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Associated ilium and femur from Koobi Fora, Kenya, and postcranial diversity in early Homo
... Fossil discoveries of the last 15 years have added substantial evidence concerning the diversity of Plio-Pleistocene pelvic morphology (Brown et al., 2004;Simpson et al., 2008;Kibii et al., 2011;Ward et al., 2015). Prior to these discoveries, it seemed possible to differentiate distinct australopith-like and Homo-like morphological types. ...
... In contrast to recent humans, Australopithecus africanus and Australopithecus afarensis had distinctly laterally flared ilia, a more posteriorly oriented iliac ala, a wide bi-iliac breadth relative to their small body size, a relatively long ischium and pubis, and a weakly developed, anteriorly positioned acetabulospinous buttress that narrows anterosuperiorly (Lovejoy et al., 1973;Stern and Susman, 1983;Berge, 1998;Haeusler, 2002;Berge and Goularas, 2010;Claxton et al., 2016). The morphology of these australopiths contrasts strongly with pelvic remains thought to represent Early Pleistocene Homo, such as the KNM-ER 3228 and OH 28 ossa coxae and the KNM-WT 15000 partial skeleton (Day, 1971;Rose, 1984;Walker and Ruff, 1993;Ruff, 1995;Simpson et al., 2008;Ward et al., 2015;Churchill and VanSickle, 2017). The seeming dichotomy between Australopithecus and Homo pelvic morphology has fueled hypotheses about the functional implications of the early Homo morphological pattern, including suggestions of adaptively important shifts in thermoregulation (Ruff, 1991), running behavior (Bramble and Lieberman, 2004), digestive anatomy (Aiello and Wheeler, 1995), and birth (Rosenberg and Trevathan, 1995; see also Ruff, 1995) with the origins of the genus Homo. ...
... The taxonomic attribution of the comparative hominin sample was taken from the published literature (Table 3). As we will demonstrate here, the attribution of isolated hominin pelvic remains to a particular species or genus is challenging; thus, the taxonomic assignment of pelvic fossils without clearly associated craniodental remains (such as BSN49/P27 [Simpson et al., 2008], KNM-ER 5881c [Ward et al., 2015], and KNM-ER 3228 [Rose, 1984]) should be considered tentative. ...
In the hominin fossil record, pelvic remains are sparse and are difficult to attribute taxonomically when they are not directly associated with craniodental material. Here we describe the pelvic remains from the Dinaledi Chamber in the Rising Star cave system, Cradle of Humankind, South Africa, which has produced hominin fossils of a new species, Homo naledi. Though this species has been attributed to Homo based on cranial and lower limb morphology, the morphology of some of the fragmentary pelvic remains recovered align more closely with specimens attributed to the species Australopithecus afar-ensis and Australopithecus africanus than they do with those of most (but not all) known species of the genus Homo. As with A. afarensis and A. africanus, H. naledi appears to have had marked lateral iliac flare and either a weakly developed or non-existent acetabulocristal buttress or a distinct, albeit weakly developed, acetabulospinous buttress. At the same time, H. naledi has robust superior pubic and ischiopubic rami and a short ischium with a narrow tuberoacetabular sulcus, similar to those found in modern humans. The fragmentary nature of the Dinaledi pelvic assemblage makes the attribution of sex and developmental age to individual specimens difficult, which in turn diminishes our ability to identify the number of individuals represented in the assemblage. At present, we can only confidently say that the pelvic fossils from Rising Star represent at least four individuals based on the presence of four overlapping right ischial fossils (whereas a minimum of 15 individuals can be identified from the Dinaledi dental assemblage). A primitive, early Australopithecus-like false pelvis combined with a derived Homo-like true pelvis is morphologically consistent with evidence from the lower ribcage and proximal femur of H. naledi. The overall similarity of H. naledi ilia to those of aus-tralopiths supports the inference, drawn from the observation of primitive pelvic morphology in the extinct species Homo floresiensis, that there is substantial variation in pelvic form within the genus Homo. In the light of these findings, we urge caution in making taxonomic attributionsdeven at the genus leveldof isolated fossil ossa coxae.
... Modern human pelves are distinct from other Pleistocene Homo spp. pelves because they are mediolaterally narrower at the level of the anterior superior iliac spine (i.e., narrower across the bispinous breadth), have ilia that are more vertically oriented, lack a welldeveloped iliac pillar (i.e., the acetabulocristal buttress), and have a short and thick superior pubic ramus that is circular in crosssection (Stringer, 1986(Stringer, , 2012Rak, 1990;Arsuaga et al., 1999;Pearson, 2000;Bonmatí et al., 2010;Gruss and Schmitt, 2015;Ward et al., 2015). Pelves have the potential to be particularly informative about hominin paleobiology because modern human pelves provide indicators of sex (Singh and Potturi, 1978;Rogers and Saunders, 1994;Bruzek, 2002;Royer, 2009), age-at-death (Lovejoy et al., 1985;Miranker, 2016), body size (Jungers, 1988;Plavcan et al., 2014a, b), obstetrics and parturition (Ruff, 1995;Rosenberg and Trevathan, 2002;Brown, 2011;Grabowski et al., 2011;Ubelaker and De La Paz, 2012), trunk morphology (Ruff, 1991(Ruff, , 2010Simpson et al., 2008;Betti et al., 2014;Middleton, 2015), physiology (Dunsworth et al., 2012;Wall-Scheffler, 2012;Wall-Scheffler and Myers, 2013), and locomotion (Robinson, 1972;O'Neill et al., 2015). ...
... The edges of Figure 4. The Omo I ilium was repositioned along a step fracture to create a more realistic profile, following the digital reconstruction methods described in Ward et al. (2015). the fracture closely match their opposing surface and these edges are about 3.0 mm apart through most of the crack. ...
... the fracture closely match their opposing surface and these edges are about 3.0 mm apart through most of the crack. As a heuristic aid to understanding the undistorted pelvic morphology of Omo I, we digitally re-positioned the ilium (Fig. 4) along the edge of the fracture using PolyWorks (following Ward et al., 2015). The digitally repositioned ilium results in a more normal contour of the bone and brings the ilium into a more sagittally oriented plane, which is consistent with modern human morphology. ...
Omo-Kibish I (Omo I) from southern Ethiopia is the oldest anatomically modern Homo sapiens skeleton currently known (196 ± 5 ka). A partial hipbone (os coxae) of Omo I was recovered more than 30 years after the first portion of the skeleton was recovered, a find which is significant because human pelves can be informative about an individual's sex, age-at-death, body size, obstetrics and parturition, and trunk morphology. Recent human pelves are distinct from earlier Pleistocene Homo spp. pelves because they are mediolaterally narrower in bispinous breadth, have more vertically oriented ilia, lack a well-developed iliac pillar, and have distinct pubic morphology. The pelvis of Omo I provides an opportunity to test whether the earliest modern humans had the pelvic morphology characteristic of modern humans today and to shed light onto the paleobiology of the earliest humans. Here, we formally describe the preservation and morphology of the Omo I hipbone, and quantitatively and qualitatively compare the hipbone to recent humans and relevant fossil Homo. The Omo I hipbone is modern human in appearance, displaying a moderate iliac tubercle (suggesting a reduced iliac pillar) and an ilium that is not as laterally flaring as earlier Homo. Among those examined in this study, the Omo I ischium is most similar in shape to (but substantially larger than) that of recent Sudanese people. Omo I has features that suggest this skeleton belonged to a female. The stature estimates in this study were derived from multiple bones from the upper and lower part of the body, and suggest that there may be differences in the upper and lower limb proportions of the earliest modern humans compared to recent humans. The large size and robusticity of the Omo I pelvis is in agreement with other studies that have found that modern human reduction in postcranial robusticity occurred later in our evolutionary history.
... Boldface features denote increased osteoligamentous reinforcement of the load transfer capabilities of the pelvis in modern humans relative to classic australopiths (see text for details). Phenetic traits following Simpson et al., 2008;Kibii et al., 2011;Grabowski and Roseman, 2015;Ward et al., 2015;VanSickle et al., in press. A third important recent discovery concerns the pelvic remains of two individuals of a new australopith species, A. sediba (Berger et al., 2010), from 1.98 Ma deposits at Malapa Cave, South Africa. ...
... Finally, fieldwork in 1.9 Ma deposits at Koobi Fora (Kenya) in 2009 resulted in the recovery of proximal right femoral fragments and a partial left ilium at the site of the earlier (1980) discovery of a right femoral midshaft, KNM-ER 5881 (Ward et al., 2015). The newly discovered femoral fragments conjoin with the original discovery, and the ilium (designated KNM-ER 5881c) also appears to represent the same individual. ...
... In the details of iliac anatomy that are preserved in KNM-ER 5881c the specimen compares favorably with other ossa coxae that have been attributed to early Homo (see above) and it is likely to belong to our genus, however the specific attribution of the material remains unclear. As with the Gona pelvis, KNM-ER 5881c is relatively small and it appears (on the basis of its arcuate line morphology) to represent an individual with a more derived, gynaecoid pelvic inlet shape (Ward et al., 2015). In its proximal and midshaft femoral diaphyseal morphology, KNM-ER 5881 appears most similar to that of the partial skeleton OH 62, attributed to H. habilis (Johanson et al., 1987: but see Berger et al., 2010 than to other specimens attributed to early Homo, such as OH 28, KNM-ER 1472, 1475, and 1481(Ward et al., 2015. ...
The evolution of the hominin pelvis is generally seen as involving two broad stages: the establishment of bipedal pelvic morphology by the mid-Pliocene (or earlier), followed by architectural changes necessary to enlarge the birth canal in response to increased encephalization in Pleistocene members of the genus Homo. Pelvic and proximal femoral morphology in early Homo (namely H. erectus) has been seen as transitional between these stages, reflecting structural changes necessitated by greater body size (and perhaps moderate increases in brain size) overlain upon a basically primitive pelvic architecture. Here we review the history of thought on the evolution of the pelvis in early Homo, as well as recent fossil discoveries that have improved our understanding of diversity in pelvic morphology in early Homo and late australopiths. These discoveries (1) suggest that the “femoropelvic complex” characteristic of H. erectus emerged after the divergence of various lineages of early Homo (that is, it is not plesiomorphic for the genus) and (2) raise questions about the role that evolutionary change in brain size in the genus Homo played in the emergence of derived features seen in the pelvis of modern humans. Anat Rec, 300:964–977, 2017.
... However, the diminutive KNM-ER 5881 pelvis (Fig. 6, Supplementary Fig. 7) has been suggested to belong to a "non-erectus" species of Homo 25 . Although incomplete, KNM-ER 5881 preserves an iliac pillar that originates quite posteriorly but is directed anteriorly 25 , reflecting a different pelvic geometry from KNM-ER 77072. ...
... There are also now three morphologically distinct pelvic specimens from this same interval: KNM-ER 5881 25 , KNM-ER 3228 38,42 , and KNM-ER 77072 (Fig. 6, Supplementary Fig. 7). The KNM-ER 5881 ilium (~1.9 Ma) differs morphologically from other fossils and is associated with a femur that is similar to Homo habilis (i.e., OH 62) in cross-section 25 . The femur cross-sectional shape, along with the pelvic morphology, has led to the conclusion that KNM-ER 5881 is likely attributed to either Homo habilis or Homo rudolfensis (for which postcranial morphology is entirely unknown) 25 . ...
... The KNM-ER 5881 ilium (~1.9 Ma) differs morphologically from other fossils and is associated with a femur that is similar to Homo habilis (i.e., OH 62) in cross-section 25 . The femur cross-sectional shape, along with the pelvic morphology, has led to the conclusion that KNM-ER 5881 is likely attributed to either Homo habilis or Homo rudolfensis (for which postcranial morphology is entirely unknown) 25 . Notably, KNM-ER 5881 has a posteriorly originating iliac pillar, whereas there is no evidence of the iliac pillar in what is preserved of KNM-ER 77072. ...
The KNM-ER 2598 occipital is among the oldest fossils attributed to Homo erectus but questions have been raised about whether it may derive from a younger horizon. Here we report on efforts to relocate the KNM-ER 2598 locality and investigate its paleontological and geological context. Although located in a different East Turkana collection area (Area 13) than initially reported, the locality is stratigraphically positioned below the KBS Tuff and the outcrops show no evidence of deflation of a younger unit, supporting an age of >1.855 Ma. Newly recovered faunal material consists primarily of C4 grazers, further confirmed by enamel isotope data. A hominin proximal 3rd metatarsal and partial ilium were discovered <50 m from the reconstructed location where KNM-ER 2598 was originally found but these cannot be associated directly with the occipital. The postcrania are consistent with fossil Homo and may represent the earliest postcrania attributable to Homo erectus.
... T he last two decades have witnessed the discovery and scientific description of new foot and ankle fossils that have been critical for reconstructing bipedalism in early hominins (Clarke and Tobias 1995;Haile-Selassie et al. 2012;Harcourt-Smith et al. 2015;Jungers et al. 2009;Pontzer et al. 2010;Ward et al. 2012;Zipfel et al. 2011). Additionally, the functional anatomy of the hip (Day 1969;Lovejoy et al. 1973;Lovejoy et al. 2002;MacLatchy 1996;Marchi et al. 2017;Napier 1964;Richmond and Jungers 2009;Ruff 1995;Stern and Susman 1983;Ward et al. 2015) and the knee (Heiple and Lovejoy 1971;Le Gros Clark 1947;Lovejoy 2007;Stern and Susman 1983;Sylvester et al. 2011;Tardieu 1981) continue to be central to reconstructions of locomotion in australopiths and early Homo. The 1.977 Ma Australopithecus sediba skeletons from Malapa, South Africa (Pickering et al. 2011), preserve lower limb bones that have been comparatively and functionally assessed in previous papers (Berger et al. 2010;Zipfel et al. 2011). ...
... Fossil Homo is human-like with the exception of LB1, which is the blue diamond to the far left of the graph. Human femora (n=183) and fossil hominins from sources listed in and Ward et al. (2015). Reduced major axis regression line drawn through the human data (R 2 =0.80; m=1.275; y= -1.38), and the australopith data (R 2 =0.66; m=1.2; y= -0.9932). ...
... As in other australopiths (Ward et al. 2015), the femoral neck of Au. sediba is long and anteroposteriorly compressed. The superoinferior height of the femoral neck is slightly smaller than expected for an australopith of its size, though MH1 and MH2 both fall within the range of variation exhibited by Australopithecus (see Figure 4). ...
... Estimation of U.W. 102a-001 FHD utilized a sphere-fitting technique incorporating preserved subchondral surfaces (Figure 4; cf., Hammond, Plavcan, & Ward, 2013;Plavcan et al., 2014;Ward et al., 2015). This procedure was undertaken in Geomagic Design X (3D Systems, 2015) using the sphere-fitting function, which applies a best-fit sphere to selected surfaces. ...
... Additionally, the patellar surface in U.W. 102a-004 is anteriorly expanded, a feature that could not be evaluated in U.W. 101-1120 and may be related to the prominent lateral lip (Lovejoy, 2007). (Ruff, 1995;Ward et al., 2015). ...
... The Dinaledi Chamber sample of H. naledi is impressively morphologically uniform (Berger et al., 2015;Garvin et al., 2017) and the Lesedi Chamber sample can mostly be encompassed within that low level of variability Homo specimen to fall in the range of australopiths (Ward et al., 2015). ...
Objectives:
The femoral remains recovered from the Lesedi Chamber are among the most complete South African fossil hominin femora discovered to date and offer new and valuable insights into the anatomy and variation of the bone in Homo naledi. While the femur is one of the best represented postcranial elements in the H. naledi assemblage from the Dinaledi Chamber, the fragmentary and commingled nature of the Dinaledi femoral remains has impeded the assessment of this element in its complete state.
Materials and methods:
Here we analyze and provide descriptions of three new relatively well-preserved femoral specimens of H. naledi from the Lesedi Chamber: U.W. 102a-001, U.W. 102a-003, and U.W. 102a-004. These femora are quantitatively and qualitatively compared to multiple extinct hominin femoral specimens, extant hominid taxa, and, where possible, each other.
Results:
The Lesedi femora are morphologically similar to the Dinaledi femora for all overlapping regions, with differences limited to few traits of presently unknown significance. The Lesedi distal femur and mid-diaphysis preserve anatomy previously unidentified or unconfirmed in the species, including an anteroposteriorly expanded midshaft and anteriorly expanded patellar surface. The hypothesis that the Lesedi femoral sample may represent two individuals is supported.
Discussion:
The Lesedi femora increase the range of variation of femoral morphology in H. naledi. Newly described features of the diaphysis and distal femur are either taxonomically uninformative or Homo-like. Overall, these three new femora are consistent with previous functional interpretations of the H. naledi lower limb as belonging to a species adapted for long distance walking and, possibly, running.
... The transition from Australopithecus to Homo probably involved changes to the postcranial skeleton ( Bramble and Lieberman, 2004;Ant on et al., 2014), but the limited number of postcranial remains assigned to early Homo has limited efforts to clarify the transition between the genera. There are isolated remains, such as KNM-ER 1472 ( Leakey, 1973), KNM-ER 1481 ( Kennedy, 1983), KNM-ER 5881 ( Ward et al., 2015), and others ( Wood and Leakey, 2011) that likely belong to Homo, however, given both the taxonomic diversity in early Homo ( Leakey et al., 2012;Spoor et al., 2015;but see Van Arsdale and Wolpoff, 2012;Lordkipanidze et al., 2013) and the spatial and temporal overlap between early Homo and the robust australopiths, attribution of isolated fossils to a species of early Homo remains speculative and controversial (e.g., Moy a Sol a et al., 2008). South African localities, in particular, have yielded very little postcranial material confidently attributed to Homo (but see McHenry, 1994;Susman et al., 2001). ...
... Relative to the subtrochanteric dimensions (square root of the product of the AP and ML diameters), the femoral neck is long in australopiths and in early Homo ( Fig. 20), with H. naledi femora falling within the overlapping ranges. However, the femoral necks are SI tall and AP compressed ( Table 3), more similar to the morphology found in australopiths ( Ruff and Higgins, 2013) and quite distinct from the femoral neck shape in specimens attributed to Homo ( Fig. 21; Ward et al., 2015). The subtrochanteric region of the shaft is platymeric ( Fig. 22), though not as platymeric as is typically found in H. erectus. ...
... While the femoral shaft of H. erectus remains mediolaterally expanded at midshaft, the Dinaledi femora all become AP expanded inferior to the platymeric subtrochanteric region and remain AP expanded throughout the length of the shaft (see description of U.W. 101-012, for example). This shaft anatomy contrasts sharply with that found in H. erectus and is more similar to earlier Homo specimens, which are AP expanded at midshaft ( Ward et al., 2015). The Dinaledi femora are characterized (especially in larger individuals, Fig. 4f) by considerable femoral anteversion, which contributes to an anterior set of the femoral neck relative to the proximal shaft ( Fig. 4, medial views), as is found in australopiths and in early Homo ( Fig. 23). ...
This paper describes the 108 femoral, patellar, tibial, and fibular elements of a new species of Homo
(Homo naledi) discovered in the Dinaledi chamber of the Rising Star cave system in South Africa.
Homo naledi possesses a mosaic of primitive, derived, and unique traits functionally indicative of a
bipedal hominin adapted for long distance walking and possibly running. Traits shared with australopiths
include an anteroposteriorly compressed femoral neck, a mediolaterally compressed tibia, and a
relatively circular fibular neck. Traits shared with Homo include a well-marked linea aspera, anteroposteriorly
thick patellae, relatively long tibiae, and gracile fibulae with laterally oriented lateral
malleoli. Unique features include the presence of two pillars on the superior aspect of the femoral neck
and a tubercular distal insertion of the pes anserinus on the tibia. The mosaic morphology of the H. naledi
thigh and leg appears most consistent with a species intermediate between Australopithecus spp. and
Homo erectus and, accordingly, may offer insight into the nature of the earliest members of genus Homo.
These fossils also expand the morphological diversity of the Homo lower limb, perhaps indicative of
locomotor diversity in our genus.
... That evidence is sorely lacking for many Homo species. For early African H. erectus, associated postcranial and cranial remains are limited to KNM-ER 803, KNM-ER 1808, and KNM-WT 15000 (see Antόn et al., [2007] and Ward et al., [2015] for reviews). For H. habilis, the postcranial record is even leaner. ...
... Body size, size variation, relative brain size, and limb proportions for H. rudolfensis are effectively unknown because no postcranial elements have been found in direct association with diagnostic skull fragments or teeth (Lieberman et al., 2008;Antόn, 2012;Antόn et al., 2014;Grabowski et al., 2015;Jungers et al., 2016). In the interval of 1.9e2.1 Ma, a few well preserved, but isolated, eastern African postcranial fossils share derived features with Homo (e.g., KNM-ER 737, KNM-ER 1472, KNM-ER 1475, KNM-ER 1481, and these specimens, which may represent H. rudolfensis, are at times included in early Homo body and skeletal size analyses (e.g., Skinner and Wood, 2006;Ward et al., 2015). Combining these isolated specimens with H. habilis into the broader H. habilis sensu lato increases the mean body mass and degree of body size variation, which, in turn, affects the interpretation of body and relative brain size variation in early eastern African Homo. ...
... Modern human pelvic morphology is distinct from other hominins in having a short and thick superior pubic ramus, narrow bispinous breadth, ilia that are more vertically oriented, and a reduced or absent iliac pillar, among other features (Rose, 1984;Stringer, 1986;Rak, 1990;Arsuaga et al., 1999Arsuaga et al., , 2015Pearson, 2000;Rosenberg et al., 2006;Simpson et al., 2008;Bonmatí et al., 2010;Ward et al., 2015;Hammond et al., 2017). The earliest known pelvis of fossil Homo sapiensdOmo 1 from Ethiopiadalready fits within the range of modern human variation for those features which are preserved (Hammond et al., 2017). ...
... Ideally, future comparisons will be made between the nearly contemporaneous UA 173/405 and BSN 49/P27 to test whether the observed differences in morphology and size are compatible with these specimens both belonging to H. erectus s.l. The only East African pelvis from the early Pleistocene that is attributed to Homo (but not H. erectus) is KNM-ER 5881 (1.9 Ma), a small and non-robust partial os coxa associated with a femoral shaft that is consistent with Homo habilis (Ward et al., 2015). Even if some of these specimens cannot be attributed to species or genus rank, UA 173/405 is substantially larger and different in morphology than BSN 49/P27 and KNM-ER 5881, yet lacks the extreme robusticity of the comparably large KNM-ER 3228 and OH 28. ...
Here we analyze 1.07–0.99 million-year-old pelvic remains UA 173/405 from Buia, Eritrea. Based on size metrics, UA 173/405 is likely associated with an already described pubic symphysis (UA 466) found nearby. The morphology of UA 173/405 was quantitatively characterized using three-dimensional landmark-based morphometrics and linear data. The Buia specimen falls within the range of variation of modern humans for all metrics investigated, making it unlikely that the shared last common ancestor of Late Pleistocene Homo species would have had an australopith-like pelvis. The discovery of UA 173/405 adds to the increasing number of fossils suggesting that the postcranial morphology of Homo erectus s.l. was variable and, in some cases, nearly indistinguishable from modern human morphology. This Eritrean fossil demonstrates that modern human-like pelvic morphology may have had origins in the Early Pleistocene, potentially within later African H. erectus.
... Palaeoanthropologists have estimated the body size of many hominin genera and species [4][5][6][7][8][9][10], but renewed interest in body size and shape has now provided novel data on diverse temporal and taxonomic parts of hominin history such as Middle and Late Pleistocene Homo [11][12][13][14], Homo erectus/ergaster [15][16][17], early Homo [18][19][20], Homo in general [15,21,22], earlier hominins before 1.5 Ma [23,24] and individual fossils such as KNM-WT 15000 [25]. While these studies provide deeper insights into particular taxa or temporal contexts, there has been no systematic and long-term overview of the evolution of body size within the hominin lineage. ...
... Ma) supports our previous findings of large-scale temporal (and spatial) heterogeneity within early Homo [20]. Our findings correspond with high variability in morphology and size of cranio-dental remains for this time frame in general [83], and early Homo in particular [29,30,71,84,85] also for postcranial material [18,19]. Data on taxonomic groupings (tables 3 and 4) demonstrate that body size variability in the chronological analyses is not exclusively a result of taxic diversity within particular timeframes, but also due to higher intra-taxic variation in earlier hominin groupings (greater than 1.0 Ma). ...
Body size is a central determinant of a species’ biology and adaptive strategy, but the number of reliable estimates of hominin body mass and stature have been insufficient to determine long-term patterns and subtle interactions in these size components within our lineage. Here, we analyse 254 body mass and 204 stature estimates from a total of 311 hominin specimens dating from 4.4Ma to the Holocene using multilevel chronological and taxonomic analytical categories. The results demonstrate complex temporal patterns of body size variation with phases of relative stasis intermitted by periods of rapid increases. The observed trajectories could result from punctuated increases at speciation events, but also differential proliferation of large-bodied taxa or the extinction of smallbodied populations. Combined taxonomic and temporal analyses show that in relation to australopithecines, early Homo is characterized by significantly larger average body mass and stature but retains considerable diversity, including small body sizes. Within later Homo, stature and body mass evolution follow different trajectories: average modern stature is maintained from ca 1.6 Ma, while consistently higher body masses are not established until the Middle Pleistocene at ca 0.5–0.4 Ma, likely caused by directional selection related to colonizing higher latitudes. Selection against small-bodied individuals (less than 40 kg; less than 140 cm) after 1.4Ma is associated with a decrease in relative size variability in later Homo species compared with earlier Homo and australopithecines. The isolated small-bodied individuals of Homo naledi (ca 0.3 Ma) and Homo floresiensis (ca 100–60 ka) constitute important exceptions to these general patterns, adding further layers of complexity to the evolution of body size within the genus Homo. At the end of the Late Pleistocene and Holocene, body size in Homo sapiens declines on average, but also extends to lower limits not seen in comparable frequency since early Homo.
... Yet morphological and perhaps functional differentiation does appear to characterize at least the hip and thigh of early Homo. Ward et al.'s [69] revealing analysis of the fragmentary KNM-ER 5881 femur and pelvis from Koobi Fora (upper Burgi Member, approx. 1.9 Ma) found a derived, distinctly Homo-like proximal femur (large head compared with neck; rounded neck cross section) and ilium (laterally flexed anterior border; distinct, craniocaudally directed iliac pillar), but a femoral shaft that lacks the derived mediolateral expansion characteristic of all early and modern Homo femora except that of OH 62 and two femora in the Dmanisi sample. ...
... 1.9 Ma) found a derived, distinctly Homo-like proximal femur (large head compared with neck; rounded neck cross section) and ilium (laterally flexed anterior border; distinct, craniocaudally directed iliac pillar), but a femoral shaft that lacks the derived mediolateral expansion characteristic of all early and modern Homo femora except that of OH 62 and two femora in the Dmanisi sample. The KNM-ER 5881 pelvis is much smaller than the similar-age KNM-ER 3228, which is usually attributed to Homo; an argument that they represent the same species would imply a gorilla-like level of sexual size-dimorphism in the early Homo pelvis [69]. Inferred pelvic inlet shape is distinct from that of the Gona H. erectus pelvis [30], which itself is more humanlike (circular) than fossil pelves typically assigned to early Homo (i.e. ...
Although the transition from Australopithecus to Homo is usually thought of as a momentous transformation, the fossil record bearing on the origin and earliest evolution of Homo is virtually undocumented. As a result, the poles of the transition are frequently attached to taxa (e.g. A. afarensis, at ca 3.0 Ma versus H. habilis or H. erectus, at ca 2.0–1.7 Ma) in which substantial adaptive differences have accumulated over significant spans of independent evolution. Such comparisons, in which temporally remote and adaptively divergent species are used to identify a ‘transition’, lend credence to the idea that genera should be conceived at once as monophyletic clades and adaptively unified grades. However, when the problem is recast in terms of lineages, rather than taxa per se , the adaptive criterion becomes a problem of subjectively privileging ‘key’ characteristics from what is typically a stepwise pattern of acquisition of novel characters beginning in the basal representatives of a clade. This is the pattern inferred for species usually included in early Homo , including H. erectus , which has often been cast in the role as earliest humanlike hominin. A fresh look at brain size, hand morphology and earliest technology suggests that a number of key Homo attributes may already be present in generalized species of Australopithecus , and that adaptive distinctions in Homo are simply amplifications or extensions of ancient hominin trends.
This article is part of the themed issue ‘Major transitions in human evolution’.
... Given that the H. naledi talus is far more derived than that of OH 8 (if that belongs to H. habilis), and the cranial morphology is closer to basal Homo than not, this indicates a different suite of locomotor adaptations in H. naledi compared to its likely closest relatives, H. habilis, H. ergaster and H. erectus. Recent descriptions of fempostcranial remains from northern Kenya (Ward et al., 2015) support this assertion. The remains are argued to be Homo-like, but possess femoral midshaft and pelvic inlet morphologies distinct from those found in African H. erectus, indicating that at 1.9 Ma there were at least two distinct postcranial morphotypes in east Africa attributed to the genus Homo. ...
... In early Homo we now see an increased diversity in postcranial anatomy and associated locomotor behavior, which indicates a continuation of locomotor experimentation late into the hominin fossil record (as indicated by H. florsiensis). New finds suggest at least two distinct postcranial morphotypes at 1.9 Ma (Ward et al., 2015), and H. habilis and H. naledi are argued to have retained a degree of arboreality in their locomotor repertoires, while H. floresiensis would have had a gait markedly distinct from that of modern humans (Jungers et al., 2009). It follows, then, that it is perhaps necessary to reevaluate obligate, human-like bipedalism as a meaningful diagnostic criterion for membership of the genus Homo. ...
Bipedalism is a defining trait of hominins, as all members of the clade are argued to possess at least some characters indicative of this unusual form of locomotion. Traditionally the evolution of bipedalism has been treated in a somewhat linear way. This has been challenged in the last decade or so, and in this paper I consider this view in light of the considerable new fossil hominin discoveries of the last few years. It is now apparent that there was even more locomotor diversity and experimentation across hominins than previously thought, and with the discovery of taxa such as H. floresiensis and H. naledi, that diversity continues well into the genus Homo. Based on these findings,we need to reevaluate how we define members of the genus Homo, at least when considering postcranial morphology, and accept that the evolution of hominin bipedalism was a complex and messy affair. It is within that context that the modern human form of bipedal locomotion emerged.
... 2-1 Ma), and does not reflect a simple dichotomy between Paranthropus and Homo. While the two species of Paranthropus are somewhat similar with respect to diaphyseal shape, the two Homo groups are distinctly different from one another, reflecting the presence of at least two postcranial morphotypes within early Homo (Ward et al., 2015). Overall, H. erectus exhibits a diaphyseal profile similar to modern humans, while specimens attributed here to non-erectus early Homo are characterized by a high degree of anteroposterior flattening (relative to mediolateral width) that is unusual among hominids. ...
... The marked variation in diaphyseal morphology observed among post-Australopithecus hominin species may reflect an increased diversity of forelimb use in the Lower Pleistocene, perhaps associated with the more pronounced habitat/resource heterogeneity associated with this time period (Antón, Potts & Aiello, 2014). The unique diaphyseal morphology associated with non-erectus early Homo presents a particularly striking contrast to the more modern-looking diaphysis of H. erectus, further emphasizing observations of postcranial diversity within early Homo (e.g., Ruff, 2009; Ward et al., 2015), as well as previous descriptions of early Homo diversification as a time of " morphological experimentation " (Antón, Potts & Aiello, 2014). Among the fossil species examined here, H. erectus shows the greatest similarities to H. sapiens, perhaps indicating a shift to a more modern pattern of upper limb use compared with earlier and contemporaneous hominin species (i.e., increased manipulatory skill in a fully committed terrestrial biped). ...
The coexistence of multiple hominin species during the Lower Pleistocene has long presented a challenge for taxonomic attribution of isolated postcrania. Although fossil humeri are well-suited for studies of hominin postcranial variation due to their relative abundance, humeral articular morphology has thus far been of limited value for differentiating Paranthropus from Homo. On the other hand, distal humeral diaphyseal shape has been used to justify such generic distinctions at Swartkrans. The potential utility of humeral diaphyseal shape merits larger-scale quantitative analysis, particularly as it permits the inclusion of fragmentary specimens lacking articular morphology. This study analyzes shape variation of the distal humeral diaphysis among fossil hominins (c. 2-1 Ma) to test the hypothesis that specimens can be divided into distinct morphotypes. Coordinate landmarks were placed on 3D laser scans to quantify cross-sectional shape at a standardized location of the humeral diaphysis (proximal to the olecranon fossa) for a variety of fossil hominins and extant hominids. The fossil sample includes specimens attributed to species based on associated craniodental remains. Mantel tests of matrix correlation were used to assess hypotheses about morphometric relationships among the fossils by comparing empirically-derived Procrustes distance matrices to hypothetical model matrices. Diaphyseal shape variation is consistent with the hypothesis of three distinct morphotypes (Paranthropus, Homo erectus, non-erectus early Homo) in both eastern and southern Africa during the observed time period. Specimens attributed to non-erectus early Homo are unique among hominids with respect to the degree of relative anteroposterior flattening, while H. erectus humeri exhibit morphology more similar to that of modern humans. In both geographic regions, Paranthropus is characterized by a morphology that is intermediate with respect to those morphological features that differentiate the two forms of early Homo. This study demonstrates the utility of the humeral diaphysis for taxonomic identification of isolated postcranial remains and further documents a high degree of postcranial diversity in early Homo.
... At this time there are no pelves assigned to Homo habilis or Homo rudolfensis. KNM-ER 5881c, at 1.9 Ma, is currently unassigned to a species, although it is thought to be in the Homo genus (Ward et al., 2015). There is a debate over the pelvic morphology of H. erectus. ...
... These pelves, despite potentially not all belonging to H. erectus, share a suite of derived features, including a markedly sigmoid iliac crest; a robust, cranio-caudally oriented and posteriorly-placed iliac pillar; a large iliac (cristal) tubercle; a robust acetabulosacral buttress; parasagittally oriented iliac blades; an attachment of the rectus femoris muscle that forms a sulcus between the posterosuperior edge of the acetabulum to the superior anterior inferior iliac spine and anterior margin of the iliac pillar; deepened fossae for attachment of the iliacus and gluteus medius; an expanded retroauricular area; a protuberant and medially displaced anterior superior iliac spine; a relatively shorter distance between the sacroiliac joint and acetabulum; a large acetabulum; a robust ilium; prominent sites for muscle and ligamentous attachments; a short ischium; a narrow tubero-acetabular sulcus (the sulcus between the ischial tuberosity and the acetabulum); everted ischial tuberosities; tall, thin pubic symphyseal faces; and potentially a birth canal expanded in the anteroposterior dimension due to upwardly-rotated pubic rami (Day, 1971;Rose, 1984;Leakey and Walker, 1985;Macchiarelli et al., 2004;Simpson et al., 2008;Kibii et al., 2011;Gruss and Schmitt, 2015;Ward et al., 2015). However, H. erectus retains some primitive features, such as more laterally angled iliac blades than are present in modern humans, and a relatively small auricular area (Churchill and VanSickle, 2017). ...
The modern human female pelvis is adapted for bipedal locomotion but must also birth highly-encephalized babies. Potentially a trade-off between locomotion and parturition created an “obstetrical dilemma”. The obstetrical dilemma asks why obstructed labor caused by cephalopelvic disproportion is relatively common in modern humans despite its reproductive cost. Although the obstetrical dilemma is traditionally framed as a trade-off between efficient locomotion and successful parturition, researchers have searched for other selective pressures antagonistic to an increase in the size of the birth canal. This dissertation explores the thermoregulation hypothesis, which argues selection for heat dissipation constrained the size of the birth canal.
A central question that needs to be answered in order to determine why the obstetrical dilemma exists is when did it first evolve in the hominin lineage. Through the examination of pubic bones from two female australopiths, as well as other hominin fossils, modern humans, and non-human primates, it was determined that the “ventral sulcus” present in the australopiths is not indicative of difficult birth and does not support early hominins experiencing cephalopelvic disproportion. Instead, the ventral sulcus is hypothesized to be the result of intra-abdominal pressure on pelvic ligaments that had to support abdominal and pelvic viscera and potentially the weight of gestating fetuses.
Bergmann’s rule states that mammalian ratios of surface area to mass are thermoregulatory adaptations. It has been argued that bi-iliac breadth determines this ratio in humans, with a decrease in bi-iliac breadth leading to a relative increase in surface area, and thus greater heat dissipation. Selection on body temperature regulation in hominins evolving in hot climates could have been in opposition to selection for a widening of the pelvis, potentially constraining the size of the birth canal. To test the relationship between core temperature and bi-iliac breadth, thirty human subjects ran for one hour at a set pace in a variety of climatic conditions. Bi-iliac breadth is a significant predictor of maximum core temperature, but not the increase in core temperature. This is explicable because bi-iliac breadth also plays a significant role in resting core temperature, meaning that individuals with smaller bi-iliac breadths start at a lower resting core temperature and reach a lower maximum temperature during running. This indicates that bi-iliac breadth is an important factor in humans’ ability to thermoregulate.
However, a smaller bi-iliac breadth does not necessarily mean a smaller birth canal. The correlation between bi-iliac breadth and the areas and linear dimensions of the birth canal in the inlet, midplane, and outlet, was tested in an ecogeographically-varied modern human female skeletal sample. All mediolateral diameters and areas of the three birth canal planes are significantly correlated with BIB (with the exception of the outlet mediolateral diameter). This provides support for the thermoregulation hypothesis.
The obstetrical dilemma is a complicated problem that most likely does not have a simple solution. Continued research is necessary to determine the relative contributions of different selective pressures on the hominin birth canal, and to determine when the obstetrical dilemma first evolved. However, the evidence from this dissertation suggests that because bi-iliac breadth is significantly correlated with birth canal size, and because thermoregulation is significantly correlated with bi-iliac breadth, selection related to thermoregulation may have played a role in constraining birth canal size in hominin evolution.
... New associated partial ilium and femur specimens from Koobi Fora, Kenya, dating to 1.9 Ma, have been attributed to the genus Homo, but display a unique combination of traits suggesting the presence of at least two post-cranial morphotypes within early Homo, reflecting underlying body form and/or adaptive differences [48]. Most recently, an assemblage of over 1500 fossil elements representing at least 15 hominin individuals recently described in detail from the Rising Star cave system near Swartkrans, South Africa, again combines primitive characteristics, such as small brain size, curved fingers and australopith-like shoulder, trunk and hip morphology, with derived features in the wrists, hands, legs and feet. ...
The discovery of the earliest known stone tools at Lomekwi 3 (LOM3) from West Turkana, Kenya, dated to 3.3 Ma, raises new questions about the mode and tempo of key adaptations in the hominin lineage. The LOM3 tools date to before the earliest known fossils attributed to Homo at 2.8 Ma. They were made and deposited in a more C 3 environment than were the earliest Oldowan tools at 2.6 Ma. Their discovery leads to renewed investigation on the timing of the emergence of human-like manipulative capabilities in early hominins and implications for reconstructing cognition. The LOM3 artefacts form part of an emerging paradigm shift in palaeoanthropology, in which: tool-use and tool-making behaviours are not limited to the genus Homo ; cranial, post-cranial and behavioural diversity in early Homo is much wider than previously thought; and these evolutionary changes may not have been direct adaptations to living in savannah grassland environments.
This article is part of the themed issue ‘Major transitions in human evolution'.
... Incomplete specimens necessarily excluded from this study include the Malapa hominins, Dinaledi Chamber hominins, Pierolapithecus catalaunicus, and KNM-ER 5881(Ward et al., 2015a). Oreopithecus bambolii was considered too deformed for inclusion in this study. ...
Elucidating the pelvic morphology of the Pan-Homo last common ancestor (LCA) is crucial for understanding ape and human evolution. The pelvis of Ardipithecus ramidus has been the basis of controversial interpretations of the LCA pelvis. In particular, it was proposed that the lower ilium became elongate independently in the orangutan and chimpanzee clades, making these taxa poor analogues for the pelvis of the LCA. This study examines the variation in relative lower ilium height between and within living and fossil hominoid species (and other anthro-poids), and models its evolution using available fossil hominoids as calibration points. We find nuanced differences in relative lower ilium height among living hominoids, particularly in regards to gorillas, which do not have elongate lower ilia (because they are likely to represent the plesio-morphic hominoid condition for this trait). We also show that differences in relative lower ilium height among hominoid taxa are not readily explained by differences in size between species. Our maximum likelihood ancestral state reconstructions support inferences that chimpanzees (Pan troglodytes in particular) and orangutans evolved their elongate lower ilia independently. We also find that the predicted lower ilium height of the Pan-Homo LCA is shorter than all great apes except gorillas. This study adds to a growing body of evidence that finds different regions of the body show different evolutionary histories in different hominoids, and underscores that the unique combinations of morphologies of each modern and fossil hominoid species should be considered when reconstructing the mosaic nature of the Pan-Homo LCA. Anat Rec, 300:828–844, 2017. V C 2017 Wiley Periodicals, Inc.
... Fovea borders were usually distinct as well, and were delimited as the location where the subchondral bone transitions to slope inwards (Fig. 2). Best-fit spheres fit to both the acetabular lunate surface and the femoral head articular surface have very low error within and between observers Plavcan et al., 2012Plavcan et al., , 2013bPlavcan et al., , 2014; see also Ward et al., 2015). ...
Objectives: The ability to reconstruct hip joint mobility from femora and pelves could provide insight into the locomotion and paleobiology of fossil primates. This study presents a method for modeling hip abduction in anthropoids validated with in vivo data.
Methods: Hip abduction simulations were performed on a large sample of anthropoids. The modeling approach integrates three-dimensional (3D) polygonal models created from laser surface scans of bones, 3D landmark data, and shape analysis software to digitally articulate and manipulate the hip joint. Range of femoral abduction (degrees) and the abducted knee position (distance spanned at the knee during abduction) were compared with published live animal data.
Results: The models accurately estimate knee position and (to a lesser extent) angular abduction across broad locomotor groups. They tend to underestimate abduction for acrobatic or suspensory taxa, but overestimate it in more stereotyped taxa. Correspondence between in vivo and in silico data varies at the specific and generic level.
Conclusions: Our models broadly correspond to in vivo data on hip abduction, although the relationship between the models and live animal data is less straightforward than hypothesized. The models can predict acrobatic or stereotyped locomotor adaptation for taxa with values near the extremes of the range of abduction ability. Our findings underscore the difficulties associated with modeling complex systems and the importance of validating in silico models. They suggest that models of joint mobility can offer additional insight into the functional abilities of extinct primates when done in consideration of how joints move and function in vivo.
... Yet, the primitive brachial proportions of Homo habilis, although in combination with human-like humerofemoral proportions (Haeusler andMcHenry, 2004, 2007) suggest that the equilibrium of the upper body in this species was different from H. erectus and modern humans. A different gait pattern from that of later Homo is also supported by the recently described hipbone fragment KNM-ER 5881 that is associated with a femur closely resembling the morphology of the OH 62 H. habilis skeleton (Ward et al., 2015). The ilium displays some characteristics typical of H. erectus but retains a distinct frontal orientation. ...
The functional linkage between pelvis and spine remained long hidden to science. Here, we recount the history of research that led in 1992 to the discovery of the “angle of sacral incidence” by the team of G. Duval-Beaupère. This angle, formed between a ray from the hip joint center to the superior sacral surface and the perpendicular to the sacral surface, was later called pelvic incidence. Specific to each individual, pelvic incidence is tightly correlated with the degree of lumbar lordosis. It is each individual's “signature” for an efficient sagittal balance since it represents the sum of two positional parameters, sacral slope and pelvic tilt. The simultaneous experimental determination of the trunk line of gravity permitted Duval-Beaupère's team to elucidate the conditions of an efficient sagittal balance of the trunk on the lower limbs. We present an in vivo EOS study of eight spino-pelvic parameters describing the sagittal balance in 131 adults. We observe a chain of correlations between the six angular parameters and discuss the functional significance of these results. We show that pelvic incidence increases and lumbar lordosis develops when the infant learns to walk, leading to a correlation between these parameters. This process of association between pelvis and spine might have acquired a solid genetic basis during hominid evolution by natural selection acting on both pelvis and spine. We suggest that this process of functional integration was only possible in the context of bipedal locomotion becoming permanent and stereotyped, expressed by a relatively invariant, periodic walking cycle. Anat Rec, 300:912–931, 2017.
... Gona pelvis (BSN49/P27) (Simpson et al., 2008(Simpson et al., , 2014; or Homo sp. indet.: 1.9-million-year-old associated lower limb elements (KNM-ER 5881 (Ward et al., 2015), KNM-ER 3228 (Leakey, 1976)). There appears to have been a twophase adaptation in the adoption of modern human limb proportions (Asfaw et al., 1999). ...
Today, it is easy to identify humans (Homo sapiens) vis-à-vis all other primates because the anatomical and behavioral gulf between us and our closest living relatives is great and obvious (e.g., the former's large brain size, technological sophistication, worldwide distribution, and language). In our practical experience, there is only one human species living today and this seems reasonable to us given that our behavioral and technological adaptations are so pervasive that there is not enough "ecological room" for another humanlike species and it is easy for us to consider that this uniqueness and suite of adaptations extended well into the past. However, this view is challenged as we learn more about the behavioral sophistication of other living apes, and as more ancient and anatomically primitive hominin fossils are recovered. While the appearance of modern humans (H. sapiens) is first documented in the fossil record at 195,000 years ago in southern Ethiopia (McDougall et al., 2008; Fleagle et al., 2008), the origins of the genus Homo extend back to 2.7-2.9 million years ago with a complex history that includes significant taxonomic diversity and marked behavioral and anatomical evolution. Here, the fossil evidence for Early Pleistocene (2.58-0.78 million years ago) Homo is reviewed.
... For the entirety of the Miocene, pelvic anatomy is known from only a handful of taxa. This absence of data makes it challenging to reconstruct the pelvic form from which the earliest hominins evolved and makes the publication of new Miocene pelves (Hammond et al., 2013;Morgan et al., 2015) and anticipated ones (Ward et al., 2008) all the more exciting. Until the time of Neanderthals and anatomically modern humans, there are about three dozen pelvic remains representing the last 5 million years of our lineage, giving us just a glimpse of pelvic anatomy on average every quarter of a million years. ...
No bone in the human postcranial skeleton differs more dramatically from its match in an ape skeleton than the pelvis. Humans have evolved a specialized pelvis, well-adapted for the rigors of bipedal locomotion. Precisely how this happened has been the subject of great interest and contention in the paleoanthropological literature. In part, this is because of the fragility of the pelvis and its resulting rarity in the human fossil record. However, new discoveries from Miocene hominoids and Plio-Pleistocene hominins have reenergized debates about human pelvic evolution and shed new light on the competing roles of bipedal locomotion and obstetrics in shaping pelvic anatomy. In this issue, 13 papers address the evolution of the human pelvis. Here, we summarize these new contributions to our understanding of pelvic evolution, and share our own thoughts on the progress the field has made, and the questions that still remain. Anat Rec, 300:789–797, 2017.
... Along the anterior portion of the ilium is a strong iliac pillar,~13.0 mm in maximum thickness. The position of the Sts 65 iliac pillar has been described as anteriorlypositioned, similar to other australopiths and unlike the more posterior position found in Homo (Ward et al., 2015). The iliac crest Figure 2. The preauricular surface of Sts 65. ...
... We included one fossil great ape specimen representing Rudapithecus hungaricus (RUD 234) from the Late Miocene site of Rudab anya (Hungary), housed at the Mining and Geological Survey of Hungary, Budapest (Begun et al., 2012;Ward et al., 2019;SOM Table S2). The Plio-Pleistocene hominin sample includes the following specimens: StW 99 and 367 from Sterkfontein Member 4, South Africa, both attributed to Australopithecus africanus and curated at the Evolutionary Studies Institute of the University of the Witwatersrand, Johannesburg, South Africa (Harmon, 2009;Ruff and Higgins, 2013;Zipfel et al., 2020;Pickering et al., 2021); SK 97 from Swartkrans Member 1, South Africa representing Paranthropus robustus curated at the Ditsong National Museum of Natural History, Pretoria, South Africa (Robinson, 1972;Susman et al., 2001;Cazenave et al., 2019Cazenave et al., , 2021; and KNM-ER 738 and 1465 from Koobi Fora, Kenya, both likely representing Paranthropus boisei curated at the National Museums of Kenya, Nairobi (Wood and Costantino, 2007;Wood and Leakey, 2011;Ward et al., 2015;Ruff et al., 2016; SOM Table S2). We also assessed additional fossil specimens including four Miocene apes (including one Dryopithecus fontani, two Hispanopithecus laietanus, and another R. hungaricus femora) and five Plio-Pleistocene hominins (representing three additional A. africanus, one P. robustus, and one P. boisei or Homo sp.); however, their poor internal preservation prevented the possibility to reliably quantify potential CF morphology (SOM Table S2; SOM Fig. S1). ...
The calcar femorale is an internal bony structure of the proximal femur considered to be functionally related to bipedal locomotion. Among extant primates, the presence of a calcar femorale has been so far documented in extant humans and Pan and, among extinct hominins, in the Late Miocene Orrorin, in a Pliocene Australopithecus, and in a Middle Pleistocene Homo specimen. Using high-resolution microcomputed tomography, we investigated the occurrence and morphology (i.e., shape, location, and size) of the calcar femorale in an adult sample of extant humans, Pan troglodytes, Gorilla gorilla, Pongo sp., and Papio ursinus. We also investigated for the first time the occurrence and morphology of a calcar femorale in the adult proximal femoral remains of a Late Miocene great ape (Rudapithecus) and five Plio-Pleistocene hominins from Southern and Eastern Africa (Australopithecus and Paranthropus). We took four measurements: periosteal-to-tip maximum length, maximum length excluding cortical thickness, maximum vertical height, and the distance between the most anterior and posterior limits of the root. To allow for intergeneric comparisons, estimated body size was used to standardize all measurements. Nine of 10 extant humans have a well-developed calcar femorale. Among the African apes, 6 of 10 Pan and 6 of 10 Gorilla also show a distinct calcar femorale. In Pongo (n = 9), it is only present in one captive individual. None of the five investigated Papio specimens show any trace of this structure. Only calcar femorale height, which is systematically taller and extends into the lower part of the lesser trochanter, discriminates humans from extant great apes, except for one Gorilla. The calcar femorale was absent in one Paranthropus robustus and variably developed in all other investigated fossils. These results indicate that this structure cannot be considered as a diagnostic feature of habitual bipedal locomotion and emphasize the need for further investigations of its functional role.
... Understanding the anatomy and inferred locomotor abilities of a fossil specimen, however, may not be representative of the actual behavior of that individual, and those behaviors may have changed through ontogeny, similar to many living primates. With changing perceptions of locomotor diversity in the fossil record (Harcourt- Smith and Aiello, 2004;Jungers et al., 2009;Haile-Selassie et al., 2015;Harcourt-Smith et al., 2015;Kivell et al., 2015;Ward et al., 2015), an ontogenetic perspective may add insight into adult locomotor morphology and distinctions between hominin taxa. With this in mind, comparisons of modern taxa with different locomotor ontogenetic strategies are necessary. ...
Chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla) both knuckle-walk in adulthood but are known to develop their locomotor strategies differently. Using dentally defined age-groups of both Pan and Gorilla and behavioral data from the literature, this study presents an internal trabecular bone approach to better understand the morphological ontogeny of knuckle-walking in these taxa. Capitate and third metacarpal bones were scanned by μCT at 23-43 μm resolution with scaled volumes of interest placed centrally within the head of the capitate and base of the third metacarpal. Trabecular measures related to activity level (size-adjusted bone volume/total volume, trabecular number, and bone surface area/bone volume) met expectations of decreasing through ontogeny in both taxa. Degree of anisotropy did not show statistical support for predicted species differences, but this may be due to the sample size as observed changes through ontogeny reflect expected trends in the capitate. Analyses of principal trabecular orientation corroborated known behavioral differences related to variation of hand use in these taxa, but only Pan showed directional patterning associated with suggested wrist posture. Assessment of allometry showed that the trabecular bone of larger animals is characterized by fewer and thinner trabeculae relative to bone size. In combination, these findings confirm the efficacy of trabecular bone in reflecting locomotor ontogeny differences between closely related taxa. These techniques show promise for use within the hominin fossil record, particularly for taxa hypothesized to be arboreal in some capacity.
... Between the thickened buttress posteriorly, AIIS anteriorly, and acetabular margin inferiorly, is a concavity or depression (Figure 4). This depression does not form a shelf-like appearance at the acetabular margin as has been described for the genus Homo (e.g.,Simpson et al., 2008;Ward et al., 2015) andA. sedibaKibii et al., 2011), but the same is true of immature human ilia.Posterior to the inferior "base" of the buttress, the gluteal surface is relatively flat and missing the thin (<1 mm), outermost layer of cortical bone inferiorly. ...
Homo naledi is represented by abundant remains from the Dinaledi Chamber of the Rising Star Cave system in South Africa. While pelvic elements from the Dinaledi Chamber of the cave are fragmentary, a relatively complete ilium (U.W. 102a–138) was recovered from the Lesedi Chamber. We reconstructed and analyzed the Lesedi ilium, providing qualitative descriptions and quantitative assessment of its morphology and developmental state. We compared the Lesedi ilium to remains from the Dinaledi Chamber, other South African hominin fossils, and an ontogenetic series of human ilia. We used the Dinaledi adults as a guide for reconstructing the Lesedi ilium. To assess development of the Lesedi ilium, we compared immature/mature proportional ilium height for fossils and humans. We used 3D geometric morphometrics (GMs) to examine size and shape variation among this sample. The Lesedi ilium showed incipient development of features expressed in adult H. naledi ilia. The proportional height of the Lesedi ilium was within the range of human juveniles between 4–11 years of age. GM analyses showed that the Lesedi ilium had an iliac blade shape similar to those of australopiths and an expanded auricular surface more similar to humans. The reconstructed Lesedi specimen represents the best preserved ilium of H. naledi, confirming the australopith‐like iliac blade morphology first hypothesized in adult specimens, and establishing that this anatomy was present early in this species' ontogeny. In contrast to australopiths, the Lesedi ilium displays an enlarged sacroiliac joint, the significance of which requires further investigation.
... Joint size may not be as useful as other features in determining taxonomic identity for these intermediate specimens. Recent discovery of a Homo erectus, KNM--ER 5881b (Ward et al., 2015), which has a femoral head diameter that falls well within the range of australopiths, supports the idea that absolute joint size may not be useful for differentiating between late ...
http://deepblue.lib.umich.edu/bitstream/2027.42/115856/1/ilundeen.pdf
... Ma Homo sp. partial skeleton KNM-ER 5881 (identified as non-erectus early Homo; Ward et al., 2015) is slightly below that of KNM-ER 3735. ...
The Rising Star cave system has produced abundant fossil hominin remains within the Dinaledi Chamber, representing a minimum of 15 individuals attributed to Homo naledi. Further exploration led to the discovery of hominin material, now comprising 131 hominin specimens, within a second chamber, the Lesedi Chamber. The Lesedi Chamber is far separated from the Dinaledi Chamber within the Rising Star cave system, and represents a second depositional context for hominin remains. In each of three collection areas within the Lesedi Chamber, diagnostic skeletal material allows a clear attribution to H. naledi. Both adult and immature material is present. The hominin remains represent at least three individuals based upon duplication of elements, but more individuals are likely present based upon the spatial context. The most significant specimen is the near-complete cranium of a large individual, designated LES1, with an endocranial volume of approximately 610 ml and associated postcranial remains. The Lesedi Chamber skeletal sample extends our knowledge of the morphology and variation of H. naledi, and evidence of H. naledi from both recovery localities shows a consistent pattern of differentiation from other hominin species.
Bipedalism is one of the criteria that paleoanthropologists use in order to interpret the fossil record and to determine if a specimen belongs to the human lineage. In the context of such interpretations, bipedalism is considered to be a unique characteristic of this lineage that also marks its origin. This conception has largely remained unchallenged over the last decades, in spite of fossil discoveries that led to the emergence of bipedalism in the human lineage being shifted back by several millions of years. In this paper, I analyze the uses of this criterion in paleoanthropology and demonstrate that interpretative biases (such as underdetermined inferences and circular reasoning) are at play in interpretations of hominin remains. By discussing Darwin’s hypotheses about the evolution of bipedalism, I identify major theoretical issues that need to be addressed in the current debates on hominin evolution. First, the assumption that “man alone has become a biped” (Darwin in The descent of man, and selection in relation to sex, John Murray, London, 1871) is analyzed in the light of recent empirical data. Three major issues are discussed: the definition of “man”, i.e. “human”, the uniqueness of human bipedalism, and the equivocal meaning of being a “biped”. Then, I highlight some of Darwin’s remarks that may be helpful for current debates in paleoanthropology, regarding natural selection in locomotor evolution, as well as taxonomic and phylogenetic significance of functional features. Finally, I analyze two examples of how fossil discoverers referred to Darwin in the recent years and discuss his role as an intellectual support.
Previous attempts to estimate body mass in pre-Holocene hominins have relied on prediction equations derived from relatively limited extant samples. Here we derive new equations to predict body mass from femoral head breadth and proximal tibial plateau breadth based on a large and diverse sample of modern humans (avoiding the problems associated with using diaphyseal dimensions and/or cadaveric reference samples). In addition, an adjustment for the relatively small femoral heads of non-Homo taxa is developed based on observed differences in hip to knee joint scaling. Body mass is then estimated for 214 terminal Miocene through Pleistocene hominin specimens. Mean body masses for non-Homo taxa range between 39 and 49 kg (39-45 kg if sex-specific means are averaged), with no consistent temporal trend (6-1.85 Ma). Mean body mass increases in early Homo (2.04-1.77 Ma) to 55-59 kg, and then again dramatically in Homo erectus and later archaic middle Pleistocene Homo, to about 70 kg. The same average body mass is maintained in late Pleistocene archaic Homo and early anatomically modern humans through the early/middle Upper Paleolithic (0.024 Ma), only declining in the late Upper Paleolithic, with regional variation. Sexual dimorphism in body mass is greatest in Australopithecus afarensis (log[male/female] = 1.54), declines in Australopithecus africanus and Paranthropus robustus (log ratio 1.36), and then again in early Homo and middle and late Pleistocene archaic Homo (log ratio 1.20-1.27), although it remains somewhat elevated above that of living and middle/late Pleistocene anatomically modern humans (log ratio about 1.15).
The recent turn to deep history reveals an interrelational story of hominin emergence among myriad other living creatures, full of bodily intimacies, shared habitats, and interspecific cultural communications. This essay examines studies of coevolution, symbiosis, and mimicry expressing pervasive intersubjectivity that are increasingly acknowledged by biologists and biosemioticians. Traditional oral narratives, rituals, and early literary texts encode sedimented evolutionary histories of such relationships, preserving and continuing memories that are semiotic scaffoldings of cultural mimicry, mirroring and mapping the living world where our ancestors saw themselves in dynamic interrelation with the other animal species around them. These constitute an eco-imaginary expressing the human participation in coevolved animality that Merleau-Ponty saw as the logos of the sensible world.
After middle Miocene, two important climatic changes took place, consisting mainly of cooling in both hemispheres. One occurred between 7 and 5.4 Ma and another at the end of the Pliocene, which marked the beginning of the Pleistocene in approximately 2.58 Ma. The proposal of this presentation is to analyze diverse forcings of these climatic changes, such as the influence of the joint occurrence of reversions of the geomagnetic field and explosions of a supernova. These events occurred coincidentally with Earth cooling. Also, biological changes in those time intervals are analyzed, especially the evolution of the Hominins since the oldest hominin fossils. The characteristics of the Galactic Cosmic Rays, its influence on the climate and its potential mutogenetic effect were taking into account. Briefly, according to our analysis, it seems to be evident that together with other factors, the joint occurrence of the explosion of a supernova at less than 100pc from the Earth and the weakening and / or reversion of the Geomagnetic Field was an important factor that promoted these two climatic and ecosystem changes.
In this chapter, we summarize vertebral remains from early Pleistocene Homo, including H. erectus, as well as H. naledi and H. floresiensis fossils from the Middle and Late Pleistocene, respectively. Two partial immature H. erectus skeletons where vertebrae are well represented are KNM-WT 15000 (“Turkana boy”) and the D2700 individual from Dmanisi. Vertebrae from H. naledi are also considered here, including those from the LES1 partial skeleton (“Neo”), despite their younger date to the Middle Pleistocene. We review the fossil record of presacral vertebrae in early Homo, and summarize work on the functional morphology, metameric patterning, and postcranial neuroanatomy of early Homo, comparing and contrasting the presacral spine with their putative australopith forbears and extant apes and humans. Based on the current evidence, the vertebral column of H. erectus possessed a modal number of twelve thoracic and five lumbar segments, as is the case in australopiths, as well as modern humans. The spine of H. erectus reveals key changes relative to earlier hominins, with an expanded thoracolumbar spinal canal offering increased neurovascular capacities, and a ventral pillar (formed by the vertebral bodies) better equipped to mitigate compressive loads and provide energy return. These biological developments are germane to understanding the advent of derived human behaviors, including efficient long-range locomotion and the first hominin expansion out of Africa.
Gorillas occupy habitats that range in elevation from 0 to 3850 m. Populations at higher elevations tend to be less arboreal than lowland populations. Variation in habitat-specific behaviors among closely related populations makes gorillas a unique model to study the relationship between locomotion and morphology. The pelvis reflects differences in locomotion in other primates, and thus may also reflect locomotor differences among gorillas. We tested the hypothesis that pelvic morphology exhibits clinal variation across elevation within Gorilla. Using 3D geometric morphometrics and principal components analysis (PCA), we characterized pelvic shape in three gorilla subspecies representing 14 localities across gorillas' full elevation range: western lowland gorillas (Gorilla gorilla gorilla), mountain gorillas (Gorilla beringei beringei), and Grauer's gorillas (Gorilla beringei graueri). We found that the first principal component (PC1) usually reflects differences between western and eastern gorillas in the lateral margin of the ilium and, in males, the obturator foramen. When sexes are considered together, the second principal component (PC2) indicates some separation between G. b. beringei and G. b. graueri, albeit with considerable overlap, corresponding to the shape of the iliac crest. When sexes were analyzed separately, there was no distinction. Phylogenetic generalized least squares regression was used to evaluate the relationship between elevation and pelvic shape under varying phylogenetic assumptions. Models were compared to assess how phylogenetic adjustment affects model fit. Neither of the first two PCs nor overall shape yielded a significant relationship with elevation in any of the pooled-sex and individual-sex samples. This suggests that covariation between pelvic morphology and elevation is sex-specific and dependent on phylogenetic assumptions. Our results find complex interactions between sex, phylogeny, elevation, and pelvic morphology, suggesting that there is not one ecomorphological pattern that characterizes all gorillas.
Cambridge Core - Biological Anthropology and Primatology - The Evolutionary Biology of the Human Pelvis - by Cara M. Wall-Scheffler
The Evolutionary Biology of the Human Pelvis - by Cara M. Wall-Scheffler January 2020
Functional analyses of the 4.4 Ma hominin Ardipithecus ramidus postcrania revealed a previously unknown and unpredicted locomotor pattern combining arboreal clambering and a form of terrestrial bipedality. To date, all of the fossil evidence of Ar. ramidus locomotion has been collected from the Aramis area of the Middle Awash Research Project in Ethiopia. Here, we present the results of an analysis of additional early Pliocene Ar. ramidus fossils from the Gona Project study area, Ethiopia, that includes a fragmentary but informative partial skeleton (GWM67/P2) and additional isolated manual remains. While we reinforce the original functional interpretations of Ar. ramidus of having a mixed locomotor adaptation of terrestrial bipedality and arboreal clambering, we broaden our understanding of the nature of its locomotor pattern by documenting better the function of the hip, ankle, and foot. The newly recovered fossils document a greater adaptation to bipedality in the Ar. ramidus ankle and hallux than previously recognized. In addition, a newly discovered scaphoid bone with a fusing os centrale provides further evidence about the nature of hominin hand evolution.
Modern humans are characterized by a highly specialized foot that reflects our obligate bipedalism. Our understanding of hominin foot evolution is, although, hindered by a paucity of well-associated remains. Here we describe the foot of Homo naledi from Dinaledi Chamber, South Africa, using 107 pedal elements, including one nearly-complete adult foot. The H. naledi foot is predominantly modern human-like in morphology and inferred function, with an adducted hallux, an elongated tarsus, and derived ankle and calcaneocuboid joints. In combination, these features indicate a foot well adapted for striding bipedalism. However, the H. naledi foot differs from modern humans in having more curved proximal pedal phalanges, and features suggestive of a reduced medial longitudinal arch. Within the context of primitive features found elsewhere in the skeleton, these findings suggest a unique locomotor repertoire for H. naledi, thus providing further evidence of locomotor diversity within both the hominin clade and the genus Homo.
Objectives
The presence of sexual dimorphism in the birth canals of anthropoid primates is well documented, and birth canal dimorphism tends to be especially robust among species that give birth to relatively large neonates. However, it is less clear whether birth canal dimorphism is accompanied by dimorphism in parts of the pelvis not directly under selection for birth, particularly including bi-iliac breadth, biactetabular breadth, lengths of the ischium and ilium, and 3D shape. This study investigates the patterns of dimorphism among anthropoid primates in those parts of the pelvis which do not directly contribute to the bony birth canal, here termed the non-obstetric pelvis.
Methods
3D landmark data were collected on the bony pelves of 899 anthropoid primates. Specifically, landmark data were collected on parts of the pelvis not thought to be directly involved in selection for parturition, including portions of the posterior and superior ilium, acetabulum, and lateral ischium. Principal components analysis and Euclidean distance matrix analysis were used to ascertain sexual dimorphism in pelvic sizes and shapes within each species.
Results
Results show that dimorphism in non-obstetric pelvic size and shape exists across anthropoids, just as is seen in the birth canal. However, the magnitude of dimorphism in non-obstetric pelvic shape tends to be greater among anthropoid species that give birth to relatively large neonates compared with those birthing smaller neonates relative to maternal pelvic size.
Conclusions
Though all anthropoids included in the study show some degree of sexual dimorphism in non-obstetric pelvic size and/or shape, species which give birth to large neonates relative to maternal pelvic size have the highest levels of dimorphism in pelvic shape. Moreover, the magnitude of dimorphism in certain parts of the non-obstetric pelvis mirrors patterns seen in the birth canal. The results of this study are promising for ascertaining pelvic dimorphism and relative neonate size in fossil primates, particularly in fragmentary remains which do not preserve a complete bony birth canal.
Bipedalism is a key human adaptation and a defining feature of the hominin clade. Fossil femora discovered in Kenya and attributed
to Orrorin tugenensis, at 6 million years ago, purportedly provide the earliest postcranial evidence of hominin bipedalism, but their functional
and phylogenetic affinities are controversial. We show that the O. tugenensis femur differs from those of apes and Homo and most strongly resembles those of Australopithecus and Paranthropus, indicating that O. tugenensis was bipedal but is not more closely related to Homo than to Australopithecus. Femoral morphology indicates that O. tugenensis shared distinctive hip biomechanics with australopiths, suggesting that this complex evolved early in human evolution and
persisted for almost 4 million years until modifications of the hip appeared in the late Pliocene in early Homo.
MAK-VP-1/1, a proximal femur recovered from the Maka Sands (ca. 3.4 mya) of the Middle Awash, Ethiopia, and attributed to Australopithecus afarensis, is described in detail. It represents the oldest skeletal evidence of locomotion in this species, and is analyzed from a morphogenetic perspective. X-ray, CT, and metric data are evaluated, using a variety of methods including discriminant function. The specimen indicates that the hip joint of A. afarensis was remarkably like that of modern humans, and that the dramatic muscle allocation shifts which distinguish living humans and African apes were already present in a highly derived form in this species. Its anatomy provides no indication of any form of locomotion save habitual terrestrial bipedality, which very probably differed only trivially from that of modern humans.
Orrorin tugenensis (Kenya, ca. 6 Ma) is one of the earliest putative hominins. Its proximal femur, BAR 1002'00, was originally described as being very human-like, although later multivariate analyses showed an australopith pattern. However, some of its traits (for example, laterally protruding greater trochanter, medially oriented lesser trochanter and presence of third trochanter) are also present in earlier Miocene apes. Here, we use geometric morphometrics to reassess the morphological affinities of BAR 1002'00 within a large sample of anthropoids (including fossil apes and hominins) and reconstruct hominoid proximal femur evolution using squared-change parsimony. Our results indicate that both hominin and modern great ape femora evolved in different directions from a primitive morphology represented by some fossil apes. Orrorin appears intermediate between Miocene apes and australopiths in shape space. This evidence is consistent with femoral shape similarities in extant great apes being derived and homoplastic and has profound implications for understanding the origins of human bipedalism.
The site of Dmanisi, Georgia, has yielded an impressive sample of hominid cranial and postcranial remains, documenting the
presence of Homo outside Africa around 1.8 million years ago. Here we report on a new cranium from Dmanisi (D4500) that, together with its
mandible (D2600), represents the world's first completely preserved adult hominid skull from the early Pleistocene. D4500/D2600
combines a small braincase (546 cubic centimeters) with a large prognathic face and exhibits close morphological affinities
with the earliest known Homo fossils from Africa. The Dmanisi sample, which now comprises five crania, provides direct evidence for wide morphological
variation within and among early Homo paleodemes. This implies the existence of a single evolving lineage of early Homo, with phylogeographic continuity across continents.
We present a magnetostratigraphic record from the western Philippine Sea that is tied to a marine δ 18 O record for the past 2.14 million years. The ages of geomagnetic reversals were astronomically calibrated by tuning the oxygen isotopic stratigraphy, yielding a chronology for the following subchrons: Matuyama/Brunhes boundary, 781 ± 3 ka (slightly above δ 18 O Stage 19.3); top of the Santa Rosa polarity interval, 920 ± 2 ka (Stage 23/24); base of the Santa Rosa polarity interval, 925 ± 1 ka (Stage 24); top of the Jaramillo subchron, 988 ± 3 ka (Stage 27); base of the Jaramillo subchron, 1072 ± 2 ka (Stage 31); top of the Cobb Mountain subchron, 1173 ± 4 ka (Stage 35/36); base of the Cobb Mountain subchron, 1185 ± 5 ka (Stage 36); top of the Olduvai subchron, 1778 ± 3 ka (Stage 63/64); base of the Olduvai subchron, 1945 ± 4 ka (Stage 71/72); top of the Réunion II subchron, 2118 ± 3 ka (Stage 80/81); and base of the Réunion II subchron, 2133 ± 5 ka (Stage 81). This astronomically calibrated chronology independently confirms the ages of major reversals in recently published astronomically calibrated polarity timescales for the Matuyama chron. It also provides the first astronomically calibrated dates for the lower and upper reversals associated with the Cobb Mountain and Santa Rosa polarity intervals, respectively.
A biomechanical analysis of the pelvic and femoral samples available for Australopithecus is presented. No feature of these samples was found to distinguish their gait pattern from that of modern man or to differ in the two presently recognized allomorphs of Australopithecus. Morphological differences between Australopithecus and modern man appear to be the result of different degrees of encephalization rather than any difference in locomotor adaptation.
Due to the fragmentary condition of most specimens, there have been few studies on the anatomy of the early hominid bony birth canal. However, recovery of an innominate and sacrum from one individual (A.L. 288-1, Australopithecus afarensis) allows reconstruction of the complete pelvis. Although A.L. 288-1 is considered to have been a female, several morphologies of its true pelvis resemble those of human males, such as sacral angulation, ischiopubic ramus and, principally, funnelling of the pelvic cavity. The implication is that some of the pelvic dimorphisms characteristic of modern Homo sapiens developed subsequent to the emergence of bipedalism. The shape of A.L. 288-l's true pelvis is compared with that of female H. sapiens and Pan troglodytes. A.L. 288-l's pelvis is platypelloid, unlike Homo and Pan. The obstetric consequence of the difference in pelvic shape would have been a unique mechanism of birth in A.L. 288-1, with the fetus being born along the transverse axis of the outlet. Rotation of the fetal cranium within the pelvic canal, a characteristic of human birth, would not have occurred in A.L. 288-1. The platypelloid (false and true) pelvis of A.L. 288-1 is related to the requirements of locomotion and visceral accommodation and support. Although the obstetric analysis indicates that birth might have been slow and difficult in A.L. 288-1, we do not consider there to have been selection for the australopithecine fetus to have been born in a more altricial state than that in pongids. However, exactly when secondary altriciality, which is a characteristic of modern humans, emerged is a current subject of debate.
The morphology of the hip region, and its functional implications, have figured prominently in discussions of the origin and nature of hominid bipedality (Dart, 1949; Broom and Robinson, 1950; Washburn, 1950; Le Gros Clark, 1955; Mednick, 1955; Napier, 1964, 1967; Day, 1969, 1973; Robinson, 1972; Lovejoy et al., 1973; McHenry, 1975; Wood, 1976; McHenry and Corruccini, 1978; Stern and Susman, 1983, 1991; Susman et al., 1984; Lovejoy, 1988; Berge, 1991; Jungers, 1991). During most of human bipedal gait, the body is balanced over one lower limb (Inman et al., 1981), a biomechanical problem not faced by quadrupeds. The solution to this problem has involved major changes in the form of the human pelvis and proximal femur (as well as structures more distal in the lower limb) from that of our primate quadrupedal contemporaries, and presumably ancestors (Le Gros Clark, 1959).
Striding bipedalism is a key derived behaviour of hominids that possibly originated soon after the divergence of the chimpanzee and human lineages. Although bipedal gaits include walking and running, running is generally considered to have played no major role in human evolution because humans, like apes, are poor sprinters compared to most quadrupeds. Here we assess how well humans perform at sustained long-distance running, and review the physiological and anatomical bases of endurance running capabilities in humans and other mammals. Judged by several criteria, humans perform remarkably well at endurance running, thanks to a diverse array of features, many of which leave traces in the skeleton. The fossil evidence of these features suggests that endurance running is a derived capability of the genus Homo, originating about 2 million years ago, and may have been instrumental in the evolution of the human body form.
Femoral head size provides important information on body size in extinct species. Although it is well-known that femoral head size is correlated with acetabular size, the precision with which femoral head size can be estimated from acetabular size has not been quantified. The availability of accurate 3D surface models of fossil acetabular remains opens the possibility of obtaining accurate estimates of femoral head size from even fragmentary fossil remains [Hammond et al.,: Am J Phys Anthropol 150 (2013) 565–578]. Here we evaluate the relationship between spheres fit to surface models of the femoral head and acetabulum of a large sample of extant anthropoid primates. Sphere diameters are tightly correlated and scale isometrically. In spite of significant taxonomic and possibly functional differences in the relationship between femoral head size and acetabulum size, percent prediction errors of estimated femoral head size remain low regardless of the taxonomic composition of the reference sample. We provide estimates of femoral head size for a series of fossil hominins and monkeys. Am J Phys Anthropol, 2014. © 2014 Wiley Periodicals, Inc.
New fossil femora attributed to Australopithecus from East Rudolf, Kenya, form the basis for a three-dimensional reconstruction of a complete femur. The reconstruction and the known fossils are compared with the femora of Homo sapiens. Although many of the features of the fossil bones fall within the overall ranges to be found in modern man, there seems, nevertheless, to be a distinctive total pattern in the femoral anatomy of Australopithecus. Biomechanical explanations for this pattern may be possible when other postcranial bones can be reconstructed with the same degree of certainty as the femur.
Among the finds of the Kenya group (led by Mr Richard Leakey) of the 1967 International Palaeontological Research Expedition to the Omo River were three skulls and some skeletal material belonging to very early representatives of Homo sapiens. The sites of the two oldest skulls are no younger than mid-Upper Pleistocene and may be as old as late Middle Pleistocene. After a short account by Mr Leakey of some of the other fossils found by the expedition, and a description of the geology of the hominid sites by Professor Karl Butzer (a member of the US group), this article ends with a preliminary description of the human remains by Dr Michael H. Day.
A redefinition of the lithostratigraphy will be useful in studying the Turkana basin. The Koobi Fora formation is <560 m thick, 4.3-0.6 m.y. old and has eight members, delineated by volcanic ash horizons and so resolving the earlier biostratigraphic zonation conflicts. This sequence has now been correlated with other deposits in the Turkana basin and with those at Hadar and in the Gulf of Aden.-R.E.S.
The climbing ability and locomotor efficiency of australopithecine species, particularlyAustralopithecus afarensis, remain controversial despite decades of research. The hip joint is an informative area of anatomy in this regard: determination of relative hip mobility contributes significantly to reconstructing climbing ability, because a mobile hip joint is useful in navigating discontinuous arboreal substrates. This study quantified the distribution of subchondral bone on the femoral head and/or acetabulum inA. afarensis,Australopithecus africanusandAustralopithecus robustus and used it to infer range of movement and loading environment at the hip. Animation of three-dimensional computer models was used to estimate maximum range of abduction for one completeA. afarensiship (AL 288-1). All of the hominid species had a preponderance of articular surface on the anterior aspect of the femoral head, a morphology associated with moderate hip mobility, and a more adducted femur. Although there was variation in the degree of development of this trait, all of the hominids differed fromPanwhich has a femoral articular surface which is distributed uniformly about the fovea capitis. The cranial acetabular articular surface of early hominids was expanded, with the exception of AL 288-1, which did not possess the same degree of cranial acetabular development. Greater cranial expansion in the acetabulum ofA. robustusas compared withA. afarensismay be indicative of a greater habituation to the cranially directed forces generated by bipedal gait. However, despite evidence for variation in the pattern of bipedal hip use among australopithecines, three-dimensional simulations of posture and maximum abduction indicate that AL 288-1 had an adducted hip and a limited range of abduction, similar to modern humans and less than chimpanzees and some monkeys. Limited hip abduction probably reflects a diminished ability to climb and cross substrate gaps using the hindlimb, alternatively, it may signify that climbing kinematics inA. afarensisdiffered from that of non-human anthropoids.
The pelvis of Sts 14 (Australopithecus africanus) was reconstructed through mirror-image moulding. A comparison with the pelvic reconstructions of AL288-1 ("Lucy"; A. ?afarensis) of Lovejoy (1979), Schmid (1983) and a preliminary reconstruction by the first author revealed marked differences between Sts 14 and AL 288-1 which are unlikely to be explained by different methods of reconstruction. A re-examination of sexual characteristics together with an analysis of the birth mechanism led to the conclusion that the morphologically different birth canals of Sts 14 and AL288-1 could be interpreted as reflecting sexual dimorphism in small-bodied gracile australopithecines.
Hip joint diameter is highly correlated with body size in primates and so can potentially provide important information about the biology of fossil hominins. However, quantifying hip joint size has been difficult or impossible for many important but fragmentary specimens. New three-dimensional technologies can be used to digitally fit spheres to the acetabular lunate surface, potentially allowing hip joint diameter estimates for incomplete joint surfaces. Here we evaluate the reliability of sphere-fitting to incomplete lunate surfaces in silico using three-dimensional polygonal models of extant anthropoid hipbones. Measurement error in lunate sphere-fitting was assessed at the individual observer level, as well as between observers. Prediction error was also established for acetabular sphere size estimates for smaller divisions of the lunate surface. Sphere-fitting techniques were then applied to undistorted regions of lunate surface in Plio-Pleistocene hominin pelves, with a range of diameters constructed from extant error estimates. The results of this study indicate that digital sphere-fitting techniques are precise and that the lunate does not need to be completely preserved to accurately infer hip dimensions, although some aspects of joint size and morphology can influence sphere size estimates. Joint diameter is strongly predicted by spheres fit to the cranial and caudal halves of the lunate in all anthropoids. We present new hip joint size estimates for a number of fossil hominins, and outline additional applications for digital sphere-fitting as a morphometric technique. Am J Phys Anthropol, 2013. © 2013 Wiley Periodicals, Inc.
BECAUSE of the importance of the femur in the gait of bipeds, it is surprising that only moderate attention has been paid to the samples of proximal femora of Australopithecus for which published descriptions and/or casts are now available (STS-14, SK-82, SK-97 and OH-20). In descriptions of these specimens, several morphological features have been claimed to separate them significantly from later Pleistocene hominids1–4. We consider that only two features may lie outside the normal range of variation of Homo sapiens.
Fully adult partial skeletons attributed to Australopithecus afarensis (AL 288-1, “Lucy”) and to Homo habilis (OH 62, “Lucy's child”), respectively, both include remains from upper and lower limbs. Relationships between various limb bone dimensions of these skeletons are compared to those of modern African apes and humans. Surprisingly, it emerges that OH 62 displays closer similarities to African apes than does AL 288-1. Yet A. afarensis, whose skeleton is dated more than 1 million years earlier, is commonly supposed to be the ancestor of Homo habilis. If OH 62, classified as Homo habilis by its discoverers, does indeed represent a stage intermediate between A. afarensis and later Homo, a revised interpretation of the course of human evolution would be necessary.
Since its discovery in 1972 (ref. 1), the cranium KNM-ER 1470 has been at the centre of the debate over the number of species of early Homo present in the early Pleistocene epoch of eastern Africa. KNM-ER 1470 stands out among other specimens attributed to early Homo because of its larger size, and its flat and subnasally orthognathic face with anteriorly placed maxillary zygomatic roots. This singular morphology and the incomplete preservation of the fossil have led to different views as to whether KNM-ER 1470 can be accommodated within a single species of early Homo that is highly variable because of sexual, geographical and temporal factors, or whether it provides evidence of species diversity marked by differences in cranial size and facial or masticatory adaptation. Here we report on three newly discovered fossils, aged between 1.78 and 1.95 million years (Myr) old, that clarify the anatomy and taxonomic status of KNM-ER 1470. KNM-ER 62000, a well-preserved face of a late juvenile hominin, closely resembles KNM-ER 1470 but is notably smaller. It preserves previously unknown morphology, including moderately sized, mesiodistally long postcanine teeth. The nearly complete mandible KNM-ER 60000 and mandibular fragment KNM-ER 62003 have a dental arcade that is short anteroposteriorly and flat across the front, with small incisors; these features are consistent with the arcade morphology of KNM-ER 1470 and KNM-ER 62000. The new fossils confirm the presence of two contemporary species of early Homo, in addition to Homo erectus, in the early Pleistocene of eastern Africa.
Knuckle-walking is a pattern of digitigrade locomotion unique to African apes among Primates. Only chimpanzees and gorillas are specially adapted for supporting weight on the dorsal aspects of middle phalanges of flexed hand digits II–V. When forced to the ground, most orangutans assume one of a variety of flexed hand postures, but they cannot knuckle-walk. Some orangutans place their hands in palmigrade postures which are impossible to African apes. The knuckle-walking hands and plantigrade feet of African apes are both morphologically and adaptively distinct from those of Pongo, their nearest relative among extant apes. These features are associated with a common adaptive shift to terrestrial locomotion and support placing chimpanzees and gorillas in the same genus Pan. It is further suggested than Pan comprises the subgenera (a) Pan, including P. troglodytes and pygmy chimpanzees, and (b) Gorilla, including mountain and lowland populations of P. gorilla.
The orientation of the iliac blade with respect to the sacral surface is studied in Australopithecus by angular measuring techniques. The results obtained do not confirm previous hypotheses regarding a nonhuman abductor mechanism in early hominids. The absence of a clearly defined iliac pillar in Australopithecus is considered to be a result of the outward bending of the anterior superior spine.
Understanding the influence of orbital climate cycles on hominin evolution remains a key challenge in paleoanthropology. The two major unresolved issues are: the absence of a climate proxy yielding high-resolution (b 20 kyr) terrestrial climate records, and the lack of age control on hominin fossil occurrences at sufficiently high resolution. Here we present a novel climate proxy, strontium isotope ratios (87 Sr/ 86 Sr) of lacustrine fish fossils from the Turkana Basin, that solves these issues by recording orbitally forced variation in summer monsoon intensity over the Ethiopian Highlands. We successfully applied the climate proxy to a ~ 150 kyr time interval of ~ 2 million year old paleolake deposits containing hominin fossils. Existing age control of the studied interval was improved by a new magnetostratigraphic record precisely locating the base of the Olduvai chron (C2n) near the bottom of the sequence. Spectral analysis demonstrates that 87 Sr/ 86 Sr variability is primarily determined by precession, which enables us to place hominin fossils in an astronomically-tuned climate framework. The Sr climate proxy is potentially applicable to all hominin-bearing lake deposits in the Turkana Basin, ranging in age from ~ 4.2 to 0.8 million years ago (Ma). Our results demonstrate that between ~ 2 and 1.85 Ma the Turkana Basin remained well-watered and inhabited by hominins even during periods of precession maxima when summer monsoon intensity was lowest. This is in contrast to other basins in the East African Rift System (EARS) that were impacted heavily by precession-forced droughts. We hypothesize that during lake phases, the Turkana Basin was an aridity refugium for permanent-water dependent fauna – including hominins – over the precessional climate cycles.
A new fossil hominid partial skeleton (KNM-ER 803) that was discovered from the Plio-Pleistocene sediments to the east of Lake Rudolf is described. It includes parts of a femur, two tibiae, an ulna, two radii, a third metatarsal and several toe bones. There are also two teeth, an upper canine and an upper central incisor. A second new fossil hominid (KNM-ER 164) is represented by a parietal fragment, two vertebrae and some hand bones. A third is represented by a massive left femur (KNM-ER 999).
The specimens are described in anatomical detail, some are illustrated and selected measurements are given. It is concluded that they should be attributed to the genus Homo sp. indet. Detailed comparative studies will be published in due course.
Variation in long bone cross-sectional geometry can be given a more precise functional interpretation using engineering beam theory. However, difficulties in measurement technique have generally prevented studies of large samples of cross sections in this way. In the present study, an automated system utilizing an electronic digitizer and computer software was used to analyze cross-sectional geometric properties of 11 femoral and tibial locations in 119 individuals from the Pecos Pueblo, New Mexico site. The data generated allow identification of clear differences in geometric properties between different regions of the femur and tibia. These differences appear to be related to specific in-vivo mechanical loadings of the lower limb bones, serving to reduce stress and strain under these loadings. The data are also used to investigate possible differences in loading of the femur and tibia in the Pecos and modern samples, and between humans and a nonhuman primate sample.
A recently discovered hominid pelvic fragment from Swartkrans (SK 3155) is described in detail with particular reference to the relationship of the two presently recognized forms of australopithecines in South Africa. Results of this examination and metrical analysis indicate that the acetabulum and iliac blade of the early hominids are similar to Homo sapiens except for a unique pattern of traits: a relatively small sacral articular surface, a relatively small acetabulum, a relatively large iliac fossa, and wide lateral splaying of the iliac blades. The new Swartkrans fossil expresses these traits more strongly than does the gracile australopithecine (Sts 14) and is therefore somewhat less similar to Homo sapiens but it is very unlike any pongid.
Four partial mandibles and three isolated teeth of Homo from East Rudolf, Kenya, are described. They represent only part of the 1972 fossil collection that has been assigned to Homo; results of detailed studies of this material will be published in a monograph.
Morphological traits of the posterior ilium are commonly used for sex determination in bioarcheological and forensic skeletal analysis. This study was designed to compare the classification correctness of standard scoring systems and measurements of the posterior ilium, including using logistic regression, to develop new formulae to predict sex. Metric measurements and morphological scores for the preauricular sulcus (PS), the elevation of the auricular surface, and the greater sciatic notch width were recorded for 97 males and 101 females of both European and African ancestry from the William M. Bass and Terry Collections. Correct classification of sex was high using individual traits such as the greater sciatic notch score (88.4%), the presence or absence of a PS (78.8%), and the scoring of a present PS as 1, 2, or 3 (100%). Furthermore, an equation combining multiple traits of the posterior ilium had a high classification of 94.9%.
Small-scale roughness on bare agricultural soils determines very important properties such as infiltration, runoff or soil erosion. In this work, a method based on photogrammetric tools has been developed for the generation of automatic digital elevation models (DEMs) in agricultural soils, and is compared with a method based on very accurate off-the-shelf three-dimensional (3D) laser scanners. High resolution and accurate DEMs are generated by both of these non-contact techniques on two agricultural field plots of about 0.2 m2: (i) untilled and smooth soil, and (ii) very cloddy tilled surface. Furthermore, classical microrelief parameters such as Random Roughness and Maximum Depressional Storage are computed from grid DEMs obtained by laser scanning and close-range photogrammetry. Both techniques are compared on agricultural soils in terms of data acquisition and analysis performance, resolution, accuracy, and capability of representing microrelief and for computing microrelief parameters. Both the techniques tested have proved able to generate, under ideal conditions, DEMs with high accuracy (standard deviations of the residuals were 0.121 mm and 0.467 mm for laser and photogrammetry, respectively) and resolution (about 0.4 mm for laser scanning and 1 mm for the photogrammetric method). It is also worth noting that soil DEMs can be generated by both methods in less than 2 h, using devices in field assays that are not too expensive. Laser scanning produces a far more detailed surface allowing it to reproduce smaller aggregates than the photogrammetric method. On the other hand, data acquisition is faster with digital photogrammetry. The worse performance with either method happens when they are used on a rougher type of soil. Regarding the proposed non-contact methodologies, field soil microrelief can be attained in a fast, accurate, and economic way. In addition, the microrelief parameters computed from agricultural soil grid DEMs by laser scanning and photogrammetry show quite similar values.
Aside from use as estimates of body mass dimorphism and fore to hind limb joint size comparisons, postcranial elements have not often contributed to assessments of variation in Australopithecus africanus. Meanwhile, cranial, facial, and dental size variation is interpreted to be high or moderately high. Further, the cranial base and face express patterns of structural (shape) variation, which are interpreted by some as evidence for the presence of multiple species. Here, the proximal femur is used to consider postcranial size and shape variation in A. africanus. Original fossils from Makapansgat and Sterkfontein, and samples from Homo, Pan, Gorilla, and Pongo were measured. Size variation was assessed by comparing the A. africanus coefficient of variation to bootstrapped distributions of coefficient of variation samples for each taxon. Shape variation was assessed from isometrically adjusted shape variables. First, the A. africanus standard deviation of log transformed shape variables was compared to bootstrapped distributions of logged standard deviations in each taxon. Second, shape variable based Euclidean distances between fossil pairs were compared to pairwise Euclidean distance distributions in each reference taxon. The degree of size variation in the A. africanus proximal femur is consistent with that of a single species, and is most comparable to Homo and Pan, lower than A. afarensis, and lower than some estimates of cranial and dental variation. Some, but not all, shape variables show more variation in A. africanus than in extant taxa. The degree of shape difference between some fossils exceeds the majority of pairwise differences in the reference taxa. Proximal femoral shape, but not size, variation is consistent with high estimates of A. africanus cranial variation.