Mojokerto revisited: Evidence for an intermediate pattern of brain growth in Homo erectus

Brain development in Homo erectus is a subject of great interest, and the infant calvaria from Mojokerto, Indonesia, has featured prominently in these debates. Some researchers have suggested that the pattern of brain development in H. erectus resembled that of non-human apes, while others argue for a more human-like growth pattern. In this study, we retested hypotheses regarding brain ontogeny in H. erectus using new methods (resampling), and data from additional H. erectus crania. Our results reveal that humans achieve 62% (±10%) and chimpanzees 80% (±9%) of their adult endocranial volume by 0.5–1.5 years of age. Using brain mass data, humans achieve on average 65% and chimpanzees 81% of adult size by 0.5–1.5 years. When compared with adult H. erectus crania (n = 9) from Indonesian sites greater than 1.2 million years old, Mojokerto had reached ∼70% of its adult cranial capacity. Mojokerto thus falls almost directly between the average growth in humans and chimpanzees, and well within the range of both. We therefore suggest that brain development in H. erectus cannot be dichotomized as either ape-like or human-like; it was H. erectus-like. These data indicate that H. erectus may have had a unique developmental pattern that should be considered as an important step along the continuum of brain ontogeny between apes and humans.     

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

Sangiran (Solo Basin, Central Java, Indonesia) is the singular Homo erectus fossil locale for Early Pleistocene Southeast Asia. Sangiran is the source for more than 80 specimens in deposits with ⁴⁰Ar/³⁹Ar ages of 1.51-0.9 Ma. In April 2001, we recovered a H. erectus left maxilla fragment (preserving P³- M²) from the Sangiran site of Bapang. The find spot lies at the base of the Bapang Formation type section in cemented gravelly sands traditionally called the Grenzbank Zone. Two meters above the find spot, pumice hornblende has produced an ⁴⁰Ar/³⁹Ar age of 1.51 ± 0.08 Ma. With the addition of Bpg 2001.04, Sangiran now has five H. erectus maxillae. We compare the new maxilla with homologs representing Sangiran H. erectus, Zhoukoudian H. erectus, Western H. erectus (pooled African and Georgian specimens), and Homo habilis. Greatest contrast is with the Zhoukoudian maxillae, which appear to exhibit a derived pattern of premolar-molar relationships compared to Western and Sangiran H. erectus. The dental patterns suggest distinct demic origins for the earlier H. erectus populations represented at Sangiran and the later population represented at Zhoukoudian. These two east Asian populations, separated by 5000 km and nearly 800 k.yr., may have had separate origins from different African/west Eurasian populations.     

Primate brains,the ‘island rule’ and the evolution of Homo floresiensis

The taxonomic status of the small bodied hominin, Homo floresiensis, remains controversial. One contentious aspect of the debate concerns the small brain size estimated for specimen LB1 (Liang Bua 1). Based on intraspecific mammalian allometric relationships between brain and body size, it has been argued that the brain of LB1 is too small for its body mass and is therefore likely to be pathological. The relevance and general applicability of these scaling rules has, however, been challenged, and it is not known whether highly encephalized primates adapt to insular habitats in a consistent manner. Here, an analysis of brain and body size evolution in seven extant insular primates reveals that although insular primates follow the ‘island rule’, having consistently reduced body masses compared with their mainland relatives, neither brain mass nor relative brain size follow similar patterns, contrary to expectations that energetic constraints will favour decreased relative brain size. Brain:body scaling relationships previously used to assess the plausibility of dwarfism in H. floresiensis tend to underestimate body masses of insular primates. In contrast, under a number of phylogenetic scenarios, the evolution of brain and body mass in H. floresiensis is consistent with patterns observed in other insular primates.     

Homo floresiensis Contextualized: A Geometric Morphometric Comparative Analysis of Fossil and Pathological Human Samples

The origin of hominins found on the remote Indonesian island of Flores remains highly contentious. These specimens may represent a new hominin species, Homo floresiensis, descended from a local population of Homo erectus or from an earlier (pre-H. erectus) migration of a small-bodied and small-brained hominin out of Africa. Alternatively, some workers suggest that some or all of the specimens recovered from Liang Bua are pathological members of a small-bodied modern human population. Pathological conditions proposed to explain their documented anatomical features include microcephaly, myxoedematous endemic hypothyroidism (“cretinism”) and Laron syndrome (primary growth hormone insensitivity). This study evaluates evolutionary and pathological hypotheses through comparative analysis of cranial morphology. Geometric morphometric analyses of landmark data show that the sole Flores cranium (LB1) is clearly distinct from healthy modern humans and from those exhibiting hypothyroidism and Laron syndrome. Modern human microcephalic specimens converge, to some extent, on crania of extinct species of Homo. However in the features that distinguish these two groups, LB1 consistently groups with fossil hominins and is most similar to H. erectus. Our study provides further support for recognizing the Flores hominins as a distinct species, H. floresiensis, whose affinities lie with archaic Homo.     

Découverte d’un nouvel hominidé à Dmanissi (Transcaucasie,Géorgie)

Four human remains: one mandible, two skulls and one metatarsus were discovered between 1991 and 1999 at the open-air site of Dmanisi, Georgia, in a precise stratigraphic, palaeontological and archaeological context, in volcanic ashes dated to 1.81 ± 0.05 Ma. The first studies of these fossils enable the authors to compare them with the morphology of archaic African Homo erectus, ascribed to Homo ergaster, and to ascertain hominid presence at the gates of Europe 300 000 years earlier than the classical scenario forecasted. In September 2000, the discovery of a second more complete and robust mandible D 2600 presents a threefold interest: palaeontological, functional and pathological. A comparison with Homo habilis and Homo erectus leads to the recognition of a new Homo species: H. georgicus sp. nov. The morphofunctional characteristics and the antiquity of H. georgicus characterise the root of a long Eurasian line.     

Phylogenetic analysis of the calvaria of Homo floresiensis

Because until 2006 the Liang Bua human fossil remains were not available to the entire paleoanthropological community, the taxonomic position of Homo floresiensis was only a matter of opinion in publications. From the beginning, two schools of thought prevailed, and this situation persists today. One purports that the Liang Bua human series belongs to a local modern human (Homo sapiens sapiens) with anatomical particularities or pathologies that may be due to insular isolation/endogamy. The second argues in favour of the existence of a new species that, depending on the authors, is either a descendant of local Homo erectus, or belongs to a much more basal taxon, closer to archaic Homo or to australopithecines. Because there are no postcranial remains confidently attributed to Homo erectus in the fossil record, and because the Homo erectus type specimen is a single and partial calvaria, a cladistic analysis was undertaken using both nonmetric morphological features and metrics of the calvariae of human fossil specimens including LB1 to test if it belongs to this taxon. Our results indicate that LB1 is included in the Homo erectus clade.     

Dental microwear texture analysis of hominins recovered by the Olduvai Landscape Paleoanthropology Project, 1995-2007

Dental microwear analysis has proven to be a valuable tool for the reconstruction of aspects of diet in early hominins. That said, sample sizes for some groups are small, decreasing our confidence that results are representative of a given taxon and making it difficult to assess within-species variation. Here we present microwear texture data for several new specimens of Homo habilis and Paranthropus boisei from Olduvai Gorge, bringing sample sizes for these species in line with those published for most other early hominins. These data are added to those published to date, and microwear textures of the enlarged sample of H. habilis (n = 10) and P. boisei (n = 9) are compared with one another and with those of other early hominins. New results confirm that P. boisei does not have microwear patterns expected of a hard-object specialist. Further, the separate texture complexity analyses of early Homo species suggest that Homo erectus ate a broader range of foods, at least in terms of hardness, than did H. habilis, P. boisei, or the “gracile” australopiths studied. Finally, differences in scale of maximum complexity and perhaps textural fill volume between H. habilis and H. erectus are noted, suggesting further possible differences between these species in diet.     

Liang Bua Homo floresiensis mandibles and mandibular teeth: a contribution to the comparative morphology of a new hominin species

In 2004, a new hominin species, Homo floresiensis, was described from Late Pleistocene cave deposits at Liang Bua, Flores. H. floresiensis was remarkable for its small body-size, endocranial volume in the chimpanzee range, limb proportions and skeletal robusticity similar to Pliocene Australopithecus, and a skeletal morphology with a distinctive combination of symplesiomorphic, derived, and unique traits. Critics of H. floresiensis as a novel species have argued that the Pleistocene skeletons from Liang Bua either fall within the range of living Australomelanesians, exhibit the attributes of growth disorders found in modern humans, or a combination of both. Here we describe the morphology of the LB1, LB2, and LB6 mandibles and mandibular teeth from Liang Bua. Morphological and metrical comparisons of the mandibles demonstrate that they share a distinctive suite of traits that place them outside both the H. sapiens and H. erectus ranges of variation. While having the derived molar size of later Homo, the symphyseal, corpus, ramus, and premolar morphologies share similarities with both Australopithecus and early Homo. When the mandibles are considered with the existing evidence for cranial and postcranial anatomy, limb proportions, and the functional anatomy of the wrist and shoulder, they are in many respects closer to African early Homo or Australopithecus than to later Homo. Taken together, this evidence suggests that the ancestors of H. floresiensis left Africa before the evolution of H. erectus, as defined by the Dmanisi and East African evidence.     

Just how strapping was KNM-WT 15000?

For over twenty years, the young, male Homo erectus specimen KNM-WT 15000 has been the focus of studies on growth and development, locomotion, size, sexual dimorphism, skeletal morphology, and encephalization, often serving as the standard for his species. Prior research on KNM-WT 15000 operates under the assumption that H. erectus experienced a modern human life history, including an adolescent growth spurt. However, recent fossil discoveries, improvements in research methods, and new insights into modern human ontogeny suggest that this may not have been the case. In this study, we examine alternative life history trajectories in H. erectus to re-evaluate adult stature estimates for KNM-WT 15000. We constructed a series of hypothetical growth curves by modifying known human and chimpanzee curves, calculating intermediate growth velocities, and shifting the age of onset and completion of growth in stature. We recalculated adult stature for KNM-WT 15000 by increasing stature at death by the percentage of growth remaining in each curve. The curve that most closely matches the life history events experienced by KNM-WT 15000 prior to death indicates that growth in this specimen would have been completed by 12.3 years of age. These results suggest that KNM-WT 15000 would have experienced a growth spurt that had a lower peak velocity and shorter duration than the adolescent growth spurt in modern humans. As a result, it is likely that KNM-WT 15000 would have only attained an adult stature of 163 cm (∼5′4″), not 185 cm (∼6′1″) as previously reported. KNM-WT 15000's smaller stature has important implications for evolutionary scenarios involving early genus Homo.     

Morphological divergence in giant fossil dormice

Insular gigantism—evolutionary increases in body size from small-bodied mainland ancestors—is a conceptually significant, but poorly studied, evolutionary phenomenon. Gigantism is widespread on Mediterranean islands, particularly among fossil and extant dormice. These include an extant giant population of Eliomys quercinus on Formentera, the giant Balearic genus †Hypnomys and the exceptionally large †Leithia melitensis of Pleistocene Sicily. We quantified patterns of cranial and mandibular shape and their relationships to head size (allometry) among mainland and insular dormouse populations, asking to what extent the morphology of island giants is explained by allometry. We find that gigantism in dormice is not simply an extrapolation of the allometric trajectory of their mainland relatives. Instead, a large portion of their distinctive cranial and mandibular morphology resulted from the population- or species-specific evolutionary shape changes. Our findings suggest that body size increases in insular giant dormice were accompanied by the evolutionary divergence of feeding adaptations. This complements other evidence of ecological divergence in these taxa, which span predominantly faunivorous to herbivorous diets. Our findings suggest that insular gigantism involves context-dependent phenotypic modifications, underscoring the highly distinctive nature of island faunas.     

Reconstructing cranial evolution in an extinct hominin

Homo erectus is the first hominin species with a truly cosmopolitan distribution and resembles recent humans in its broad spatial distribution. The microevolutionary events associated with dispersal and local adaptation may have produced similar population structure in both species. Understanding the evolutionary population dynamics of H. erectus has larger implications for the emergence of later Homo lineages in the Middle Pleistocene. Quantitative genetics models provide a means of interrogating aspects of long-standing H. erectus population history narratives. For the current study, cranial fossils were sorted into six major palaeodemes from sites across Africa and Asia spanning 1.8–0.1 Ma. Three-dimensional shape data from the occipital and frontal bones were used to compare intraspecific variation and test evolutionary hypotheses. Results indicate that H. erectus had higher individual and group variation than Homo sapiens, probably reflecting different levels of genetic diversity and population history in these spatially disperse species. This study also revealed distinct evolutionary histories for frontal and occipital bone shape in H. erectus, with a larger role for natural selection in the former. One scenario consistent with these findings is climate-driven facial adaptation in H. erectus, which is reflected in the frontal bone through integration with the orbits.     

Cranial vault shape in fossil hominids: Fourier descriptors in norma lateralis

Two major views of human evolution have elicited considerable controversy. These are: [1] the “out of Africa” hypothesis and [2] the “multiregional” hypothesis. This paper is an attempt to try to reconcile these two scenarios using hominid cranial vault data. Elliptical Fourier functions (EFFs) were used to describe, in visual and numerical terms, the shape of the human cranial vault in norma lateralis.Using jpeg images, contours of the cranial vault of a large sample of hominid specimens were pre-processed in Photoshop CS and rotated in 2D space (positional-orientation) so that a line drawn from nasion to porion was horizontal. The cranial vault image was then digitized with 72 closely-spaced points and submitted to a specially written routine that computed EFFs normalized by scaling (size-standardization). This ensured that the representation was invariant with respect to starting point, size and orientation.Statistically significant differences were found between the H. sapiens sample and both the H. erectus and H. neanderthalensis samples. In contrast, there were no statistically significant differences between the H. erectus and H. neanderthalensis groups, leading to three conclusions: [1] the similarity in cranial vault shape between H. erectus and H. neanderthalensis suggests a single gradually evolving lineage; [2] The taxon H. heidelbergensis can be embedded into the H. erectus → H. neanderthalensis line; and [3] H. sapiens seems to be a separate evolutionary development and is considered here either as a separate species or as a possible example of an allopatric semispecies (Grant, 1977). The results here suggest that human evolution over the last 2 Ma may turn out to be neither totally multiregional or simply out of Africa but rather represents a considerably more complicated picture.     

Nacurrie 1: Mark of ancient Java, or a caring mother’s hands, in terminal Pleistocene Australia?

There has been a protracted debate over the evidence for intentional cranial modification in the terminal Pleistocene Australian crania from Kow Swamp and Coobool Creek. Resolution of this debate is crucial to interpretations of the significance of morphological variation within terminal Pleistocene-early Holocene Australian skeletal materials and claims of a regional evolutionary sequence linking Javan Homo erectus and Australian Homo sapiens. However, morphological comparisons of terminal Pleistocene and recent Australian crania are complicated by the significantly greater average body mass in the former. Raw and size-adjusted metric comparisons of the terminal Pleistocene skeleton from Nacurrie, south-eastern Australia, with modified and unmodified H. sapiens and H. erectus, identified a suite of traits in the frontal, parietal, and occipital bones associated with intentional modification of a neonate’s skull. These traits are also present in some of the crania from Kow Swamp and Coobool Creek, which are in close geographic proximity to Nacurrie, but not in unmodified H. sapiens or Javan H. erectus. Frontal bone morphology in H. erectus was distinct from all of the Australian H. sapiens samples. During the first six months of life, Nacurrie’s vault may have been shaped by his mother’s hands, rather than though the application of fixed bandages. Whether this behaviour persisted only for several generations, or hundreds of years, remains unknown. The reasons behind the shaping of Nacurrie’s head, aesthetics or otherwise, and why this cultural practice was adopted and subsequently discontinued, will always remain a matter of speculation.     

Fission-fusion and the evolution of hominin social systems

The course of hominin evolution has involved successive migrations towards higher absolute latitudes over the past three million years. Poorer habitat quality further from the equator has led to the necessity for groups occupying higher latitudes to live at lower population densities. Coupled with a trend towards increasing group size over this time period, this tendency towards expansion has led to exponential increases in the area requirements of hominin groups, and a concomitant need to adjust foraging patterns. The current analyses suggest that the development of increasingly complex, multi-level fission-fusion social systems could have freed hominins of the foraging constraints imposed by large group sizes and low population densities. Analyses of the fossil record suggest latitudinally-driven differences in area requirements of the australopithecines from East and South Africa, and African and Asian Homo erectus. In contrast, chronologically-driven differences appear between H. erectus as a whole and Homo heidelbergensis, and between H. heidelbergensis and the Neanderthals. These results are discussed in relation to studies of the foraging patterns of primates and hunter-gatherers.     

Conclusion. Bilan des recherches interdisciplinaires effectuées sur le site de l’Homo erectus de Denizli,Kocabaş, Bassin de Denizli,Anatolie, Turquie. L’Homo erectus aux portes de l’Europe

The study of the site of Kocaba?, which yielded an archaic Homo erectus skullcap, was undertaken in 2011 and 2012, at the request of Professor Mehmet Cihat Alçiçek. This interdisciplinary French–Turkish research programme comprised the geochronological, magnetostratigraphic, biochronological and paleoenvironmental study of the site and the paleoanthropological study of the skullcap itself. The association of large mammals enabled us to attribute the travertine formations bearing the skullcap to the second part of the Upper Pleistocene, and more specifically to between 1.5 and 1.2 million years, because of the disappearance or appearance of certain species. This biochronological age is confirmed by the paleomagnetism study, which places the travertines bearing the skullcap in a period of reversed polarity, underlying a normal polarity formation, which could be attributed to the Cobb Mountain paleomagnetic excursion, dated to 1,194,000 years. The dating of these fauna by the ²⁶Al/¹⁰Be cosmogenic nuclide method by Anne-Elisabeth Lebatard yielded an age older than 1.22 Ma and more recent than 1.5 Ma. The Hominid skullcap from this formation can be attributed to a Homo erectus, slightly more evolved than those of Homo ergaster KNM-ER 3733 (1.78 Ma) and KNM-ER 15,000 (1.5 Ma), similar to that of Daka (Bouri), which is about a million years old and older than the Bodo fossil (estimated at 600,000 years) and Kabwe (between 300,000 and120,000 years). The archaic Homo erectus skullcap from Kocaba?, referred to as Denizli Man, proves that Homo erectus was already present in Anatolia, at the crossroads of Africa, Asia and Europe, a little more than 1.2 million years ago.     

Calvarial shape variation among Middle Pleistocene hominins: An application of surface scanning in palaeoanthropology

The increasing availability of 3D data and tools offers new analytical perspectives in palaeoanthropology, such as the quantitative testing of opposing phylogenetic scenarios. Using optical surface scan data and geometric morphometric techniques, this study explores calvarial shape variation in the “Middle Pleistocene muddle”. The morphological variability between H. erectus on the one hand and H. sapiens/neanderthalensis on the other has long remained obscure: opposing views have attributed the known specimens to any of the three species and possibly one or two more. A large number of landmarks and semilandmarks was extracted from the braincase and the face, in order to quantify the calvarial shape differences among species and key fossils. The results are incompatible with the hypothesis that H. rhodesiensis is the exclusive ancestor of H. sapiens, and offer only weak support for an exclusively European ancestor of Neandertals.     

Réflexions sur l’Acheuléen d’Anatolie

The Anatolia occupies one of the main routes for the dispersal of Homo erectus into the Eurasia. The Acheulean bifaces found on each region of Anatolia are the most important evidences of this situation. This vast distribution of the Acheulean bifaces in Anatolia indicates that all of the Anatolia should stay in the Movius Line. This means that the Movius Line should be reexaminate. Recently, the fossil remains of Homo erectus found in Dmanisi (Georgia) and their very old dates around 1.8 million years put forward the importance of Anatolia one more time. Homo erectus who came in Anatolia by following the Levant Corridor might used the Anatolian bridge for passing to the Transcaucasia. If the well-preserved cave site on the line that expands from Hatay to Kars in Anatolia founds and excavates, it will prove additional information some problems about the Homo erectus movements and distribution of Acheulean Industrial Tradition in West Asia. This paper reviews the evidence for the Acheulean in Anatolia and discusses the distribution of Acheulean bifaces in Anatolia, generally found in open air site.