New fossil hominids from Laetolil, Tanzania

New fossil hominid specimens from the Laetolil fossil locality in Tanzania are described. The material includes mandibles and teeth derived from reliably-dated deposits of Pliocene age. Preliminary descriptions, measurements and illustrations are presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37572/1/1330460203_ftp.pd

Cortically evoked motor responses in patients with Xp22.3-linked Kallmann's syndrome and in female gene carriers

Patients with Kallmann's syndrome show hypothalamic hypogonadism, hyposmia, and congenital mirror movements. As a correlate, a defect of gonadotropic neuron migration into the brain was recently detected. Considering abnormal outgrowth of neurons also as a possible substrate underlying mirror movements, we studied 3 patients and 2 asymptomatic female gene carriers from a kindred with proven linkage to Xp22.3, using focal transcranial magnetic stimulation of motor cortex hand areas with a figure-eight coil. In all 3 affected brothers, bilateral responses could be evoked almost simultaneously in their thenar muscles (slight latency differences were statistically insignificant). In contrast, the mother and the maternal aunt showed only unilateral, normal thenar responses, even with maximum tolerable stimulator output and high signal amplification. Correspondingly, mirror movements were present in the patients, but not in the gene carriers. Bilaterality of cortically evoked hand muscle responses and mirror movements, therefore, behaved as X-chromosomal recessive traits. A likely cause might be a disorder of neuronal outgrowth in the motor system, particularly of inhibitory callosal fibers. For normal anatomical development of the motor system, one intact Xp22.3 gene seems necessary

Ultrastructure of calcified cartilage in the endoskeletal tesserae of sharks

The tesserate pattern of endoskeletal calcification has been investigated in jaws, gill arches, vertebral arches and fins of the sharks Carcharhinus menisorrah, Triaenodon obesus and Negaprion brevirostris by techniques of light and electron microscopy. Individual tesserae develop peripherally at the boundary between cartilage and perichondrium. An inner zone, the body, is composed of calcified cartilage containing viable chondrocytes separated by basophilic contour lines which have been called Liesegang waves or rings. The outer zone of tesserae, the cap, is composed of calcified tissue which appears to be produced by perichondrial fibroblasts more directly, i.e., without first differentiating as chondroblasts. Furthermore, the cap zone is penetrated by acidophilic Sharpey fibers of collagen. It is suggested that scleroblasts of the cap zone could be classified as osteoblasts. If so, the cap could be considered a thin veneer of bone atop the calcified cartilage of the body of a tessera. By scanning electron microscopy it was observed that outer and inner surfaces of tesserae differ in appearance. Calcospherites and hydroxyapatite crystals similar to those commonly seen on the surface of bone are present on the outer surface of the tessera adjacent to the perichondrium. On the inner surface adjoining hyaline cartilage, however, calcospherites of variable size are the predominant surface feature. Transmission electron microscopy shows calcification in close association with coarse collagen fibrils on the outer side of a tessera, but such fibrils are absent from the cartilaginous matrix along the under side of tesserae. Calcified cartilage as a tissue type in the endoskeleton of sharks is a primitive vertebrate characteristic. Calcification in the tesserate pattern occurring in modern Chondrichthyes may be derived from an ancestral pattern of a continuous bed of calcified cartilage underlying a layer of perichondral bone, as theorized by Ørvig (1951); or the tesserate pattern in these fish may itself be primitive.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50272/1/1051600106_ftp.pd

The hand of Homo naledi

A nearly complete right hand of an adult hominin was recovered from the Rising Star cave system, South Africa. Based on associated hominin material, the bones of this hand are attributed to Homo naledi. This hand reveals a long, robust thumb and derived wrist morphology that is shared with Neandertals and modern humans, and considered adaptive for intensified manual manipulation. However, the finger bones are longer and more curved than in most australopiths, indicating frequent use of the hand during life for strong grasping during locomotor climbing and suspension. These markedly curved digits in combination with an otherwise human-like wrist and palm indicate a significant degree of climbing, despite the derived nature of many aspects of the hand and other regions of the postcranial skeleton in H. naledi

Sagittal Growth of the Nasomaxillary Complex during the Second Trimester of Human Prenatal Development

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66545/2/10.1177_00220345650440010401.pd

Patterns of dental development in Homo, Australopithecus, Pan , and Gorilla

Smith ([1986] Nature 323 :327–330) distinguished patterns of development of teeth of juvenile fossil hominids as being “more like humans” or “more like apes” based on statistical similarity to group standards. Here, this central tendency discrimination (CTD) is tested for its ability to recognize ape and human patterns of dental development in 789 subadult hominoids. Tooth development of a modern human sample (665 black southern Africans) was scored entirely by an outside investigator; pongid and fossil hominid samples (59 Pan , 50 Gorilla , and 14 fossil hominids) were scored by the author. The claim of Lampl et al. ([1993] Am. J. Phys. Anthropol. 90 :113–127) that Smith's 1986 method succeeds in only 8% of human cases was not sustained. Figures for overall success of classification (87% humans, 68% apes) mask important effects of teeth sampled and age class. For humans, the power of CTD varied between 53% and 92% depending on the number and kind of teeth available—-nearly that of a coin toss when data described only two nearby teeth, but quite successful with more teeth or distant teeth. For apes, only age class affected accuracy: “Infant” apes (M 1 development < root cleft complete, unemerged) were usually classed as humans, probably because the present developmental standard for great apes is in substantial error under 3 years of age. “Juvenile” apes (M 1 ges; root 1/4), however, were correctly discriminated in 87% of cases. Overall, CTD can be considered reliable (accuracy of 92% for humans and 88% for apes) when data contrast development of distant dental fields and subjects are juveniles (not infants). Restricting analysis of fossils to specimens satisfying these criteria, patterns of dental development of gracile australopithecines and Homo habilis remain classified with African apes. Those of Homo erectus and Neanderthals are classified with humans, suggesting that patterns of growth evolved substantially in the Hominidae. To standardize future research, the computer program that operationalizes CTD is now available. © 1994 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37668/1/1330940303_ftp.pd

Tooth eruption and browridge formation

One of the most reasonable hypotheses regarding the functional significance of the browridge is that the supraorbital torus forms in response to masticatory stress during development. Oyen, Walker, and Rice (1979) have recently proposed a model that tests this hypothesis: if browridges are functionally related to masticatory stresses on the cranial vault, then changes in the biomechanics of the masticatory system ought to be reflected by changes in the browridge. To test their model they attempted to relate biomechanical discontinuities resulting from tooth eruption to episodes of bone deposition on the supraorbital tori of a developmental series of dry Papio crania. This paper reports on a parallel test of the model on a cross-sectional sample of Australian Aboriginal juvenile crania. This sample showed no relation between tooth eruption and the supraorbital surface morphology thought to be indicative of active bone deposition. It is also demonstrated that no significant relationship between tooth eruption and episodes of bone deposition is shown by the Papio sample. It is concluded that the use of small cross-sectional samples of dry crania does not provide a valid test of the model.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37614/1/1330580107_ftp.pd

Unique ramus anatomy for Neandertals?

The ramus of Neandertal mandibles is said to show a suite of uniquely Neandertal character states that demonstrate the independent course of Neandertal evolution. This is the latest of numerous attempts to define cranial and mandibular autapomorphies for Neandertals. We examine variation in the four presumably autapomorphic ramal features and show they are neither monomorhic within Neandertals (to the contrary Neandertals are at least as variable as other human samples) nor unique to Neandertals, since they regularly appear in populations predating and postdating them. Neandertals differ from other human populations, both contemporary and recent, but the question of whether this fact reflects a divergent evolutionary trajectory must be addressed by the pattern of differences. In this case, as in the other attempts to establish Neandertal autapomorphies, rather than showing restricted variation and increased specialization, the Neandertal sample shows that the range of human variation in the recent past encompasses, and in some cases exceeds, human variation today, even in the very features claimed to be autapomorphic. Am J Phys Anthropol, 2005. © 2005 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48752/1/10432_ftp.pd

Upper pleistocene human remains from Vindija cave, Croatia, Yugoslavia

Human remains excavated from Vindija cave include a large although fragmentary sample of late Mousterian-associated specimens and a few additional individuals from the overlying early Upper Paleolithic levels. The Mousterian-associated sample is similar to European Neandertals from other regions. Compared with earlier Neandertals from south central Europe, this sample evinces evolutionary trends in the direction of Upper Paleolithic Europeans. Compared with the western European Neandertals, the same trends can be demonstrated, although the magnitude of difference is less, and there is a potential for confusing temporal with regional sources of variation. The early Upper Paleolithic-associated sample cannot be distinguished from the Mousterian-associated hominids. We believe that this site provides support for Hrdlička's “Neandertal phase” of human evolution, as it was originally applied in Europe.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37603/1/1330540407_ftp.pd

Life without the Movius Line: The structure of the East and Southeast Asian Early Palaeolithic

© 2015 Elsevier Ltd and INQUA.The starting point of this paper is that the Movius Line is no longer an appropriate way of studying the Early Palaeolithic of East and Southeast Asia, and should be disregarded. Instead, it is argued that the Early Palaeolithic of East and Southeast Asia needs to be seen as comparable to that in the rest of Eurasia, rather than the product of an isolated backwater. Contra Movius, East Asia was not isolated throughout the entire Early and Middle Pleistocene, but open to immigration during interglacials, as is indicated by its fossil hominin record. As in Europe and Southwest Asia, both bifacial and non-biface assemblages are present in China and Korea, thus indicating the presence of an Acheulean component, although the lack of agreement over how the Acheulean should be defined creates difficulties in establishing its extent in Southeast Asia. Regarding non-biface assemblages, Zhoukoudian was an unfortunate choice of an East Asian site that lacked bifaces, as bifaces are also rare or absent in a number of caves in Southwest Asia and Europe. Additionally, the absence of bifaces in some sites is not convincingly demonstrated because of the small size of the lithic assemblage. Finally, the simple flake industries in Southeast Asia are likely contemporary with Upper Pleistocene, Middle Palaeolithic and microlithic assemblages in India rather than with Middle Pleistocene, Acheulean assemblages, as proposed by Movius