new 1.5 million-year-old homo erectus maxilla from sangiran

lable at ScienceDirect

Journal of Human Evolution 61 (2011) 363e376

Contents lists avai

Journal of Human Evolution

journal homepage: www.elsevier .com/locate/ jhevol

New 1.5 million-year-old Homo erectus maxilla from Sangiran(Central Java, Indonesia)

Yahdi Zaim a, Russell L. Ciochon b,*, Joshua M. Polanski c, Frederick E. Grine d, E. Arthur Bettis III e,Yan Rizal a, Robert G. Franciscus f, Roy R. Larick g, Matthew Heizler h, Aswan a, K. Lindsay Eaves f,Hannah E. Marsh f

aDepartment of Geology, Institute of Technology Bandung, Bandung, Java 40132, IndonesiabDepartment of Anthropology and Museum of Natural History, Macbride Hall, University of Iowa, Iowa City, IA 52242, USAcDepartment of Anthropology, University of Arkansas, Fayetteville, AR 72701, USAdDepartments of Anthropology and Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794, USAeDepartment of Geoscience, University of Iowa, Iowa City, IA 52242, USAfDepartment of Anthropology, University of Iowa, Iowa City, IA 52242, USAgHelios Laser, 160 East 238th Street, Euclid, OH 44123, USAhNew Mexico Bureau of Mines and Mineral Resources, Socorro, NM 87801, USA

a r t i c l e i n f o

Article history:Received 9 January 2009Accepted 23 April 2011

Keywords:Southeast AsiaHominin evolutionHomo habilisGrenzbank ZoneBapang formationSangiran formation40Ar/39Ar datingZhoukoudianDmanisi

* Corresponding author.E-mail address: [email protected] (R.L. C

0047-2484/$ e see front matter � 2011 Elsevier Ltd.doi:10.1016/j.jhevol.2011.04.009

a b s t r a c t

Sangiran (Solo Basin, Central Java, Indonesia) is the singular Homo erectus fossil locale for Early Pleis-tocene Southeast Asia. Sangiran is the source for more than 80 specimens in deposits with 40Ar/39Ar agesof 1.51e0.9 Ma. In April 2001, we recovered a H. erectus left maxilla fragment (preserving P3- M2) fromthe Sangiran site of Bapang. The find spot lies at the base of the Bapang Formation type section incemented gravelly sands traditionally called the Grenzbank Zone. Two meters above the find spot,pumice hornblende has produced an 40Ar/39Ar age of 1.51 � 0.08 Ma. With the addition of Bpg 2001.04,Sangiran now has five H. erectus maxillae. We compare the new maxilla with homologs representingSangiran H. erectus, Zhoukoudian H. erectus, Western H. erectus (pooled African and Georgian specimens),and Homo habilis. Greatest contrast is with the Zhoukoudian maxillae, which appear to exhibit a derivedpattern of premolar-molar relationships compared to Western and Sangiran H. erectus. The dentalpatterns suggest distinct demic origins for the earlier H. erectus populations represented at Sangiran andthe later population represented at Zhoukoudian. These two east Asian populations, separated by5000 km and nearly 800 k.yr., may have had separate origins from different African/west Eurasianpopulations.

� 2011 Elsevier Ltd. All rights reserved.

Introduction

Originally published under various names, Homo erectus fossilswere first found in the Far East at Trinil (in 1891), Zhoukoudian (in1921), and Sangiran (in 1937). Initially, an East Asia origin for thespecies was deemed probable, but as African paleoanthropologyascended during the 1960s, the origins and taxonomy of H. erectusbecame largely an Afro-centric topic, with East Asian fossils rep-resenting a dispersal endpoint. However, as Eurasian paleoan-thropology resurged during the 1990s, the spatial center-of-gravityfor H. erectus has again shifted eastward. Three Eurasian sites now

iochon).

All rights reserved.

account for the vastmajority ofH. erectus fossils: Dmanisi, Sangiran,and Zhoukoudian. While the assumption remains that H. erectusemerged from an African hominin, the species had its greatest, and,possibly, earliest presence across southern Eurasia (see also Lepreand Kent, 2010). Here, we present a new Sangiran maxilla,increasing the number and known morphometric variation of JavaH. erectus specimens.

In 1998, the Institute of Technology Bandung and the Universityof Iowa began joint interdisciplinary research at Sangiran (CentralJava, Indonesia). The program has focused on the hominin-bearingsedimentary sequence of the upper portion of the SangiranFormation and the overlying Bapang Formation. More than 80H. erectus fossils have been found in this sequence. The earliestH. erectus are found in sediments ranging in age from >1.5 Mathrough to about 0.9Ma (Larick et al., 2001; Ciochon et al., 2001). At

mailto:[email protected]

www.sciencedirect.com/science/journal/00472484

http://www.elsevier.com/locate/jhevol

http://dx.doi.org/10.1016/j.jhevol.2011.04.009



Y. Zaim et al. / Journal of Human Evolution 61 (2011) 363e376364

Sangiran, the research focus has since turned to understanding thelocal conditions that sustained H. erectus on Sunda, the earlyPleistocene emergent landmass currently represented by theIndonesian and Philippine archipelagos (Ciochon et al., 2003, 2007;Bettis et al., 2004, 2009a; Dizon and Pawlik, 2010; Larick andCiochon, 2012). Sangiran is the only site that represents the earlyPleistocene H. erectus population across all Southeast Asia. Workcommenced with 40Ar/39Ar age analysis of volcanic heavyminerals,and interpreting the stratigraphic sequence as a set of sedimentarycycles.

On April 22, 2001, local team member, Samingan, recovereda partial H. erectus maxilla (Bpg 2001.04) at the base of the BapangFormation reference section, in a unit traditionally known as theGrenzbank Zone (Larick et al., 2000). The find spot lay about 2 mbelowa level fromwhich pumice hornblende produced an 40Ar/39Arage of 1.51 � 0.08 Ma (Ciochon et al., 2005). The incontestableprovenience linked directlywith dated volcanicmaterial makes thismaxilla one of the oldest Sangiran dentate specimens. It lies withinthe geochronological range ofH. erectus in Africa, and is twice as oldas the oldest fromZhoukoudian inNortheast Asia (Shen et al., 2009).

Along with specimens S4, S17, S27 and Tjg 1993.05, Bpg 2001.04represents thefifthH. erectusmaxilla recovered fromSangiran.Here,wedescribe the specimenand its local geological andenvironmentalcontext.We then turn to inter-site quantitative comparisons of basicmaxillary dental morphology. Bpg 2001.04 is compared with theother Sangiran maxillary specimens, and with homologous mate-rials from Northeast Asia, Southwest Eurasia, and Africa.

Figure 1. (a) Plan view showing the location and regional geology of the Sangiran Dome inexplained in the key. Hominin find spots are depicted with a skull, calvaria, or mandible, a

Geological and paleoclimate background

H. erectus fossils are found in a long succession of lowlanddeposits exposed in the Sangiran area of Central Java (Figure 1a).The upper reaches of the Sangiran Formation contain the oldestH. erectus fossils in Southeast Asia, dating to 1.6 Ma, while theoverlying Bapang Formation has yielded a large number of H. erec-tus remains dating to 1.5e0.9 Ma (Larick et al., 2001). During thisperiod, depositional environments change from lake margin andmarsh to riverine. The oldest H. erectus fossils occur as onecomponent of the fully terrestrial and endemic island-type Ci Saatfauna, which occurs within dark-colored siltstones and mudstonesin the upper reaches of the Sangiran Formation (Watanabe andKadar, 1985; de Vos et al., 1994; Larick et al., 2001; Ciochon et al.,2003; Bettis et al., 2004). When H. erectus first arrived in the San-giran area, sometime between 1.66 Ma and 1.57 Ma, streamsdraining nearby volcanic highlands intermittently flooded the lakemargins and marshes, and occasional volcanic eruptions depositedthin blankets of ash (Swisher, 1997, 1999; Bettis et al., 2004).Freshwater lake-edge and marsh environments supported sedges,ferns, water-tolerant grasses, and trees (Sémah, 1984; Tonkunagaet al., 1985), in addition to a variety of aquatic and semi-aquaticvertebrate (Hexaprotodon, various cervids, crocodiles, turtles, andfish) and invertebrate species. Wet grasslands with scatteredshrubs occupied slightly higher parts of the Early Pleistocenelandscape, where water tables fluctuated from near the landsurface to a depth of about 1 m on an annual basis (Bettis et al.,

Central Java. The formations within the large dome map are delineated by the colors ass appropriate. (b) Satellite image of the Bapang site and the Bpg 2001.04 find spot.

Y. Zaim et al. / Journal of Human Evolution 61 (2011) 363e376 365

2009a). Still higher, better-drained parts of the landscape sup-ported savanna vegetation, which was most likely dominated bysedges, grass, and ferns with scattered trees.

Between 1.6 Ma and 1.5 Ma, large streams draining volcanichighlands to the northwest and southeast began to locally scourand fill in the lowland in the Sangiran area (Larick et al., 2001; Bettiset al., 2004, 2009a). Local variations in stream flow and channelcharacteristics and distance from river channels were importantelements that influenced the depth of scour, the nature of sedimentthat accumulated and that controlled edaphic conditions andvegetation patterns during this time. Riparian forest occupied theactive channel belt where shifting channels left many sandbars andshallow abandoned channels, low-lying and frequently floodedareas supported a moist savanna with scattered trees and shrubs,and well-drained terraces and valley slopes were covered withopenwoodlands (Ciochon et al., 2007; Bettis et al., 2009a). It was inthis setting that the hominin reported here lived at about 1.5 Ma. Inaddition to H. erectus, these environments supported the Trinil H.K.fauna represented by Panthera, various cervids, Sus branchygnatus,and primates (Larick et al., 2000, 2001; van den Bergh et al., 2001).

Locally, the Bapang Formation is conformably overlain by fluvialdeposits of the Pohjajar Formation that have a higher proportion ofair-fall tuffs, fluvially reworked ash fall, and lahar-formeddiamictons.

Stratigraphy and dating of the Bpg 2001.04 locality

The Bpg 2001.04 H. erectus maxilla was found in the basalBapang Formation eroding from a carbonate-cemented, pebblychannel sand, which has traditionally been called the GrenzbankZone, near the low-relief erosional contact between the Bapang and

Figure 2. (a) Bapang Formation stratigraphy, dating, and sedimentary cycles. The Bpg 200stratigraphic section showing the precise Bpg 2001.04 find spot in the Grenzbank Zone, 2 m

Sangiran Formations (Figures 1b and 2aeb). At the find spot, thiscemented zone occupies the central portion of a shallow fluvialchannel locally cut into a 20�40 cm-thick basal Bapang Formationmatrix-supported conglomerate, dominated by rip-up clastsderived from the underlying Sangiran Formation siltstones andmudstones. The maxilla was located in the upper meter of thechannel sand approximately 20 cm above the contact with theSangiran Formation (Figure 2a; UTM Zone 49 483990E 9174670N).A modern intermittent stream has cut through overlying depositsand exposed the channel sands just north of the find spot. Thecemented channel sands grade laterally into uncemented troughcrossbedded pebbly sand that is overlain by a silt-filled trough thatcontains lenses of reworked tuff (Figure 2a). The silts are overlainby trough crossbedded pebbly sand with lenses of epiclasticpumice. The 40Ar/39Ar date of 1.51 � 0.08 Ma was obtained onhornblende extracted from pumice in one of these lenses strati-graphically about 2m above and 45m northwest of themaxilla findsite. This date agrees well with a 40Ar/39Ar age of 1.58 � 0.02 Mafrom the basal Bapang Formation in the same stratigraphic section(Swisher, 1997, 1999) as well as other 40Ar/39Ar ages from theH. erectus-bearing interval in Sangiran (Larick et al., 2001; Ciochonet al., 2001; Bettis et al., 2004).

The sediment at the discovery site is a poorly sorted, subangularto subrounded, carbonate-cemented, volcaniclastic sandstone thatcontains a few granules. The sandstone is composed of a variety ofintermediate igneous rock fragments (granodiorite, diorite, anddacite, but dominantly andesite), as well as welded tuff and pumice,with subordinate amounts of sedimentary rock fragments such assandstone, limestone, quartzite, phyllite, and fragments of erodedcarbonate nodules. The sand and granule matrix is cemented bysparry calcite with euhedral to subeuhedral crystal development.

1.04 find spot, at the base of the section, is depicted with a white star. (b) Detailedbelow the pumice horizon dated to 1.51 � 0.08 Ma.


Similar sediment fills themaxillary sinus floor of Bpg 2001.04, tyingthe specimen to this localized stratigraphic horizon (see Figure 3dand comparative description below).

The composition of this fluvial sandstone indicates that itsclastic grains were derived dominantly from volcanic sources. Thefresh appearance of individual feldspar crystals indicates that thegrains underwent little to no chemical weathering prior to, during,and subsequent to transport from volcanic highlands into the SoloBasin. Cementation by carbonate occurred at a later date asa precipitate from calcite-saturated groundwater preferentiallymoving through the coarse channel sands at the Bapang/Sangirancontact. Cementation, the primary distinguishing characteristic ofthe Grenzbank Zone, is a horizontally discontinuous, post-depositional phenomenon formed in a geochemical environmentthat postdates the affected sediment. The cementation has norelationship to the age of the affected sediment, and we have

Figure 3. Bpg 2001.04 maxilla: (a) occlusal aspect; (b) buccal aspect; (c) lingual aspe

observed similar cemented sediments in other stratigraphic posi-tions in Pleistocene deposits elsewhere in Central Java. Thus, theGrenzbank Zone should not be considered a stratigraphic markerbed as has been done in the past (e.g., Sudijono, 1985).

Approximately 15% of the 80 H. erectus specimens recovered inSangiran have provenience in the thin zone of cemented GrenzbankZone sediments at the base of the Bapang Formation (Larick et al.,2004). Though fluvial reworking that concentrated fossilsoccurred throughout accumulation of the Bapang Formation, theprocess was enhanced during development of the fluvial erosionsurface that marks the contact between the Sangiran and BapangFormations. This erosion surface, and another marking the contactbetween the Bapang and overlying Pohjajar Formation, representperiods of net sediment removal from the Sangiran area (Bettiset al., 2009b). During these periods, heavy clasts, including largevertebrate fossils, were concentrated and subjected to multiple

ct; (d) superior aspect; (e) anterior aspect; (f) posterior aspect. Scale bar is 1 cm.


reworking events that generally resulted in breakage and selectiveremoval of less dense elements. The general absence in the basalBapang Formation of low-density skeletal elements such as cal-variae, the common occurrence of mandibular and maxillary frag-ments and teeth, and the overall concentration of fossils in thiszone is a product of these geologic processes.

Comparative description

Root of the zygomatic arch

The zygomatic root arises opposite the M1 and follows a gentleupward curve (Figure 3aef). In this respect, its configuration isreminiscent of that exhibited by Sangiran 17 (H. erectus), theeastern and southern African specimens KNM-WT 15000 and SK847 (H. erectus) (but see Grine et al., [1996] for an alternate taxo-nomic placement for SK 847), and the D2282 and D2700 craniafrom Dmanisi, Georgia (H. erectus). The arch of Bpg 2001.04 differsnoticeably from the tightly curved zygomatics of ZhoukoudianSkulls XIII and IX.

In its placement, the arch arises at the same level as the zygo-matics in Sangiran 17, Zhoukoudian Skulls XIII and IX, andSwartkrans SK 847. The KNM-WT 15000 subadult zygomatic archarises more anteriorly, at the level of P3� P4. Although the zygo-matic root of Bpg 2001.04 is incomplete, it appears to have beenrather thin anteroposteriorly (c.16�18mm). This contrasts with therobust arches of Sangiran 17 (c. 26 mm) and KNM-WT 15000 (c.22�23 mm), and is more similar to those of Skull XIII (c. 21 mm)and SK 847 (16 mm). The inferior surface of the zygomatic arch ofBpg 2001.04 appears to level off at about 14 mm above the buccal

Figure 4. Computed tomography (CT) virtual reconstruction of Bpg 2001.04. (a) Posterior viM2 lingual root. (b) Scan of maxilla fragment, looking posteriorly at the sinus in-filled with mM2, the arrow points to the lingual root of M2 without the encompassing matrix. (d) View wiarrow again indicates the M2 lingual root. [CT scanning by Yahdi Zaim in Bandung. Slice th

cervical margin of the M1. In this respect, it is similar to the archesof Sangiran 17 (c. 12 mm) and Zhoukoudian Skulls XIII and IX (13.0and 14.5 mm, respectively), and lower than in KNM-WT 15000 (c.17 mm) and especially SK 847 (est. 21.5 mm).

The maxillary sinus

The maxillary sinus can be viewed in computed tomography(CT) scans by segmenting the bone from the less dense gravelmatrix that covers the sinus (Figure 4aed). The anterior extent ofthe sinus is a vertical coronal wall superior to the posterior half ofP4, possibly similar to A.L. 666-1 when viewed in profile (Kimbelet al., 1997). The sinus extends into the root of the zygomaticarch, although the lateral, posterior, and medial extent of the sinuscannot be fully determined due to fragmentation of the fossil. Thesinus fills the observable mid-facial region, but does not inflate theexternal mid-face, or create a short, sloping region between theanterior sinus and the root of the zygomatic arch, which is seen inHomo aff. Homo habilis (Kimbel et al., 1997). The chamber isperforated by the lingual roots of M1 and M2 (Figure 4c). Unlike theA.L. 666-1maxilla, inwhich the sinus is partitioned into 2 chambers(Kimbel et al., 1997), the Bpg 2001.04 sinus is not partitioned.

The maxillary alveolus

The specimen exhibits a very slight degree of physiologicalalveolar resorption, particularly lingually. Palatal depth cannot bemeasured from the original, but appears rather shallow. In thisrespect, the specimen resembles Sangiran 17 more closely thaneither Sangiran 4 or Sangiran 1a.

ew of the original maxillary fragment with matrix-filled sinus. The arrow indicates theatrix. The arrow points to a bump created by the lingual root of M2. (c) Posterior view ofth matrix removed from the left maxillary sinus. The rim of the sinus is highlighted. Theickness: 1.3 mm].

Table 1List of mesio-distal (MD) and bucco-lingual (BL) measurements (mm) for Bpg 2001.04 and for the Homo specimens used in these analyses. TheWesternH. erectus sample poolsthe Dmanisi and Africa specimens. Specimen numbers in boldface indicate complete dentitions for this study; “?” refers to isolated teeth with side-indeterminate. Additionally,parenthetical numbers indicate estimates.

Specimen Side P3 P4 M1 M2

MD/BL MD/BL MD/BL MD/BL

Bpg 2001.04 L 8.1 11.3 7.6 12.2 12.5 13.5 12.5 13.8

Sangiran H. erectusS 7-3a, b, ca R 7.3 10.2 11.0 12.5 11.6 12.5S 7-8a L 11.5 12.6S 7-9 a R 12.0 13.4S 7-10b R 11.6 12.0S 7-27c L 7.8 10.4S 7-29a R 8.2 10.3S 7-30a R 7.9 10.2S 7-31a L 7.9 10.6S 7-32a R 7.9 10.8S 7-35a L 8.5 12.2S 7-37d R 11.4 12.5S 7-38a L 12.8 13.9S 7-40a R 13.6 13.8S 7-53a L 13.5 14.0S 7-58a L 9.1 11.5Sangiran 4c AVG 8.4 12.4 8.4 12.2 12.2 13.6 13.6 15.2Sangiran 15Ae L 7.8 11.0Sangiran 15Be R 7.5 10.1Sangiran 16f L 7.1 9.9Sangiran 17g AVG 7.2 10.6 10.8 12.6 10.7 12.5Sangiran 27h AVG 8.9 12.8 7.3 12.4 11.9 14.5 12.9 14.8Tjg 1993.05, Skull IXi R 10.1 9.5 7.2 11.3 11.0 10.6 10.9Zhoukoudian H. erectusZdn Skull Vj L 8.5 12.2 7.0 11.0 10.5 12.0 10.0 11.9Zdn Skull XIf AVG 7.4 10.5 7.4 11.0 10.0 12.0 10.3 12.8Zdn Skull XIIIk L 8.0 11.6 7.3 11.1 10.6 12.4 10.6 13.4Zhoukoudian 104l R 10.3 12.8Zhoukoudian 105l L 10.2 12.8Zhoukoudian 133l L 8.8 11.7Zhoukoudian 140l L 11.1 13.7Zhoukoudian 142j ? 8.0 11.6Zhoukoudian 143l L 7.3 11.1Zhoukoudian 144l ? 10.6 12.4Zhoukoudian 145l ? 10.6 13.4Zhoukoudian 19f R 9.2 12.8Zhoukoudian 25l L 7.9 11.3Zhoukoudian 26l ? 8.3 11.2Zhoukoudian 27l L 8.3 12.1Zhoukoudian 28l R 7.2 10.3Zhoukoudian 32l R 11.3 11.7Zhoukoudian 33l L 12.1 13.4Zhoukoudian 39f ? 10.5 12.3Zhoukoudian 40f L 12.2 12.2Zhoukoudian 41f L 11.1 13.2Zhoukoudian 42f R 11.4 12.4Zhoukoudian 77f L 8.7 12.6Zhoukoudian 78f R 7.4 10.5Zhoukoudian 86l ? 8.9 12.5Zhoukoudian 87l R 7.3 10.8Zhoukoudian 88j L 7.4 11.2Zhoukoudian 94j R 10.0 11.7Zhoukoudian 95j L 10.2 12.3Western H. erectus (Dmanisi and Africa)D2700m AVG 8.9 11.5 6.8 11.5 13.0 13.1 12.7 12.9D2282n AVG 9.2 11.0 12.5 12.9 12.5 12.1KNM-ER 1808l L 8.5 13.8 11.5 13.0KNM-ER 3733l AVG 8.7 12.0 8.1 12.1 12.3 12.4 13.9KNM-ER 807l R (13) (14) (14)KNM-ER 808o R 8.7 12.5 13.2 13.0KNM-WT 15000l AVG 8.6 11.8 8.3 11.8 11.8 12.2 13.4 12.2OH 38p AVG 9.6 12.9SE 255f,* R 13.4 13.2SK 27c, * L 9.6 13.3 13.5 13.7 13.7 14.7SKX 268q, * 13.2 12.9H. habilis (Eastern Africa)*KNM-ER 1506r R 8.3 11.9 9.1 12.2KNM-ER 1805f AVG 8.0 11.5 9.0 11.6 13.2 13.4 13.1 14.3KNM-ER 1813l L 8.0 11.1 9.0 11.3 12.2 12.5 12.2 13.6OH 13e R 8.3 11.4 8.7 11.5 12.5 12.6 12.8 13.8


OH 65s AVG 9.3 12.7 9.1 13.1 12.8 13.6 13.1 14.4Omo L894-1f AVG 8.8 12.7 9.2 12.2 12.7 13.2 11.8 12.6KNM-ER 42703s R 9.0 12.0 8.8 12.4 12.6 13.3 13.0 14.1

*For this study, we define Homo habilis as an eastern African early hominin with a temporal range between 1.9 and 1.6 Ma, thus A.L. 666-1 is excluded from our sample. Thereare specimens from South Africa that have been described as Homo aff. H. habilis or as Homo erectus. At Swartkrans, SK 27 and SKX 268 have been suggested by some to belongto a taxon with closer affinities to H. habilis (sensu stricto) than to H. erectus (e.g., Howell, 1978; Grine et al., 2009). However, for the purpose of this study, we have followedothers (e.g., Rightmire, 1990) who have included SK 27 and SKX 268 in Homo erectus. Similarly, at Sterkfontein, SE 255 derives from Member 5 “West” and while it mightrepresent H. erectus, many workers have considered it to represent the same species as Stw 53 (i.e., something with closer affinities to Homo habilis). Of course, the Member 5deposit is not a single deposit, and it does contain material that is most likely attributable to H. erectus (e.g., the Stw 80 mandible from Member 5 “West” [Kuman and Clarke,2000; Moggi-Cecchi et al., 2006]). Thus, while it is not unreasonable to place SE 255 in the H. erectus sample as we have done, we wish to point out that there is a controversyover the species attribution in Sterkfontein Member 5. That is, Australopithecus sp. for some of the material (Kuman and Clarke, 2000), Homo aff. H. habilis (Tobias, 1978) forsome of the material (at least that from Member 5A), and H. erectus for some of the material (at least that from Member 5B, or Member 5 “West”) (Kuman and Clarke, 2000).

a Grine and Franzen, 1994.b Tobias and von Koenigswald, 1964.c Wolpoff, 1971.d Dean, 2007.e Blumenberg and Lloyd, 1993.f Wood, 1991.g Jacob, 1975.h Indriati and Antón, 2008.i Arif, 1998; Arif et al., 2001.j Weidenreich, 1937a.k Weidenreich, 1937b.l Walker and Leakey, 1993.

m Rightmire et al., 2006n Martínon-Torres et al., 2008.o Leakey et al., 1978.p Tobias, 1968.q Grine, 1989.r Boaz and Howell, 1977.s Spoor et al., 2007.


Dental morphology and crown size

The P3 crown has an ovorectangular occlusal outline, witha slightly dominant paracone (Figure 3a). The mesial marginalridge, which is slightly thicker than the distal marginal ridge, isincised by a narrow furrow such that the mesial end of the longi-tudinal furrow between the paracone and protocone is open. Themesial surface preserves a 3 mm long, oblong contact facet for thecanine. Occlusal wear is slight to moderate; both cusps are blunted,and there is a small dentine exposure in the center of the paracone.Its mesio-distal (MD) diameter is 8.1 mm. The bucco-lingual (BL)diameter is 11.3 mm.

The crown of P4 also presents an ovorectangular outline, thoughthe lingual face of the protocone is skewed very slightly mesially(Figure 3a). The protocone and paracone are approximately equal insize. The mesial and distal marginal ridges are complete, but low,and the longitudinal furrow between the paracone and protoconecuts through the lingual end of the principal paracone crest, thusseparating it from the protocone. Occlusal wear is slight; both cuspsare blunted, but dentine is not exposed. It measures 7.6 mm MD.The BL diameter is 12.2 mm.

The crown of M1 has a nearly square occlusal outline, witha more prominent mesio-buccal corner compared to the dis-tobuccal corner (Figure 3a). The BL breadth across the trigon(13.5 mm) is slightly greater than across the talon (12.4 mm). Thefour principal cusps are well developed: the protocone is thelargest, and the paracone, metacone, and hypocone are of approx-imately equal size. The distal marginal ridge is thin and incised atthe base of the metacone by a very narrow fissure. The cristaobliqua appears to have been complete, although constricted. Themesio-lingual and lingual aspects of the protocone preserve short,slightly oblique fissures at the occlusal margin that represent theremnants of the Carabelli trait. This feature would likely have beenfairly large based on the distance between the furrows (3.7 mm).Occlusal wear is moderate. The lingual cusps have been reduced toa flat platform and the buccal cusps are rounded. The paracone,metacone, and hypocone exhibit small dentine islands, and there is

moderate, concave exposure on the protocone. The MD diameter ofthe crown is 12.5 mm. The maximum BL diameter is 13.5 mm.

The crown of M2 has a square occlusal outline, although thedistobuccal corner is very slightly reduced (Figure 3a). The BLbreadth of the trigon (13.7 mm) is somewhat greater than acrossthe talon (12.3 mm). The four principal cusps are present, and theprotocone is the largest, followed closely by the paracone. Thehypocone is considerably smaller than the paracone, and the met-acone is reduced, making it the smallest cusp. The mesial marginalridge, while worn, appears to have been thick and is complete. Thethinner distal marginal ridge is complete, and encloses a foveaposterior (talon basin) that takes the form of a narrow T-shapedfissure, the tines of which comprise a transverse fissure distal to theprincipal crests of the metacone and hypocone. The crista obliqua isincised by a narrow furrow. There is no evidence of the presence ofthe Carabelli trait. Occlusal wear is slight, with all cusps reducedand rounded, though dentine is not exposed. The distal surfacepreserves a slightly concave, moderately broad (c. 5 mm) contactfacet for the M3 (Figure 3f). The MD diameter of the crown is12.5 mm. The maximum BL diameter is 13.8 mm.

Materials and methods

Odontometric comparisons

The MD, BL, and crown area (CA ¼ MD � BL) dimensions of Bpg2001.04, and means for these measurements in several compara-tive samples, were used to create individual tooth profile graphs toinvestigate trends in size differences of P3�M2 following themethods advocated by Rosas and Bermúdez de Castro (1998). Assuch, most of the comparisons involve shape using InterdentalIndices to characterize crown shape relationships (Rosas andBermúdez de Castro, 1998; Bermúdez de Castro et al., 1999) andAverage Dental Ratios (Bermúdez de Castro et al., 1999). To this end,we calculated WF distances (F) to assess phenetic affinitiesfollowing Rosas and Bermúdez de Castro (1998) and Bermúdez de


Castro et al. (1999), and analyzed the WF distances by clusteranalysis using the statistical software package NCSS (Hintze, 2001).

Only 13 specimens of H. habilis and H. erectus preserve the samefour teeth as Bpg2001.04 (see boldface entries inTable 1). In order toincrease the comparative base, site samples using the mean valuesfor eachdimension of each toothwere constructed.We included anyspecimen that possessed at least one of the teeth preserved in Bpg2001.04, as long as it preserved both BL and MD dimensions. Spec-imens were assigned to one of four comparative samples, eachrepresenting a different Old World hominin population by site orregion: Sangiran H. erectus (Early Pleistocene Southeast Asia);Zhoukoudian H. erectus (Middle Pleistocene Northeast Asia);Western H. erectus (Early Pleistocene of Africa and Georgia [Dma-nisi]), and H. habilis (Plio-Pleistocene East Africa). The comparativesample groups range temporally from the Late Pliocene (1.9 Ma) tothe Middle Pleistocene (0.4e0.78 Ma) (Ciochon and Bettis, 2009;Shen et al., 2009) and derive from all areas of the Old World occu-pied by H. erectus (Kramer, 1993). Antón (2002) and Kaifu (2006)have emphasized the need to recognize regional and temporalvariation among Asian H. erectus samples. Although there isa decrease in mandibular post-canine tooth size during the entire600 k.yr. of SangiranH. erectus (Kaifu, 2006), our sample ofmaxillarydentition is derived from a 300 k.yr. portion of the total H. erectustemporal range; therefore we feel justified in including all relevantindividuals for comparison in order to maximize sample size.

The goals of the metric analyses performed here are descriptiveand do not test for statistical significance. This is because the indi-vidual comparative samples are too small to avoid Type-II compar-ison errors. Under these conditions, descriptive results that identifymetric patterns between samples and specimens and are suggestiveof overall trends are preferable to error-prone statistical tests.

Methodology

Raw measurements for the MD, BL, and crown area(CA ¼ MD � BL) dimensions in Bpg 2001.04, and means for thesemeasurements in the comparative samples (Table 1), are used tocreate individual tooth profile graphs to investigate trends in sizedifferences of P3�M2. It has been argued, however, that shape isa more useful indicator than size when taxonomic affinity is con-cerned (Rosas and Bermúdez de Castro, 1998); as such, most of thecomparisons in the present study involve shape using the followingmeasurements.Interdental indices Interdental indices (6 in total) were con-structed using the CAs for the preserved teeth (e.g., P3/P4) tocharacterize crown shape differences or similarities (Rosas andBermúdez de Castro, 1998; Bermúdez de Castro et al., 1999) ofeach comparative sample and Bpg 2001.04.Average dental ratios The relative differences in the proportions ofBpg 2001.04 relative to the comparative samples were investigatedusing “average dental ratios” (ADR) following Bermúdez de Castroet al. (1999). This methodology allows for comparison of therelative proportions of each dimension of each tooth in Bpg2001.04 to each dimension of each tooth in the comparativesample means. We use the following procedures. First, the rawdata are scaled relative to Bpg 2001.04 using the formula:ðBpg 2001:04Vi$2Þ=ðBpg 2001:04Vi þ SiÞ

whereVi is the rawdimensionof Bpg2001.04 (e.g., P3 BL) andSi is thesame dimension of the comparative sample mean (e.g., P3 BL forWestern H. erectus). The resulting value of this formula is thereforea size ratio between the comparative sample and Bpg 2001.04. Theformulahas avalueof 1.0 if theVi forBpg2001.04 is equal to thevalueof that same variable for the comparative sample (Si). If Si is larger

than that of Bpg 2001.04, the formula will yield a value of <1.0. Thevalues of the resulting formula for eachdimensionof each tooth (8 inall) are averaged together to form the average dental ratio (ADR). Ifthe ADR < 1.0, this indicates that, on average, the value for eachdimension of the comparative sample mean is greater than Bpg2001.04. These ADR values can be compared in scatter-plots relativeto the value from the original formula to investigate relative pro-portionality of each dimension of the individual teeth to Bpg2001.04. In the bivariate scatter-plots, points above the X ¼ Y lineimply that those specimens have proportionately lower values thanBpg 2001.04; those below the line have proportionately highervalues than Bpg 2001.04. The greater the difference between thevalue for the formula and theADR, the further fromtheX¼Y line thecomparative sample will be. While the interdental index values andthe ADR values are not independentdsince they are both based onthe same initial starting valuesdthe precise information eachconveys (i.e., specific crown shape differences among the separatepaleodemes vs. more precise information regarding why suchdifferences manifest) is useful in quantifying the crown shaperelationships of Bpg 2001.04 to the other samples.WF distance (F) WF distances, following Bermúdez de Castro et al.(1999), are defined as the variance (s2) of all the values for theformula: ðBpg 2001:04Vi$2Þ=ðBpg 2001:04Vi þ SiÞ; thus, theyrepresent the distance between a given comparative sample and Bpg2001.04. WF distances were also calculated for the comparativesamples relative to each other; e.g., the formula (SA 2)/(SA þ SB), is usedto compare H. erectus and H. habiliswhere SA ¼Western H. erectus andSB ¼ H. habilis for any of the individual dimensions of interest. Theresulting WF distances for all pairwise comparisons between samplesis used to assess the phenetic affinities following Rosas and Bermúdezde Castro (1998) and Bermúdez de Castro et al. (1999).Cluster analysis The WF distances are also used in cluster analysesto further assess overall phenetic similarity/dissimilarity in dentalcrown size and shape patterns among the comparative samples andBpg 2001.04. All analyses were performed using the statisticalsoftware package NCSS (Hintze, 2001).

Results

Individual tooth profile graphs

The BL measurements (Figure 5a) present three configurations.The first is of increasing length from the P3 to M2, as exemplified inBpg 2001.04. The second is of virtually no change in the breadthdimension from P3 to P4, as is seen in H. habilis and SangiranH. erectus. The third is of wide P3s followed by a decrease in the P4

breadth, a configuration shared by Western H. erectus and Zhou-koudian. In all three patterns, M1 is narrower than M2.

In the MD dimension (Figure 5b), all the samples show the samepattern of decrease in size from P3 to P4, with the exception ofH. habilis, which possesses the opposite pattern. In terms of molarlength, the samples and specimen are characterized by little to nochange in length from M1 to M2.

In the computed crown areas (Figure 5c), Bpg 2001.04 is char-acterized by a small increase in size from P3 to P4. The Sangiransample is characterized by virtually no change in crown areabetween the premolars, while Zhoukoudian andWestern H. erectusshow a decrease in crown area. H. habilis shows a large increase inpremolar crown area. All sample groups, except Western H. erectus,show an increase in molar crown area from M1 to M2.

Interdental indices

The interdental indices created from the computed crown areasare presented in Table 2. Bpg 2001.04 shows a premolar interdental

Figure 5. Individual tooth measurement (raw data) profiles for Bpg 2001.04 and mean values for H. erectus (early African, Sangiran, and Zhoukoudian) and H. habilis. From top left tobottom right, they include (a) bucco-lingual length (BL), (b) mesio-distal length (MD), and (c) computed crown area.


index of slightly less than 1.0, revealing that Bpg 2001.04 hasa slight increase in overall crown area from P3 to P4. This rela-tionship is not shared by any of the other comparative samples,save for H. habilis, which shows an even larger increase in crownarea. The three H. erectus samples are characterized by slightdecreases in P4 crown area, with Western and ZhoukoudianH. erectus showing a larger decrease than Sangiran. The molarinterdental index for Bpg 2001.04 shows a slight increase in crownarea from M1 to M2; this condition is shared with the othersamples, and is seen in the most extreme with Western H. erectusand H. habilis.

In the P3/M1 index, Bpg 2001.04 displays a third premolar crownarea which is roughly half the area of its M1. This same relationshipcan be seen with Sangiran H. erectus. Western H. erectus andH. habilis share similar values with each other for this index, witha P3 crown area roughly two-thirds the size of their M1 crown area.

Table 2Interdental indices created from computed crown areas of Bpg 2001.04 and thecomparative samples.

Specimen/Sample P3/P4 M1/M2 P3/M1 P3/M2 P4/M1 P4/M2

Bpg 2001.04 0.99 0.98 0.54 0.53 0.55 0.54Sangiran H. erectus 1.04 0.94 0.58 0.55 0.56 0.53Zhoukoudian H. erectus 1.09 0.98 0.72 0.70 0.66 0.64Western H. erectus 1.23 0.99 0.66 0.66 0.53 0.53H. habilis 0.94 0.94 0.61 0.58 0.65 0.61

Zhoukoudian is the most disparate, displaying a crown area for P3

that is roughly three-quarters the size of its M1 crown area.Specimen Bpg 2001.04 has a P3/M2 index of 0.53. The Sangiran

sample has a nearly identical ratio between these two teeth, andH. habilis has a similar value (0.58). Both theWestern H. erectus andZhoukoudian samples have larger ratios, with Zhoukoudian havingthe largest P3 crown area relative to its M2 crown area of anysample.

The P4/M1 of Bpg 2001.04 equals its P3/M1 index. This result isnot surprising given that the premolar crown area index was nearly1.0. It shares the same value for this index with the SangiranH. erectus sample, and the Western H. erectus sample. H. habilis andthe Zhoukoudian sample have similar index values, both of whichare larger than the Bpg 2001.04 index value.

The ratios for P4/M2 show that Bpg 2001.04, the Sangiransample, andWestern H. erectus sample are characterized by similarrelationships, that is, a fourth premolar with a crown area roughlyhalf the size of the crown area of the second molar. H. habilis andthe Zhoukoudian sample have a larger index for these two teeth,with a fourth premolar roughly two-thirds the size of the secondmolar.

Average dental ratios

P3 Bucco-lingually (Figure 6a), the distribution of the regionalsamples relative to Bpg 2001.04 shows both the WesternH. erectus and Zhoukoudian samples falling furthest from the line


in the lower quadrant, indicating that they are relatively larger inthis dimension than Bpg 2001.04. While H. habilis is close to theX ¼ Y line, Sangiran H. erectus falls directly on the line, indicatingthat Bpg 2001.04 and the Sangiran sample possess similar BLproportions.

In the MD dimension (Figure 6b), all samples fall below theX ¼ Y line, indicating that all three regional samples are pro-portionately larger in this dimension than Bpg 2001.04. The sampleclosest to the X¼ Y line, and therefore most similar to Bpg 2001.04,is H. habilis, followed closely by the Sangiran H. erectus sample.Zhoukoudian H. erectus andWestern H. erectus are further from theline, possessing relatively larger MD dimensions.P4 The BL dimension of Bpg 2001.04 (Figure 6c) is relatively largerthan the comparative samples, all of which fall above the X¼ Y line.While the comparative samples do fall close to the line, theZhoukoudian sample is closest, followed by H. habilis andWestern H. erectus. Sangiran H. erectus is furthest from the line,indicating that in this dimension, Bpg 2001.04 least resembles itslocal analogs.

Bpg 2001.04’s MD dimension (Figure 6d) is relatively smallerthan all the comparative samples. However, Western H. erectus andSangiran H. erectus fall closest to the X ¼ Y line, indicating thatthese two regional samples are generally similar to Bpg 2001.04 inthis dimension. The H. habilis sample, on the other hand, is locatedfar from the line, revealing that in the MD dimension, H. habilis isconsiderably larger than Bpg 2001.04. Zhoukoudian H. erectus fallsbelow the line, as well, and is relatively larger in this dimensionthan Bpg 2001.04.M1 Bpg 2001.04 is relatively larger than the comparative samplesin the BL dimension (Figure 7a), all of which fall above the X ¼ Yline. Western H. erectus and H. habilis are furthest above the line,indicating that these specimens are relatively smaller than Bpg

Figure 6. Bivariate scatter-plots of the average dental ratios (ADR) versus the values of eqpresented on top from left (a) bucco-lingual length, to right (b) mesio-distal length. P4 is pre

2001.04, with H. habilis being furthest from the line. Sangiran andZhoukoudian H. erectus are closer to the line than the Westernsamples, with Sangiran falling almost directly on the X ¼ Y line.The results show an Asian/African dichotomy, with the Asianspecimens having larger BL dimensions.

Like the BL relationship, the MD dimension (Figure 7b) of M1

shows that Bpg 2001.04 is relatively larger than most of thecomparative samples. Sangiran H. erectus, Western H. erectus andH. habilis all cluster tightly around the X ¼ Y line, with WesternH. erectus falling slightly under the X ¼ Y line, and therefore beingslightly larger in this dimension to Bpg 2001.04. Zhoukoudian isconsiderably smaller in this M1 dimension than Bpg 2001.04 or anyof the other samples, falling quite far above the line in the upperquadrant.M2 The results for BL analysis (Figure 7c) show that Bpg 2001.04possesses a relatively larger dimension, with the exception ofSangiran H. erectus. All of the samples show tight clusteringaround the line. Sangiran H. erectus is on the X ¼ Y line,indicating that this population is very similar in its BL dimensionto Bpg 2001.04. The next closest sample to the X ¼ Y line isH. habilis, followed by Zhoukoudian H. erectus, and finally,Western H. erectus, all of which are relatively smaller than Bpg2001.04 in the BL dimension.

The analysis of the MD dimension of M2 (Figure 7d) showsa nearly identical pattern to that of the MD dimension of M1.Again, H. habilis, Western H. erectus, and the Sangiran H. erectussamples cluster close to the line, with the placement of theH. habilis and Western H. erectus indicating that they are slightlysmaller than Bpg 2001.04. Sangiran is nearly identical to Bpg2001.04, being located just below the X ¼ Y line. Zhoukoudian fallsfar above the line, and its M2 is much smaller in the MD dimensionthan Bpg 2001.04.

uation 1 of the bucco-lingual (BL) and mesio-distal (MD) dimensions of P3eP4. P3 issented on the bottom from left (c) bucco-lingual length, to right (d) mesio-distal length.

Figure 7. Bivariate scatter-plots of the average dental ratios versus the values of equation 1 of the bucco-lingual (BL) and mesio-distal (MD) dimensions of M1eM2. M1 is presentedon top from left (a) bucco-lingual length, to right (b) mesio-distal length. M2 is presented on the bottom from left (c) bucco-lingual length, to right (d) mesio-distal length.


WF distances

Overall relationships between samples based on the WFdistance statistic are shown in Table 3. The smallest WF distancebetween Bpg 2001.04 and any of the other samples is with SangiranH. erectus, which is a reflection of the similarity between thesegroups on nearly all of the tooth dimensions. The next closest toBpg 2001.04 is Western H. erectus. H. habilis is the next most similarto Bpg 2001.04. Finally, ZhoukoudianH. erectus, more than 800 k. yr.younger than Bpg 2001.04, is the most dissimilar, and this is indi-cated by virtually all of the individual average dental ratios.

A cluster analysis based on the WF values found in Table 3, viathe unweighted pair-group method using the arithmetic averagesmethod (UPGMA), is shown in Figure 8. Twomain divisions presentthemselves; an older African-Southeast Asian cluster, anda younger, mainland China group, consisting only of the Zhou-koudian sample. Within the older African-Southeast Asian division,Bpg 2001.04 and the Sangiran H. erectus sample cluster together asmost similar, with the Western H. erectus sample being the nextmost similar to the southeast Asia cluster, and finally H. habilisbeing the least similar within this division of the dendrogram.

Table 3Values of the WF distance.

F Sangiran Zhoukoudian Western H. erectus H. habilis

Bpg 2001.04 0.0003245 0.0013852 0.0007482 0.0010206Sangiran H. erectus 0.0010153 0.0005934 0.0004798Zhoukoudian

H.erectus0.00010783 0.0008221

Western H. erectus 0.0010314

Some variation from this clustering result occurred usingvarious alternative clustering algorithms (e.g., Nearest Neighborlinkage, Wards, etc.) when the WF values were calculated using alleight linear tooth dimensions. However, small sample size effectsfor P4 BL dimension (see discussion) is likely affecting this result.When the P4 BL dimension was excluded from the calculation ofWR values, the alternative clustering algorithms produced identicalor nearly identical patterns to that evident in Figure 8.

Discussion

In East Asia, two fossiliferous sites account for the vast majorityof H. erectus fossils: south equatorial Sangiran (07�27.4600 S,110�50.3600 E) and north temperate Zhoukoudian (39�4400" N,115�5500" E). More than 5000 km separate the localities. The

Figure 8. UPGMA linkage dendrogram on Euclidean distances of the WF distances.


hominin arrival in Sangiran commenced before 1.6 Ma and lasted atleast 700 k.yr. The occupation at Zhoukoudian began at about0.78 Ma and lasted approximately 400 k.yr. (Shen et al., 2009). Thebasal occupations at Sangiran precede those of Zhoukoudian by asmuch as 800 k.yr. Historically, all H. erectus fossils from Sangiranand Zhoukoudian have been lumped together and considered theresult of a singular African exodus. Under this model, Bpg 2001.04and the other Sangiran maxillae should be most similar to Zhou-koudian H. erectus and display lower phenetic resemblance to theWestern fossils. Our analysis, however, supports the research ofKaifu et al. (2005a, b), which shows that the Sangiran specimens aremorphologically more similar to Western H. erectus populationsthan they are to the Zhoukoudian H. erectus sample, due to theabsolutely and relatively smaller M1 and M2 dimensions of theZhoukoudian sample.

Given that later populations of Sangiran H. erectus have signifi-cantly smaller tooth crowns (Kaifu, 2006), similar to those seen inthe Zhoukoudian sample, it is possible that Zhoukoudian was colo-nized by later hominins from Sangiran, or that Java experienceda second colonization from the same population as did Zhoukoudian.Our results cannot answer that question. They do support thehypothesis, based on the differences in tooth dimensions (particu-larly the dissimilarity in the preserved molars of Sangiran andZhoukoudianH. erectus), that Zhoukoudianwas not part of the initialwave of hominin dispersal that entered Java approximately 1.6 Ma.

In overall morphology of the zygomatic arch root, Bpg 2001.04and S17 share numerous features with contemporary (Early Pleis-tocene) Western H. erectus (e.g., D2282 and D2700, SK 847, KNM-WT 15000) and the later (Middle Pleistocene) Zhoukoudiansample (e.g., Skulls IX and XIII). However, while the Sangiransample shares aspects of the zygomatic arch root with the WesternH. erectus specimens to the exclusion of the Zhoukoudian sample,the reverse is not true.

The similarity between Bpg 2001.04 and other SangiranH. erectus maxillary fossils is especially strong in the dentition. Bpg2001.04 and the Sangiran H. erectus fossils cluster together in ADRresults. In only one dental dimension in the ADR results (P4 BLdiameter) does Bpg 2001.04 cluster more with Zhoukoudian thanthe Sangiran sample (Figures 6 and 7).

Similarities between Bpg 2001.04 and the Sangiran sample canalso be seen in the interdental indices (Table 2). While all H. erectussamples possess similar interdental indices in the P3/P4 and M1/M2

crown area ratios, in the premolar/molar indices, the Bpg 2001.04values are most similar to those of other Sangiran fossils, whereinthe premolars are roughly half the size of the molars.

The similarity between Bpg 2001.04 and the Sangiran samplecan be seen in theWF distance values, where these two samples arethe most similar (Table 3). Bpg 2001.04 is next most similar to theWestern H. erectus sample, then the H. habilis sample, and finallythe Zhoukoudian sample is the most dissimilar to Bpg 2001.04 forthis value. The relative similarities between Bpg 2001.04 and San-giran H. erectus with the Western H. erectus sample is likely due totheir close temporal proximity, and the Western H. erectus sampleserving as the ancestral stock for the population of Java byH. erectus.

As can be seen in Table 2, Zhoukoudian H. erectus has the largestWF distance value from the Sangiran sample. The interdentalindices of P3 to M1 and M2 also show this separation betweenZhoukoudian H. erectus and Sangiran, with the former having a P3

crown area roughly seventy-five percent the size of its molar crownareas. This is, in large part, accounted for by the absolutely shortermolars in Zhoukoudian compared to the other samples. This resultand others reflecting the dissimilarity of the Zhoukoudian andSangiran H. erectus samples can be understood in a chronologicalframework.

The Sangiran sample is chronologically much closer to theWestern H. erectus sample than it is to Zhoukoudian, for which themost current age analysis suggests a range of 400e780 ka (Shenet al., 2009; Ciochon and Bettis, 2009). With a radiometric age of1.5 Ma, Bpg 2001.04 is chronologically closer to some of theyounger H. habilis specimens included in this study than to theZhoukoudian fossils. It is therefore likely that the similaritiesbetween the Sangiran hominins and both Western H. erectus andH. habilis samples seen in the WF distances (Table 3), the WF-baseddendrogram (Figure 8), and the ADR scatter-plots (Figures 6 and 7)reflect ancestral retentions.

The clustering of Western H. erectus and the Sangiran H. erectussample (including Bpg 2001.04) with H. habilis (and not with theZhoukoudian H. erectus sample) is more likely due to the primitive(basal) morphology of the first hominin to disperse to SoutheastAsia. After all, H. habilis-like cranial and dental features are found inthe DmanisiH. erectus population (Rightmire et al., 2006;Macaluso,2006; Martinón-Torres et al., 2008; Margvelashvili, 2008;Rightmire and Lordkipanidze, 2009). Most authorities nowconsider H. habilis and H. erectus as sister group species (Liebermanet al., 1996; Spoor et al., 2007). Some even consider these taxa torepresent a single chronospecies (Howell, 1982; Tobias, 1989, 1991).If that is the case, then the basal Western H. erectus population thatfirst dispersed to Southeast Asia may have retained some H. habilis-like features in its morphology. Rightmire and Lordkipanidze(2009: 47) reached a similar conclusion in that “. the Dmanisihominins individuals had a habilis-like ancestor.” Indeed, Homofloresiensis, thought by many to be a descendant of the foundingH. erectus deme in Southeast Asia, appears to retain a H. habilis-likewrist and foot bone morphology (Tocheri et al., 2007; Jungers et al.,2009).

The west-east links and south-north contrasts evident in themorphometric data considered here may have implications fordispersal patterns in H. erectus. One contributing factor to thesouth-north contrasts may have been an ecological barrier tolatitudinal displacement in East Asia. There are two lines ofevidence in support of this scenario of dual dispersal. First, theregion’s numerous hominin-like fossil teeth may, in reality,represent a small, as yet unidentified hominoid member of thefauna (Ciochon, 2009). Second, all undisputed mainlandH. erectus remains lie north of the Stegodon-Ailuropoda zone:Zhoukoudian (Hebei province), Gongwangling (Shaanxi prov-ince), Hexian (Anhui province), and Nanjing (Jiangsu province)(Ciochon, 2010).

If H. erectus could not penetrate the Stegodon-Ailuropoda faunalcomplex, the equatorial and north temperate populationsmay havehad two separate geographic origins and little genetic connection(Ciochon, 2009, 2010). This preliminary hypothesis envisionsdispersals from two Western H. erectus populations. One held anearly H. erectus/H. habilis-like premolar-molar pattern anddispersed early along a southern route to equatorial Southeast Asia:the result we know as Sangiran (Java) H. erectus. Another pop-ulation held the more derived premolar-molar pattern anddispersed later along a northerly route toward Northeast Asia.These we know as Zhoukoudian H. erectus. Finally, we note theimplications of the Late Pleistocene nuclear genome extracted froma finger bone of an archaic hominin found in Denisova Cave insouthern Siberia (Krause et al., 2010; Reich et al., 2010). While thesignificance of this discovery is not yet fully digested, theDenisovan-Melanesian link reported by Reich et al. (2010) estab-lishes that, by the Late Pleistocene, there were complex populationdynamics between mainland and island Southeast Asia. If oneapplies the implications of this later dynamic to the earlier Pleis-tocene, we can no longer regard H. erectus as an undifferentiatedpaleodeme.


Conclusion

Resurgence in Eurasian paleoanthropology has broadened ourknowledge of H. erectus beyond Africa. This species, whose conti-nent of origin remains unknown, quickly came to occupy a diverseset of open-land resources across southern Eurasia. The site ofSangiran represents the Early Pleistocene emplacement ofH. erectus in equatorial Southeast Asia. The Bpg 2001.04 partialmaxilla is a significant addition to the Sangiran collection,providing a sample of five specimens that preserve this part of theface and dentition. Our analysis of the Sangiran maxillary dentitionsuggests that an east-dispersing H. erectus paleodeme may havecarried a H. habilis/early Western H. erectus-like premolar-molarpattern along a southern route to the equatorial zone, whilea separate H. erectus paleodememay have carried the more derivedpremolar-molar pattern along a northerly route to the temperatezone of China. In any event, the dental patterns revealed heresuggest distinct and separate demic origins for the only two true(and highly disparate)H. erectus population samples in East Asia. Asadditional fossil and genetic evidence accumulates for Early andMiddle Pleistocene East Asia, the H. erectus paleodeme may splitfurther into a number of regionally distinct, but still geographicallyfluid populations.

Acknowledgments

The Institute of Technology Bandung (ITB) and the University ofIowa (UI) collaborated in this research, with assistance from theIndonesian Geological Research and Development Centre (GRDC) inBandung. This research was carried out under the following fieldresearch permits from the Indonesian Institute of Sciences andRISTEK: 7450/V3/KS/1998, 3174/V3/KS/1999, 4301/1.3/KS/2001,4212/SU/KU/2003, 03799/SU/KS/2006, 1718/FRP/SM/VII/08, and04/TKPIPA/FRP/SM/IV/2010. Providing field assistance were JohanArif (ITB), Suminto, Sutikno Bronto, the late Sudijono (GRDC), andSujatmiko (National Archaeological Research Centre, Jakarta). At UI,James W. Rogers refined the digital graphics while AnnaWatermanassisted with editing and referencing. Fieldwork funds wereprovided by the L.S.B. Leakey Foundation and the following UIsources: Center for Global and Regional Environmental Research,Central Investment Fund for Research Enhancement, Office of theVice-President for Research, the Office of the Dean of the College ofLiberal Arts and Sciences, and the Human Evolution Research Fundat the University of Iowa Foundation.

References

Antón, S.C., 2002. Evolutionary significance of cranial variation in Asian Homoerectus. Am. J. Phys. Anthropol. 118, 301e323.

Arif, J., 1998. Morphological study of Homo erectus skull (skull IX) from Sangiran,Central Jawa, Indonesia. Ph.D. Dissertation, Kyoto University.

Arif, J., Baba, H., Suparka, M.E., Zaim, Y., Setoguchi, T., 2001. Preliminary study ofHomo erectus skull IX (Tjg-1993.05) from Sangiran, central Java, Indonesia. Bull.Natl. Sci. Mus. (Japan) D 27, 1e27.

Bermúdez de Castro, J.M., Rosas, A., Nicolas, M.E., 1999. Dental remains from Ata-puerca�TD6 (Gran Dolina site, Burgos, Spain). J. Hum. Evol. 37, 523e566.

Bettis III, E.A., Zaim, Y., Larick, R.R., Ciochon, R.L., Suminto, Rizal, Y., Reagan, M.,Heizler, M., 2004. Landscape development preceding Homo erectus immigrationinto central Java, Indonesia: the Sangiran formation lower lahar. Palaeogeogr.Palaeoclimatol. Palaeoecol. 206, 115e131.

Bettis III, E.A., Milius, A.K., Carpenter, S.J., Larick, R., Zaim, Y., Rizal, Y., Ciochon, R.L.,Tassier-Surine, S.A., Murray, D., Suminto, Bronto, S., 2009a. Way out of Africa:early Pleistocene paleoenvironments inhabited by Homo erectus in Sangiran,Java. J. Hum. Evol. 56, 11e24.

Bettis III, E.A., Zaim, Y., Rizal, Y., 2009b. Plio-Pleistocene climatic and volcaniccontrols on high to moderate accommodation space systems in the Solo Basin,Central Java, Indonesia. AAPG Hedberg Research Conference on Variations inFluvial-Deltaic and Coastal Reservoirs Deposited in Tropical Environments.Jakarta, Indonesia.

Blumenberg, B., Lloyd, A.T., 1993. Australopithecus and the origin of the genus Homo:aspects of biometry and systematics with accompanying catalog of tooth metricdata. BioSystems 16, 127e167.

Boaz, N.T., Howell, F.C., 1977. A gracile hominid cranium from upper member G ofthe Shungura formation. Ethiopia. Am. J. Phys. Anthropol. 46, 93e108.

Ciochon, R.L., 2009. The mystery ape of Pleistocene Asia. Nature 458, 910e911.Ciochon, R.L., 2010. Divorcing hominins from the Stegodon-Ailuropoda fauna: new

views on the antiquity of hominins in Asia. In: Fleagle, J.G., Shea, J.J., Grine, F.E.,Leakey, R.E.F. (Eds.), Out of Africa I: The First Hominin Colonization of Eurasia.Springer, New York, pp. 111e126.

Ciochon, R.L., Bettis III, E.A., 2009. Palaeoanthropology: Asian Homo erectusconverges in time. Nature 448, 153e154.

Ciochon, R.L., Bettis III, E.A., Carpenter, S.J., Zaim, Y., Marsh, H.E., 2007. Paleoeco-logical setting for the arrival and early evolution of Homo erectus in the Solobasin, Java. Am. J. Phys. Anthropol., 87. Suppl. 44.

Ciochon, R.L., Bettis III, A.E., Larick, R., Zaim, Y., Suminto, Rizal, Y., Reagan, M.,Heizler, M., 2003. Homo erectus landscapes: paleosols in the Bapang andupper Sangiran formations, Solo basin, central Java. Am. J. Phys. Anthropol.,77. Suppl. 36.

Ciochon, R.L., Larick, R.R., Zaim, Y., Sudijono, Heizler, M., 2001. Early Pleistocenedates and sedimentary cycles for new bapang formation hominins, central Java,Indonesia. Am. J. Phys. Anthropol., 50. Suppl. 32.

Ciochon, R.L., Zaim, Y., Grine, F.E., Rizal, Y., Larick, R.R., Bettis III, E.A., Franciscus, R.G.,Polanski, J.M., 2005. A new Homo erectus maxilla from the Bapang basal unit,Sangiran dome, central Java. Am. J. Phys. Anthropol., 86. Suppl. 40.

Dean, M.C., 2007. Dental development and life history in primates and a comparisonof cuspal enamel growth trajectories in a specimen of Homo erectus from Java(Sangiran S7e37), a Neanderthal (Tabun C1), and an early Homo sapiensspecimen (Skhul II), from Israel. In: Faerman, M., Horwitz, L.K., Kahana, T.,Zilberman, U. (Eds.), Faces from the Past: Diachronic Patterns in the Biology ofHuman Populations from the Eastern Mediterranean. Oxford, pp. 21e27. BARInternational Series.

Dizon, E.Z., Pawlik, A.F., 2010. The lower paleolithic record in the Philippines.Quatern. Int. 223e224, 444e450.

de Vos, J., Sondaar, P.Y., van den Bergh, G.D., Aziz, F., 1994. The Homo bearingdeposits of Java and its ecological context. In: Franzen, J.L. (Ed.), 100 Years ofPithecanthropus: The Homo erectus Problem, vol. 171. Courier Forschungs-Institut Senckenberg, pp. 129e140.

Grine, F.E., 1989. New hominid fossils from the Swartkrans formation (1979e1986Excavations): craniodental specimens. Am. J. Phys. Anthropol. 79, 409e449.

Grine, F.E., Franzen, J.L., 1994. Fossil hominid teeth from the Sangiran dome (Java,Indonesia). In: Franzen, J.L. (Ed.), 100 Years of Pithecanthropus: The Homoerectus Problem, 171. Courier Forschungs-Institut Senckenberg, pp. 75e103.

Grine, F.E., Jungers, W.L., Schultz, J., 1996. Phenetic affinities among early Homocrania from East and South Africa. J. Hum. Evol. 30, 189e225.

Grine, F.E., Smith, H.F., Heesy, C.P., Smith, E.J., 2009. Phenetic affinities of Plio-Pleistocene Homo fossils from South Africa: molar cusp proportions. In:Grine, F.E., Fleagle, J.G., Leakey, R.E. (Eds.), The First Humans: Origin and EarlyEvolution of the Genus Homo. Springer, Dordrecht, pp. 49e62.

Hintze, J., 2001. Number Cruncher Statistical Systems. NCSS and PASS, Kaysville,Utah.

Howell, F.C., 1978. Hominidae. In: Maglio, V.J., Cooke, H.B.S. (Eds.), Evolution ofAfrican Mammals. Harvard University Press, Cambridge, pp. 154e248.

Howell, F.C., 1982. Origins and evolution of African Hominidae. In: Clark, J.D. (Ed.),The Cambridge History of Africa. From the Earliest Times to c. 500 BC, vol. 1.Cambridge University Press, Cambridge, pp. 70e156.

Indriati, E., Antón, S.C., 2008. Earliest Indonesian facial and dental remains fromSangiran, Java: a description of Sangiran 27. Anthropol. Sci. 116, 219e229.

Jacob, T., 1975. Morphology and paleoecology of early man in Java. In: Tuttle, R.H.(Ed.), Paleoanthropology, Morphology and Paleoecology. Mouton, The Hague,pp. 311e326.

Jungers, W.L., Harcourt-Smith, W.E.H., Wunderlich, R.E., Tocheri, M.W., Larson, S.G.,Sutikna, T., Awe Due, Rhokus, Morwood, M.J., 2009. The foot of Homo flor-esiensis. Nature 459, 81e84.

Kaifu, Y., Aziz, F., Baba, H., 2005a. Hominid mandibular remains from Sangiran:1952e1986 collection. Am. J. Phys. Anthropol. 128, 497e519.

Kaifu, Y., Baba, H., Aziz, F., Indriati, E., Schrenk, F., Jacob, T., 2005b. Taxonomicaffinities and evolutionary history of the early Pleistocene hominids of Java:dentognathic evidence. Am. J. Phys. Anthropol. 128, 709e726.

Kaifu, Y., 2006. Advanced dental reduction in Javanese Homo erectus. Anthropol. Sci.114, 35e43.

Kimbel, W.H., Johanson, D.C., Rak, Y., 1997. Systematic assessment of a maxilla ofHomo from Hadar, Ethiopia. Am. J. Phys. Anthropol. 103, 235e262.

Kramer, A., 1993. Human taxonomic diversity in the Pleistocene: does Homo erectusrepresent multiple hominid species? Am. J. Phys. Anthropol. 91, 161e171.

Krause, J., Fu, Q., Good, J.M., Viola, B., Shunkov, M.V., Derevianko, A.P., Pääbo, S.,2010. The complete mitochondrial DNA genome of an unknown hominin fromsouthern Siberia. Nature 464, 894e897.

Kuman, K., Clarke, R.J., 2000. Stratigraphy, artefact industries and hominid associ-ations for Sterkfontein, Member 5. J. Hum. Evol. 38, 827e847.

Larick, R.R., Ciochon, R.L., The Early Paleolithic of southeast Asia. In: Renfrew, C.,Bahn, P. (Eds.), The Cambridge World Prehistory. Cambridge University Press,Cambridge, in press.

Larick, R.R., Ciochon, R.L., Zaim, Y., 2004. Homo erectus and the emergence of Sundain the Tethys Realm. Athena Rev. 4, 32e39.


Larick, R.R., Ciochon, R.L., Zaim, Y., Sudijono, Suminto, Rizal, Y., Aziz, F., 2000.Lithostratigraphic context for the Kln-1993.05-SJN, a fossil colobine maxillafrom Jokotinkir, Sangiran Dome. Int. J. Primatol 21, 731e759.

Larick, R.R., Ciochon, R.L., Zaim, Y., Suminto, Rizal, Y., Aziz, F., Reagan, M., Heizler, M.,2001. Early Pleistocene 40Ar/39Ar ages for Bapang Formation hominins, centralJawa, Indonesia. Proc. Natl. Acad. Sci. 98, 4866e4871.

Leakey, R.E., Leakey, M.G., Behrensmeyer, A.K., 1978. The hominid catalogue. In:Leakey, M.G., Leakey, R.E. (Eds.), The Fossil Hominids and an Introduction toTheir Context, 1968e1974, Koobi Fora Research Project, vol. 1. Clarendon Press,Oxford, pp. 174e175.

Lepre, C.L., Kent, D.V., 2010. New magnetostratigraphy for the Olduvai Subchron inthe Koobi Fora formation, northwest Kenya, with implications for early Homo.Earth Planet. Sci. Lett. 290, 362e374.

Lieberman, D.E., Wood, B.A., Pilbeam, D.R., 1996. Homoplasy and early Homo: ananalysis of the evolutionary relationships of Homo habilis sensu stricto andHomo rudolfensis. J. Hum. Evol. 30, 97e120.

Macaluso Jr., P.J., 2006. Descriptions and comparative studies of the hominin dentalremains from Dmanisi, Georgia: 1991e2002 collections. Ph.D. Dissertation,State University of New York at Binghamton.

Margvelashvili, A., 2008. The morphological description of the dental remains fromtheEarlypaleolithic siteof Dmanisi (Georgia). Annali dell’Universitàdegli Studi diFerrara Museologia Scientifica e Naturalistica 2008, 117e122. Volume Speciale.

Martinón-Torres, M., Bermúdez de Castro, J.M., Gómez-Robles, A.,Margvelashvili, A., Prado, L., Lordkipanidze, D., Vekua, A., 2008. Dental remainsfrom Dmanisi (Republic of Georgia): morphological analysis and comparativestudy. J. Hum. Evol. 55, 249e273.

Moggi-Cecchi, J., Grine, F.E., Tobias, P.V., 2006. Early hominid dental remains fromMembers 4 and 5 of the Sterkfontein formation (1966e1966 excavations):catalogue, individual associations, morphological descriptions and initialmetrical analysis. J. Hum. Evol. 50, 239e328.

Reich, D., Green, R.E., Kircher, M., Krause, J., Patterson, N., Durand, E.Y., Viola, B.,Briggs, A.W., Stenzel, U., Johnson, P.L.F., Maricic, T., Good, J.M., Marques-Bonet, T., Alkan, C., Fu, Q., MallickLi, S.H., Meyer, M., Eichler, E.E., Stoneking, M.,Richards, M., Talamo, S., Shunkov, M.V., Derevianko, A.P., Hublin, J.-J., Kelso, J.,Slatkin, M., Pääbo, S., 2010. Genetic history of an archaic hominin group fromDenisova cave in Siberia. Nature 468, 1053e1060.

Rightmire, G.P., 1990. The Evolution of Homo erectus. Cambridge University Press,Cambridge.

Rightmire, G.P., Lordkipanidze, D., 2009. Comparisons of early Pleistocene skullsfrom east Africa and the Georgian Caucasus: evidence bearing on the origin andsystematics of genus Homo. In: Grine, F.E., Fleagle, J.G., Leakey, R.E. (Eds.), TheFirst Humans e Origin and Early Evolution of the Genus Homo. Springer, Dor-drecht, pp. 39e48.

Rightmire, G.P., Lordkipanidze, D., Vekua, A., 2006. Anatomical descriptions,comparative studies and evolutionary significance of the hominin skulls fromDmanisi, Republic of Georgia. J. Hum. Evol. 50, 115e141.

Rosas, A., Bermúdez de Castro, J.M., 1998. On the taxonomic affinities of the Dmanisimandible (Georgia). Am. J. Phys. Anthropol. 107, 145e162.

Sémah, A.-M., 1984. Palynology and Javanese Pithecanthropus paleoenvironment. In:Andrews, P., Franzen, J.L. (Eds.), The Early Evolution of Man with SpecialEmphasis on Southeast Asia and Africa, vol. 69. Courier Forschungs-InstitutSenckenberg, pp. 237e243.

Shen, G., Gao, X., Gao, B., Granger, D.E., 2009. Age of Zhoukoudian Homo erectusdetermined with 26Al/10Be burial dating. Nature 458, 198e200.

Spoor, F., Leakey, M.G., Gathogo, P.N., Brown, F.H., Antón, S.C., McDougall, I.,Kiarie, C., Manthi, F.K., Leakey, L.N., 2007. Implications of new early Homo fossilsfrom Ileret, east of Lake Turkana, Kenya. Nature 448, 688e691.

Sudijono, 1985. The Grenzbank, a key marker bed. In: Watanabe, N., Kadar, D. (Eds.),Quaternary Geology of the Hominid Fossil Bearing Formations in Java: Report ofthe Indonesia�Japan Joint Research Project, CTA�41, 1976�1979. GeologicalResearch and Development Centre, Bandung, Indonesia, pp. 135e138. SpecialPublication no. 4.

Swisher III, C.C., 1997. A revised geochronology for the Plio-Pleistocene hominid-bearing strata of Sangiran Java, Indonesia. J. Hum. Evol. 32, A23.

Swisher III, C.C., 1999. The antiquity of Homo erectus in Java: 40Ar/39Ar dating andpaleomagnetic study of the Sangiran and Kendungbrubus areas. Abstracts ofthe International Symposium on Paleoanthropology, in Commemoration of the70th Anniversary of the Discovery of the First Skull of Peking Man at Zhou-koudian, October 1999, Beijing, China, pp. 78.

Tocheri, M.W., Orr, C.M., Larson, S.G., Sutikna, T., 2007. The primitive wrist of Homofloresiensis and its implications for hominin evolution. Science 317, 1743e1745.

Tobias, P.V., von Koenigswald, G.H.R., 1964. A comparison between the Olduvaihominines and those of Java and some implications for hominid phylogeny.Nature 204, 515e518.

Tobias, P.V., 1968. Olduvai Gorge. In: The Cranium and Maxillary Dentition of Aus-tralopithecus ("Zinjanthropus") boisei, vol. 2. Cambridge University Press,Cambridge.

Tobias, P.V., 1978. The earliest transvaal members of the genus Homo with anotherlook at some problems of hominid taxonomy and systematics. Z. Morph.Anthropol. 69, 225e265.

Tobias, P.V., 1989. The status of Homo habilis in 1987 and some outstanding prob-lems. In: Giacobini, G. (Ed.), Hominidae. Jaca Books, Milan, pp. 141e149.

Tobias, P.V., 1991. Olduvai Gorge. In: The Skulls and Endocasts of Homo habilis, vol. 4.Cambridge University Press, Cambridge.

Tonkunaga, S., Oshima, H., Polhaupessy, A.A., Ito, Y., 1985. A palynological study ofthe Pucangan and Kabuh formations in the Sangiran area. In: Watanabe, N.,Kadar, D. (Eds.), Quaternary Geology of the Hominid Fossil Bearing Formationsin Java: Report of the Indonesia-Japan Joint Research Project, CTA�41,1976�1979. Geological Research and Development Centre, Bandung, Indonesia,pp. 199e217. Special Publication no. 4.

van den Bergh, G., De Vos, J., Sondaar, P.Y., 2001. The late quaternary palae-ogeography of mammal evolution in the Indonesian Archipelago. Palaeogeogr.Palaeoclimatol. Palaeoecol. 171, 385e408.

Walker, A., Leakey, R. (Eds.), 1993. The Nariokotome Homo erectus Skeleton. HarvardUniversity Press, Cambridge.

Watanabe, N., Kadar, D. (Eds.), 1985. Quaternary Geology of the Hominid FossilBearing Formations in Java: Report of the Indonesia-Japan Joint ResearchProject, CTA�41, 1976�1979. Geological Research and Development Centre,Bandung, Indonesia Special Publication no. 4.

Weidenreich, F., 1937a. The Dentition of Sinanthropus pekinensis. A ComparativeOdontography of the hominids. Palaeont. Sinica New Ser. D 1, 1-181(text), 1e121(atlas).

Weidenreich, F., 1937b. Reconstruction of the entire skull of an adult female indi-vidual of Sinanthropus pekinensis. Nature 140, 1010e1011.

Wolpoff, M.H., 1971. Metric Trends in Hominid Dental Evolution. The Press of CaseWestern Reserve University, Cleveland.

Wood, B., 1991. Koobi Fora Research Project. In: Hominid Cranial Remains, vol. 4.Clarendon Press, Oxford.

new 1.5 million-year-old homo erectus maxilla from sangiran

Documents