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Gauteng, South Africa (24, 25) preserve 23 pre- sacral vertebrae and a partial, five-element (Fig. 1). Here, we describe vertebrae assigned to The of the juvenile male holotype [Malapa Hominin 1 (MH1)] and the adult female paratype (MH2), sediba in addition to the previously published sacrum of MH2 (26). Scott A. Williams,1,2* Kelly R. Ostrofsky,3 Nakita Frater,4 Steven E. Churchill,3,5 The MH1 partial vertebral column consists of Peter Schmid,4,5 Lee R. Berger5 four cervical, six thoracic, and two lumbar verte- brae; that of MH2 is composed of two cervical, Two partial vertebral columns of Australopithecus sediba grant insight into aspects of early hominin seven thoracic, and two lumbar vertebrae, as well spinal mobility, lumbar curvature, vertebral formula, and transitional vertebra position. Au. sediba as a sacrum. Specimen numbers and identifica- likely possessed five non–rib-bearing lumbar vertebrae and five sacral elements, the same configuration tions are provided in table S1. Vertebrae belong- thatoccursmodallyinmodernhumans.Thisfinding contrasts with other interpretations of early ing to MH1 are readily distinguished from those hominin regional vertebral numbers. Importantly, the transitional vertebra is distinct from and above of MH2 by their lack of apophyseal rings. As the last rib-bearing vertebra in Au. sediba, resulting in a functionally longer lower back. This with modern human juveniles and the Nariokotome configuration, along with a strongly wedged last lumbar vertebra and other indicators of lordotic juvenile skeleton (KNM-WT 15000) (1), MH1 posture, would have contributed to a highly flexible spine that is derived compared with earlier possesses short vertebral centra relative to superior- members of the genus Australopithecus and similar to that of the Nariokotome Homo erectus skeleton. inferior interfacet distance, consistent with its juvenile status (27). In contrast, MH2’s centra he vertebral column plays a central role to Au. africanus (Sts 14 and Stw 431) and Homo demonstrate ratios similar to those of adult mod- in posture, locomotion, and overall trunk erectus (KNM-WT 15000). Thoracic and lum- ern humans. Tstability and mobility in vertebrate ani- bar vertebrae have been defined in two ways in mals. The hominin vertebral column is distinct the recent literature: (i) based on the presence Cervical Vertebrae in its role in force transmission and weight- and absence of ribs (i.e., the last thoracic verte- A small cervical body fragment of unknown se- bearing in an upright torso balanced over two bra is identified as the last rib-bearing vertebra) rial position, two fragmentary mid-cervical verte- legs. Owing to these biomechanical demands, (8, 15, 16), and (ii) based on the orientation of brae, and a nearly intact last cervical (C7) vertebra the hominin spine has several specialized traits the articular facets (i.e., the last thoracic vertebra (fig. S1) are associated with MH1. Two mid-level not seen in other mammals, including sigmoid is identified as the transitional vertebra, one that cervical vertebrae are attributed to MH2: a nearly curvature; a pyramidal configuration of articu- bears thoracic-like, coronally oriented superior ar- complete C3 or C4 (fig. S2) and a partially com- lar facets with descent through the lower lum- ticular facets and lumbar-like, curved and laterally plete C5 or C6. These vertebrae do not articulate bar column; and a wide, curved sacrum (1–6). directed inferior articular facets) (6, 17, 18). In and, thus, likely represent either C3 and C5 or C4 Whereas these adaptations are present in modern modern humans and other extant hominoids, the and C6. humans and currently known extinct hominins, last rib-bearing vertebra and the transitional ver- other aspects of the modern human vertebral tebra generally occur at the same vertebral level Rib-Bearing Vertebrae column—for instance, large relative lumbosacral (i.e., are the same vertebral element) and, there- Six rib-bearing vertebrae are attributed to MH1: body size—are not present in early hominins such fore, yield identical numbers of thoracic and lum- two upper thoracic, one mid-thoracic, and three as Australopithecus afarensis and Au. africanus bar vertebrae under either definition [(15, 18, 19), lower thoracic vertebrae. An upper thoracic verte- (2, 3, 7), suggesting that the vertebral column but see (20)]. bra (fig. S3) demonstrates superior articular facet evolved in a mosaic fashion. Therefore, an under- In contrast, recent evidence indicates that shape and orientation and relationships among standing of which adaptations characterized early fossil hominins may not follow this pattern the body, transverse process, and superior articu- various fossil species and when the full com- (9, 15). Newly identified vertebral and rib frag- lar facets diagnostic of a second thoracic vertebra plement of modern humanlike features evolved is ments associated with KNM-WT 15000 show (T2). The middle thoracic vertebra, which likely integral to reconstructing postural and locomotor that the transitional vertebra is cranially adjacent represents T7, is complete but pathological: The evolution in the hominin lineage. to the last rib-bearing vertebra in this specimen dorsal surface of the right lamina exhibits a rounded Recently, two key components of the hominin (9). This configuration yields contrasting num- triangular lytic lesion extending ventrally into vertebral column—its numerical composition and bers of lumbar vertebrae when different opera- the lamina (fig. S4). Poor preservation precludes degree of lumbar lordosis—have been at the tional definitions are employed: five nonribbed certainty of articulation between the three lower forefront of discussion (4, 6, 8–17). However, lumbar vertebrae and six vertebrae with sagittally thoracic vertebrae, although spinous and trans- adequately preserved vertebral columns that lend oriented upper articular facets (posttransitional verse process morphologies and orientations and themselves to reconstructions of regional verte- vertebrae). Sts 14 also seems to demonstrate this costal facet configurations suggest the associa- bral numbers are rare in the hominin fossil record, pattern (8, 15), although the last rib-bearing ver- tion and possible affiliation of two of these verte- particularly before 50 thousand years ago, and tebra in this specimen is somewhat anomalous brae as T9 and T10. are best represented by partial skeletons assigned in that it bears a lumbar-like structure on one side, There are seven rib-bearing vertebrae asso- giving it an intermediate (half-thoracic-, half-lumbar) ciated with MH2 (table S1), including a block of appearance (8, 10, 15, 21, 22). Dissociated verte- four consecutive upper–to–mid-thoracic vertebrae 1Center for the Study of Human Origins, Department of An- thropology, New York University, 25 Waverly Place, New York, bral bodies and neural arches at the thoraco-lumbar and a block of three articulating lower rib-bearing NY 10003, USA. 2New York Consortium in Evolutionary Pri- border in Stw 431 have led to contrasting recon- vertebrae. The upper block contains variably com- matology, New York, NY 10024, USA. 3Department of Evolu- structions of this specimen (8, 23), precluding a plete fragments of what likely represent either tionary Anthropology, Box 90383, Duke University, Durham, definitive assessment of the relationship between a T3-T6 or T4-T7 series. The lower block is of NC 27708, USA. 4Anthropological Institute and Museum, Uni- versity of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, last rib-bearing and transitional vertebrae. Clearly, particular interest because it preserves in artic- Switzerland. 5Evolutionary Studies Institute, University of the additional specimens that preserve this region ulation the penultimate and ultimate rib-bearing Witwatersrand, Private Bag 3, Wits 2050, South Africa. of the vertebral column are needed. The 1.977 vertebrae (Fig. 2). The antepenultimate rib-bearing *Corresponding author. E-mail: [email protected] Ma partial skeletons of Au. sediba from Malapa, vertebra is also preserved but is displaced slightly EMBARGOED UNTIL 2PM U.S. EASTERN TIME ON THE THURSDAY BEFORE THIS DATE: www.sciencemag.org SCIENCE VOL 340 12 APRIL 2013 1232996-1 Australopithecus sediba

from articulation with the penultimate vertebra. the articular facet joints onto the laminae and nial body of S1 through the caudal body of S5; The penultimate vertebra bears a full costal facet habitual lordotic posture (fig. S7). Both the pe- five distinct sacral bodies are recognizable. The at the body-pedicle border and lacks an inferior nultimate and ultimate lumbar vertebra are wedged sacrum is incomplete medio-laterally, with the facet or demi-facet. The zygapophyses bear flat, dorsally (–1.5° and –10.9°, respectively) (Fig. 4, alae broken at its lateral aspects on both sides. dorsally (and slightly laterally) directed superior fig. S8, and table S2). The left ala and sacral foramina are missing en- articular facets and curved, laterally directed in- tirely, whereas the right side retains four large and ferior articular facets; that is, the penultimate rib- Sacrum complete sacral foramina and part of the auricu- bearing vertebra is the transitional vertebra. The The MH2 sacrum is cranio-caudally complete lar surface. The preserved right zygapophysis is ultimate thoracic vertebra bears a full costal facet along the anterior midline (except for the de- curved and postero-medially oriented at an an- on the superior aspect of the posterior vertebral tached portion of the S1 body) from the cra- gle of ~45°. The posterior surface of the sacrum body that extends onto the pedicle. Its superior and inferior articular facets are curved and dorso- medially directed; therefore, it is both rib-bearing and posttransitional.

Lumbar Vertebrae There are two non–rib-bearing lumbar vertebrae associated with MH1, both lacking apophyseal rings. One is a nearly complete first lumbar (L1) vertebra that bears asymmetrical lumbar trans- verse processes (fig. S5). Another lumbar ver- tebra is also nearly complete, with a broken left transverse process (fig. S6). Body-proportion dif- ferences that can be observed between the two vertebrae suggest that they were separated by an additional element, rendering this likely the third lumbar vertebra (L3). In both vertebrae, but par- ticularly marked on L3, “imbrication pockets” (4) are present on the dorsal neural arch inferior to the superior articular facets in a region known as the pars interarticularis (1, 5). These laminar fossae are nonarticular and thought to be me- chanically induced (5). They allow room for the inferior zygapophyses of the cranially adjacent vertebra during extension of the articular facet joints and are indicative of a lordotic spine (1, 4, 5). Body dimensions and vertebral wedging are re- ported in table S2. These measurements and wedging estimates should be treated with caution due to both the lack of apophyses and the asso- ciated juvenile developmental status of MH1. The first lumbar vertebra is ventrally wedged (4.1°), whereas L3 is wedged dorsally (–1.6°). The penultimate and ultimate lumbar vertebrae belonging to MH2 directly articulate with each other and, in turn, with the sacrum (Fig. 3). The lumbar bodies and neural arches are separated, broken at the pedicle bases. The neural arches were discovered in articulation with each other and with the articular facets of the sacrum; the vertebral bodies were found in articulation with each other (with a fragment of the sacral S1 body) and refit cleanly with their respective neural arches. The MH2 lumbar vertebrae were reconstructed digitally (fig. S7), combining the broken neural arches with the vertebral bodies. The cranial portion of the neural arch of the pe- nultimate lumbar vertebra is missing and pre- serves only a partial spinous process and inferior zygapophyses; that of the ultimate lumbar is intact, except for the left transverse process and pedicle, the latter of which is broken along with part of the superior zygapophysis. The ultimate Fig. 1. Vertebral specimens for MH1 (left) and MH2 (right). See corresponding specimen iden- lumbar vertebra bears strong imbrication pockets tifications in table S1. MH1 cervical vertebrae UW88-71 and UW88-73 are encased in matrix and, thus, on the pars, again consistent with extension of not shown here. EMBARGOED UNTIL 2PM U.S. EASTERN TIME ON THE THURSDAY BEFORE THIS DATE: 1232996-2 12 APRIL 2013 VOL 340 SCIENCE www.sciencemag.org RESEARCH ARTICLES is mostly complete on the right side and along Although a full complement of lumbar vertebrae configuration (6L:4S) due to homeotic change and, the midline, with the maintenance of largely sep- is not associated with either MH1 or MH2, both rather, suggests a five-five configuration (5L:5S), arate S1, S2, S3, and S4 spinous processes. Over- the thoraco-lumbar transition and the sacrum of which is consistent with the majority of modern all sacral curvature is greater and more humanlike MH2 provide indirect evidence that Au. sediba humans. Although this does not entirely rule out in MH2 than in A.L. 288-1 (fig. S9). possessed five non–rib-bearing lumbar vertebrae. the possibility of six lumbar vertebrae in combi- Hypotheses for six lumbar vertebrae in early nation with a five-element sacrum (6L:5S), this Thoraco-Lumbar Transition and Inferred hominins due to an interspecific homeotic shift configuration occurs at a very low frequency in Numerical Composition at the lumbo-sacral border have been proposed modern humans (10, 34). Ever since the description and interpretation of on the basis of recent interpretations of four- Additionally, the dissociation between the a partial Au. africanus skeleton (Sts 14) from element sacra in A.L. 288-1 and KNM-WT 15000 transitional and last rib-bearing vertebrae in Sterkfontein, Gauteng, South Africa more than (10, 13, 33). However, both fossil specimens are MH2 provides further support for the presence 40 years ago (21), researchers have grappled damaged and preclude certainty in this assess- of five non–rib-bearing lumbar vertebrae in this with the number of lumbar vertebrae in early ment (22). The presence of five sacral elements specimen. In other early hominins, the thoraco- hominins (1–3, 8–13, 16, 17, 21–23, 28–32). in MH2 challenges the hypothesis of a six-four lumbar transition is either anomalous in appear- ance (Sts 14, which includes what superficially resembles a half-thoracic, half-lumbar vertebra) (8, 15, 21, 22) or damaged (Stw 431 and KNM- WT 15000); reconstructions of the latter differ and result in divergent numbers of lumbar verte- brae (1, 3, 8, 9, 23, 28, 29). In MH2, if six in- stead of five non–rib-bearing lumbar vertebrae were present, seven vertebrae with curved, sag- ittally oriented articular facets would follow the transitional vertebra, a configuration that is not observed in other fossil hominins or modern hu- mans [(9, 15, 19), but see (20)]. Rather, cranial placement of the transitional vertebra relative to the last rib-bearing vertebra suggests that the MH2 vertebral column consisted of five non–rib- bearing lumbar vertebrae and six posttransitional vertebrae. In fact, recent evidence and interpreta- tions suggest that other early hominins demonstrate this configuration as well, including KNM-WT Fig. 2. Lower thoracic block of MH2. Right lateral (left), anterior (middle), and left lateral (right) 15000 (9), Sts 14 (8, 15), and possibly Stw 431, views of the antepenultimate (top, off-set vertebra), penultimate (middle), and ultimate (bottom) rib- depending on the association between its broken bearing vertebrae. Arrows identify costal facets (note that the ultimate vertebra is obscured by an neural arches and vertebral bodies (8, 23, 29). unassociated rib on its left side; however, computed tomography (CT) slices confirm the presence of costal Unlike the case with other partial hominin verte- facets on both sides). Notice that the penultimate rib-bearing vertebra bears flat, posteriorly oriented bral columns, the penultimate and ultimate tho- superior articular facets and curved, sagittally oriented inferior articular facets—it is the transitional racic vertebrae of MH2 are articulated and were vertebra; thus, the ultimate rib-bearing vertebra is posttransitional. found as such in situ, rendering discrepancies

Fig. 3. Penultimate (L4) and ultimate (L5) lumbar vertebrae and sacrum of MH2. The articulated lumbar bodies are united with their respective neural arches, which are, in turn, cemented in articulation to the sacrum. Note the high degree of dorsal wedging of L5 and the presence of four large and complete sacral foramina on the right side of the sacrum. EMBARGOED UNTIL 2PM U.S. EASTERN TIME ON THE THURSDAY BEFORE THIS DATE: www.sciencemag.org SCIENCE VOL 340 12 APRIL 2013 1232996-3 Australopithecus sediba

in reconstructions that plague other specimens a Au. sediba and H. erectus relative to earlier spe- tween the orientation of the and vertebral nonissue. cies; together with a more anterior position of the column (48–50) and integration within (51, 52) shoulder joint (37), this high degree of lordosis and between morphologies in these complex ana- Function, Posture, and Locomotion helps to position the center of gravity of the trunk tomical systems are understudied areas (49, 50) The presence of lumbar dorsal wedging and other more posteriorly. However, as other partial skel- that will undoubtedly contribute to our under- morphological features (for instance, imbrica- etons belonging to early members of the genus standing of posture and gait in Au. sediba and tion pockets on lumbar laminae) in the MH1 and Homo do not preserve lower lumbar vertebrae other early hominins. MH2 partial vertebral columns demonstrates (38–41), this hypothesis awaits future discoveries. an intrinsic lumbar lordosis and adaptation to The likely presence of six posttransitional verte- References and Notes upright posture and bipedal locomotion in brae (probably shared with other early hominins), 1. B. Latimer, C. V. Ward, in The Nariokotome Homo Au. sediba. MH2 also shows a cranial position in combination with dorsal wedging of the lower erectus Skeleton, A. Walker, Ed. (Harvard Univ. Press, – of the transitional vertebra relative to the last rib- lumbar vertebrae (MH1 L3, as well as MH2 L4 Cambridge, MA, 1993), pp. 266 293. 2. W. J. Sanders, thesis, New York University (1995). bearing vertebra, resulting in six vertebrae with and L5), including extreme dorsal wedging at 3. W. J. Sanders, Comparative morphometric study of the curved, sagittally oriented articular facets on the L5, reveals a highly mobile lower back in Au. australopithecine vertebral series Stw-H8/H41. J. Hum. zygapophyses that allow flexion and extension of sediba (Fig. 4 and fig. S8). Functional analyses Evol. 34, 249 (1998). doi: 10.1006/jhev.1997.0193; the torso and constrain its rotation (35, 36). A of lower limb remains suggest that MH2 em- pmid: 9547457 4. C. O. Lovejoy, The natural history of human gait and numerically longer posttransitional region would, ployed a bipedal gait characterized by hyperpro- posture. Part 1. Spine and pelvis. Gait Posture 21,95 therefore, facilitate postural lordosis over a longer nation of the feet during stance phase (42, 43). (2005). pmid: 15536039 range of the lower back than the modal condition Based on biomechanical principles and clinical 5. C. V. Ward, B. Latimer, Human evolution and the in modern humans [(1, 2, 4, 15, 17), but see (9)]. assumptions, a kinematic chain involving foot pro- development of spondylolysis. Spine 30, 1808 (2005). doi: 10.1097/01.brs.0000174273.85164.67; pmid: In addition, the L5 vertebra of MH2 is extremely nation, anterior pelvic tilt, and increased lumbar 16103848 dorsally wedged (–10.9°), greatly surpassing lor- lordosis has been proposed and tested in mod- 6. K. K. Whitcome, L. J. Shapiro, D. E. Lieberman, Fetal load dotic wedging observed at the last lumbar verte- ern humans, with mixed results (44–47). Previ- and the evolution of lumbar lordosis in bipedal hominins. brae in other Australopithecus specimens and, ous studies have assessed these relationships Nature 450, 1075 (2007). doi: 10.1038/nature06342; pmid: 18075592 although within the range of modern human var- only during quiet stance on two feet, and data on 7. L. Shapiro, Evaluation of “unique” aspects of human iation, outside the lower limit of their 95% predic- the kinematics of bipedal locomotion are needed; vertebral bodies and pedicles with a consideration of tion intervals. In this regard, the MH2 L5 vertebra nevertheless, the relatively strong lordotic mor- Australopithecus africanus. J. Hum. Evol. 25, 433 (1993). is very similar to that of KNM-WT 15000 (Fig. 4). phology observed in the lower back of MH2 is doi: 10.1006/jhev.1993.1061 consistent with such a kinematic hypothesis (43). 8. M. Haeusler, S. A. Martelli, T. Boeni, Vertebrae numbers When lordotic wedging is estimated from both of the early hominid lumbar spine. J. Hum. Evol. 43, 621 L4 and L5, KNM-WT 15000 possesses a greater Additionally, this finding suggests that MH2 may (2002). doi: 10.1006/jhev.2002.0595; pmid: 12457852 degree of summed dorsal wedging (–16.0°) than have been characterized by a pelvis tilted more 9. M. Haeusler, R. Schiess, T. Boeni, New vertebral and rib MH2 (–12.4°), both surpassing values calculated anteriorly than that of modern humans (fig. S10), material point to modern bauplan of the Nariokotome for Au. africanus specimens (Stw 431 at –5.7°, which has also been proposed for other members Homo erectus skeleton. J. Hum. Evol. 61, 575 (2011). – Australopithecus 48 49 doi: 10.1016/j.jhevol.2011.07.004; pmid: 21868059 Sts 14 at 8.9°) (fig. S8 and table S2). Although a of the genus ( , ). Wheth- 10. D. Pilbeam, The anthropoid postcranial axial skeleton: complete lumbar column is required to measure er or not these morphologies characterized Au. comments on development, variation, and evolution. the overall lumbar angle (14), this trend toward sediba as a species is unknown and will require J. Exp. Zool. B Mol. Dev. Evol. 302, 241 (2004). strong lordotic wedging of the lower lumbar the recovery and biomechanical analysis of ad- pmid: 15211685 11. B. A. Rosenman, thesis, Kent State University (2008). bodies may represent an evolutionary trend in ditional skeletal materials. The relationship be- 12. C. O. Lovejoy, G. Suwa, S. W. Simpson, J. H. Matternes, T. D. White, The great divides: Ardipithecus ramidus reveals the postcrania of our last common ancestors with African apes. Science 326, 100 (2009). doi: 10.1126/science.1175833; pmid: 19810199 13. M. A. McCollum, B. A. Rosenman, G. Suwa, R. S. Meindl, C. O. Lovejoy, The vertebral formula of the last common ancestor of African apes and humans. J. Exp. Zool. B Mol. Dev. Evol. 314, 123 (2010). pmid: 19688850 14. E. Been, A. Gómez-Olivencia, P. A. Kramer, Lumbar lordosis of extinct hominins. Am. J. Phys. Anthropol. 147, 64 (2012). doi: 10.1002/ajpa.21633; pmid: 22052243 15. S. A. Williams, Placement of the diaphragmatic vertebra in catarrhines: Implications for the evolution of dorsostability in hominoids and bipedalism in hominins. Am. J. Phys. Anthropol. 148, 111 (2012). doi: 10.1002/ajpa.22049; pmid: 22419482 16. S. A. Williams, Variation in anthropoid vertebral formulae: Implications for homology and homoplasy in hominoid evolution. J. Exp. Zool. B Mol. Dev. Evol. 318, 134 (2012). doi: 10.1002/jezb.21451; pmid: 22532475 17. K. K. Whitcome, Functional implications of variation in lumbar vertebral count among hominins. J. Hum. Evol. 62, 486 (2012). doi: 10.1016/j.jhevol.2012.01.008; pmid: 22425070 18. L. Shapiro, in Postcranial Adaptation in Nonhuman Primates, D. L. Gebo, Ed. (North Illinois Univ. Press, Fig. 4. Wedging angle of the last lumbar vertebra in MH2 compared with other fossil hominins De Kalb, IL, 1993), pp. 121–149. and modern humans. Modern human (n = 88 specimens) sex differences are not significant [female 19. S. A. Williams, Modern or distinct axial bauplan in early (n =45):m = –6.4°, male (n =43):m = –6.6°; P = 0.576]. Notice that MH2 is at the extreme end of hominins? Comments on Haeusler et al. (2011). J. Hum. m T s – Evol. 63, 552 (2012). doi: 10.1016/j.jhevol.2012.01.007; modern human variation and lies outside the range of 95% prediction intervals ( 1.96* )( 2.2°, pmid: 22414447 –10.8°) for H. sapiens. Whiskers represent the minimum and maximum values of the modern human 20. M. Haeusler, S. Regula, B. Thomas, Modern or data set. See table S1 for raw data used to calculate wedging angles. distinct axial bauplan in early hominins? A reply EMBARGOED UNTIL 2PM U.S. EASTERN TIME ON THE THURSDAY BEFORE THIS DATE: 1232996-4 12 APRIL 2013 VOL 340 SCIENCE www.sciencemag.org RESEARCH ARTICLES

to Williams (2012). J. Hum. Evol. 63, 557 (2012). 38. M. R. Meyer, thesis, University of Pennsylvania (2005). Foundation and the African Origins Platform, the Institute for doi: 10.1016/j.jhevol.2012.05.011 39. D. Lordkipanidze et al., Postcranial evidence from early Human Origins, University of the Witwatersrand, the University 21. J. T. Robinson, Early Hominid Posture and Locomotion Homo from Dmanisi, Georgia. Nature 449, 305 (2007). of the Witwatersrand’s Vice Chancellor’s Discretionary Fund, (Univ. of Chicago Press, Chicago, 1972). doi: 10.1038/nature06134; pmid: 17882214 the National Geographic Society, the Palaeontological 22. Supplementary materials are available on Science Online. 40. A. Walker, M. R. Zimmerman, R. E. Leakey, A possible case Scientific Trust, the Andrew W. Mellon Foundation, the Ford 23. M. Toussaint, G. A. Macho, P. V. Tobias, T. C. Partridge, of hypervitaminosis A in Homo erectus. Nature 296, 248 Foundation, the U.S. Diplomatic Mission to South Africa, the A. R. Hughes, The third partial skeleton of a late Pliocene (1982). doi: 10.1038/296248a0; pmid: 7038513 French Embassy of South Africa, the A.H. Schultz Foundation, hominin (Stw 431) from Sterkfontein, South Africa. S. Afr. 41. D. C. Johanson et al., New partial skeleton of Duke University, the Ray A. Rothrock ’77 Fellowship and J. Sci. 99, 215 (2003). Homo habilis from Olduvai Gorge, Tanzania. Nature 327, International Research Travel Assistance Grant of Texas 24. L. R. Berger et al., Australopithecus sediba: A new species 205 (1987). doi: 10.1038/327205a0; pmid: 3106831 A&M University, and the Oppenheimer and Ackerman of Homo-like australopith from South Africa. Science 42. B. Zipfel et al., The foot and ankle of Australopithecus families and R. Branson for funding; the University of the 328, 195 (2010). doi: 10.1126/science.1184944; sediba. Science 333, 1417 (2011). doi: 10.1126/ Witwatersrand’s Schools of Geosciences and Anatomical pmid: 20378811 science.1202703; pmid: 21903807 Sciences and the Bernard Price Institute for Palaeontology for 25. R. Pickering et al., Australopithecus sediba at 1.977 Ma 43. J. M. DeSilva et al., The lower limb and mechanics of support and facilities; the Gauteng Government, and the and implications for the origins of the genus Homo. walking in Australopithecus sediba. Science 340, Gauteng Department of Agriculture, Conservation and Science 333, 1421 (2011). doi: 10.1126/science.1203697; 1232999 (2013). doi: 10.1126/science.1232999 Environment and the Cradle of Humankind Management pmid: 21903808 44. D. Levine, M. W. Whittle, The effects of pelvic movement Authority; and our respective universities for ongoing support. 26. J. M. Kibii et al., A partial pelvis of Australopithecus on lumbar lordosis in the standing position. J. Orthop. We thank E. Mbua, P. Kiura, V. Iminjili, the National Museums sediba. Science 333, 1407 (2011). doi: 10.1126/ Sports Phys. Ther. 24, 130 (1996). pmid: 8866271 of Kenya, B. Billings, B. Zipfel, the School of Anatomical science.1202521; pmid: 21903805 45. S. Khamis, Z. Yizhar, Effect of feet hyperpronation on Sciences at the University of the Witwatersrand, S. Potze, 27. Vertebral centrum growth occurs in a similar way as long pelvic alignment in a standing position. Gait Posture 25, L. C. Kgasi, and the Ditsong Museum for access to comparative bone growth. Substantial longitudinal growth of the 127 (2007). doi: 10.1016/j.gaitpost.2006.02.005; specimens; the Virtual Image Processing lab of the centrum occurs until at ~10 years of age, after which a pmid: 16621569 Palaeosciences Centre and the Microfocus X-ray CT facility of small amount of growth takes place until the obliteration 46. K. Duval, T. Lam, D. Sanderson, The mechanical relationship the Palaeosciences Centre at Wits for funding these facilities; of the growth plates occurs at ~25 years of age (53). between the rearfoot, pelvis and low-back. Gait Posture the University of the Witwatersrand Office of Research 28. A. Walker, R. Leakey, in The Nariokotome Homo erectus 32, 637 (2010). doi: 10.1016/j.gaitpost.2010.09.007; and the National Research Fund Strategic Research skeleton, A. Walker, Ed. (Harvard Univ. Press, Cambridge, pmid: 20889344 Infrastructure Grant and African Origins Platform funding MA, 1993), pp. 95–160. 47. M. Betsch et al., Influence of foot positions on the spine programs; and Duke University and the University of Zurich 29. M. M. Benade, thesis, University of Witwatersand (1990). and pelvis. Arthritis Care Res. 63, 1758 (2011). 2009 and 2010 Field Schools for technical and material 30. P. V. Tobias, New researches at Sterkfontein and Taung doi: 10.1002/acr.20601; pmid: 22127967 support. Numerous individuals have been involved in the with a note on Piltdown and its relevance to the history of 48. M. M. Abitbol, Evolution of the lumbosacral angle. ongoing preparation and excavation of these fossils, including palaeo-anthropology. Trans. R. Soc. S. Afr. 48, 1 (1992). Am. J. Phys. Anthropol. 72, 361 (1987). C. Dube, C. Kemp, M. Kgasi, M. Languza, J. Malaza, doi: 10.1080/00359199209520253 doi: 10.1002/ajpa.1330720309; pmid: 3107397 G. Mokoma, P. Mukanela, T. Nemvhundi, M. Ngcamphalala, 31. P. V. Tobias, Ape-like Australopithecus after seventy 49. C. Berge, D. Goularas, A new reconstruction of Sts 14 S. Jirah, S. Tshabalala, and C. Yates. Other individuals who years: Was it a hominid? J. R. Anthropol. Inst. 4, 283 pelvis (Australopithecus africanus) from computed have given substantial support to this project include B. de Klerk, (1998). doi: 10.2307/3034503 tomography and three-dimensional modeling techniques. W. Lawrence, C. Steininger, B. Kuhn, L. Pollarolo, B. Zipfel, 32. H. M. McHenry, in Integrative Paths to the Past: J. Hum. Evol. 58, 262 (2010). doi: 10.1016/ J. Kretzen, D. Conforti, J. McCaffery, C. Dlamini, H. Visser, Paleoanthropological Advances in Honor of F. Clark j.jhevol.2009.11.006; pmid: 20138331 R. McCrae-Samuel, B. Nkosi, B. Louw, L. Backwell, F. Thackeray, Howell, R. S. Corruccini, R. L. Ciochon, Eds. (Prentice-Hall, 50. M. M. Abitbol, Lateral view of Australopithecus afarensis: and M. Peltier. J. Smilg facilitated computed tomography Englewood Cliffs, NH, 1994), pp. 251–268. Primitive aspects of bipedal positional behavior in the scanning of the specimens, A. Val provided information of 33. C. O. Lovejoy, M. A. McCollum, Spinopelvic pathways earliest hominids. J. Hum. Evol. 28, 211 (1995). CTslices,W.SandersandK.Whitcomemadedataonfossil to bipedality: Why no hominids ever relied on a doi: 10.1006/jhev.1995.1017 specimens and casts available, M. Grabowski provided helpful bent-hip-bent-knee gait. Philos. Trans. R. Soc. London 51. M. W. Grabowski, J. D. Polk, C. C. Roseman, Divergent comments on the manuscript, and M. Shattuck provided valuable Ser. B 365, 3289 (2010). doi: 10.1098/rstb.2010.0112; patterns of integration and reduced constraint in the comments and assisted substantially with the revision of this pmid: 20855303 human hip and the origins of bipedalism. Evolution 65, manuscript. The Au. sediba specimens are archived at the 34. S. A. Williams, thesis, University of Illinois, Urbana-Champaign, 1336 (2011). doi: 10.1111/j.1558-5646.2011.01226.x; Evolutionary Studies Institute at the University of the Witwatersrand. IL (2011). pmid: 21521191 All data used in this study are available upon request, including 35. H. Rockwell, F. G. Evans, H. C. Pheasant, The comparative 52. K. L. Lewton, Evolvability of the primate pelvic girdle. Evol. access to the original specimens. Data reported in this study morphology of the vertebrate spinal column. Its form as Biol. 39, 126 (2012). doi: 10.1007/s11692-011-9143-6 are available in the supplementary materials. related to function. J. Morphol. 63, 87 (1938). doi: 53. R. A. Dickson, P. Deacon, Spinal growth. J. Bone Joint 10.1002/jmor.1050630105 Surg. Br. 69, 690 (1987). pmid: 3680325 Supplementary Materials www.sciencemag.org/cgi/content/340/6129/1232996/suppl/DC1 36. G. A. Russo, Prezygapophyseal articular facet shape in the catarrhine thoracolumbar vertebral column. Am. J. Phys. Acknowledgments: We thank the South African Heritage Supplementary Text Anthropol. 142, 600 (2010). doi: 10.1002/ajpa.21283; Resource agency for the permits to work at the Malapa site; Figs. S1 to S11 Tables S1 and S2 pmid: 20310062 the Nash family for granting access to the Malapa site and – 37. S. E. Churchill et al., The upper limb of continued support of research on their reserve; the South References (54 58) Australopithecus sediba. Science 340, 1233477 African Department of Science and Technology, the Gauteng 20 November 2012; accepted 12 March 2013 (2013). doi: 10.1126/science.1233477 Provincial Government, the South African National Research 10.1126/science.1232996

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