Bipedalism in Orrorin tugenensis revealed by its femora

Three fragments of femora of Orrorin tugenensis, a 6 Ma hominid from the Lukeino Formation, Kenya, possesses a suite of derived characters that reveal that the species was habitually bipedal. Detailed anatomical comparisons with modern humans, Australopithecines and Miocene and extant African apes, reveal that Orrorin shares several apomorphic features with Australopithecines and Homo, but none with Pan or Gorilla. Within the Hominidae, the femur of Orrorin is closer morphologically to that of modern humans than it is to those of australopithecines.     

Patterns of evolution in Middle Pleistocene hominids

This paper reviews the chronology and morphological variability of Middle Pleistocene H. erectus. specimens. Functional complexes are delineated within the skull and dentition, and their total morphological patterns quantified using univariate and multivariate statistical analysis. Statistical distances are calculated between H. erectus and other hominid samples for each complex, compared to illustrate patterns of mosaic evolution within the skull and dentition of middle Quaternary hominids, and estimated evolution rates are derived. An attempt is made to relate the observed morphological patterns to ecological shifts by early hominid communities, and to assess their significance for hominid taxonomy.     

Fossil human crania from Yunxian, China: Morphological comparison withHomo erectus crania from Zhoukoudian

Two fossil hominid crania from Yunxian were found in 1989 and 1990 respectively, and were attributed toHomo eretus. For the purpose of examining the “Homo erectus features” in Yunxian crania, comparisons with crania from Zhoukoudian are made in this paper. The features examined include supraobital tori, occipital torus, angle between the occipital and nuchal planes, postorbital constriction, skull breadth conditions, lowness of skull, and frontal flatness and receding. Results show that the “Homo erectus features” are doubtful owing to damage to and distortion of Yunxian crania. Morphologically, the crania from Yunxian are likely ofHomo sapiens.     

An alternative interpretation ofAustralopithecus afarensis fossil material

Hominoid fossils from Hadar, in Ethiopia and Laetoli, in Tanzania, and dated from the late Pliocene, were described as a new species of hominid, “Australopithecus afarensis,”Johanson, White andCoppens, 1978. A comparative morphological analysis of the lectotype and several paralectotypes reveal that that two taxa were synthesized and that “Australopithecus afarensis” represents a hominid and a pongid. The hominid is relatively unspecialized, and the pongid is remarkably similar toDryopithecus (Sivapithecus) sivalensis (Lydekker), 1879. The pongid is the first anthropoid ape recorded from the late Pliocene in Africa.     

A hominid tooth from Bulgaria: the last pre-human hominid of continental Europe

A hominid upper premolar was discovered in the Azmaka quarry, near Chirpan (Bulgaria). The associated fauna, especially the co-occurrence of Choerolophodon and Anancus among the proboscideans, and Cremohipparion matthewi and Hippotherium brachypus among the hipparions, constrains the age of the locality to the second half of the middle Turolian (ca. 7 Ma), making it the latest pre-human hominid of continental Europe and Asia Minor. The available morphological and metric data are more similar to those of Ouranopithecus from the Vallesian of Greece than to those of the early to middle Turolian hominids of Turkey and Georgia, but the time gap speaks against a direct phyletic link, and Turolian migration from the east cannot be rejected.     

Early Homo at Kromdraai B: probabilistic and morphological analysis of the lower dentition

Kromdraai B, situated less than 2 km east of Sterkfontein, in the Gauteng province of South Africa, has yielded 27 specimens, attributed to a single Plio-Pleistocene hominid species, including the type specimen of Paranthropus (Australopithecus) robustus. By using resampling and morphological analysis, and after considering the most diagnostic features that have been used in the past for the lower dentition, we here suggest that one specimen from Kromdraai B, KB 5223, is clearly distinct from P. robustus and represents early Homo. To cite this article: J. Braga, J.F. Thackeray, C. R. Palevol 2 (2003).     

Hominid-pongid distinctiveness in the miocene-pliocene fossil record: The lothagam mandible

The Lothagam mandibular fragment, found in 1967 west of Lake Turkana, Kenya, has been dated to 5.5 million years ago. This date is significant because it may lie within the suggested time range during which the hominid and pongid clades diverged. Because of its fragmentary condition and great age, this specimen has run the gamut of taxonomic assignations, from ramapithecine to pongid to hominid. These three nomenclatural categories serve as the basis for three hypotheses tested in this study. First, morphological and metric comparisons between Lothagam and a sample of Euroafrican ramapithecines address the hypothesis of “Lothagam as predi-vergence hominoid.” Second, comparisons with a sample of Pan test the “Lothagam as postdivergence, African protopongid” hypothesis. Finally, samples of Australopithecus afarensis and A. africanus were utilized to evaluate the hypothesis of “Lothagam as postdivergence, early hominid.” Unlike previous studies attempting to ascertain the evolutionary affinities of this enigmatic fossil, this work benefits from the large sample of A. afarensis specimens now generally available for study. Metric and morphological comparisons demonstrate Lothagam's affinity to A. afarensis in sharing derived, hominid states in such features as the mental foramen vertical position, the ascending ramus origin, the breadth of the alveolar margin, the reduction of the hypoconulid, the dimensions of the M₁ and the dimensions of the mandibular corpus. It is suggested that the dental/gnathic features enumerated in this study can be employed to distinguish ancestral hominid from pongid in future Mio/Pliocene paleontological discoveries.     

A Homo habilis maxilla and other newly-discovered hominid fossils from Olduvai Gorge, Tanzania

In 1995, a 1.8 million year old hominid maxilla with complete dentition (OH 65) was excavated from Bed I in the western part of Olduvai Gorge. The molar crowns are small relative to the long flaring roots, and the root of the canine is very long and straight. The broad maxilla with wide U-shaped palate and the form of the tooth roots closely match those of KNM-ER 1470 which, in its parietal size and morphology, matches the type specimen of Homo habilis, OH 7. Thus, OH 65 and KNM-ER 1470 group with OH 7 as representatives of H. habilis while some other Olduvai specimens, such as OH 13 and OH 24, have more in common in terms of morphology and brain size with Australopithecus africanus. Between 1995 and 2007, the OLAPP team has recovered teeth of eight other hominid individuals from various parts of Olduvai Gorge. These have been identified as belonging to H. habilis, Paranthropus boisei, and Australopithecus cf. africanus.     

The biological and chronological maturation of early hominids

Recent studies on the rate and pattern of dental development indicate that the growth and maturation of early hominids were more similar to the extant apes than to modern humans. This contrasts with the previously held opinion derived from combined dental development, pattern and attrition studies claiming that early hominids were more hominine in their development (Mann, 1975). This paper explores the origin of this difference of opinion and reviews immature hominid dentitions with the benefit of improved radiographs and new data on the pattern and rate of pongid dental development. Paranthropus and Australopithecus specimens are shown to possess an ape-like development pattern but incisor development is specialized in the former and superficially human-like in pattern. The present and recent studies on dental development rate and pattern justify the position that early hominids were more ape-like in their growth and development. Therefore, ages at death calculated from pongid dental development schedules are provided for most immature early hominids. More detailed studies of early hominid developmental biology are now possible. It is suggested that divergent heterochronic processes characterize changes in brain/body proportions during hominid evolution. Relative rates of bone remodeling processes can now be identified on early hominid skeletons. The paleodemographic analysis of early hominids is little changed by the developmental model one chooses.     

Hominid cranial capacity versus time: A regression approach

The application of a linear regression approach to hominid data shows that there is more regularity in hominid cranial capacity over time than has been supposed. Two outcomes of this analysis are: (1) the possibility that the South African Australopithecus africanus sites are older than the presently accepted estimates of perhaps around 2·5 million years and (2) the suggestion that the Ngandong (Solo) cranial material is also considerably older than generally assumed; probably, in excess of approximately 250,000 years B.P.     

The dental developmental status of six East African juvenile fossil hominids

Radiographs of five juvenile fossil hominids from Koobi Fora, Kenya are described and presented together with measurements and observations made on the original speciments. Data are also presented for a single specimen from Olduvai Gorge, Tanzania. Four of these specimens are attributed to Paranthropus boisei (KNM ER 812, 1477 1820 and OH 30), and are all of remarkably similar dental developmental status. Conventional age estimates for these specimens of Paranthropus based on the first permanent molar, indicate an age at death of around 2·2 to 3 years. Perikymata counts on permanent lower central incisors of these specimens also indicate an age at death between 2·5 and 3 years. Two specimens attributed to early Homo (KNM ER 820 and 1507), are dentally more mature than specimens of Paranthropus boisei described here being closer to 5 years of age. Differences between the spacing and distribution of perikymata on the surfaces of incisor teeth are now apparent between Homo, Australopithecus. Paranthropus boisei and Paranthropus robustus: these are described in this paper. Details of the dental developmental patterns of these hominids are also discussed in the light of recent publications that have presented data about hominid eruption sequences and fossil hominid growth periods.     

Disproportionate Cochlear Length in Genus Homo Shows a High Phylogenetic Signal during Apes’ Hearing Evolution

Changes in lifestyles and body weight affected mammal life-history evolution but little is known about how they shaped species’ sensory systems. Since auditory sensitivity impacts communication tasks and environmental acoustic awareness, it may have represented a deciding factor during mammal evolution, including apes. Here, we statistically measure the influence of phylogeny and allometry on the variation of five cochlear morphological features associated with hearing capacities across 22 living and 5 fossil catarrhine species. We find high phylogenetic signals for absolute and relative cochlear length only. Comparisons between fossil cochleae and reconstructed ape ancestral morphotypes show that Australopithecus absolute and relative cochlear lengths are explicable by phylogeny and concordant with the hypothetized ((Pan,Homo),Gorilla) and (Pan,Homo) most recent common ancestors. Conversely, deviations of the Paranthropus oval window area from these most recent common ancestors are not explicable by phylogeny and body weight alone, but suggest instead rapid evolutionary changes (directional selection) of its hearing organ. Premodern (Homo erectus) and modern human cochleae set apart from living non-human catarrhines and australopiths. They show cochlear relative lengths and oval window areas larger than expected for their body mass, two features corresponding to increased low-frequency sensitivity more recent than 2 million years ago. The uniqueness of the “hypertrophied” cochlea in the genus Homo (as opposed to the australopiths) and the significantly high phylogenetic signal of this organ among apes indicate its usefulness to identify homologies and monophyletic groups in the hominid fossil record.     

History of American paleoanthropological research on early Hominidae, 1925–1980

Understanding of the early stages of hominid evolution prior to 1925 was based primarily on comparative morphological evidence derived from extant primates. With the publication of Australopithecus by Dart in 1925 and subsequent research in South Africa, new possibilities for empirical assessment of early hominid evolutionary history were opened. It was Gregory's work, with Hellman, reported at the first meeting of the AAPA in 1930, that convinced many workers of the hominid status of Australopithecus. The debunking of Eoanthropus as a Pliocene hominid, far from having a totally negative effect, showed that cranial expansion had occurred after bipedalism in hominid evolution, demonstrated that chemical dating had come of age, and in a broader sense, had underlined that phylogenetic hypotheses are falsifiable by recourse to the evidence. The input of biological sciences into early hominid studies, as exemplified by Washburn's “new physical anthropology,” reduced taxonomic diversity and focused attention on paleoecology and behavior. The development of the multidisciplinary approach to field research, pioneered by L. Leakey and brought to fruition by Howell, was of fundamental importance in accurately dating and understanding the context of early hominids. Archaeology, primatology, comparative and functional morphology, and morphometrics have contributed substantially in recent years to a fuller understanding of early hominid evolution. American granting agencies have heavily supported early hominid research but patterns of funding have not kept pace with the change from research based largely on individualistic enterprise to multidisciplinary research projects. Future early hominid research, if funding is available, will likely be directed toward investigating temporal and geographic gaps now known in the fossil record and in more rigorous and multidisciplinary investigations of early hominid behavior.     

Homo erectus found still further west: Reconstruction of the Kocabaş cranium (Denizli,Turkey)

Few human fossils are known in Turkey and no Homo erectus has been discovered until now. In this respect, the newly discovered partial skull from Kocaba? is very important: (1) to assess the pattern of the first settlements throughout the Old World; and (2) to document the extension of the species H. erectus to the west of continental Asia. Using CT data and 3D imaging techniques, this specimen was reconstructed and a more detailed analysis was done, including the inner anatomical features. The preliminary results of this study highlight that the fossil hominid from Kocaba? is close to the H. erectus species regarding the following cranial patterns: presence of a clear post-orbital constriction, strong development of the frontal brow-ridge with a depressed supratoral area in the lateral part, as well as endocranial patterns such as the development and orientation of the middle meningeal artery and the presence of a frontal bec. The Kocaba? skull is morphologically very close to the fossils from Zhoukoudian L-C. The partial Kocaba? skull is the oldest H. erectus known in Turkey and the only one from this species to have settled so far west in Asia.     

A multivariate study of evolutionary change in the hominid cranial vault and some evolution rates

Multivariate analysis is used to describe the total morphological pattern of the hominid cranial vault, and to obtain distances between samples of Plio-Pleistocene Hominidae. Such techniques provide a means of quantifying phyletic change within a lineage, and therefore usefully complement the traditional Linnean nomenclature. When divided by elapsed time, the multivariate distances between groups provide a measure of the rate of evolution of a character complex and such data are given for the hominid cranial vault over the Quaternary as a whole, and for more detailed changes within Upper Pleistocene H. sapiens. The evolutionary significance of the observed rates, and their implications for the construction of phyletic schemes, are discussed.     

Endocranial shape asymmetries in Pan paniscus, Pan troglodytes and Gorilla gorilla assessed via skull based landmark analysis

Brain shape asymmetries or petalias consist of the extension of one cerebral hemisphere beyond the other. A larger frontal or caudal projection is usually coupled with a larger lateral extent of the more projecting hemisphere relative to the other. The concurrence of these petalial components is characteristic of hominins. Studies aimed at quantifying petalial asymmetries in human and great ape endocasts rely on the definition of the midline of the endocranial surface. Studies of brain material show that, at least in humans, most of the medial surface of the left occipital lobe distorts along the midline and protrudes on to the right side, making it difficult for midline and corresponding left and right reference point identification. In order to accurately quantify and compare brain shape asymmetries in extant hominid species, we propose here a new protocol based on the objective definition of cranial landmarks. We describe and quantify for the first time in three dimensions the positions of frontal and occipital protrusions in large samples of Pan paniscus, Pan troglodytes and Gorilla gorilla. This study confirms the existence of frontal and occipital petalias in African apes. Moreover, the detailed analysis of the 3D structure of these petalias reveals shared features, as well as features that are unique to the different great ape species.     

An enlarged postcranial sample confirms Australopithecus afarensis dimorphism was similar to modern humans

In a previous study, we introduced the template method as a means of enlarging the Australopithecus afarensis postcranial sample to more accurately estimate its skeletal dimorphism. Results indicated dimorphism to be largely comparable to that of Homo sapiens. Some have since argued that our results were biased by artificial homogeneity in our Au. afarensis sample. Here we report the results from inclusion of 12 additional, newly reported, specimens. The results are consistent with those of our original study and with the hypothesis that early hominid demographic success derived from a reproductive strategy involving male provisioning of pair-bonded females.     

Hominid brain size versus time: Revised regression estimates

This paper represents a revision of the regression estimates proposed in an earlier version (Journal of Human Evolution 1973 2, 405–411). An attempt has been made to incorporate new fossil material and the increasing number of absolute dates. The results of this new analysis suggest that the trend in the relationship of hominid cranial capacity with time remains consistent but the regression parameters have changed.