reconstructed homo habilis type oh 7 suggests deep-rooted species diversity in early homo

LETTERdoi:10.1038/nature14224

Reconstructed Homo habilis type OH 7 suggestsdeep-rooted species diversity in early HomoFred Spoor1,2*, Philipp Gunz1*, Simon Neubauer1, Stefanie Stelzer1, Nadia Scott1, Amandus Kwekason3 & M. Christopher Dean2

BesidesHomo erectus (sensu lato), the easternAfrican fossil recordof early Homo has been interpreted as representing either a singlevariable species, Homo habilis1, or two species26. In the latter case,however, there is no consensus over the respective groupings, andwhich of the two includes OH 7, the 1.8-million-year-old H. habilisholotype7. This partial skull and hand fromOlduvai Gorge remainspivotal to evaluating the early evolutionof theHomo lineage, andbypriority names one or other of the two taxa. However, the distortedpreservationof the diagnostically importantOH7mandible has hin-dered attempts to compare this specimen with other fossils8,9. Herewe present a virtual reconstruction of theOH7mandible, and com-pare it to other early Homo fossils. The reconstructed mandible isremarkably primitive, with a long and narrow dental arcade moresimilar to Australopithecus afarensis than to the derived parabolicarcades ofHomo sapiens orH. erectus.We find that this shape vari-ability is not consistentwith a single species of earlyHomo. Import-antly, the jaw morphology of OH 7 is incompatible with fossilsassigned to Homo rudolfensis8 and with the A.L. 666-1 Homomaxilla. The latter is morphologically more derived than OH 7 but500,000 years older10, suggesting that the H. habilis lineage origi-nated before 2.3 million years ago, thus marking deep-rooted spe-cies diversity in the genusHomo.Wealso reconstructed the parietalbones of OH 7 and estimated its endocranial volume. At between729 and 824ml it is larger than any previously published value, andemphasizes the near-complete overlap in brain size among speciesof earlyHomo.Our results clarify theH. habilis hypodigm, but raisequestions about its phylogenetic relationships. Differences betweenspecies of early Homo appear to be characterized more by gnathicdiversity than by differences in brain size, which was highly variablewithin all taxa.

Computed tomography (CT) reveals that distortionof theOH7man-dible mostly involves a small number of fractures and displacements,without evidence of larger-scale plastic deformation (Fig. 1a). In a CT-based virtual reconstruction the individual parts of the corpuswere there-fore realigned by simple repositioning. The dental arcade from the leftM2 to the right M1 was restored using combined clues from the inter-stitial facets, the alveoli and the observation that the displacement ofthe incisors occurred along a single transverse crack through their roots(Fig. 1d andExtendedDataFigs 13).Thedislocated right corpus coversawell-preserved lingual symphyseal surfacewith amarked genial spineand bilateral genioglossal pits (Fig. 1c). These features and the symmet-rically placed apical halves of the I1 roots jointly mark the midsagittalplane (Fig. 1b). Using this plane a second reconstruction was made bymirror-imaging the left side fromM2 to C to the right (Fig. 1f). The CTscans show that root formationof theCandM2was incomplete (Fig. 1c;contrary to ref. 9), confirming the original suggestion that OH 7 was alate juvenile11, rather than an adult12 (SupplementaryNote 1). Conclu-sions formed on the basis of the specific morphological analyses pre-sented below are unlikely to be affected by the sub-adult status ofOH7and some other early Homo fossils (Extended Data Figs 4 and 5 andSupplementary Note 2).The two mandibular reconstructions of OH 7 are characterized by

relatively long andparallel post-canine tooth rows.This primitivemor-phologycontrastswith several other earlyHomo specimens,which showderived parabolic arcade shapes (Extended Data Fig. 6). We thereforetest whether this shape variability is consistent with a single species ofearlyHomo (H. erectus, following ref. 13). Alternative evolutionary sce-narios invokemultiple species of earlyHomo that differ, at least, indentalarcade shape.Weused geometricmorphometrics to quantify the shapevariability of dental arcade shape in earlyHomo, in the context of (1) the

*These authors contributed equally to this work.

1Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany. 2Department of Cell andDevelopmental Biology, University College London, LondonWC1E6BT, UK. 3Museum and House of Culture, National Museum of Tanzania, Dar es Salaam, Tanzania.

a d f

b c e

Figure 1 | CT-based visualization of the OH 7mandible. a, As preserved, marking individualparts that were adjusted in the reconstruction.b, c, The anterior corpus showing the midsagittalplane in relation to the incisor roots(b, transparent, anterior view), and the genial spineand pits (c, posterior view; arrows indicate pits).d, e, The reconstructed mandible in occlusal andleft lateral views, respectively. f, The mandiblereconstructed using the mirror-imaged left corpus;M2s duplicated asM3s, and a small damaged area inthe midline of the post-incisive plane shaded.Scale bar is 2 cm.

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within-group shape variability of extant apes and humans, and (2) theeffect of allometry on dental arcade shape. These analyses show thatthe shape of the OH 7 arcade is close to that of the early Homoman-dibles KNM-ER 1802 and OH 13, and is more similar to shapes foundin great apes and Australopithecus than inH. sapiens (Fig. 2a and Ex-tendedData Figs 4 and 5). Comparedwithother earlyHomo specimensit strongly contrasts with mandibles of H. erectus and with KNM-ER1482 and KNM-ER 60000, specimens that have been associated withthe iconic craniumKNM-ER 1470 (ref. 8; Fig. 2a, b). This difference isas large as betweenGorilla gorilla andPan troglodytes.Whenspecimensare attributed to H. habilis (OH7, OH 13, KNM-ER 1802), H. erectus(Dmanisi) andH. rudolfensis (KNM-ER1482,KNM-ER60000; follow-ing ref. 8) the respective within-group shape variations are consistentwith those shownby extant hominids (Fig. 2c). In contrast, pooling anyof these earlyHomo groups yields shape distances that far exceed thosefound in extant species, and distributions are mostly bimodal (Fig. 2c).We found no static allometric effects on dental arcade shape (ExtendedData Fig. 7).To compareOH7withkeymaxillae attributed toearlyHomowepre-

dicted the shapeof itsmaxillarydental arcadeusingmultiplemultivariateregression analysis, on the basis of the strong and consistent pattern ofcovariation between themaxillary andmandibular dental arcade shapesof extant humans and great apes (ExtendedData Figs 8 and 9). In addi-tion,wemanually reconstructed themaxillary arcadeofOH7on thebasisof an occlusalmatch between lower and upper tooth crowns (Extended

Data Fig. 6c). The predicted maxillary arcade follows the same mor-phological pattern as the mandible, is most similar in shape to that ofA. afarensis, and is different from those of other early Homomaxillae(Fig. 2d, e and ExtendedData Figs 4 and 5). The inferredOH7maxillais most similar to KNM-ER 1813, but at the extreme boundaries of theintraspecific shape differences found between two individuals in extanthumans and great apes (Fig. 2e). The difference between theH. erectusmaxillaD2282andOH7 falls justwithin the 95%boundary ofG.gorilla,but the better preserved mandible D211 of the same individual clearlydiffers fromOH7 (Fig. 2c).OH7 ismost distinct fromKNM-ER62000,a specimen that closely resembles KNM-ER 1470 (ref. 8). This shapedifference is as large as that between some extant H. sapiens and Pantroglodytes individuals (Fig. 2e) and variation of the pooled earlyHomosamplewell exceeds that of extant hominid taxa (ExtendedData Fig. 5a).The left and right parietal bones of OH 7 are both incomplete, but

bilaterally preservedparts complement eachother1, enabling reconstruc-tion of the entire parietal portion of the vault (Fig. 3a, b and ExtendedData Fig. 10). In extant humans and great apes the endocranial volume(ECV) is strongly correlatedwith the form(combined shape and size) oftheparietal endocranial surface.Using this relationship and twomethodswe estimated four separate ECVs from the reconstructedOH7 parietals,with values between 729and824ml (combineduncertainty range 630967ml).TheseECVsare considerably larger thanprevious estimates1,1420,typically given as 647687ml1,20 (Fig. 3c).We consider our valuesmorereliable as they are calculated on the basis of larger and taxonomically

ER1482ER60k

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Figure 2 | Analysis of the OH 7 jaw. a, Plot of principal components(PC) 1 and 2 describing the shape of the mandibular dental arcade; associatedshape changes three standard deviations away from the mean are shown.OH 7 is represented by the full-corpus (red) and symmetry-based (white)reconstructions. b, Procrustes distances between OH 7 and other early Homomandibles compared to frequency plots of distances between all possibleindividual pairs within and between extant groups (colours as in a; linesrepresent 5% and 95% limits of intraspecific distributions). c, Frequency plots

of the mandibular shape differences between all pairs within extant groups(as inb), a pooled sample of chimps and gorillas (top), and various groupings ofearly Homo fossils (lower five), with black ticks showing the distance betweeneach pair. d, Same as a for maxillary shape. For OH 7 the two statisticalpredictions and one anatomical prediction (purple) are plotted. e, Same as c forpairwise shape differences between maxillae. As in d three reconstructions ofOH 7 are plotted.

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more diverse comparative samples, and the linear regression model isnot taxon-dependent, performing equallywell for great ape species andhumans (Extended Data Fig. 10f).TheECVestimatesobtained forOH7 fallwellwithin the rangeof early

H. erectus (5461067ml) and are among the largest values reported forother specimen attributed to earlyHomo13,20 (Fig. 3c). Specimens thatshow affinities with OH 7 in dental arcade shape and have estimatedECVs are OH 13 and KNM-ER 1813. The difference in ECV betweenOH13 (650ml, ref. 15) andOH7 falls well within the intraspecific var-iation of extant hominids (Fig. 3c). The difference between KNM-ER1813 (509ml, ref. 20) andOH 7 is substantially larger, and can only besampled in extant humans and great apes when the lower ECVpredic-tions are considered for OH 7.The reconstructed mandible and parietals of OH 7 reveal that the

holotypeofH.habilis is characterizedbyprimitive gnathicmorphology;a long and narrow dental arcade indicative of a subnasally prognathicface, combined with a larger ECV than assumed thus far. Analysingshape variation of the dental arcades shows that the earlyHomo sam-ple representsmore than one species (contrary to ref. 13), and that aH.habilis hypodigm of OH 7 combined with KNM-ER 1802 and OH 13is consistentwith intraspecific variation seen in extant hominids (Fig. 2c).Bothgnathic andparietal evidence indicate that it is possible thatKNM-ER 1813 is also part of this hypodigm. If so,H. habiliswould have beenvariable, suggesting considerable sexual dimorphism as well as evolu-tionary changes over the documented temporal range of these speci-mens from 2million years (Myr) to 1.65Myr ago21,22.In terms of arcade shape OH 7 is most distinct from the partial cra-

nium KNM-ER 62000 and the mandible KNM-ER 1482. These speci-mens have both been associated with KNM-ER 1470, and are markedby shorter post-canine tooth rows and a non-projecting anterior row9.The KNM-ER 1470 maxilla is incompletely preserved and could notbe included in the analyses, but visual comparisonwithOH7neverthe-less suggests a comparable difference in arcade shape (Extended DataFig. 6h, i). This major difference in gnathic morphology fully supportsthe view that KNM-ER 1470 and associated specimens are best attrib-uted to a species other thanH. habilis (contrary to ref. 13) for which thename H. rudolfensis is available23. The mandible KNM-ER 60000 hasbeen associated with KNM-ER 1470, KNM-ER 62000 and KNM-ER

1482 (ref. 8), but the shape of its dental arcade shows the closest simi-larity to earlyH. erectusmandibles fromDmanisi rather than toKNM-ER 1482 (Fig. 2a). Clearly, the relationship betweenH. rudolfensis andearlyH.erectuswarrants further quantitative analysisusing an expandedlandmark data set which comprehensively captures the facial featuresreported to characterizeH. rudolfensis3,4,8 but this lies beyond the scopeand focus of this paper.The maxillae OH 65 and A.L. 666-1 have been associated with H.

habilis6,10. However, considered by the standards of intraspecific vari-ation among extant hominids, their morphology is incompatible withOH 7 (Fig. 2e), and henceH. habilis. Both are close tomodern humansin dental arcade shape (Fig. 2d and Extended Data Fig. 4c, d), but lackthe unique facial morphology used to diagnose H. rudolfensis8,10. Sug-gested similarities to earlyH. erectus13 are consistent with the evidencepresented here, but require further examination. Regardless of speciesaffinities it is remarkable that the 2.3-Myr-old10 A.L. 666-1 is 0.5Myrolder thanOH7, but is distinctlymore derived in gnathicmorphology.This pattern suggests that theH.habilis lineage originatedbefore 2.3Myrago, predating the oldest fossil evidence for the genusHomo10. OH 13shows thatH.habilis surviveduntil at least 1.65Myrago, but apreviouslyreported last appearance date of 1.44Myr21 can no longer be demon-strated in light of new evidence presented here and elsewhere13 (Sup-plementary Note 3).Our newECVestimates ofOH7 support the view that for the period

between 2.1 and 1.5Myr ago the ECVs ofH. habilis,H. rudolfensis andH. erectus largely overlapped in range24, and broadly fell between 500and 900ml (Fig. 3c). Hence, althoughH. erectus shows autapomorphicfeatures of the calvaria21, there is little evidence that the early radiationof the genusHomowasmarked by interspecific diversification in brainsize. In contrast, it is facialmorphology that appears to distinguish thesethree species. The dental arcades ofH. habilis show themost primitivemorphology, with long and parallel post-canine dental rows suggestiveof a subnasally prognathic face, as opposed to the more diverging andreduced post-canine rows seen in earlyH. erectus,H. sapiens and A.L.666-1, the currently earliest known Homo. The dental arcade of theH. rudolfensis face KNM-ER 62000 also shows shorter post-caninerows, but these are more parallel, and the incisor row is distinctly flatand retracted along the bi-canine line (Extended Data Fig. 5b and

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Figure 3 | Reconstruction and analysis of the OH 7 parietals. a, b, Twoalternative anatomical reconstructions in posterolateral view, with temporallines shown in white (left side) and black (mirrored right side), mirror-imagedbones in darker shade. c, Means and ranges of four ECV predictions for OH 7(red 1 and 2, regression-based and geometric reconstruction based estimatesfor first anatomical reconstruction; red 3 and 4, corresponding estimates for

second anatomical reconstruction), compared with typical values reportedpreviously1,19 (black), and with other early Homo specimens. d, Difference inECV between OH 7, OH 13 and KNM-ER 1813 compared with pairwiseintraspecific differences within extant hominid species as a ratio of the smallerECV divided by the larger ECV. Lines represent the 5% limits of thesedistributions.

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SupplementaryNote 2). Brain size increase in the genusHomo, andH.erectus in particular, has been linked with a shift towards energy- andnutrient-rich diets and a reduced masticatory system2528. Neverthe-less, the H. habilis type specimen, OH 7, demonstrates that increasedbrain size, equivalent to that in earlyH. erectus, occurred in combina-tion with a more primitive gnathic morphology without any signs ofreduced dental size or corpus robusticity (Supplementary Note 4).

Note added in proof: The recently described LD350-1 partialmandi-ble fromEthiopianowprovides the earliest evidence of the genusHomoat 2.8Myr (Villmoare, B. et al. EarlyHomo at 2.8Ma fromLedi-Geraru,Afar, Ethiopia. Science, in the press). Its morphology ismore primitivethan seen in the mandibles we attribute to H. habilis, and this newevidence supports the conclusions of our study.

Online ContentMethods, along with any additional Extended Data display itemsandSourceData, are available in theonline versionof thepaper; referencesuniqueto these sections appear only in the online paper.

Received 1 April 2014; accepted 8 January 2015.

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Olduvai Gorge. Nature 202, 79 (1964).8. Leakey, M. G. et al. New fossils from Koobi Fora, northern Kenya, confirm

taxonomic diversity in early Homo. Nature 488, 201204 (2012).9. Anton, S. C., Potts, R.& Aiello, L. C. Evolution of earlyHomo: an integratedbiological

perspective. Science 345 (2014).10. Kimbel, W. H., Johanson, D. C. & Rak, Y. Systematic assessment of a maxilla of

Homo from Hadar, Ethiopia. Am. J. Phys. Anthropol. 103, 235262 (1997).11. Leakey, L. S. B. New finds at Olduvai Gorge. Nature 189, 649650 (1961).12. Schwartz, J. H. & Tattersall, I. The human fossil record, Vol. 2 (Wiley-Liss, 2003).13. Lordkipanidze, D. et al. A complete skull from Dmanisi, Georgia, and the

evolutionary biology of early Homo. Science 342, 326331 (2013).14. Tobias, P. V. Cranial capacity in anthropoid apes, Australopithecus and Homo

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15. Holloway, R. L. New endocranial values for the East African early hominids.Nature243, 9799 (1973).

16. Holloway, R. L. TheOH7 (Olduvai Gorge, Tanzania) hominid partial brainendocastrevisited. Am. J. Phys. Anthropol. 53, 267274 (1980).

17. Wolpoff, M. H. Cranial capacity estimates for Olduvai Hominid 7. Am. J. Phys.Anthropol. 56, 297304 (1981).

18. Holloway, R. L. The OH 7 (Olduvai Gorge, Tanzania) parietal fragments and theirreconstruction: a reply to Wolpoff. Am. J. Phys. Anthropol. 60, 505516 (1983).

19. Vaisnys, J. R., Lieberman, D. & Pilbeam, D. An alternativemethod of estimating thecranial capacity of Olduvai Hominid 7. Am. J. Phys. Anthropol. 65, 7181 (1984).

20. Holloway, R. L., Broadfield, D. C. & Yuan, M. S. The human fossil record, Vol. 3(Wiley-Liss. 2004).

21. Spoor, F. et al. Implications of new early Homo fossils from Ileret, east of LakeTurkana, Kenya. Nature 448, 688691 (2007).

22. Joordens, J. C. A. et al. Improved age control on earlyHomo fossils from the upperBurgi Member at Koobi Fora, Kenya. J. Hum. Evol. 65, 731745 (2013).

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The raw and the stolen. Cooking and the ecology of human origins Curr. Anthropol.40, 567594 (1999).

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Supplementary Information is available in the online version of the paper.

AcknowledgementsWe thank the National Museum of Tanzania, the TanzaniaCommission for Science and Technology and the National Museums of Kenya forgiving access to fossils in their care, and the Imaging Plus Medical Centre, Dar esSalaam, for CT scanning facilities. We are grateful to M. Leakey, L. Leakey, J.-J. Hublinand S. Anton for support and encouragement, and to R. Blumenschine, P. Corujo,R. David, P. Gokarn, W. Kimbel, K. Kupczik, R. Leakey, J. Lewis, E. Mbua, R. McCarthy,M. Meyer, P. Mitteroecker, P. Msemwa, J. Njau, D. Reinhardt, L. Schroeder, M. Skinner,A. Stoessel, A. Strauss, H. Temming and B. Wood for help with aspects of this study.Research was supported by the Max Planck Society.

Author Contributions F.S., S.N., S.S., N.S., A.K. and C.D. collected data. F.S., P.G., S.N.and C.D. performed analyses. F.S. wrote the paper, with contributions from P.G., S.N.and C.D.

Author Information Reprints and permissions information is available atwww.nature.com/reprints. The authors declare no competing financial interests.Readers are welcome to comment on the online version of the paper. Correspondenceand requests for materials should be addressed to F.S. ([email protected]) orP.G. ([email protected]).

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METHODSCT scanning. In December 2010 OH 7 was CT scanned with a Siemens Somatom4, using a slice collimation of 1.0mm. The image stacks used for 3D visualizationswere reconstructedwith a voxel size of 0.230.230.5mm,H70h kernel and extendedCT scale. The reconstructions of themandible and parietals use images in the trans-verse and coronal planes, respectively. OH 7X (right M2; ref. 29) is housed in theNational Natural History Museum in Arusha rather the Museum and House ofCulture in Dar es Salaam, and was studied but not CT scanned. Specimens in thecomparative sample were scannedwith amedical CT scanner (parameters similarto those for OH 7) or with a BIR ACTIS 225/300 (Max Planck Institute for Evolu-tionaryAnthropology, Leipzig), isotropic voxel size of 0.1mmor less.Avizo 6.3-7.1(Visualization Sciences Group) and Geomagic Studio 2013 (Geomagic Inc.) wereused for visualization, segmentation, reconstruction and 3D landmarking.Reconstructionof theOH7mandible.The reconstructionprocedure is discussedin more detail in the SupplementaryMethods. The OH 7mandible was examinedby F.S. andM.C.D. tomap thepattern of externally visible cracks, displacements andcrucial morphological details such as interstitial facets of the tooth crowns. Thisinformation was combined with the internal morphology as shown in CT images.The main distortion concerns displacement of teeth and corpus parts along threewell-defined fractures: (1) labiolingually through the right C alveolus; (2) throughthe left corpus fromP4 lingually toC labially; and (3) transversely through the anteriorcorpus and tooth roots, marking the dislocation of the I crowns (Extended DataFigs 1 and 2).The 13 teeth and seven corpus parts were digitally separated, as colour coded

in Extended Data Fig. 1. The fragmented buccal wall on the right and remnants ofmatrix were removed, and six corpus parts realigned, guided by their edges and sur-faces. Subsequently, the incisors could be realigned, on the basis of the interstitialfacets and the apical portion of their roots that remain in their original alveolar posi-tions. The other teeth were repositioned on the basis of their interstitial facets andalveoli. Only the mesial half of the right corpus is preserved, and a second, morecomplete reconstructionwas thereforemade, using a copyof the left corpus instead.The latter was mirror-imaged across the midsagittal plane of the anterior corpus,marked by the genial spine and genioglossal pits on the posterior symphyseal sur-face in combination with the apical halves of the I1 roots (Fig. 1b, c). The rightcorpus surrogate thus obtained and the actual right corpus fragment are close inorientation,with the latter being 1 degreemore divergent relative to themidsagittalplane. The good match between individual parts confirms that the corpus experi-enced little or no plastic deformation and that the estimated midsagittal plane is agood reflection of bilateral symmetry (Extended Data Fig. 2e). Finally, to facilitatevisual comparisons of overall dental arcade shape the leftM2 was used to representthe similarly sized right M2, and the missing M3s (Fig. 1f). However, theM3s werenot considered in any of the shape analyses of the dental arcade. Measurements ofthe mandibular reconstructions are given in Supplementary Note 5.Shape analyses of the mandibular and maxillary dental arcades. Landmarks.Dental arcadeswerequantified using 3D landmarks, taken either directly fromorig-inal specimens or casts with a Microscribe digitizer (Solution Technologies), orfrom digital volume or surface data using Avizo 6.3 or 7.1 (Visualization SciencesGroup). Eighty landmarks are definedwhichdescribe themesial, distal, lingual andbuccal/labial alveolarmargins of themaxillary andmandibular dental arcade fromleft to rightM3 (ExtendedData Fig. 2f, g). Themesial and distal roots of themolarsand premolars were landmarked separately, but in the analyses their coordinateswere averaged.Mesial and distal landmarks between the tooth crowns are difficultto reach with the Microscribe. These are therefore calculated from pairs of land-marks positioned slightly more buccally/labially and lingually. The M3s of OH 7arenotpreserved andanalyses therefore use a subset of landmarks from left to rightM2.Results of comparative analyses with orwithoutM3s are notmeaningfully dif-ferent. For visualization the 43M2-to-M2 landmarks are connected by awireframe.Extant species. Specimens are pairs of matching maxillae and mandibles, withoutdistinct pathologies ormalocclusion. Late juveniles are specimens similar indevelop-mental age to OH 7, with erupted Cs and unerupted M3 s. The number of latejuveniles that couldbe includedwas lowbecause amongmodernHomo sapiens thisage group is sparsely represented inmuseumcollections, andamong great apes thispattern of dental eruption is rare because eruption of the M3 usually precedes orcoincides with eruption of the canine. To maximize sample sizes the late juvenilestherefore include a few crania without mandibles.

Homosapiens: adults 80,worldwide populations; late juveniles 7maxillae, 5man-dibles. Pan troglodytes: adults 41, including P. t. troglodytes, P. t. verus and P.t.schweinfurthii; late juveniles 11 maxillae, 10 mandibles. Gorilla gorilla: adults 46;late juveniles 4 maxillae, 2 mandibles. Pongo sp.: adults 22.Fossil specimens. Sample composition of early Homo reflects preservation of thedental arcade, a developmental agemarked by erupted Cs, and availability of data.Australopithecus specimens were included to represent the ancestral or primitivestate of gnathic morphology relative to the genusHomo. Specimens are labelled in

the graphs by their accession number, leaving off the prefix KNM- for specimenshoused in the National Museums of Kenya, and the designation -1 for A.L. spec-imens housed in the National Museum of Ethiopia.

Australopithecus anamensis KNM-KP29281: CT scan. Landmarks taken fromthe right side and mirror imaged using the midsagittal plane of the symphysis.

Australopithecus afarensis: A.L. 200-1, A.L. 288-1 and A.L. 400-1: CT-based 3Dsurface of plaster casts (source: Cleveland Museum of Natural History). Missinglandmark data for the left M2 of A.L. 288-1 estimated using reflected relabelling30.A.L. 822-1: casts of the reconstructed craniumandmandible31, courtesy ofW.Kimbeland Y. Rak.

Homoerectus: D211,D2282,D2600,D2735:CT-based 3D surface of casts (source:Georgian National Museum). The right side of D2282 landmarked and mirror-imaged using the midsagittal plane of the palate. Missing landmarks of the left P4and M1 alveoli of D2600 mirror-imaged from the right and matched into the lefttooth row on the basis of the shared P3 and M3 landmarks. Sangiran 4: CT scan.Landmarks taken fromthe right side andmirror-imagedusing themidsagittal planeof the palate.

Homo habilis: OH 7: CT-based 3D reconstructions (this paper). Missing land-mark data for the M1 (buccal, distal) and M2 (all) of the partial right corpus wereestimated using reflected relabelling30. The second reconstruction employingmirror-imaging provides all landmarks.

Homo sp.: A.L. 666-1: orthogonal, parallel projected 3D surface views of a cast20.KNM-ER 1482: CT scan. Landmarks taken from the left side and mirror-imagedusing themidsagittal plane of the symphysis. KNM-ER1802,KNM-ER60000, KNM-ER 62000: CT-based 3D reconstructions8. KNM-ER 1813: CT scan. The left P3 toM2 were mirror-imaged and matched into the right tooth row. Landmarks weretaken from the right side andmirror-imaged using themidsagittal plane of the palate.OH 13: laser scan of the mandible, courtesy of L. Schroeder. OH 65: CT-based 3Dsurface of a cast, courtesy of R. Blumenschine and R. Leakey.Prominent earlyHomo specimens not included: KNM-ER 992, 1470, 3733 and

UR501 (insufficiently preserved), KNM-ER 730 (in-vivo infill and resorption ofincisor alveoli), KNM-ER1805 (maxillawith severe post-mortemdistortion;man-dible with deformed symphyseal area, likely associated with in-vivo loss of anteriordentition), KNM-WT 15000 (developmentally too young), OH 24 (insufficientlypreserved and plastic deformation), andD2700 (multiple casts inconclusive regard-ing poorly preserved alveolar margins and palatal preservation).Analyses were done using the full hominid sample as well as just the hominins

(Fig. 2, ExtendedDataFigs4 and5andSupplementaryNote2).This approachassessesthe fossil hominins with andwithout the context of the strongmorphological con-trast between modern humans and great apes.Procrustes superimposition and principal component analysis. As several fossil spec-imens were reconstructed using mirror-imaging, we symmetrized all specimensusing reflected relabelling30,32. The symmetrized landmark coordinates were thenconverted to shape variables using generalized least squares Procrustes super-imposition33. This superimposition standardizes position, orientation and scale;the resultingProcrustes coordinateswere analysedusingmultivariate statistics.Weused principal component analysis to reduce the dimensions of the high-dimensionaldata set. Landmarks on the maxilla and mandible were analysed separately. Allgeometric morphometric and statistical analyses were performed inMathematica(Wolfram Research) using scripts written by P.G.Statistical prediction of OH 7 maxillary arcade. So as to compare the dental arcadeshape ofOH7with relevant fossil specimens for which onlymaxillae exist, we esti-mated the shape of itsmaxillary arcade shape using two approaches: an anatomicalprediction on the basis of crown occlusion, described below, as well as a statisticalmodel30 dependent on the covariation of the upper and lower jaw (Extended DataFig. 8). For the latterwe computed fivemultiplemultivariate regressionmodels basedon extant great apes and humans to predict the maxillary landmarks from man-dibular shape: one regression model pooling all extant species, as well as separateregressionmodels for the extant species.Weused principal component analysis toreduce the dimensions of the predictor variables; the regressions were computedin the subspace of the first seven principal components, which together explainmore than 95% of the total sample variation. We used multiple reconstructionsof the OH 7 maxillary dental arcade to assess the reconstruction uncertainty: oneocclusal prediction and five statistical predictions (extant species pooled,H. sapiens,P. troglodytes, G. gorilla, and Pongo sp., respectively) for both mandibular recon-structions of OH 7. Our analyses therefore use 11 estimates of the OH 7 maxilla.We assessed the reliability of our statistical approach by computing a maxillary

prediction for every extantmandible on the basis of a cross-validatedmultiplemul-tivariate regression model (pooling all extant species). A comparison of the actualmaxillae to the predicted shapes (ExtendedData Fig. 9) shows that the shape of themaxillary arcade can be predicted with high accuracy from the mandibular land-marks. When we applied the extant regression models to the two reconstructionsof the OH 7mandible the predicted maxillae look very similar to one another and

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to the anatomical predictiondependent on crownocclusion (ExtendedDataFig. 8m).These predictedmaxillary shapes differmostly in the size of the anterior dentition,reflecting the differences among the reference species. The overall arcade shapes ofall 11 predictions, however, are almost identical.Comparisonswithin and between groups. Inorder to provide a framework for inter-preting the shape differences between fossil specimens we computed Procrustesdistances between all possible individual pairs within extant species as a net dis-similarity measure for quantifying the large-scale shape differences. The pairwiseProcrustes distances between earlyHomo fossil specimens are plotted in the con-text of frequency distributions of pairwise Procrustes distances among specimensintraspecifically and interspecifically (Fig. 2b, c, e). The 5% and 95% boundaries ofthe intraspecific distributions are plotted as vertical lines in the respective groupcolour.In Fig. 2b, e and ExtendedData Figs 4 and 5 fossils are not assigned groupmem-

bership a priori. On the basis of these plots it is possible to assess the likelihood thatthe shape difference between two fossils can be found between any two humans,chimpanzees, orang-utans, or gorillas, andhow it compares to the interspecific dif-ferences betweenany two representatives of these extant taxa. Pairwise comparisonsof maxillary shape differences include the three predictions of the OH 7 maxilla(Fig. 2e) and, given separately, all five predictionsbasedon individual hominid taxa(Extended Data Fig. 4f). These analyses do not make any assumptions whether aparticular fossil is typical for its species or an outlier. They are powerful in dem-onstrating major species differences, but similarity in arcade shape does not implyconspecificity unless other diagnostic morphology is consistent with the results.In Fig. 2c we compared the frequency distributions of pairwise Procrustes dis-

tances within extant hominidmandibles to within-group distances for earlyHomosamples pooling different combinations of specimens attributed toH. habilis (OH7, OH 13, KNM-ER 1802), H. erectus (Dmanisi specimens D2600, D2735, D211)andH. rudolfensis (KNM-ER 1482, KNM-ER 60000). For fossils the Procrustes dis-tances between each pair of specimens are given, as well as smooth kernel histo-grams. For comparison we also simulated a mixed species sample by pooling Pantroglodytes and Gorilla gorilla; this illustrates the wide within-group distributionof a largemixed-species sample. As a yardstick for assessing the shape variation infossil groupings we plotted the upper limit of theG. gorilla distribution as a dottedblack line. Pooling different combinations of specimens attributed to H. habilis,H. erectus and H. rudolfensis yields within-group shape distances that far exceedthose found in gorillas, the most variable extant apes.Westress that our conclusions rest on theProcrustesdistancewithin groups (that

is, species).Herevariationdue to size allometry andneutral evolutionarydivergencebetween populations is expected to bemore important than variation due to adap-tive divergence between populations (specimens belonging to the same biologicalspecies share the same functional adaptation).Size and allometry. To assess the static allometric effects of jaw size on the shape ofthe dental arcade, we computed principal component (PC) analyses for bothmax-illary andmandibular dental arcades inProcrustes form space (ExtendedData Fig. 7),andmultivariate regressions of upper and lower jaw shape on the respective naturallogarithms of centroid size within extant species. The statistical significance of theregression was tested using a permutation test based on the explained variance. Inparticular, wewanted to explorewhetherwithin extant species largemandibles areassociated with a narrow dental arcade shape andmore parallel post-canine toothrows than in smallmandibles (OH7 andKNM-ER 1802 have largemandibles). Inthe Procrustes form space plots (ExtendedData Fig. 7ad) large jaws have low PCscores, and small jawshave high PC scores. As expected, the highly sexually dimor-phic gorillas and orang-utans aremore variable alongPC1 in Procrustes form space.For maxillary dental arcade shape allometry explains 4% of the total sample vari-ation inH. sapiens, 9% in P. troglodytes, 18% inG. gorilla and 25% in Pongo sp. (allP, 0.001). For mandibular dental arcade shape allometry accounts for 2% of thetotal sample variation inH. sapiens, 5% in P. troglodytes, 15% inG. gorilla and 21%in Pongo sp. (all P, 0.001). In all species, these allometric effects are driven by thesize of the canine (Extended Data Fig. 7el). These species differences in the frac-tions of variance explained by static allometry reflect the amount of sexual dimorph-ism. As expected, this percentage is smallest in humans, and largest in gorillas andorang-utans. Importantly, however, the static allometric effects of jaw size on arcadeshape are negligible in all extant species.Occlusal prediction of the OH 7 maxillary dental arcade. The maxillary denti-tion of KNM-ER 1590 was chosen as the best match in both size and morphologyfor themandibular dentition ofOH7.The totalmesiodistal crown length of the leftC toM2 is 612mminKNM-ER1590 (ref. 34) and592mminOH7 (ref. 1). Siliconemoulds were taken of the original teeth of KNM-ER 1590 (left I1, right and left C,P3, P4,M1, leftM2), and cast in dental stone by one of us (MCD). Amicro-CT basedsurface model of the left M2 was mirror-imaged to obtain the right M2, and dupli-cateM2swere used as surrogateM3s. The right I1 was adapted andmodelled inwaxfrom the preserved left I1, and I2s were modelled, in proportion and size, on those

of OH 16 and KNM-WT 15000 to match the I1s of KNM-ER 1590. The recon-struction of the OH 7 mandible was stereolithographically printed at 103% toobtain a good size match with the KNM-ER 1590 teeth.A cast of theOH7mandibular dental arcadewasmounted in an adjustable dental

articulator (Hanau). Themaxillarydentitionwas positionedonebyone in edge-to-edge (anterior teeth) or centric occlusion (posterior teeth) using the vertical incisalpin to define themidline.Master casts weremade of the completedmaxillary dentalarcade, first in epoxy-resin and then indental stone. The latterwasmicro-CT scanned,and a surface model was reduced to 97% to obtain the correct size for the OH 7mandible (Extended Data Fig. 6c).Reconstruction of the OH 7 parietals. On the basis of the CT data a currentlymisaligned anterior fragment on the right parietal was restored to the publishedconfiguration1 (ExtendedData Fig. 10). Subsequently, we aligned themirror-imagedright parietal fragment to the larger left side using the following criteria: (a) super-imposition of left and mirror-imaged right asterion and mastoid angle; (b) align-ment of the temporal lines on the left and mirror-imaged right parietal fragments;and (c) formation of a continuous sagittal suture. We mirror-imaged the therebyreconstructed left side to the right andaligned both sides.Vault curvature along thesagittal suture and remnants of the right parietal along the suture constrain this align-ment and thereby the biparietal width of the resulting reconstruction (ExtendedData Fig. 10c). For a second reconstruction (ExtendedData Fig. 10d)we realignedthe individual pieces thatmake up the left and right parietal sides. Cracks betweenthe pieceswere thereby diminished and the endocranial surfaces of the left and themirror-imaged right parts could be better aligned, mostly because of the resultingchanges in coronal curvature. Compared with the first reconstruction this versionis narrower anteriorly and slightly broader posteriorly. Both reconstructions seemvalidwhen different natural anatomical asymmetries are assumed. It has been sug-gested that the right parietal part, which preserves the occipital angle, could in factbe a left parietal of a second individual, preserving the frontal angle12.However, thissuggestion is incompatible with the presence of a temporal line that turns inferiorlyjust anterior to the lambdoid suture (Fig. 3a). Measurements of the parietal recon-structions are given in Supplementary Note 5.Estimation of the ECV of OH 7. To predict the ECV of OH 7 we quantifiedparietal size and shape of the two anatomical reconstructions as well as a compar-ative sample of extant hominids, and used regression-based and thin-plate-spline(TPS) geometric reconstruction methods.Quantification & sample. On the basis of a published endocranial landmark set35,we defined 68 3D (semi-)landmarks located on the parietal endocranial surface ofOH 7 (Extended Data Fig. 10e). The same subset was retrieved from a sample of257 extant hominids (84 H. sapiens35, 55 P. troglodytes36, 54 G. gorilla37 and 64Pongo sp37).Among these are 124 juvenileswith at leastM1 fully erupted to bracketthe late juvenile age of OH7. To validate our approach, we used several fossils withknownECVs (Australopithecus africanus: Sts 5, Sts 60, Sts 71, StW505,MLD37/38;Homo habilis: KNM-ER 1813; Homo erectus: KNM-ER 3733, KNM-ER 3883,KNM-WT15000, OH9). To gain point-to-point correspondence, semi-landmarkswere allowed to slide to the landmark configuration onOH7 (ref. 38). Subsequentlywe transformed the resulting coordinates into Procrustes shape variables39,40 andcomputedProcrustes formvariables that captureboth shape and size information41.Regressionmodel. On the basis of the extant sample, we established a linear regres-sionmodel (adjustedR25 0.9908) to estimateECV fromparietal endocranial formvariables. ThepredictedECV for the extant hominids is highly correlated to the actualECV without a taxon-dependent bias towards over- or underestimation (ExtendData Fig. 10f). This also applies to the fossil specimens that were not part of thesample to establish the regression model.TPS reconstructions. Assuming that each individual of the extant sample had onlythe parietal area preserved as inOH7,we predicted the shape of its complete endo-cast based on TPS warping of all other individuals, and measured the ECV of theresulting 256 reconstructions for each individual. The predicted ECV (themean ofmultiple estimates) is highly correlated to the actual ECV (ExtendedData Fig. 10g).While there is less discrepancy of predicted versus actual ECV for humans as com-pared to the regression-based estimation method, the ECV of some species, espe-cially gorillas, is consistently underestimated.ECVestimates ofOH7. For both anatomical reconstructions ofOH7,we predictedthe ECVbased on the regressionmodel and themultiple endocast reconstructionsgenerated by TPS-warping. Given that only the parietals are preserved, the ECVestimates inevitably have high uncertainty, reported here as 95% single-predictionbands (regression) and the range ofmultiple estimates42 (TPS reconstructions). Forthe first anatomical reconstruction, the regression-based and TPS-reconstruction-based estimates are 790ml (678921ml) and 771ml (663907ml), respectively, andfor the second anatomical reconstruction the estimates are 729ml (630844ml) and824ml (710967ml), respectively. We consider brain growth completed in indivi-duals with the second molar and canine in occlusion43,44, and do not make correc-tions to obtain an adult value (contrary to ref. 1). We consider these values more

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reliable than previous ones1,1420: the (semi-)landmark-based quantification of pari-etal form is more accurate than the individual chords, arcs or volumes used pre-viously; all data were taken from digital copies of the original specimens (avoidingproblems of shrinkage or distortion of casts); the comparative sample is large and tax-onomicallydiverse; particularly the regression-basedmethod isnot taxon-dependent;and methods were validated for fossil hominins with known ECVs.ECV comparison ofOH7,OH13&KNM-ER1813. Sample.Homo sapiens 1509(refs 35, 4547, Lewis J. E. &MeyerM., personal communication, 2014; worldwidepopulations). Pan troglodytes 184 (refs 4850, McCarthy R., personal communi-cation, 2005).Gorilla gorilla 101 (ref. 48, newdata,McCarthyR., personal commu-nication, 2005). Pongo pygmaeus 111 (refs 37, 48).Pongo abelli 34 (refs 37, 48). Thehuman brain-weight data from ref. 47 were converted to millilitres, by correctingfor the density of fresh brain tissue (1.036 gml21 following ref. 48).Pairwise comparisons within groups. In light of the large ECV differences betweenOH7 (796ml; 684927ml) and thepotentially conspecific specimenKNM-ER1813(509ml, ref. 19) we tested whether such ECV differences could be sampled fromrecentH. sapiens,P. troglodytes,P. pygmaeus,P. abelli andG. gorilla.We comparedECVs of all possible pairs of individualswithin extant groups, and divided the smallerby the larger value; the corresponding frequency distributions and their 5%bound-aries are shown inFig. 3c.This figure also comparesOH7andOH13(650ml, ref. 20),as well as OH 13 and KNM-ER 1813.

29. Clarke, R. J. A Homo habilismaxilla and other newly-discovered hominid fossilsfrom Olduvai Gorge, Tanzania. J. Hum. Evol. (2012).

30. Gunz, P., Mitteroecker, P., Neubauer, S., Weber, G. W. & Bookstein, F. L. Principlesfor the virtual reconstruction of hominin crania. J. Hum. Evol. 57, 4862 (2009).

31. Kimbel,W.H.&Rak, Y. Thecranial baseofAustralopithecusafarensis: new insightsfrom the female skull. Phil. Trans. R. Soc. B 365, 33653376 (2010).

32. Mardia, K. V., Bookstein, F. L. & Moreton, I. J. Statistical assessment of bilateralsymmetry of shapes. Biometrika 87, 285300 (2000).

33. Rohlf, F. J. & Slice, D. Extensions of the Procrustes method for the optimalsuperimposition of landmarks. Syst. Zool. 39, 4059 (1990).

34. Wood,B. A.Koobi ForaResearchProject, vol. 4.HominidCranial Remains. (ClarendonPress, 1991).

35. Neubauer, S., Gunz, P. &Hublin, J. J. Thepattern of endocranial ontogenetic shapechanges in humans. J. Anat. 215, 240255 (2009).

36. Neubauer, S., Gunz, P. & Hublin, J. J. Endocranial shape changes during growth inchimpanzees and humans: a morphometric analysis of unique and sharedaspects. J. Hum. Evol. 59, 555566 (2010).

37. Scott, N., Neubauer, S., Hublin, S. & Gunz, P. A shared pattern of postnatalendocranial development in extant hominoids. Evol. Biol. 41, 572594 (2014).

38. Gunz, P., Mitteroecker, P. & Bookstein, F. L. inModern Morphometrics in PhysicalAnthropology (ed.Slice,D.E.) 7398 (KluwerAcademic/PlenumPublishers,2005).

39. Gower, J. C. Generalized Procrustes analysis. Pyschometrika 40, 3351 (1975).40. Rohlf, F. J. & Slice, D. Extensions of the Procrustes method for the optimal

superimposition of landmarks. Syst. Zool. 39, 4059 (1990).41. Mitteroecker, P., Gunz, P., Bernhard,M., Schaefer, K. & Bookstein, F. L. Comparison

of cranial ontogenetic trajectories amonggreat apes andhumans. J. Hum. Evol.46,679697 (2004).

42. Neubauer, S., Gunz, P., Weber, G. W. & Hublin, J. J. Endocranial volume ofAustralopithecus africanus: newCT-basedestimatesand theeffects ofmissingdataand small sample size. J. Hum. Evol. 62, 498510 (2012).

43. Leigh, S. R. Brain growth, life history, and cognition in primate and humanevolution. Am. J. Primatol. 62, 139164 (2004).

44. Leigh, S. R. Brain size growth and life history in human evolution. Evol. Biol. 39,587599 (2012).

45. Lewis, J. E. et al. The mismeasure of science: Stephen Jay Gould versus SamuelGeorge Morton on skulls and bias. PLoS Biol. 9, e1001071 (2011).

46. Brown, P. Australian & Asian Palaeoanthropology; Research resources. http://www.peterbrown-palaeoanthropology.net (2014).

47. Marchand, F. Uber das Hirngewicht des Menschen. (Teubner, Leipzig, 1902).48. Isler, K. et al. Endocranial volumes of primate species: scaling analyses using a

comprehensive and reliable data set. J. Hum. Evol. 55, 967978 (2008).49. Zuckerman, S. Age-changes in the chimpanzee,with special reference togrowth of

brain, eruption of teeth, and estimation of age; with a note on the Taung ape. Proc.Zool. Soc. Lond. 1, 142 (1928).

50. Neubauer, S., Gunz, P., Schwarz,U., Hublin, J.-J.&Boesch, C.Brief communication:endocranial volumes in an ontogenetic sample of chimpanzees from the TaForest National Park, Ivory Coast. Am. J. Phys. Anthropol. 147, 319325 (2012).

51. vanderMerwe,N. J.,Masao, F. T.&Bamford,M.K. Isotopic evidence for contrastingdiets of early homininsHomo habilis and Australopithecus boisei of Tanzania. S. Afr.J. Sci. 104, 153155 (2008).

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Extended Data Figure 1 | Reconstruction of the OH 7 mandible. ae, Aspreserved in occlusal view (a), left lateral view (b), inferior view (c), without theright corpus, showing the matrix fill (d), without the right corpus, matrixand dentition (e). f, Reconstruction in left lateral view without the right corpus.g, Occlusal view of corpus only. hj, Full reconstruction in anterior view (h),

posterior view (i) and occlusal view (j). km, Reconstruction using themirror-imaged left corpus in anterior view (k), posterior view (l) and occlusalview (m). Parts are colour-coded as described in the Supplementary Methods.Scale bar is 2 cm.

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Extended Data Figure 2 | The OH 7 anterior corpus and landmarks of thedental arcade. a, Coronal CT section of the anterior corpus showing, fromleft to right, the roots of the left C to the right I2, as well as the course of theirregular transverse fracture marked by white dots. bd, Labiolingual CTsections through the left C (b), I2 (c) and I1 (d). All three show the fracture, andb shows the open C root and closed apical alveolar wall. e, Anterior corpus aspreserved (red) compared with a copy mirror-imaged across the midsagittalplane used for the reconstruction (cyan). The canine alveoli and the anterior

symphyseal surface of both sides match well, indicating a lack of overall plasticdeformation. The plastically deformed interalveolar septa of the incisors reflectthe dislocation of these teeth. Scale bar for ae is 1 cm. f, g, Right maxilla (f)and mandible (g) of a modern human, showing the landmark positions. Fulldata sets include both sides of the arcade. Blue and red landmarks were takenfrom the specimens. The green landmarks were obtained by averaging pairsof red ones, and these were analysed with the blue ones to represent thearcade from left to right M2 (wireframe).

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Extended Data Figure 3 | The reconstructed OH 7 mandible.ac, Reconstruction using the right corpus in occlusal (a), anterior (b) andposterior (c) view. df, Reconstruction on the basis of mirror-imaged leftcorpus in occlusal (d), anterior (e) and posterior (f) view. g, h, Reconstruction

without right corpus in left lateral view (g) and left medial view (h). The holevisible on the lingual crown face of the leftM2wasmade to sample tooth enamelfor isotope studies51. Scale bar is 2 cm.

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Extended Data Figure 4 | Shape analysis of mandibular and maxillarydental arcades. Group colour codes as in Fig. 2. ad, Principal componentanalysis showing plots of mandibular dental arcade (a, PC 1 and PC 2; b, PC 1and PC 3), and maxillary dental arcade (c, PC 1 and PC 2; d, PC 1 and PC 3).The convex hulls of the extant samples are given, with late juveniles shownas open circles. Wireframes show the shape changes associated with therespective PC axes three standard deviations away from the mean.e, Superimposed mean shapes of late juveniles (black) and adults (group

colour); maxillary (left) andmandibular (right) dental arcade ofGorilla gorilla,Pan troglodytes andHomo sapiens. f, Pairwise Procrustes distances between thenine different maxillary reconstructions of OH 7 and other early Homomaxillae: eight statistical predictions are plotted in the colour of the referencespecies, one occlusal prediction (purple). Frequency plots of the Procrustesdistances between all possible individual pairs within (group colour) andbetween groups (grey); lines represent the 5% limits and 95% limits of thesedistributions, respectively.

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Extended Data Figure 5 | Shape analysis of mandibular and maxillarydental arcades. a, Frequency plot of themaxillary shape differences between allpairs within extant groups (colours as in Fig. 2) andwithin the pooled sample ofearly Homo fossils (black solid lines using statistical predictions of the OH 7maxilla, dotted line using the occlusal prediction). bc, Principal componentanalyses showing plots of the mandibular (b) and maxillary (c) dental arcades.Recent Homo sapiens are plotted in blue; late juveniles are shown as opencircles. Wireframes show the shape changes associated with the respectiveprincipal component axes three standard deviations away from the mean. Thered and open circles represent the two alternative mandibular reconstructionsof OH 7 (b), and the respective statistical predictions of the maxillary dentalarcade (c). The OH 7 reconstruction of the maxillary dental arcade based onocclusion is plotted in purple (c).

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Extended Data Figure 6 | Comparisons of OH 7 mandible. af, Occlusalview of KNM-ER 1802 (a), OH 7 (b), OH 7 maxillary dental arcade (occlusalprediction) (c), A.L 400-1 (d), KNM-ER 1482 (e) and D211 (f). g, MidsagittalCT sections of the symphyses of OH 7 (left) and KNM-ER 1802 (right)showing similar ovoid cross-sectional shapes. h, Left lateral view of KNM-ER1470 and OH 7, aligning the reliably identifiable M1 crown position with the

corresponding part of theOH7 row. ForC to P4 lines link alveolarmargins andcorresponding crown position along the OH 7 row. i, Anterior view aligningKNM-ER 1470 and OH 7 by their midsagittal plane. KNM-ER 1470 is markedby a shorter C-M1 row, and a non-projecting anterior row but a widerdental arcade, shown by the position of its left M1 alveolus well lateral to thecorresponding part of OH 7. Scale bar is 3 cm.

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ExtendedData Figure 7 | Allometry and dental arcade shape. ad, Principalcomponent analysis in Procrustes form space of mandibular dental arcade(a, PC 1 and PC 2; b, PC 1 and PC 3) and maxillary dental arcade (c, PC 1 andPC 2; d, PC 1 and PC 3). Colour codes as in Fig. 2. A multivariate regressionmodel was used to assess the covariation of dental arcade shape with size

(log centroid size) within extant groups. el, Wireframes show shapepredictions for smallest (black) and largest (group colour) centroid sizefor upper (eh) and lower (il) jaw of H. sapiens (e, i), P. troglodytes (f, j),G. gorilla (g, k) and Pongo (h, l). The allometric effects of jaw size on arcadeshape are negligible.

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Extended Data Figure 8 | Wireframes of maxillary dental arcades.a, Predicted OH 7 maxillary arcade, based on dental occlusion. b, c, Statisticalpredictions for OH 7 maxilla based on two alternative mandibularreconstructions using a regression model based on all extant species. d, Threemaxillary predictions of OH 7 (ac) superimposed. el, Statistical predictions

of OH 7 maxillary dental arcade based on separate regression models foreach extant species (applied to two alternative reconstructions of the OH 7mandible). e, i,H. sapiens; f, j, P. troglodytes; g, k,G. gorilla; h, l, Pongo sp.m, Allpredictions of the OH 7 maxillary dental arcade superimposed.

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Extended Data Figure 9 | Reconstruction uncertainty of the maxillarydental arcade. a, For every extant specimen we predicted the shape of themaxillary arcade from the mandibular landmarks using a multivariateregression model. Arrows show the difference between the actual and thepredicted maxilla in the space of the first two principal components. Colourcodes as in Fig. 2. b, Box and whisker chart of the Procrustes distances betweenoriginal and predicted maxillae in the context of the pairwise Procrustesdistances within extant groups. Shape differences between original and

prediction are usually much smaller than typical within-group shapedifferences. Even the five outliers with the largest reconstruction errors fallwell within the range of shape differences within groups. cf, Representativeexamples of the actual (black) versus predicted (group colour) maxillawireframes, given for one individual each of: c, Homo sapiens; d, Pantroglodytes; e, Gorilla gorilla; f, Pongo sp. These predictions use a regressionmodel based on all extant species together.

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Extended Data Figure 10 | OH 7 parietal reconstructions and ECVestimation. a, b, Left and right parietals, with bregma (br), lambda (la) andasterion (ast) indicated. Dashed lines demarcate pieces that were realigned forthe second reconstruction. The transparent part of right parietal represents thecurrent, incorrect alignment, corrected for both reconstructions. c, Firstanatomical reconstruction in (left to right) superior, anterior and posteriorview, combining the left and right side without realignment of smaller parts

(mirror-imaged pieces in darker shade). d, Second anatomical reconstructionin (left to right) superior, anterior and posterior view, based on additionalrealignment of smaller parts. e, Endocranial (semi-)landmarks quantifyingparietal form. Scale bar, 5 cm. f, Regression-based ECV estimates plottedagainst actual values; grey line indicates perfect match between predicted andactual ECVs; group colours as in Fig. 3 and fossils in black. g, Predicted ECVsfrom TPS reconstructions plotted against actual values.

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TitleAuthorsAbstractReferencesMethodsCT scanningReconstruction of the OH 7 mandibleShape analyses of the mandibular and maxillary dental arcadesOcclusal prediction of the OH 7 maxillary dental arcadeReconstruction of the OH 7 parietalsEstimation of the ECV of OH 7ECV comparison of OH 7, OH 13 & KNM-ER 1813

Methods ReferencesFigure 1 CT-based visualization of the OH 7 mandible.Figure 2 Analysis of the OH 7 jaw.Figure 3 Reconstruction and analysis of the OH 7 parietals.Extended Data Figure 1 Reconstruction of the OH 7 mandible.Extended Data Figure 2 The OH 7 anterior corpus and landmarks of the dental arcade.Extended Data Figure 3 The reconstructed OH 7 mandible.Extended Data Figure 4 Shape analysis of mandibular and maxillary dental arcades.Extended Data Figure 5 Shape analysis of mandibular and maxillary dental arcades.Extended Data Figure 6 Comparisons of OH 7 mandible.Extended Data Figure 7 Allometry and dental arcade shape.Extended Data Figure 8 Wireframes of maxillary dental arcades.Extended Data Figure 9 Reconstruction uncertainty of the maxillary dental arcade.Extended Data Figure 10 OH 7 parietal reconstructions and ECV estimation.

reconstructed homo habilis type oh 7 suggests deep-rooted species diversity in early homo

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