Anthropological Science Vol. 125(2), 67–83, 2017

Global and local perspectives on cranial shape variation in Indonesian Homo erectus

Karen L. Baab1*, Yahdi Zaim2 1Department of Anatomy, Midwestern University, Arizona College of Osteopathic Medicine, 19555 N. 59th Avenue, Glendale, AZ 85012, USA 2Department of Geology, Institut Technologi Bandung (ITB), Jl. Ganesa No. 10, Bandung–40132, Indonesia

Received 5 December 2016; accepted 13 April 2017

Abstract Homo erectus is among the best-represented fossil hominin species, with a particularly rich record in Indonesia. Understanding variation within this sample and relative to other groups of H. erectus in China, Georgia, and Africa is crucial for answering questions about H. erectus migration, local adap- tation, and evolutionary history. Neurocranial shape is analyzed within the Indonesian sample, including representatives from Sangiran, Ngandong, Sambungmacan, and Ngawi, as well as a comparative sample of H. erectus from outside of Java, using three-dimensional geometric morphometric techniques. This study includes several more recently described Indonesian fossils, including Sambungmacan 4 and Skull IX, producing a more complete view of Indonesian variation than seen in previous shape analyses. While Asian fossils can be distinguished from the African/Georgian ones, there is not a single cranial Bauplan that distinguishes all Indonesian fossils from those in other geographic areas. Nevertheless, late Indone- sian H. erectus, from sites such as Ngandong, are quite distinct relative to all other H. erectus groups, including earlier fossils from the same region. It is possible that this pattern represents a loss of genetic diversity through time on the island of Java, coupled with genetic drift, although other interpretations are plausible. A temporal pattern of diachronic change was identified within Indonesia for the posterior neu- rocranium such that younger Sangiran fossils more closely approached the Ngandong/Sambungmacan/ Ngawi pattern, but there was not a linear trend of shape change from Sangiran to Sambungmacan to Ngandong, as has been suggested previously. The Sambungmacan 3 fossil, which often appears as a morphological outlier, fits the general pattern of late Indonesian vault shape, but has a more extreme expression of the shape trends for this group than other individuals.

Key words: Homo erectus, Sangiran, Ngandong, cranial shape, geometric morphometrics

dong, Sambungmacan, and Ngawi is generally considered to Introduction be Middle Pleistocene or even Late Pleistocene in age. The The Homo erectus fossil record from Java is extensive and Ngandong fossils, consisting of numerous partial and com- has wide-ranging implications for evolutionary questions plete calvaria and well as a few postcranial elements, were about the timing of early Homo migration, the effects of recovered from excavations on the high terraces of the Solo stochastic evolution on islands, local adaptation, and a po- River. However, the three Sambungmacan and single Ngawi tential speciation event that gave rise to Homo floresiensis, calvaria were recovered by local inhabitants from three dif- known from the nearby island of Flores (Brown et al., 2004; ferent sites along this river, and the exact stratigraphic prov- Baab, 2016a). Moreover, the time span, which may encom- enance of these fossils is uncertain. Most of these sites are pass more than a million years of evolution, allows us to situated along the Solo River in east Java, with the exception probe issues of diachronic change in this species. The oldest of the more eastern site of Modjokerto, which has yielded fossils (early Pleistocene) from Java are those from Trinil one young individual, and the more western site of Cisanca, and the Sangiran dome. The young individual recovered from which a single incisor was recovered (Kramer et al., from Modjokerto may also be Early Pleistocene in age, but 2005). this is less certain. A second group of fossils from Ngan- The Asian hominin record has been subject to a continu- ous stream of analyses beginning with the initial description of the Trinil fossils by Dubois (1894). Additional earlier * Correspondence to: Karen Baab, Department of Anatomy, Mid- western University, 19555 N. 59th Avenue, Glendale, AZ 85012, discoveries were also from the earlier time frame. The first USA. fossils recovered from the Middle/Late Pleistocene were E-mail: [email protected] from Ngandong in the 1930s. The Ngandong fossils were Published online 30 June 2017 initially placed in a distinct species, Homo (Javanthropus) in J-STAGE (www.jstage.jst.go.jp) DOI: 10.1537/ase.170413 soloensis (Oppenoorth, 1932), and similarities to other Mid-

© 2017 The Anthropological Society of Nippon 67 68 K.L. BAAB AND Y. ZAIM Anthropological Science dle Pleistocene hominins or late Pleistocene Homo sapiens descent” and Antón (2002: 319), who asserted that “the rela- from Australasia were noted. However, monographs on the tively small differences between the earlier and later Indone- Zhoukoudian (China) and Ngandong fossils by Weidenreich sian fossils must certainly be accepted as temporal changes were particularly influential (Weidenreich, 1943, 1951) in within a lineage, rather than indicative of a different line- establishing two common themes that have persisted until age.” Both workers identified non-metric features (e.g. fron- the present: the fossils from Trinil/Sangiran, Zhoukoudian, tal keel and anterior projection of the medial part of the su- and Ngandong share a common Bauplan but with regional praorbital torus) unique to this group, and Antón (2002) and temporal variations overprinted on this shared architec- further found similarity in size/shape of the cranial vault ture. Santa Luca’s (1980) in-depth analysis of the Ngandong based on quantitative measures. fossils further solidified this sample as part of the broader Nevertheless, there are differences of opinion regarding H. erectus type. Additional fossil discoveries have occurred the details of that evolutionary transition. In particular, re- in both the earlier time frame, including additional Sangiran cent analyses of 2D linear dimensions and non-metric fea- dome localities (Sartono and Tyler, 1993; Widianto et al., tures supported a linear transition from Sangiran/Trinil 1994; Widianto and Grimaud-Herve, 2000; Grimaud-Hervé through Sambungmacan/Ngawi and onto Ngandong (Baba et al., 2005; Zaim et al., 2011), and the later time frame, such et al., 2003; Kaifu et al., 2006, 2008, 2015), a view also em- as the three calvaria from Sambungmacan (Jacob et al., braced by Wolpoff (1999). This conclusion was based on 1978; Márquez et al., 2001; Baba et al., 2003) and the one observations that geochronologically younger Sangiran fos- from Ngawi (Sartono, 1991). Sambungmacan and Ngawi sils were more similar to later Indonesian fossils than were are considered to have particular affinities with Ngandong. older ones, and that both Ngawi and the three Sambung- More recent work that has focused on the cranial mor- macan specimens displayed intermediate morphologies be- phology of the Asian H. erectus fossil record includes evalu- tween Sangiran/Trinil and Ngandong. Durband (2006) sug- ations of the metric and non-metric diversity of Asian or gested near stasis in the vault shape in Indonesia for specifically the Indonesian fossil record (Antón, 2002; Kaifu 0.7–1.0 Myr based on canonical variate analysis of size- et al., 2008), cranial shape variation in the Asian fossils corrected neurocranial length and breadth dimensions, but (Baab, 2010; Zeitoun et al., 2010), and analyses focused on identified a handful of non-metric features in the later Indo- the affinities of particular fossils (Delson et al., 2001; nesian sample not present in Sangiran/Trinil. He attributed Widianto et al., 2001; Antón et al., 2002; Widianto and this combined pattern to geographic and genetic isolation of Zeitoun, 2003; Durband, 2006; Kaifu et al., 2006, 2015; these populations on Java. In contrast, analysis of vault Indriati and Antón, 2010). It was demonstrated that Asian, shape via 3D landmarks demonstrated distinct neurocranial along with numerous African and Georgian fossils assigned shape in the Sambungmacan/Ngawi, Ngandong, and Trinil/ to H. erectus, were distinct from or displayed minimal over- Sangiran groups, and the differences among them were lap with other archaic Homo species on the basis of three- non-linear (Baab, 2010; Zeitoun et al., 2010). At least some dimensional (3D) neurocranial shape (Zeitoun et al., 2010; of the differences between the early Indonesian and the Baab, 2016b). There is substantial variation within this sam- Ngandong fossils appear to relate to the increased size of the ple that spans three continents and more than a million years latter (Antón, 2002; Baab, 2016b). A small number of work- of evolutionary change. Some of this variation is attributable ers argue that the morphological distance between the Trinil/ to diachronic change (Wolpoff et al., 1994; Antón, 2003; Sangiran and later Indonesian fossils should perhaps be rec- Kaifu et al., 2005, 2008), and to geography (perhaps related ognized at the species level (Schwartz and Tattersall, 2005; to genetic drift or local adaptation) (Antón, 2002; Kidder Zeitoun et al., 2010), with a further possible split between and Durband, 2004; Durband, 2006; Baab, 2010), but is also Sambungmacan/Ngawi and Ngandong (Tattersall and influenced by cranial size (Santa Luca, 1980; Antón et al., Schwartz, 2009), but with the recognition that these samples 2007; Baab, 2008b; Kaifu et al., 2008). Some studies have form a single clade. Methodological and sample details dif- found that the Zhoukoudian hominins are particularly dis- fered among these studies. In particular, none of the 3D tinct in their craniometric dimensions (Antón, 2002; Kidder shape analyses included Sambungmacan 4 (Sm 4) or Skull and Durband, 2004), while others have indicated that the IX (Tjg-1993.05) (Baab, 2010, 2016b; Zeitoun et al., 2010). Ngandong/Sambungmacan/Ngawi series of calvaria are at Therefore, while there is consensus regarding the close evo- least as distinct (Baab, 2010; Zeitoun et al., 2010). lutionary relationship among the populations represented by The Ngandong/Sambungmacan/Ngawi fossils are often these fossils, there is disagreement regarding the patterning grouped together, in contrast to the presumably older Sangi- of morphological variation among these groups and its im- ran/Trinil fossils, and there is general consensus that the plications for their historical relationships. latter are broadly ancestral to the former. This position was A recent analysis demonstrated the utility of 3D neurocra- supported by Weidenreich (1940: 377–378), who argued that nial shape information for defining the boundaries of “Homo soloensis [Ngandong] has to be regarded as a direct H. erectus, broadly defined to include fossils from Africa, descendent from Pithecanthropus and represents really a Georgia, China, and Indonesia (Baab, 2016b). That study succeeding phase” based on the observation that, “in all es- focused on interspecific variation, but it was apparent that sential details which define theHomo soloensis type, there is there was also substantial intraspecific variation, and further, a surprising correspondence to Pithecanthropus.” This has that this variation was structured with respect to geography, been echoed more recently by Wolpoff (1999: 573) who geochronological age, and brain size. Intraspecific variation stated that similarities between early Indonesian fossils and in neurocranial shape was also touched on in earlier studies, Ngandong/Ngawi “indicate relationship, almost certainly including one that specifically assessed Asian H. erectus Vol. 125, 2017 CRANIAL SHAPE IN INDONESIAN HOMO ERECTUS 69

(Baab, 2008b, 2010). This current study aims to expand on cent geological work at Ngandong by Indriati et al. (2011) this work by evaluating patterns of variation in the Indone- found two internally consistent but mutually exclusive sets sian H. erectus sample, and how this sample relates to other of dates based on 40Ar/39Ar dating of hornblende from within H. erectus groups from across the Old World. This study the fossiliferous layers versus ESR and U-series dating of improves on the earlier 3D studies by including the Sm 4 and fossil teeth. The former suggested a Middle Pleistocene age Skull IX calvaria, which results in a more complete sam- of 546 ka, while the latter suggested younger ages between pling of Indonesian fossils than in previous 3D shape analy- 77 and 143 ka for combined ESR and U-series dating, and as ses, and utilizing an updated geochronology, which mostly young as 44 ka based on the closed system ESR alone. Indri- involves the Indonesian fossils. This study cannot address ati et al. (2011) conclude that a reasonable age range for the question of non-metric character variation and evolution Ngandong is 546–143 ka, but do not rule out that the fossils and, despite focused efforts to improve fossil representation may be closer to the older end of the range, with the younger noted above, is unable to evaluate fragmentary fossils that dates reflecting a more recent geomorphologic or hydrologic fail to preserve certain key landmarks. Furthermore, the na- event. However, Yokoyama et al.’s (2008) gamma-ray spec- ture of geometric morphometric analysis of shape requires trometric dating of three hominin fossils from Ngandong an assessment of many aspects of shape simultaneously and Sambungmacan yielded young ages between 40 and which restricts the ability to partition out the specifics of re- 70 ka, which is more consistent with the ESR dates. gional morphological change. The Sambungmacan calvaria (Sm 1, 3 and 4) are often grouped with the Ngandong fossils (Antón et al., 2002; Geochronology Baab, 2016b), but the former were all found by local inhab- There are currently two chronologies for Indonesian itants rather than during controlled excavations and may not H. erectus that are mutually exclusive. The long chronology be contemporaneous with each other or with the Ngandong suggests that the oldest hominin fossils are >1.5 Ma in the fossils (Kaifu et al., 2008). Yokoyama et al. (2008) found Sangiran dome and 1.8 Ma at Modjokerto according to similar dates for two Ngandong (Ng 1 and Ng 7) and one 40Ar/39Ar analysis of hornblende samples (Swisher et al., Sambungmacan (Sm 1) fossil, suggesting that this assump- 1994; Larick et al., 2001). At Sangiran, a high-resolution tion may be correct for at least some of the specimens. Yet, paleomagnetic record that documents the Matuyama– the very young date reported by Yokoyama et al. (2008) may Brunhes transition (Hyodo et al., 2011), fission-track dating reflect more recent hydrological activity unrelated to the ac- (Suzuki and Wikarno, 1982; Suzuki et al., 1985), faunal tual deposition of these fossils (Indriati et al., 2011). Depos- analysis (van den Bergh et al., 2001), and dating of tektites its spanning the Pleistocene are found in the area of the Sm (Itihara et al., 1985) contradict this long chronology. Where- 1 findspot (Kaifu et al., 2008). Sm 3 and 4 were found at the as many fossils from the Sangiran basin were dated to ~1 Ma bottom of the Solo River in the same location, which was by 40Ar/39Ar dating, these same fossils fall closer to 0.78 Ma 4 km from the Sm 1 site. Kaifu et al. (2011a) recently used according to the short chronology. An age of 1.66 Ma, the the mineral composition of matrix adhering to the Sm 4 cal- oldest date proposed for any Sangiran fossils, as well as a varia to identify its likely stratigraphic level which was then date of 1.8 Ma for the Modjokerto child (Swisher et al., fission-track dated to ~0.27 Ma. Matsu’ura et al. (2000) ap- 1994), were both criticized on the basis of erroneous geolog- plied multi-element analysis of inductively coupled plasma ical sampling (de Vos and Sondaar, 1994; Sémah et al., spectrometry to a hominin tibia (Sm 2) recovered from the 1997; Huffman, 2001; Bettis et al., 2004; Huffman et al., same site as Sm 1 and concluded that it derived from the 2006). The type specimen of H. erectus, the Trinil II calotte, lower part of the Bapang Formation or possibly the very late has been dated via stratigraphic correlation between Trinil Matuyama, which correlates to ~890–780 ka based on the and Sangiran dome. The current consensus seems to be a paleomagnetic study of Hyodo et al. (2011) at Sangiran. It is stratigraphic position near the base of the Bapang (Kabuh) unclear whether or how the Sm 1 and Sm 2 fossils are relat- formation, which is likely ~1.0 Ma based on the short chro- ed, but this could lend support to an older age for the Sam- nology (van den Bergh et al., 2001). On balance, the young bungmacan hominins. However, both Swisher et al. (1996) chronology is better supported and will be used in this study. and Yokoyama et al. (2008) support very late Pleistocene The other large group of H. erectus fossils are from the ages for Sambungmacan as discussed above (but see Indriati sites of Ngandong, Sambungmacan, and Ngawi. Fossils et al. (2011)). Thus, the range of dates for Sambungmacan from these sites are generally thought to be younger than encompasses the Early to Late Pleistocene and may pre- those from the Sangiran Basin or Trinil, but the exact ages date, post-date, or be synchronous with Ngandong. The remain uncertain. The Ngandong fossils were recovered Ngawi calvaria is also frequently grouped with Ngandong from an excavation of the Solo River terraces. Middle Pleis- and Sambungmacan on the basis of shared morphology tocene ages have often been proposed for these fossils based (Widianto and Zeitoun, 2003; Baab, 2016b) but there is no on faunal correlation, paleomagnetism, and fission-track date available for this fossil. dating of the underlying Pohjajar (Notoporo) beds (Jacob, What evidence we have regarding the geological age of 1978; Suzuki and Wikarno, 1982; Sémah, 1984). However, the Ngandong/Sambungmacan/Ngawi fossils points to a earlier workers suggested early Pleistocene dates Middle or possibly Early Pleistocene age. However, we can- (Oppenoorth, 1932; von Koenigswald, 1934). Itihara et al. not be certain that all of these fossils are contemporaneous (1985) suggested a Late Pleistocene age for these same de- nor is it possible to establish the chronological positions of posits, and Swisher et al. (1996) posited a very young age of these fossils relative to one another. 53–27 ka for both Ngandong and Sambungmacan. More re- 70 K.L. BAAB AND Y. ZAIM Anthropological Science

expand the relatively small sample sizes of well-preserved Materials and Methods African and Georgian fossils assigned to H. erectus. Moreo- The H. erectus specimens included in this study are listed ver, the D2700 specimen has a cranial shape within the range in Table 1, alongside information about whether the original of adult H. erectus and its neurocranium was within the fossil, a cast, or a surface rendering generated from micro- range of expected shapes for an adult H. erectus of equiva- computed tomography (micro-CT) data was utilized. The lent size (Baab, 2008a; Baab and McNulty, 2009). Likewise, specimens together create a representative sample that cap- Zkd 3, identified as a subadult by Black (1931) and tures the spatiotemporal and size variation of this species. Weidenreich (1943), but as an older subadult or young adult Although data were available from the Daka (BOU- by Antón (2001), was shown previously to fit well within the VP-2/66) fossil, it was excluded from the analyses because range of cranial shape exhibited by adult Zhoukoudian fos- though it was originally assigned to H. erectus (Asfaw et al., sils (Baab, 2010) and is thus included here. 2002), its more derived neurocranial shape and cranial non- Data were available from Ng 1, but initial analysis indi- metric features could position this as a stem H. heidelber- cated that the Ng 1 calvaria is an outlier, due to the antero- gensis s.l. (Baab, 2016b). medial angulation of the temporal base structures. This is Two of the specimens are clearly subadult: KNM-WT consistent with the distortion noted in Ng 1 by previous 15000 (Nariokotome Boy) and D2700 from Kenya and workers. Weidenreich (1951: 228) described the Ng 1 calva- Georgia, respectively. KNM-WT 15000 was probably 8–10 ria as “somewhat twisted. The right temporal bone and the years of age at death (Dean et al., 2001; Dean and Smith, right half of the nuchal plane of the occipital bone are de- 2009) and exhibited unerupted third molars. D2700 had an pressed inward.” Santa Luca (1980: 18) states that the “right unfused spheno-occipital synchondrosis but partially erupt- temporal squama compressed medially.” Kaifu et al. (2008) ed M3s and is thus older than Nariokotome Boy—perhaps also noted twisting of the frontoparietal fragment and an ≤13 years of age based on comparisons with the immature anomalous flexion of the midparietal region in lateral view. OH 13 Homo habilis specimen (Rightmire et al., 2006). For this reason, Ng 1 was excluded from the analysis. Their inclusion is justified primarily on the grounds that they Weidenreich (1943: 222) further noted less severe distor-

Table 1. Fossils included in this study, with associated endocranial volumes and geological ages Abbrevia- Data Fossil Endocranial volume and citation Geological age (Ma) and citation tion source INDONESIA Sangiran 2 Sang 2 Original 813 Holloway, 1981 0.90 Extrapolated from Hyodo et al. (1993; 2011) Sangiran 4 Sang 4 Original 908 Holloway, 1981 0.90 Extrapolated from Hyodo et al. (1993; 2011) Sangiran 10 Sang 10 Original 855 Holloway, 1981 0.79 Extrapolated from Hyodo et al. (2011) Sangiran 17 Sang 17 Cast 1004 Holloway, 1981 0.84 Extrapolated from Hyodo et al. (2011) Tjg-1999.05 Skull IX Virtual 870 Kaifu et al., 2011b 0.84 Extrapolated from Hyodo et al. (2011) Ngandong 1 Ng 1 Original 1172 Holloway, 1980 0.546/0.040 Indriati et al. (2011)/Yokoyama et al. (2008) Ngandong 6 Ng 6 Original 1251 Holloway, 1980 0.546/0.040 Indriati et al. (2011)/Yokoyama et al. (2008) Ngandong 7 Ng 7 Original 1013 Holloway, 1980 0.546/0.040 Indriati et al. (2011)/Yokoyama et al. (2008) Ngandong 10 Ng 10 Original 1135 Weidenreich, 1943 0.546/0.040 Indriati et al. (2011)/Yokoyama et al. (2008) Ngandong 11 Ng 11 Original 1231 Holloway, 1980 0.546/0.040 Indriati et al. (2011)/Yokoyama et al. (2008) Ngandong 12 Ng 12 Original 1090 Holloway, 1980 0.546/0.040 Indriati et al. (2011)/Yokoyama et al. (2008) Sambungmacan 1 Sm 1 Original 1035 Baba et al., 2003 0.546/0.040 Indriati et al. (2011)/Yokoyama et al. (2008) Sambungmacan 3 Sm 3 Original 917 Holloway et al., 2004 0.546/0.040 Indriati et al. (2011)/Yokoyama et al. (2008) Sambungmacan 4 Sm 4 Virtual 1006 Baba et al., 2003 0.546/0.0401 Indriati et al. (2011)/Yokoyama et al. (2008) Ngawi Ngawi Cast 870 Widianto and Zeitoun, 2003 0.546/0.040 Assumed synchrony with Ngandong/Samb. CHINA Zhoukoudian 3 Zkd 3 Cast 915 Weidenreich, 1943 0.8 Extrapolated from Shen et al. (2009) Zhoukoudian 5 Zkd 5 Cast 1140 Qiu et al., 1973 0.4 Extrapolated from Shen et al. (2009) Zhoukoudian 11 Zkd 11 Cast 1015 Weidenreich, 1943 0.75 Extrapolated from Shen et al. (2009) Zhoukoudian 12 Zkd 12 Cast 1030 Weidenreich, 1943 0.75 Extrapolated from Shen et al. (2009) GEORGIA D2280 D2280 Cast 780 Rightmire et al., 2006 1.77 Ferring et al. (2011) D2700 D2700 Cast 612 Rightmire et al., 2006 1.77 Ferring et al. (2011) D3444 D3444 Cast 625 Rightmire et al., 2006 1.77 Ferring et al. (2011) AFRICA KNM-ER 3733 ER 3733 Original 848 Holloway, 1983 1.78 Feibel et al. (1989) KNM-ER 3883 ER 3883 Original 804 Holloway, 1983 1.57 Feibel et al. (1989) KNM-WT 15000 WT 15000 Original 909 Walker and Leakey, 1993 1.53 Brown and McDougall (1993) 1 Kaifu et al. (2011a) provide a date of 270 ka for Sm 4, which is encompassed within this range. Vol. 125, 2017 CRANIAL SHAPE IN INDONESIAN HOMO ERECTUS 71 tion of Ng 6 in the form of “The right side, from the temporal ed across the regions of the cranium most often preserved in line down, is pressed inward and is broken in part … all this H. erectus: the cranial vault, including the supraorbital re- produced a slight asymmetry of the calvarium.” Kaifu et al. gion, and the basicranium. Landmark definitions and abbre- (2008) confirmed this distortion, noting that the “vault is viations are provided in Table 2 and illustrated in Figure 1. slightly deformed to its right. … In basal view, the right Different subsets of the full landmark protocol were analyz- temporal bone is anteroposteriorly extended so that the ed in order to optimize both morphological representation nuchal squama of the occipital faces slightly toward the and sample sizes (see Table 3). Similar approaches were specimen’s left. In addition, the right temporal squama is described previously (Baab, 2010, 2016b). pushed inward medially.” To accommodate these issues, the The ‘Original Analysis’ primarily optimizes landmark following landmarks were recorded only from the less af- coverage. This landmark protocol captures cranial vault fected left temporal bone: porion, auriculare, parietal notch, morphology including the midline profile from glabella an- asterion, and mid-temporal squama. These landmarks were teriorly through inion posteriorly, supraorbital torus shape, reflected to the right, creating a more symmetrical and bio- and the lateral temporal bone on the cranial base. The sample logically accurate landmark configuration. Any remaining included fossils from Indonesia, China, Georgia, and Africa. asymmetries should be minor and not explicitly evaluated as For this landmark set, both the full sample and a subsample only the symmetric component of shape was retained for of just Indonesian fossils were subjected to analysis. analysis (see below). Similar procedures were used to cor- Three additional variants on this analysis were performed rect for distortion in KNM-WT 15000 and KNM-ER 3883 to allow for the inclusion of Sang 2 and Sm 1 (‘Sangiran 2 as described in Baab (2016b). and Sambungmacan 1’), Ng 1, 7 and 10 (‘Ngandong’) and 3D cranial landmarks were acquired using a Microscribe Skull IX (‘Skull IX’). Skull IX (Sangiran IX; Tjg-1993.05) (3D mechanical arm digitizer) in all cases with the exception was originally described in 2002 by Arif et al. (2002) and of Sm 4 and Skull IX where landmarks were captured from more recently subjected to micro-CT scanning and recon- the in silico surface rendering using AVIZO software at the struction by Kaifu et al. (2011b). Data were collected on a Tsukuba Research Departments of the National Museum of surface rendering of the reconstructed specimen. For these Nature and Science, Tokyo. These landmarks were distribut- three analyses, a small number of landmarks were excluded

Table 2. Landmarks used in this study Abbrevi- Landmark Definition ation Inion IN Point at which superior nuchal lines merge in midsagittal plane Lambda LA The apex of the occipita bone at its junction with the parietals, in the midline Apex AX Highest midline point on the vault in Frankfort horizontal Bregma BR Posterior border of the frontal bone in the midsagittal plane Post-toral sulcus PTS Minima of concavity on midline post-toral frontal squama Glabella GL Most anterior midline point on the frontal bone, usually above the frontonasal suture Supraorbital notch SON Point of greatest projection of notch into orbital space, taken on medial side of notch Frontomalaretemporale FMT Point where the frontozygomatic suture crosses the temporal line Frontomalareorbitale FMO Point where the frontozygomatic suture crosses the inner orbital rim Mid-torus inferior MTI Point on inferior margin of supraorbital torus at the middle of the orbit (on superior margin of orbit) Mid-torus superior MTS Point on superior aspect of supraorbital torus, directly above mid-torus inferior on anterior aspect of torus Anterior pterion AP Intersection of coronal suture and sphenofrontal or sphenoparietal suture Porion PO Uppermost point on the margin of the external auditory meatus Auriculare AU Point vertically above the center of the external auditory meatus at the root of the zygomatic process Frontotemporale FT Point where the temporal line reaches its most anteromedial position on the frontal Parietal notch PN Posterosuperior border of the temporal where the squamosal and parietomastoid sutures meet Asterion AS Common meeting point of the temoral, parietal, and occipital bones, on either side Opisthion OP Midline point at the posterior margin of the foramen magnum Tympanomastoid junction TM Point on lateral border of the tympanomastoid fissure Entoglenoid EG Most inferior point on the entoglenoid pyramid Temporosphenoid TS Point where temporosphenoid suture passes from squama to cranial base (often on infratemporal crest) Metopion MET Point midway between glabella and bregma on the midline (calculated from semilandmark data) Mid-temporal squama MS Point on the temoral squama midway between temporosphenoid and parietal notch (calculated from semilandmark data) Mid-parietal MP Point on sagittal suture midway between bregma and lambda (calculated from semilandmark data) Postglenoid process PG Inferolateral-most point posterior to glenoid fossa and anterior to ectotympanic tube (postglenoid tuberosity or crest) 72 K.L. BAAB AND Y. ZAIM Anthropological Science

Table 3. Details of landmarks and fossils included in each analysis Landmark set Fossils Indonesia China Georgia Africa Landmarks Original Early: Sang 17 Late: Ng 6, Zkd 3, 5, 11, 12 D2280, D2700, KNM-ER 3733, IN, LA, BR, PTS, GL, SON, 11, 12, Sm 3, 4, Ngawi D3444 3883 FMT, FMO, MTI, MTS, AP, PO, AU, FT, PN, AS, TM, EG, TS, MET, MS, MP Sangiran 2 and Same as Original + Not included Not included Not included Same as Original – PTS, GL, Sambungmacan 1 Sang 2, Sm 11 SON, MTI, MTS, MET Ngandong Same as Original + Not included Not included Not included Same as Original – FMT, FMO, Ng 7, 102 AP, MS Skull IX Same as Original + Not included Not included Not included Same as Original – GL, FMO Skull IX, Ng 7 Posterior Early: Sang 2, 10 and 17, Zkd 3, 5, 11, 12 D2280, D2700, KNM-ER 3733, IN, LA, BR, AP, AU, PN, AS, PG, Neurocranium Skull IX Late: Ng 6, 7, D3444 3883, KNM-WT TS, MP 10, 11, 12, Sm 1, 3, 4 15000 Sangiran 4 Same as Posterior Same as Posterior Same as Posterior Same as Posterior Same as Posterior Neurocranium Neurocranium + Sang 4 Neurocranium – Neurocranium Neurocranium – BR, AP, MP + AX Zkd 5 1 The minus (–) and plus (+) signs indicate the exclusion or addition of specimens/landmarks, respectively. 2 Ng 1 was found to be an outlier due to taphonomic distortion and was excluded from this and all subsequent analyses.

pose the corresponding landmarks (Gower, 1975; Rohlf and Slice, 1990; Baab et al., 2012). The GPA process first trans- lates all specimen landmark configurations centroids to a common location, scales each to unit centroid size (CS), then rigidly rotates them to minimize distance among corre- sponding landmarks jointly across all landmarks. It is possi- ble in this process to separate the symmetric and asymmetric components of shape, and only the symmetric component as calculated by the MorphoJ software program (Klingenberg, 2011) was used here. Therefore asymmetries due to both bi- ological and taphonomic processes were excluded from the analysis. The symmetric component of superimposed coor- dinate data (shape variables) for each landmark set were subjected to a principal components analysis (PCA). The first PC reflects the direction of maximum shape variation in Figure 1. Right lateral view of Sambungmacan 4 with all land- the data, with each subsequent PC oriented to capture the marks utilized in this study labeled. Landmark definitions and details of direction of maximum shape variation orthogonal to preced- which landmarks were used in each analysis are in Table 3. ing components. The PC ordinations are presented, along with wireframes that summarize the shape differences cap- tured by each component. The proportion of shape variance from the original landmark protocol to account for preserva- accounted for by each component is reported in the figure tion issues in these fossils (Table 3). These modifications captions. were significant as the sample sizes for both the early and It is important to recognize that scaling all landmark con- late Indonesian fossils were expanded considerably, making figurations to unit CS as part of the superimposition process this analysis more comparable to those of Kaifu and col- means that interpretation of shape difference is relative to leagues based on linear and character data (Kaifu et al., overall size. For example, if a specimen is described has 2006, 2008, 2011b, 2015). Only the Indonesian fossils were having a taller vault, this may or may not be true in terms of analyzed for these smaller landmark protocols. The final linear dimensions (e.g. opisthion–basion length), but is true analysis focuses on the posterior neurocranium in order to relative to overall vault size. Two specimens that are isomet- analyze an additional early Indonesian fossil, Sang 10, ric variants of one another differing not in shape but only in which lacks the frontal bone and much of the cranial base. A size would plot in the same position in a PC ordination. It is modified version of the posterior neurcranial landmark set possible to evaluate the effect of size on shape by regressing was evaluated to include Sang 4 (‘Sangiran 4’). All thirteen either the shape variables themselves or PC scores on a size Indonesian H. erectus fossils examined in this study were variable. Centroid size for each specimen (defined as the included in the ‘Sangiran 4’ analysis. Both the full sample square root of the sum of squared distances of the centroid to and the Indonesian subsample were analyzed for the posteri- each landmark) is generated during the GPA and can be uti- or neurocranium landmarks. lized for this type of analysis. While CS is frequently used as For each analysis, the 3D landmarks (more specifically, a proxy for cranial size, this practice has a drawback in this the x, y, z coordinates for all landmarks) were subjected to a particular context. Cranial superstructures, as well as cranial generalized Procrustes analysis (GPA) to optimally superim- vault thickness influence CS as landmarks are positioned on Vol. 125, 2017 CRANIAL SHAPE IN INDONESIAN HOMO ERECTUS 73 the surface of these structures (e.g. glabella and the mid- in the same direction from Chinese fossils as does the Geor- torus landmarks on the supraorbital torus) but are not gener- gian from the African, although there is much greater spread ally considered as part of overall cranial size. An alternative within the Asian sample along this component. The Geor- to using CS as a scaling variable is to use endocranial vol- gian and later Indonesian fossils (Figure 2e) are distin- ume (EV). While EV avoids the issue of superstructures, it is guished by their taller and anteroposteriorly shorter vaults, not available for specimens with poor preservation of the greater breadth across the midvault and frontotemporale, vault and there is error associated with estimating EV, par- elongated parietomastoid suture, and taller supraorbital tori. ticularly for partially preserved calvaria (e.g. Ng 10). Despite S 17 from Sangiran is positioned close to the center of the these potential issues, EV was used for the scaling variable plot, and is thus intermediate between the older African/ in this study and the EV for each fossil is reported in Table 1. Georgian and Asian fossils as well as between the Chinese It is also important to note that while landmarks are local- and Indonesian samples in these aspects of shape. It is the ized on specific features, a difference in the position of that later Indonesian fossils that are most isolated along this landmark between specimens (or groups) may or may not be component. attributable to a direct change in the size/orientation of that Zkd 3 and particularly Zkd 5 occupy an extreme position feature. For example, a more inferiorly positioned entogle- in the subspace spanned by PCs 1 and 2. The nature of the noid landmark may be due to a relatively larger and more Zkd 5 reconstruction may account in part for its extreme inferiorly projecting entoglenoid process or to a relative en- position in this ordination (Baab, 2016b). This specimen has largement of the entire temporal bone that pushes the region a large fragment consisting of the supraorbital torus, much containing the entoglenoid inferiorly even without any of the frontal squama and smaller parts of the parietal and change to the process itself. There are often clues in the sur- greater wing of the sphenoid that does not directly articulate rounding morphology that make certain scenarios more with the posterior vault (Qiu et al., 1973; Wu et al., 2010). likely (e.g. comparing the position of other temporal base Yet all the Zhoukoudian fossils differ in having a posteriorly landmarks in the example above), but these are not always projecting inion and inferiorly positioned frontotemporale simple to discern. Therefore, discussion of differences in (Figure 2c) and it is difficult to evaluate whether, and to landmark position should not necessarily be read as differ- what extent, the reconstruction may affect its position in ences in that localized structure. shape space. In addition to evaluating scaling effects, PCs were also The third component contrasts the Koobi Fora H. erectus regressed on geochronological age to assess shape trends sample at one end of the axis with D3444, Sm 3, and Zkd 5 through time. Due to substantial disagreement concerning at the other end (Figure 2b). The latter fossils have a higher the age of the Ngandong and Sambungmacan fossils (see and anteroposteriorly shorter vault with a more vertical oc- Introduction), two sets of dates were used that bracket cur- cipital plane (or less-developed occipital torus), a long pari- rent proposals: one in the Middle Pleistocene (546 ka—the etal squama in the median plane and a thicker supraorbital oldest age included in Indriati et al.’s (2011) preferred range) torus at the zygomaticofrontal suture (Figure 2f, g). The and one in the later Pleistocene (40 ka—the youngest age three Ngandong fossils score higher than the two Sambung- indicated by Yokoyama et al.’s (2008) analysis). It remains macan and Ngawi fossils along this axis, although it is Sm 3 possible that Sambungmacan fossils are of greater antiquity that is most distinct from all other late Indonesian specimens (Matsu’ura et al., 2000), a possibility not evaluated here. The on PC 3. Ngandong, Sambungmacan, and Ngawi fossils are treated The analysis was re-run with only the Indonesian fossils. here as synchronous with the recognition that this may not Sang 17 was clearly differentiated from the later Indonesian be correct. Therefore, the results of the diachronic assess- fossils on the second PC, while the Ngandong fossils scored ment are exploratory and should be interpreted cautiously. lower than Ngawi and the Sambungmacan fossils on PC1, with Ng 6 particularly distant from the rest. The results were Results generally similar to those presented below in the ‘Ngan- dong’ analysis, and given the larger sample size in that anal- Original analysis ysis, the results are not presented here. The analysis was first run with the H. erectus samples from Indonesia, China, Africa, and Georgia (Figure 2a). This Sangiran 2 and Sambungmacan 1 analysis landmark set is similar to the ‘Maximum Chinese’ landmark Results are reported for only the Indonesian fossils. It was set used in Baab (2010), but also includes a landmark on the possible to evaluate both Sang 2 and Sm 1 in the analysis by temporosphenoid suture as it crosses from the squama to the excluding landmarks from the central part of the frontal cranial base. There was separation between western (African/ bone (glabella, post-toral sulcus, supraorbital notch, midto- Georgian) and eastern (China/Indonesia) fossils on PC 2. rus, and metopion). The Sangiran sample differed from the The shape differences relate to the greater constriction at later Indonesian fossils on a combination of PCs 1 and 2, but frontotemporale and the more posteriorly projecting inion in Sang 17 was more similar to the Ngandong/Sambungmacan/ the former (Figure 2d), as well as less breadth across the Ngawi fossils than was Sang 2, which was quite distinct midvault, a wider (mediolaterally) and more arched supraor- (Figure 3a). In general, the later group had a more vertical bital torus, and a more inferiorly projecting entoglenoid occipital plane, broader frontal bone, higher temporal squa- region. ma, more posteriorly positioned anterior temporal squama, The first component highlights variation within the west- and long parietomastoid suture. Within the later Indonesian ern and eastern samples: the later Indonesian sample differs sample, the Ngandong hominins score lower on PC 2 and 74 K.L. BAAB AND Y. ZAIM Anthropological Science

Figure 2. Principal components ordination and associated shape changes for ‘Original’ landmark set. The ordinations show (A) PC 1 (25.9% of total shape variance) and PC 2 (18.9%) and (B) PC 1 and PC 3 (11.7%). Shapes associated with the (C) Zhoukoudian, (D) African/Georgian and (E) late Indonesian groups, as well as the (F) negative and (G) positive ends of PC 3 are shown in right lateral and superior views. Lines connecting the landmarks (wireframes) are for visualization purposes only and do not represent actual data. higher on PC 3 than the Sambungmacan/Ngawi as well as (at pterion), less projecting glabella, and longer parietomas- the Sangiran hominins. The Sangiran hominins are further toid sutures (Figure 4b, c). Variation within the later Indone- distinguished from each other on PC 3 where Sang 17 in sian group contrasts most Ngandong hominins (particularly particular scored lower than all other hominins due to its low Ng 6 and 11) with the Sambungmacan hominins (particular- vault with more of the vault height inferior to the temporal ly Sm 3). Ng 7 and Ngawi occupy intermediate positions squama than above, a more inferiorly projecting entoglenoid between the Sambungmacan and other Ngandong fossils. process and laterally positioned temporal base (entoglenoid The shape differences within this group are of a similar scale process, tympanomastoid junction, and temporosphenoid to those seen on PC 1 (PCs 1 and 2 account for 25.0% and suture as it crosses from the base to the wall of the vault). 22.2% of total shape variance, respectively). The low- Although not figured, when H. erectus fossils from other er-scoring Sambungmacan fossils have an anteroposteriorly regions are included in this analysis, Sang 2 clusters with the shorter and more rounded vault in lateral view, as well as a Zhoukoudian hominins (see also Baab, 2010). This result is relatively wider anterior and mid-vault. In addition, fronto- driven by a lower neurocranium with a relatively narrow temporale is in a more inferior position and the parietomas- anterior vault, more posteriorly projecting inion, and a lower toid suture is more obliquely oriented (rather than horizon- temporal squama in Sang 2 than in the later hominins and tal) (Figure 4d, e). Sang 17. Skull IX analysis Ngandong analysis To include the Skull IX fossil from Sangiran, the fron- The exclusion of the lateral supraorbital torus landmarks tomalareorbitale and glabella landmarks were dropped from as well as anterior pterion and mid-temporal squama al- the original set of landmarks. Analysis of the full sample lowed for the addition of two more calvaria from Ngandong: yields three main clusters in the subspace of PCs 1 and 2: Ng 7 and 10. African/Georgian, late Indonesian, and Chinese/Skull IX. In the subspace spanned by the first two components, S 17 Sang 17 is situated approximately equidistant to the three is isolated from the later Indonesian hominins by conse- groups. Shape differences among these groups are much as quence of scoring low on the first axis (Figure 4a). The later described for the ‘Original’ analysis. Indonesian hominins differ from S 17 in their relatively an- When restricted to the Indonesian fossils only, the result is teroposteriorly shorter and taller vaults, wider anterior vaults very similar to that presented above in the ‘Sangiran 2 and Vol. 125, 2017 CRANIAL SHAPE IN INDONESIAN HOMO ERECTUS 75

Figure 4. Principal components ordination and associated shape changes for ‘Ngandong’ landmark set. (A) The ordination shows PC 1 Figure 3. Principal components ordination and associated shape (25.0%) and PC 2 (22.2%). Shapes representing the contrast the nega- changes for ‘Sangiran 2 and Sambungmacan 1’ landmark set. (A) The tive (B) and positive (C) ends of PC 1, which reflect some of the differ- ordination shows PC 1 (36.7%) and PC 2 (16.9%). Shape differences ences between S17 and the later Indonesian H. erectus group, respec- from the (B) negative to the (C) positive end of PC 1 are shown in right tively, are shown in right lateral and superior views, as are contrasts lateral and superior views. This contrasts Sang 2 with the rest of the between the negative (D) and positive (E) ends of PC 2, which reflect Indonesian fossils, particularly the younger group. variation within the later Indonesian group.

Sambungmacan 1’ analysis with Skull IX falling quite far Posterior neurocranium analysis from the other Indonesian fossils, as did Sang 2 (Figure 5a). The posterior neurocranium analysis primarily excluded Sang 17 again plotted closer to the later Indonesian fossils landmarks from the frontal bone, but also porion and mid- and away from the other Sangiran skull. This is due to the temporal squama landmarks. However, the sample size for longer, narrower vault and lower profile anteriorly coupled H. erectus is 22 specimens, of which 12 are from Indonesia. with a supraorbital torus that is taller at mid-orbit and a low- The African/Georgian sample is mostly separated from the er temporal squama of Skull IX (Figure 5b, c). The frontal Asian fossils on the second component, although Sang 17 squama is more obliquely oriented anteroposteriorly (less overlaps the former distribution and WT 15000 is closer to vertical), more constricted across anterior pterion and fron- the later Indonesian cluster (Figure 6a). With the exception totemporale, and frontomalaretemporale is more anteriorly of Sang 17, the Asian fossils have a relatively shorter pari- positioned. To the extent that the same morphology is ana- etal bone in the median plane, a more vertical occipital squa- lyzed in both analyses, there is correspondence between the ma, and less inferiorly projecting entoglenoid process and a features that distinguish both Skull IX and Sang 2 from Sang longer and more inferiorly positioned parietomastoid suture 17 and later Indonesian hominins. Within the later Indone- (Figure 6c, e). There is also less breadth across the temporal sian hominins, the Sambungmacan and Ngawi fossils scored base (entoglenoid process and temporosphenoid suture). lower than the Ngandong hominins, particularly Ng 6, along These shape differences are relative to posterior (not overall) the second component (Figure 5d, e). In contrast to the neurocranial size. ‘Ngandong Landmarks’ analysis, Ng 7 does not overlap the The first component differentiates the higher-scoring Sambungmacan/Ngawi group, although it is positioned clos- Ngandong/Sambungmacan fossils and Sang 10 from the est to them of the Ngandong hominins. This was due to their Chinese and other Sangiran fossils (Skull IX and Sang 2) anteroposteriorly shorter and wider vaults (with the excep- (Figure 6a). D3444 and WT 15000 likewise score higher tion of the posterior vault), and more posteriorly positioned than the other Georgian and African fossils as well as Sang pterion. The third component contrasts Sang 17 from the 17. The higher-scoring groups are distinguished by their other hominins. taller vault with a more vertical coronal suture and a longer and more vertical occipital plane, an anteroposteriorly elon- gated temporal squama with a longer parietomastoid suture, 76 K.L. BAAB AND Y. ZAIM Anthropological Science

is wider across the pterion, and a longer and more horizon- tally oriented parietomastoid suture (compare Figure 6f and Figure 6g). The coronal suture is also more vertically orient- ed due to the more posterior position of the anterior temporal squama. Sang 10 scores higher than the other specimens on PC 2 (not figured) and Skull IX plots away from the rest of the sample on PC 3 (not figured). Sang 10’s uniqueness is related to its posterior position of the asterion, resulting in a small asterion–lambda–inion angle. Skull IX stands apart mainly because its midline structures (sagittal suture, inion) are shifted posteriorly relative to the lateral structures (e.g. pterion, porion, asterion) and it has a vertically short occipi- tal squama. With the exception of Ng 10, the Ngandong fossils are distinguished from the rest of the Indonesian hominins on PC 4 (Figure 6b) due to their taller vault, longer occipital plane, and decreased breadth across the temporal base relative to the vault walls. A very similar analysis was run that replaced the postglenoid process with the entogle- noid process. This led to the exclusion of Sang 10 but the inclusion of Ngawi. The results were quite similar, and Nga- wi looked similar to Sm 3 in these ordinations. Given that all three Asian temporospatial groups (Zhouk- oudian, Sangiran, late Indonesian) were represented by three or more individuals, PCA and canonical variate analysis (CVA) were performed on the Asian sample to see whether it was possible to separate the Zhoukoudian and Sangiran groups. The Zhoukoudian and early Indonesian fossils over- lapped in the PCA (not figured) but could be separated in the CVA when they were assigned to these groups a priori, al- though Skull IX approached the Chinese distribution (Fig- ure 7). Based on the CVA, the early Indonesian fossils were relatively taller at bregma with a less posteriorly projecting inion, resulting in a more acute asterion–lambda–inion an- gle. The temporal bone was also longer anteroposteriorly and the vault was broader across the parietal notch, postgle- noid process, temporosphenoid suture, and pterion. Figure 5. Principal components ordination and associated shape changes for ‘Skull IX’ landmark set. (A) The ordination shows PC 1 Sangiran 4 analysis (41.0%) and PC 2 (16.1%). Shapes representing the contrast between The final analysis was a variant on the ‘Posterior Neuro- (B) Skull IX and (C) the rest of the Indonesian sample, as well as be- cranium’ analysis that included the incomplete but important tween (D) Sambungmacan/Ngawi and (E) Ngandong (particularly Ng Sang 4 fossil. This had two fewer landmarks and a substitu- 6) samples are shown in right lateral and superior views. tion of apex for bregma. The ordination of the first two PCs using the full sample was similar (though not identical) to that described for the posterior neurocranium above (Fig- and greater breadth across the pterion (Figure 6d). The third ure 8a). Differences included the position of Sang 10 and component (not figured) contrasts KNM-ER 3733 from the WT 15000 within the late Indonesian cluster, and the posi- rest of the sample due to its high score and, with the excep- tion of Skull IX and D 3444 on the periphery of this cluster. tion of Ng 10, the Ngandong fossils score higher than the In contrast, Sang 2 was within the Zhoukoudian cluster and Sambungmacan ones. The Chinese fossils are not distinct on Sang 2 and 17 plotted with some of the Georgian and Afri- any of the next few components, nor do the early and later can fossils. Shape differences among groups related to in- Indonesian fossils group together to the exclusion of the creased posterior projection at inion in the Zhoukoudian and other groups. Sang 2 fossils (Figure 8e), a relatively higher and more ante- When the analysis was restricted to just the Indonesian rior position of the vault apex in later Indonesian fossils fossils, there was nearly complete separation between the (Figure 8c), and a shorter parietomastoid suture and longer older Sangiran and younger Ngandong/Sambungmacan anterior temporal bone in the Georgian and some African samples on PC 1, although Sang 10 and Ng 6 overlap on this and Sangiran fossils (Figure 8d). component (Figure 6b). The greatest contrast was between As above, when the analysis was restricted to just the In- Sang 2 and Sm 3, which can be seen as exemplars of the donesian fossils, there was separation of the earlier and later extremes of variation in the Indonesian sample. The younger samples on PC 1, with overlap of Sang 10 and the younger fossils have a more vertical occipital plane, a taller vault that fossils on this component (Fib. 8b). Sm 3 is contrasted most Vol. 125, 2017 CRANIAL SHAPE IN INDONESIAN HOMO ERECTUS 77

Figure 6. Principal components ordination and associated shape changes for ‘Posterior Neurocranium’ landmark set. (A) The ordinations show PC 1 (30.9%) and PC 2 (16.1%) for the full sample and (B) PC 1 (34.0%) and PC 4 (10.2%) for the Indonesian-only sample. Shapes corresponding to the major clusters of (C) Zhoukoudian and some Sangiran fossils, (D) African/Georgian fossils and Sang 17 and (E) late Indonesian fossils are shown in right lateral and superior views. The shapes associated with the (F) late Indonesian and (G) Sangiran fossils are also shown based on the Indonesian-only sample.

longer parietomastoid suture (Figure 8f). The second com- ponent captures variation in both the early and late samples, with the Sambungmacan fossils scoring higher than the Ngandong ones (though Ng 6 is very close to the Sambung- macan range). Most Ngandong fossils (but not Ng 10) are also separate from the Sambungmacan fossils on PC 5 (not figured), but this accounts for only 8.1% of the shape vari- ance. The shape differences captured on PC 2 indicate that the Sambungmacan fossils have less height at apex and lambda, a shorter occipital squama with less projection at the inion, and a more posteriorly positioned asterion, leading to a longer parietomastoid suture.

Size and geological age To evaluate scaling, the PC scores were regressed on the natural logarithm of EV. This was first performed for the full Figure 7. Canonical variates analysis for Asian fossils using ‘Pos- sample of H. erectus based on the ‘Skull IX’ landmarks be- terior Neurocranium’ landmarks. cause this provided good landmark coverage of the neuro- cranium but also included more than one representative of each temporospatial group. Size did not affect the position of strongly with Sang 2 and Sang 4. The later Indonesian specimens along the first component, but did account for fossils differ in their taller vault at apex, longer and more 55.9% of the variance in PC 2 scores (R2 = 0.559; P < 0.001). vertical occipital plane, narrower posterior vault, antero- In this context Skull IX is actually the outlier, scoring higher posteriorly shorter anterior temporal squama (between the on PC 2 than expected based on its size. The first component postglenoid process and the temporosphenoid suture), and separated the late Indonesian sample from other Asian fos- 78 K.L. BAAB AND Y. ZAIM Anthropological Science

Figure 8. Principal components ordination and associated shape changes for ‘Sangiran 4’ landmark set. (A) The ordinations show PC 1 (34.8%) and PC 2 (16.2%) for the full sample and (B) PC 1 (34.5%) and PC 2 (19.1%) for the Indonesian-only sample. Shapes corresponding to the major clusters of (C) Late Indonesian, (D) African/Georgian fossils, and (E) Zhoukoudian fossils are shown in right lateral and superior views. The San- giran fossils overlap each of these three groups. The shapes associated with the negative (F) and positive (G) ends of PC 1, which reflect differenc- es between late Indonesian and Sangiran fossils, respectively, are also shown based on the Indonesian-only sample.

sils and the Georgian from the African fossils. PC 2 separat- regression results in a significant scaling relationship (R2 = ed the Asian and African/Georgian fossils from one another. 0.474, P = 0.013) and stronger age–shape relationships To evaluate diachronic trends, PC scores were regressed (R2 = 0.782, p < 0.001; R2 = 0.698, p < 0.001) on PC 1. on geological age of the fossils. Again, age (using the older age for the Ngandong/Sambungmacan/Ngawi fossils) ac- Discussion counted for a significant proportion of the variance in PC 2 scores (R2 = 0.779; P < 0.001). This result reflected the Geographic variation strong contrast between the much older African/Georgian The Asian fossils differ from the African/Georgian sample fossils and the younger Asian fossils; there was no relation- in having a longer neurocranium with more posterior projec- ship between age and PC 2 scores within the Asian sample tion at the inion, longer frontal squama in the median plane, itself. Skull IX was again an outlier, scoring higher than lower temporal squama, and greater breadth across the tem- predicted by its age. Using the younger end of the age for the poral and frontal squama (including behind the supraorbital Ngandong/Sambungmacan/Ngawi group results in a weaker tori). These shape changes may be due to the underlying in- but still significant relationship between age and PC 2 scores crease in brain size in these groups or may reflect an inde- (R2 = 0.649; P < 0.001). There was a weak, borderline sig- pendent selective force acting over the >1.5 Myr spanned by nificant relationship between age and PC 1 using this young- the H. erectus samples studied here. It is unclear what single er chronology as well (R2 = 0.220; P = 0.049). force would be continuously acting in such different envi- The same analyses were performed for just the Indonesian ronmental contexts, and it is more likely that this reflects fossils using the ‘Sang 4’ landmark set. Although this pro- brain size increase within certain morphological constraints. vides only limited information about cranial shape, this It was shown previously that brain size increase in more de- analysis includes the largest number of Indonesian fossils rived Homo species occurred along a different shape axis and encompasses the greatest temporal depth. Size does not than it did in H. erectus (Baab, 2016b), so perhaps this re- explain a significant proportion of the variance in PC1 flects strong genetic integration of cranial shape in H. scores, but age accounts for 63–69% of the variation in PC 1 erectus. Moreover, it is clear that there was not linear evolu- scores (R2 = 0.692, P < 0.001 based on an age of 546 ka for tion within the Asian record as the temporally intermediate Ngandong and Sambungmacan; R2 = 0.630, P = 0.001 based Zhoukoudian fossils are in no way transitional between the on an age of 143 ka for Ngandong and Sambungmacan). The early and later Indonesian fossils (see also Antón, 2002). extreme position of Sm 3 at the negative end of the first com- Previous analyses based on linear dimensions (and some- ponent impacts both relationships. Excluding Sm 3 from the times EV) by Anton and colleagues (Antón, 2002; Antón et Vol. 125, 2017 CRANIAL SHAPE IN INDONESIAN HOMO ERECTUS 79 al., 2002) found a distinction between Chinese and Indone- distinct cranial architecture that was not related to brain size sian fossils based on a PCA of logged values of five cranial increase relative to other Asian H. erectus as there is overlap dimensions (including EV) and a second PCA of three pos- in brain size between them and both Zhoukoudian and San- terior cranial dimensions. The Zhoukoudian fossils were giran. The later Indonesian fossils are unique in having a differentiated in those analyses mostly on the basis of their taller neurocranium with more vertical occipital plane, narrower biasterionic and wider biauricular breadths com- longer parietomastoid suture, less constriction behind the pared to the Indonesian sample. The isolation of the Zhouk- orbits (along with a more posteriorly positioned frontotem- oudian sample on the basis of its narrow biasterionic and porale), a more posteriorly positioned anterior temporal frontal breadths and wider biauricular breadth was further squama, a wider anterior vault, and a thicker lateral supraor- confirmed in CVAs of size-corrected linear dimensions bital torus. Many of these features were also identified by (Kidder and Durband, 2004; Durband et al., 2005; Durband, Kaifu et al. (2008) as differentiating between earlier Sangi- 2006). Based on the ‘Original’ analysis presented here, this ran fossils and later Ngandong fossils, including the relative- pattern did differentiate the Zhoukoudian H. erectus from ly tall vault, longer parietomastoid suture, reduced postor- the Indonesian, particularly the later Indonesian, fossils, but bital constriction, wider frontal bone, and thicker lateral was not as diagnostic for Zhoukoudian compared to African supraorbital torus. and Georgian fossils. On the other hand, the analysis pre- Kaifu et al. (2008) furthermore argued that the longer pa- sented here shows that relative to overall cranial size, the rietomastoid suture occurred simultaneously with a decrease Zhoukoudian fossils are differentiated from all other H. in temporal squama length related to a shortening of the erectus groups by a low cranial profile combined with a temporal muscle during in situ evolution on Java. Our anal- short occipital squama that is posteriorly projecting at inion ysis confirms their observation that this proportional ‘trade- and a frontal bone that is slightly narrower across the su- off’ in length differentiates the Sang 2 and 17 hominins from praorbital region with an inferiorly positioned frontotempo- the later group (Figure 3, Figure 4), but does not do so in rale. Skull IX (Figure 5) (Kaifu et al., 2011b). (While Figure 6 The earlier and later samples of Indonesian fossils did not appears to support this feature for all of the Sangiran fossils, form a distinct regional cluster, particularly when the poste- PC 3 (not shown) indicates the opposite pattern in Skull IX.) rior neurocranium was evaluated: individual Sangiran fos- Skull IX shares an elongated parietomastoid suture with the sils overlapped the Zhoukoudian or late Indonesian fossil later Indonesian hominins but also two other Sangiran fos- distributions, while others were intermediate between these sils (Bukuran and Sendang Klampok: Kaifu et al., 2008; two groups. In both the ‘Posterior Neurocranium’ and ‘San- Grimaud-Hervé et al., 2016) which indicates that this varia- giran 4’ analyses, Sang 2 overlapped the Zhoukoudian distri- tion was already present in the earlier Javanese population. bution while Sang 10 overlapped the late Indonesian fossils. Nevertheless, it is worth noting that the linear measurements Sang 17 was consistently intermediate. Sang 4 was only in provided by Kaifu et al. (2008) and Grimaud-Hervé et al. the latter analysis, and was likewise intermediate in position (2016) for the same fossils are very different, leaving open between Zhoukoudian and late Indonesian shapes. Skull IX some ambiguity regarding this character. For example, the overlapped the Chinese fossils in the former and fell inter- value for Sang 10 is 13 mm in Kaifu et al. (2008) but 33 mm mediate in the latter. It was possible to distinguish the three in Grimaud-Hervé et al. (2016). The length of this suture groups using CDA, but the greater contrast was between the based on the landmarks recorded for this study is 28 mm, late Indonesian fossils and the other two groups. One inter- much closer to the latter. This is consistent with the position pretation that fits these observations is that the Sangiran of Sang 10 closer to the later hominin distribution in the population captures the greater variation initially present in posterior neurocranium analysis; this is due largely to its Asian H. erectus, with the more homogeneous Zhoukoudian more posterior position of the asterion, which is a unique and later Indonesian morphologies representing only a sub- feature of Sang 10. set of that original variation as the result of stochastic evolu- tion, adaptation, or sampling effects. Variation within Indonesian subsamples Even in the analyses of more complete landmark sets, the The higher interindividual variation exhibited by the San- Sangiran fossils were not consistently positioned within or giran hominins compared to the later Indonesian sample is near to the range of variation encompassed by the later Indo- apparent in several analyses presented here. Higher variation nesian sample. Sang 17, Skull IX, and Sang 2 did not group in the early Indonesian record was also documented by with the later Indonesian fossils when the full sample was Antón (2002, 2003) and Kaifu et al. (2008). One possibility considered, despite the presence of some anterior neurocra- is that some of the individual differences in the early part of nial landmarks in their respective landmark sets (the ‘Origi- the record are enhanced by taphonomic processes as all of nal’ analysis in Figure 2, as well as ‘Skull IX’ and ‘Sangiran the Sangiran fossils evaluated here have cracks running 2 and Sambungmacan 1’ landmark sets, not figured here). throughout, some were substantially reconstructed (Skull Thus, there is some evidence to suggest that in fact the Indo- IX), and, in the case of Sang 4, the two pieces of the posteri- nesian fossils, including both the older and younger groups, or vault are not attached. That said, some of the Ngandong cannot be delineated from the rest of the sample on the basis fossils also exhibit cracks (e.g. Ng 10) and the Sangiran of neurocranial shape. specimens differ from the Ngandong/Sambungmacan/ Ngawi samples in the same direction and not randomly as Differences between early and later Indonesian samples might be expected if taphonomic processes were primarily The later Indonesian hominins exhibited a consistently responsible. Alternatively, we may be sampling temporal 80 K.L. BAAB AND Y. ZAIM Anthropological Science change in the Sangiran sample, which spans ~110 kyr. In tion. This distinction could indicate temporal separation of particular, younger Sangiran fossils are more similar to the these samples as it is difficult to imagine that populations Ngandong/Sambungmacan/Ngawi fossils, whereas the old- perhaps 35 km apart would be genetically isolated if they est, Sang 2 and 4, are the most distinct. This resulted in a overlapped in time. However, there was not a linear transi- significant relationship between age and PC 1 scores in the tion of shape from Sangiran to Sambungmacan to Ngandong ‘Sangiran 4’ analysis seen in Figure 7. Kaifu et al. (2005) in any of the within-Indonesia analyses. This contrasts with also argued for diachronic change in craniodental morpholo- the results based on non-metric traits and linear dimensions gy in the early part of the Javanese record, specifically point- presented by Kaifu et al. (2008, 2011a, 2015). Of course, ing to a decrease in dental size over time. On the other hand, stochastic forces could easily result in a non-linear pattern of Antón (2002) found that some early fossils were more simi- change along a chain of ancestor-descendent populations lar in overall size and shape to later fossils than were later within a species. A combination of linear and non-linear Sangiran specimens but based on a limited number of meas- evolution in different features would result in a non-linear urements and measurements taken from Skull IX prior to the ordination based on overall shape but a linear pattern of Kaifu et al. (2011b) reconstruction. In the ‘Skull IX’ analy- change in some measures. sis, which included Skull IX and Sang 17, thought to be The overlap between Ngandong and Sambungmacan fos- roughly contemporaneous (Kaifu et al., 2011b), the latter sils in the posterior neurocranium may indicate that this was much more similar to Ngandong and other younger fos- morphological region is insufficient to distinguish between sils than was Skull IX; this may suggest that while the poste- these groups. For example, Kaifu et al. (2008) identified rior cranium shows some change in the direction of later midline curvature of the vault and increased lateral supraor- fossils, this is not the case for overall cranial shape. In large bital thickness as features which mostly or entirely set the part the greater separation of Skull IX was driven by the very Ngandong sample apart from the Sambungmacan fossils, short upper scale of the occipital bone (see also Kaifu et al., neither of which are captured in the posterior neurocranium 2011b). analyses. The relative homogeneity of the later Indonesian fossils The three Sambungmacan fossils are well situated within could be interpreted in any number of ways including genet- the broader pattern of later Indonesian cranial shape in the ic drift, selection, or sampling effects. Regarding the latter, analyses of fossils from all four regions. Sm 3 often falls at the Ngandong sample appears to represent individuals from the edge of the H. erectus distribution, and is strongly con- the same population that died around the same time trasted with the earlier Indonesian fossils. Within the later (Huffman et al., 2010), but it is uncertain whether the Sam- Indonesian group, Sm 3 is the most extreme example of the bungmacan and Ngawi populations coexisted with the trend found in other Sambungmacan and Ngawi hominins to Ngandong group or each other. On the other hand, reduced have an anteroposteriorly shorter vault with greater breadth gene flow and founder effects may have reduced genetic and across the temporal and frontal squamae and a shorter, more morphological diversity through time in this endemic line- vertical nuchal plane with a more inferior position of fronto- age or selection. temporale. Some of these same features were discussed by Márquez et al. (2001) and Delson et al. (2001) who observed Interpretation of later Indonesian samples the more open occipital/nuchal angle, vertical frontal squa- A previous study suggested that Ngandong and Sambung- ma, and globular neurocranium of Sm 3. In interspecific macan/Ngawi were distinct morphs in terms of neurocranial analyses that included other archaic Homo species, these shape (Baab, 2010). Indeed, the Ngandong fossils tended to same tendencies produced superficial convergences on the cluster independently of the Sambungmacan and sometimes later Homo pattern (Delson et al., 2001; Baab, 2016b). Kaifu Ngawi fossils, particularly in the ‘Original’, ‘Sangiran 2 & et al. (2015) also found that Sm 3 was a morphological out- Sambungmacan 1’ and ‘Skull IX’ landmark sets. However, lier in some respects, as was Ng 6, which likewise occupied there were instances where the separation between the an extreme position in several of the analyses presented here groups was incomplete, including in the ‘Ngandong’ analy- even after correction for distortion (e.g. ‘Original’ and ‘Skull sis and the two analyses of the posterior neurocranium. IX’ analyses). Ngawi either grouped with the Sambungmacan sample or The observation that Sm 3 presented unique aspects of was positioned intermediate between Sambungmacan and cranial shape and some non-metric traits suggested several Ngandong. To the extent that the Ngandong fossils differ possibilities to the original describers, including additional from Sambungmacan and Ngawi, this is due to their longer taxonomic variation in Southeast Asia (Márquez et al., vault, more mediolateral restriction across temporal bone 2001), and individual- or population-level variation (Delson structures, more superiorly positioned frontotemporale, et al., 2001). This study indicates that the shape of Sm 3 is more medial position of the mid-toral landmarks, and differ- consistent with other late Indonesian fossils, particularly ences in the height of the inferior temporal bone features. those from Sambungmacan, and is unlikely to represent ad- Kaifu et al. (2008) also noted some of these differences as ditional taxonomic variation in Southeast Asia. On the other distinguishing features for Ngandong: longer and less hand, several interpretations of Sm 3 remain viable, includ- curved profile as well as a narrower frontal squama. ing individual- or population-level variation. The grouping Based on current evidence, the group centroids for Ngan- of Sm 3 with Sm 1, Sm 4, and sometimes Ngawi provides dong and Sambungmacan differ but there is some overlap in support for the latter, while its consistently more extreme vault shape among fossils from these groups. The tendency position within this cluster provides support for the former. to plot away from one another hints at some genetic separa- Vol. 125, 2017 CRANIAL SHAPE IN INDONESIAN HOMO ERECTUS 81

(2002) Preliminary observation of a new cranium of Homo Conclusions erectus (Tjg-1993.05) from Sangiran, Central Jawa. Anthro- pological Science, 110: 165–177. A few generalizations are possible when the results of the Asfaw B., Gilbert W.H., Beyene Y., Hart W.K., Renne P.R., various analyses are viewed jointly: WoldeGabriel G., Vrba E.S., and White T.D. (2002) Remains 1. There are consistent shape differences between the early of Homo erectus from Bouri, Middle Awash, Ethiopia. Nature, African/Georgian fossils and the later Asian ones. These 416: 337–320. differences may relate to increasing brain size in the Baab K.L. (2008a) The taxonomic implications of cranial shape Asian record or to diachronic evolution, or both. variation in Homo erectus. Journal of Human Evolution, 54: 827–847. 2. There does not appear to be a single neurocranial shape Baab K.L. (2008b) A re-evaluation of the taxonomic affinities of that defines the Indonesian clade to the exclusion of the the early Homo cranium KNM-ER 42700. Journal of Human other geographic samples, but later Indonesian fossils are Evolution, 55: 741–746. characterized by a distinct neurocranial shape compared Baab K.L. (2010) Cranial shape in Asian Homo erectus: geograph- to all other regional/temporal samples of H. erectus. ic, anagenetic, and size-related variation. In: Norton C.J. and 3. The Sangiran sample exhibits a high degree of variation Braun D.R. (eds.), Asian Paleoanthropology: From Africa to China and Beyond. Springer Verlag, New York, pp. 57–79. in cranial shape; individual fossils overlap each of the Baab K.L. (2016a) The place of Homo floresiensis in human evolu- major temporospatial groups when evaluated against all tion. Journal of Anthropological Sciences, 94: 5–18. H. erectus fossils, but are distinct from the later fossils Baab K.L. (2016b) The role of neurocranial shape in defining the when only intra-Indonesian variability is considered. boundaries of an expanded Homo erectus hypodigm. Journal 4. The posterior neurocranium shows a pattern of diachron- of Human Evolution, 92: 1–21. ic change within the Sangiran sample such that younger Baab K.L. and McNulty K.P. (2009) Size, shape, and asymmetry in fossil hominins: the status of the LB1 cranium based on 3D fossils are more similar to the Ngandong/Sambung- morphometric analyses. Journal of Human Evolution, 57: macan sample. 608–622. 5. Delineation among fossils from the sites of Ngandong, Baab K.L., McNulty K.P., and Rohlf F.J. (2012) The shape of Sambungmacan and Ngawi is subtle and there is often human evolution: A geometric morphometrics perspective. some overlap between these groups. There is not a clear Evolutionary Anthropology, 21: 151–165. linear transition in vault shape from Sangiran to Sam- Baba H., Aziz F., Kaifu Y., Suwa G., Kono R.T., and Jacob T. (2003) Homo erectus calvarium from the Pleistocene of Java. bungmacan to Ngandong. Science, 299: 1384–1388. 6. Sm 3 fits the general pattern of later Indonesian variabil- Bettis E.A., Zaim Y., Larick R.R., Ciochon R.L., and Suminto R. ity, but is often at the extreme of the H. erectus distribu- (2004) Landscape development preceding Homo erectus im- tion. migration into Central Java, Indonesia: the Sangiran Forma- tion Lower Lahar. Palaeogeography, Palaeoclimatology, Pala- eoecology, 206: 115–131. Acknowledgments Black D. (1931) On an adolescent skull of Sinanthropus pekinensis in comparison with an adult skull of the same species and with The author is grateful to the curators and staff of the fol- other hominid skulls, recent and fossil. Palaeontologia Sinica lowing institutions and agencies for access to fossil data: Series D, 7: 1–144. American Museum of Natural History, Gadja Mada Univer- Brown F.H. and McDougall I. (1993) Geologic setting and age. In: sity, Lembaga Ilmu Pengetahuan Indonesia (LIPI), National Walker A. and Leakey R. (eds.), The Nariokotome Homo Museums of Kenya, National Museum of Tanzania, and erectus Skeleton. Harvard University Press, Cambridge, MA, COSTECH. Particular thanks to Mr Iwan Kurniawan (Geo- pp. 9–20. Brown P., Sutikna T., Morwood M.J., Soejono R.P., Jatmiko, logical Museum, Bandung) for access to Sm 4 and Dr Saptomo E.W., and Due R.A. (2004) A new small-bodied Yousuke Kaifu for arranging access to the CT scans of fos- hominin from the Late Pleistocene of Flores, Indonesia. Na- sils at the National Museum of Nature and Science, Tokyo. ture, 431: 1055–1061. de Vos J. and Sondaar P. (1994) Dating hominid sites in Indonesia. Science, 266: 1726–1727. References Dean C., Leakey M.G., Reid D., Schrenk F., Schwartz G.T., Stringer C., and Walker A. (2001) Growth processes in teeth Antón S.C. (2001) Cranial growth in Homo erectus. In: Minugh- distinguish modern humans from Homo erectus and earlier Purvis N. and McNamara K.J. (eds.), Human Evolution hominins. Nature, 414: 628–631. through Developmental Change. Johns Hopkins University Dean M.C. and Smith B.H. (2009) Growth and development of the Press, Baltimore, MD, pp. 349–380. Nariokotome youth, KNM-WT 15000. In: Grine F.E., Fleagle Antón S.C. (2002) Evolutionary significance of cranial variation in J.G., and Leakey R.E. (eds.), The First Humans: Origin and Asian Homo erectus. American Journal of Physical Anthro- Early Evolution of the Genus Homo. Springer Verlag, New pology, 118: 301–323. York, pp. 101–120. Antón S.C. (2003) Natural history of Homo erectus. Yearbook of Delson E., Harvati K., Reddy D., Marcus L.F., Mowbray K., Physical Anthropology, 46: 126–170. Sawyer G.J., Jacob T., and Marquez S. (2001) The Sambung- Antón S.C., Márquez S., and Mowbray K. (2002) Sambungmacan macan 3 Homo erectus calvaria: a comparative morphometric 3 and cranial variation in Asian Homo erectus. Journal of Hu- and morphological analysis. Anatomical Record, 262: 380– man Evolution, 43: 555–562. 397. Antón S.C., Spoor F., Fellmann C.D., and Swisher III C.C. (2007) Dubois E. (1894) Pithecanthropus erectus, Eine Menschenahnliche Defining Homo erectus: size considered. In: Henke W. and Uebergangsfom aus Java. Landes Drucherei, Batavia. Tattersall I. (eds.), Handbook of Paleoanthropology. Springer Durband A.C. (2006) Craniometric variation within the Pleistocene Verlag, Berlin, pp. 1655–1693. of Java: the Ngawi 1 cranium. Human Evolution, 21: 193– Arif J., Kaifu Y., Baba H., Suparka M.E., Zaim Y., and Setoguchi T. 201. 82 K.L. BAAB AND Y. ZAIM Anthropological Science

Durband A.C., Kidder J.H., and Jantz R.L. (2005) A multivariate area. In: Watanabe N. and Kadar D. (eds.), Quaternary Geolo- examination of the Hexian calvaria. Anthropological Science, gy of the Hominid Fossil Bearing Formations in Java. Geolog- 113: 147–154. ical Research and Development Centre, Special Publication 4, Feibel C.S., Brown F.H., and McDougall I. (1989) Stratigraphic Bandung, pp. 11–43. context of fossil hominids from the Omo group deposits, Jacob T. (1978) The puzzle of Solo Man. Modern Quaternary northern Turkana Basin, Kenya and Ethiopia. American Jour- Reserach in Southeast Asia, 4: 31–40. nal of Physical Anthropology, 78: 595–622. Jacob T., Soejono R.P., Freeman L.G., and Brown F.H. (1978) Ferring R., Oms O., Agustí J., Berna F., Nioradze M., Shelia T., Stone tools from mid-Pleistocene sediments in Java. Science, Tappen M., Vekua A., Zhvania D., and Lordkipanidze D. 202: 885–887. (2011) Earliest human occupations at Dmanisi (Georgian Kaifu Y., Baba H., Aziz F., Indriati E., Schrenk F., and Jacob T. Caucasus) dated to 1.85–1.78 Ma. Proceedings of the Nation- (2005) Taxonomic affinities and evolutionary history of the al Academy of Sciences of the United States of America, 108: early Pleistocene hominids of Java: dentognathic evidence. 10432–10436. American Journal of Physical Anthropology, 128: 709–726. Gower J.C. (1975) Generalized Procrustes analysis. Psychometri- Kaifu Y., Baba H., and Aziz F. (2006) Indonesian Homo erectus and ka, 40: 33–51. modern human origins in Australasia: new evidence from the Grimaud-Hervé D., Widianto H., Détroit F., and Jacob T. (2005) Sambungmacan Region, Central Java. National Science The new skull of Bukuran from Sangiran dome, Java, Indone- Museum Monographs, 34: 289–294. sia. PaleoAnthropology, Supplement: A46. Kaifu Y., Aziz F., Indriati E., Jacob T., Kurniawan I., and Baba H. Grimaud-Hervé D., Balzeau A., Widianto H., Djubiantono T., (2008) Cranial morphology of Javanese Homo erectus: new Détroit F., Moigne A.M., Sémah A.M., Purnomo A., Ansyori evidence for continuous evolution, specialization, and termi- M., Brasseur B., Ingicco T., and Sémah F. (2016) Position of nal extinction. Journal of Human Evolution, 55: 551–580. the posterior skullcap fragment from Sendang Klampok (San- Kaifu Y., Kurniawan I., Yokoyama K., Sano T., Hasebe N., Aziz F., giran Dome, Java, Indonesia) among the Javanese Homo Indriati E., Setiyabudi E., Otsuka H., and Baba H. (2011a) erectus record. Quaternary International, 416: 193–209. Stratigraphy, taphonomy, and age of a Homo erectus calvaria Holloway R.L. (1980) Indonesian “Solo” (Ngandong) endocranial from Sambungmacan. American Journal of Physical Anthro- reconstructions: some preliminary observations and compari- pology, S52: 181 (Abstract). sons with Neandertal and Homo erectus groups. American Kaifu Y., Zaim Y., Baba H., Kurniawan I., Kubo D., Rizal Y., Arif Journal of Physical Anthropology, 53: 285–295. J., and Aziz F. (2011b) New reconstruction and morphological Holloway R.L. (1981) The Indonesian Homo erectus brain endo- description of a Homo erectus cranium-Skull IX (Tjg- casts revisited. American Journal of Physical Anthropology, 1993.05) from Sangiran, Central Java. Journal of Human 55: 503–521. Evolution, 61: 270–294. Holloway R.L. (1983) Human brain evolution: a search for units, Kaifu Y., Kurniawan I., Kubo D., Sudiyabudi E., Putro G.P., models and synthesis. Canadian Journal of Anthropology, 3: Prasanti E., Aziz F., and Baba H. (2015) Homo erectus calva- 215–229. ria from Ngawi (Java) and its evolutionary implications. An- Holloway R.L., Broadfield D.C., and Yuan M.S. (2004) The Hu- thropological Science, 123: 161–176. man Fossil Record: Brain Endocasts—The Paleoneurological Kidder J.H. and Durband A.C. (2004) A re-evaluation of the metric Evidence, Vol. 3. John Wiley, Hoboken, NJ. diversity within Homo erectus. Journal of Human Evolution, Huffman O.F. (2001) Geologic context and age of the Perning/ 46: 299–315. Mojokerto Homo erectus, East Java. Journal of Human Evolu- Klingenberg C.P. (2011) MorphoJ: an integrated software package tion, 40: 353–362. for geometric morphometrics. Molecular Ecology Resources, Huffman O.F., Zaim Y., Kappelman J., Ruez Jr. D.R., de Vos J., 11: 353–357. Rizal Y., Aziz F., and Hertler C. (2006) Relocation of the 1936 Kramer A., Djubiantono T., Aziz F., Bogard J.S., Weeks R.A., Mojokerto skull discovery site near Perning, East Java. Jour- Weinand D.C., Hames W.E., Elam J.M., Durband A.C., and nal of Human Evolution, 50: 431–451. Agus (2005) The first hominid fossil recovered from West Huffman O.F., De Vos J., and Berkhout A.W. (2010) Provenience Java, Indonesia. Journal of Human Evolution, 48: 661–667. reassessment of the 1931–1933 Ngandong Homo erectus Larick R., Ciochon R.L., Zaim Y., Sudijono, Suminto, Rizal Y., (Java), confirmation of the bone-bed origin reported by the Aziz F., Reagan M., and Heizler M. (2001) Early Pleistocene discoverers. PaleoAnthropology, 2010: 1–60. 40Ar/39Ar ages for Bapang Formation hominins, Central Hyodo M., Watanabe N., Sunata W., Susanto E.E., and Wahyono H. Jawa, Indonesia. Proceedings of the National Academy of (1993) Magnetostratigraphy of hominid fossil bearing forma- Sciences of the United States of America, 98: 4866–4871. tions in Sangiran and Mojokerto, Java. Anthropological Sci- Márquez S., Mowbray K., Sawyer G.J., Jacob T., and Silvers A. ence, 101: 157–186. (2001) New fossil hominid calvaria from Indonesia—Sam- Hyodo M., Matsu’ura S., Kamishima Y., Kondo M., Takeshita Y., bungmacan 3. Anatomical Record, 262: 344–368. Kitaba I., Danhara T., Aziz F., Kurniawan I., and Kumai H. Matsu’ura S., Kondo M., Aziz F., Sudijono, Narasaki S., and (2011) High-resolution record of the Matuyama–Brunhes Watanabe N. (2000) First known tibia of an early Javanese transition constrains the age of Javanese Homo erectus in the hominid. Current Anthropology, 41: 297–300. Sangiran dome, Indonesia. Proceedings of the National Acad- Oppenoorth W.F.F. (1932) Homo (Javanthropus) soloensis, een emy of Sciences of the United States of America, 108: 19563– pleistoceene mensch van Java. Wetesch Mededee. Dienst 19568. Mijnbauw Nederl Indie, 20: 49–74. Indriati E. and Antón S.C. (2010) The calvaria of Sangiran 38, Qiu Z.L., Gu Y.M., Zhang Y.Y., and Zhang S.S. (1973) New discov- Sendangbusik, Sangiran Dome, Java. HOMO—Journal of ery of the fossils and cultural remains of Sinanthropus pekin- Comparative Human Biology, 61: 225–243. ensis from Zhoukoudian. Vertebrata PalAsiatica, 11: 109–131 Indriati E., Swisher C.C., III, Lepre C., Quinn R.L., Suriyanto R.A., (In Chinese). Hascaryo A.T., Grün R., Feibel C.S., Pobiner B.L., Aubert M., Rightmire G.P., Lordkipanidze D., and Vekua A. (2006) Anatomi- Lees W., and Antón S.C. (2011) Age of the 20 Meter Solo cal descriptions, comparative studies and evolutionary signifi- River Terrace, Java, Indonesia and the survival of Homo cance of the hominin skulls from Dmanisi, Republic of Geor- erectus in Asia. PLoS ONE, 6: e21562. gia. Journal of Human Evolution, 50: 115–41. Itihara M., Sudijono, Kadar D., Shibasaki T., Kumai H., Yoshikawa Rohlf F.J. and Slice D. (1990) Extensions of the Procrustes method S., Aziz F., Soeradi T., Wikarno, Kadar A.P., Hashibuan F., and for the optimal superimposition of landmarks. Systematic Kagemori Y. (1985) Geology and stratigraphy of the Sangiran Zoology, 39: 40–59. Vol. 125, 2017 CRANIAL SHAPE IN INDONESIAN HOMO ERECTUS 83

Santa Luca A.P. (1980) The Ngandong Fossil Humans: A Compar- Walker A.C. and Leakey R.E.F. (1993) The Skull. In: Walker A.L. ative Study of a Far Eastern Homo erectus Group. Yale Uni- and Leakey R.E.F. (eds.), The Nariokotome Homo erectus versity Press, New Haven, CT. Skeleton. Harvard University Press, Cambridge, MA, pp. 63– Sartono S. (1991) A new Homo erectus skull from Ngawi, east 94. Java. Indo-Pacific Prehistory Association Bulletin, 11: 14–22. Weidenreich F. (1940) Some problems dealing with ancient man. Sartono S. and Tyler D.E. (1993) A new Homo erectus skull from American Anthropologist, 42: 375–383. Sangiran, Java: an announcement. International Conference Weidenreich F. (1943) The skull of Sinanthropus pekinensis: a on Human Paleoecology, 1–4. comparative study on a primitive hominid skull. Palaeontolo- Schwartz J.H. and Tattersall I. (2005) The Human Fossil Record. gia Sinica Series D, 10: 1–298. Vol. 4: Craniodental Morphology of Early Hominids (Genera Weidenreich F. (1951) Morphology of Solo Man. Anthropological Australopithecus, Paranthropus, Orrorin) and Overview. Papers of the American Museum of Natural History, 43: 222– Wiley-Liss, New York. 288. Sémah F. (1984) The Sangiran dome in the Javanese Plio-Pleistocene Widianto H. and Grimaud-Herve D. (2000) Un nouveau crâne hu- chronology. Courier Forschungsinstitut Senckenberg, 69: main fossile dans le dôme de Sangiran (Java, Indonésie). 245–252. Comptes Rendus de l’Academie des Sciences Series IIA Earth Sémah F., Falgueres C., Yokoyama Y., Féraud G., Saleki H., and and Planetary Science, 330: 883–888. Djubiantono T. (1997) Arriveé et disparition des Homo erectus Widianto H. and Zeitoun V. (2003) Morphological description, bi- à Java, les données actuelles. Abstracts of the Third Meeting ometry and phylogenetic position of the skull of Ngawi 1 of the European Association of Archaeologists, 11–12. (East Java, Indonesia). International Journal of Osteoarchae- Shen G., Gao X., Gao B., and Granger D.E. (2009) Age of Zhouk- ology, 13: 339–351. oudian Homo erectus determined with 26Al/10Be burial dat- Widianto H., Sémah A.M., Djubiantono T., and Sémah F. (1994) A ing. Nature, 458: 198–200. tentative reconstruction of the cranial human remains of Han- Suzuki M. and Wikarno (1982) Fission-tracks ages of pumice tuff, oman 1 from Bukuran, Sangiran (Central Java). Courier tuff layers and Javites of hominid bearing formations in San- Forschungsinstitut Senckenberg, 171: 47–59. giran, Central Java. Communications of the XI International Widianto H., Grimaud-Herve D., and Sartono S. (2001) The evolu- Congress of INQUA, 2: 322. tionary position of the Ngawi calvaria. Indo-Pacific Prehistory Suzuki M., Wikarno, Budisantoso, Saefudin I., and Itihara M. Association Bulletin, 21: 162–169. (1985) Fission track ages of pumice tuff, tuff layers and Wolpoff M.H. (1999) Paleoanthropology. McGraw-Hill, Boston, Javites of hominid fossil bearing formations in Sangiran area, MA. Central Java. In: Watanabe N. and Kadar D. (eds.), Quaternary Wolpoff M.H., Thorne A.G., Jelínek J., and Zhang Y. (1994) The Geology of the Hominid Fossil Bearing Formations in Java. case for sinking Homo erectus. 100 years of Pithecanthropus Geological Research and Development Center Bandung, Spe- is enough! Courier Forschungs-Institute Senckenberg, 171: cial Publication 4, pp. 309–357. 341–361. Swisher C.C., III, Curtis G.H., Jacob T., Getty A.G., Suprijo A., and Wu X., Schepartz L.A., and Liu W. (2010) A new Homo erectus Widiasmoro (1994) The age of the earliest hominids in Java, (Zhoukoudian V) brain endocast from China. Proceedings of Indonesia. Science, 263: 1118–1121. the Royal Society B: Biological Sciences, 277: 337–344. Swisher C.C., III, Rink W.J., Antón S.C., Schwarcz H.P., Curtis Yokoyama Y., Falguères C., Sémah F., Jacob T., and Grün R. G.H., Suprijo A., and Widiasmoro (1996) Latest Homo erectus (2008) Gamma-ray spectrometric dating of late Homo erectus of Java: potential contemporaneity with Homo sapiens in skulls from Ngandong and Sambungmacan, Central Java, In- southeast Asia. Science, 274: 1870–1874. donesia. Journal of Human Evolution, 55: 274–277. Tattersall I. and Schwartz J.H. (2009) Evolution of the genus Zaim Y., Ciochon R.L., Polanski J.M., Grine F.E., Bettis E.A., Homo. Annual Review of Earth and Planetary Sciences, 37: Rizal Y., Franciscus R.G., Larick R.R., Heizler M., Aswan, 67–92. Eaves K.L., and Marsh H.E. (2011) New 1.5 million-year-old van den Bergh G.D., de Vos J., and Sondaar P.Y. (2001) The Late Homo erectus maxilla from Sangiran (Central Java, Indone- Quaternary palaeogeography of mammal evolution in the In- sia). Journal of Human Evolution, 61: 363–376. donesian Archipelago. Palaeogeography, Palaeoclimatology, Zeitoun V., Détroit F., Grimaud-Hervé D., and Widianto H. (2010) Palaeoecology, 171: 385–408. Solo man in question: Convergent views to split Indonesian von Koenigswald G.H.R. (1934) Zur Stratigraphie des javanischen Homo erectus in two categories. Quaternary International, Pleistocän. De Ingenieur in Nederlandsch-Indie, 1: 185–201. 223–224: 281–292.