al., 2000a); and also with data gathered by one of us (Détroit) from late Discussion Upper Pleistocene and Holocene H. sapiens from Indonesia and the Philippines (see Détroit et al., 2004; Détroit, 2006). This first For more detailed future comparisons, it is important to take approach confirmed that one of the most striking features of the into account the paucity of Southeast Asian Homo erectus and Callao specimen is its overall small size. As a result, it was decided Upper Pleistocene H. sapiens postcranial remains. The fossil record to focus, for comparative morphological purposes (and not taxo- is particularly deficient in foot bones, with none recorded so far for nomic identifications), on a series of third metatarsals of recent Southeast Asian H. erectus (Widianto, 1993; Antón, 2003). For Negritos from the collections of Musée de l’Homme (Muséum H. sapiens, several rather complete late Upper Pleistocene and national d’Histoire Naturelle) in Paris (Table 1). Indeed, Negritos are Holocene human skeletons have been recovered from Indonesia small-sized and slightly built Philippine H. sapiens, inhabiting (Jacob, 1967; Détroit, 2002, 2006; Simanjuntak, 2002; Sémah et al., regions of Luzon Island close to where Callao Cave is located. The 2004), and a few fragmentary postcranial remains come from the collections from Musée de l’Homme also have the advantage of Philippines, including foot bones (Détroit et al., 2004). For those being well documented and repeatedly studied from various specimens we are able to observe and measure, the dimensions anthropological perspectives (see, for instance, Genet-Varcin, 1951, largely exceed the dimensions of the Callao metatarsal, and the who includes sex determinations of the skeletons; and Volkov, proportions of the base are never reduced to the extent seen in the 1903e1904 for the first published study of the foot bones). Callao metatarsal. The partial length of the Callao bone, taken parallel to the main From broader taxonomic, chronological and geographic axis of the shaft from the proximal tip of the base to the level of the perspectives, metatarsal bones appear to have been relatively medial tubercle, overlaps with the range of variation measured for stable in terms of overall morphology and size since the first African A.S. Mijares et al. / Journal of Human Evolution 59 (2010) 123e132 131

Table 1 Comparative measurements of the Callao metatarsal with Negrito samples

Total length Partial length Shaft Proximal facet for lateral Facet 1 (dorsal) Facet for (from the base to cuneiform for metatarsal 2 metatarsal 4 the medial tubercle) Dorso-plantar Medio-lateral Dorso-plantar Medio-lateral Length Height Length Height diameter diameter height breadth Callao 60.99a 52.58 6.58 5.99 11.28 8.69 5.76 3.82 6.46 4.92

Negritos males (n ¼ 11) Mean 64.69 55.66 8.51 7.32 18.79 11.72 6.46 4.74 8.02 7.73 Std error 0.862 1.033 0.107 0.268 0.427 0.245 0.418 0.269 0.277 0.323 Min. 59.5 49.4 8 6.5 16 10.2 4.5 3.2 7 6 Max. 68.3 60.5 9.1 9.6 21.1 13.3 8.9 6.3 10.2 9 Median 65.2 56.8 8.5 7.1 18.8 11.7 6.3 4.7 8 7.7

Negritos females (n ¼ 12) Mean 59.21 51.33 7.33 6.42 16.87 10.88 6.54 4.95 8.06 7.98 Std error 0.554 0.357 0.091 0.179 0.209 0.211 0.198 0.131 0.353 0.329 Min. 56.5 49.2 6.9 5.1 15.5 9.5 5 4.3 6.2 5.7 Max. 62.7 53.5 7.8 7.3 17.9 12.3 7.4 5.9 10.5 9.9 Median 58.55 51.15 7.35 6.45 16.95 10.8 6.8 4.8 7.9 8

a Estimated from the regression of total length against partial length for the pooled-sex sample of 23 adult Negrito metatarsals III (r ¼ 0.93, p < 0.01; Ltot ¼ 1.022Lpart þ 7.2519). representatives of the genus Homo (i.e., H. habilis and Homo Provisionally attributed to a rather small-bodied H. sapiens, the rudolfensis). Differences in function have been widely discussed for Callao MT3 documents the presence of a hominin species on the the morphology and anatomical position of MT1, as well as the island of Luzon as early as 67 ka, and is testimony to a capability to implication of metatarsals in the development of longitudinal and colonize new territories across open sea gaps. The Philippine transverse plantar arches (see for instance Aiello and Dean, 1990; specimen also indicates that Flores was not the only island in Berillon, 2000; Zipfel et al., 2009). As far as the third metatarsal is Wallacea to be occupied by hominins more than 50,000 years ago. concerned, the particular form (or relative proportions) of the base The discoveries at Callao Cave also raise some other important and shaft of the Callao bone has apparently not been described so questions about the cultural behavior of these early colonizers of far from other early fossil specimens of the genus Homo from the Philippine archipelago. For example, even though there is Eastern Africa, Southern Europe, or the Caucasus. This observation evidence of butchery in the animal bone assemblage, not a single is confirmed by direct comparison with the H. habilis left MT3 of stone implement was recovered, suggesting perhaps the use of an OH8 (Fig. 8, and see Day and Napier,1964; Kidd et al.,1996; Berillon, alternative technology. To answer such questions, more archaeo- 2000), and from comparisons with published data from Atapuerca logical research in the of karstic formations of the Gran Dolina (Lorenzo et al., 1999) and Dmanisi (Gabunia et al., Philippines is required. 2000a,b; Lordkipanidze et al., 2007). Interestingly, the remains discovered at in Flores, Acknowledgement representing several individuals attributed to the species H. flor- esiensis, include foot bones, and especially the complete series of We are grateful for the support of the National Museum of the right and left metatarsals of the individual LB1 (Brown et al., 2004; Philippines, the Cagayan Provincial Government, and the Protected Morwood et al., 2005; Jungers et al., 2009a). The length of the left Area Management Board-Peñablanca. Roberto Macchiarelli and MT3 (LB1/23), at 60.4 mm (Jungers et al., 2009b), is near the esti- Arnaud Mazurier are acknowledged for the CT-scan of the bone. We mated length for the Callao specimen (60.99 mm; see Table 1). are also grateful to Eduardo Bersamira and Myra Lara for the Although few details are available regarding the exact morphology illustrations, and Archie Tiauzon as a member of the excavation and shape of this particular bone, it certainly calls for interesting team. Funding for this research came from an Australian Research future comparisons. It is very difficult to determine accurately Council Discovery Grant to Peter Bellwood and a University of the a taxonomic attribution from a single bone and, with the exception Philippines Research Grant to Armand Mijares. Florent Détroit of the Liang Bua remains, the MT3 recovered from Callao Cave on received support from Asia-Link HOPsea and Erasmus Mundus Luzon Island is the only Upper Pleistocene foot bone attributed to Action 3 exchange programs. We are grateful for the support of the genus Homo discovered beyond Wallace’s Line in Island Philippe Mennecier and Aurélie Fort for the access to the collections Southeast Asia. Additionally, the preliminary description of the at the Musée de l’Homme. The Office of the Vice Chancellor for Callao MT3 clearly indicates a reduced general size only known in Research and Development, University of the Philippines funded this region in H. floresiensis and in small-bodied H. sapiens, such as Philip Piper. The dating aspects of this study were supported by present-day Philippine Negritos. Australian Research Council Grant DP0664144 (Grün et al.) Micro- analysis of human fossils: new insights into age, diet and migration. Conclusions References The Callao Cave metatarsal indicates that a species of hominin crossed water gaps between Sundaland and Wallacea to reach Aiello, L., Dean, C., 1990. An Introduction to Human Evolutionary Anatomy. northern Luzon by 67,000 years ago. 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