Showing papers in "American Journal of Physical Anthropology in 1995"
TL;DR: This paper reviewed the distinguishing features of ratios and residuals and their relationships to other methods of "size-adjustment" for continuous data for comparative biology and biological anthropology require meaningful definitions of relative size and shape.
Abstract: Many problems in comparative biology and biological anthropology require meaningful definitions of “relative size” and “shape” Here we review the distinguishing features of ratios and residuals and their relationships to other methods of “size-adjustment” for continuous data Eleven statistical techniques are evaluated in reference to one broadly interspecific data set (craniometries of adult Old World monkeys) and one narrowly intraspecific data set (anthropometries of adult Native American males) Three different types of residuals are compared to three versions of shape ratios, and these are contrasted to “cscores,” Penrose shape, and multivariate adjustments based on the first principal component of the logged variance-covariance matrix; all methods are also compared to raw and logged raw data In order to help us identify appropriate; methods for size-adjustment, geometrically similar or “isometric” versions of the male vervet and the Inuit male were created by scalar multiplication of all variables The geometric mean of all variables is used as overall “size” throughout this investigation, but our conclusions would be the same for most other size variables
Residual adjustments failed to correctly identify individuals of the same shape in both sampkles Like residuals, cscores are also sample-specific and incorrectly attribute different shape values to individuals known to be identical in shape Multivariate “residuals” (eg, discarding the first principal component and Burnaby's method) are plagued by similar problems If one of the goals of an analysis is to identify individuals (OTUs) of the same shape after accounting for overalll size differences, then none of these methods can be recommended We also reject the assertion that size-adjusted variables should be unciorrelated with size of “size-free”; rather, whether or not shape covaries with size is an important empirical determination in any analysis Without explicit similarity criteria, “lines of subtraction” can be very misleading
Only variables in the Mosimann family of shape rations allowed us to identify sized individuals of the same shape (“Iso-OUTs”) Residuals from isometric lines in logarithmic space, projections of logged data to a plane orthogonal to an isometric vector, and Penrose shape distance based on logged data are also part of this shape family Shape defined in this manner can be significantly correlated with size in allometric data sets (eg, guenon craniometrics); ratio shape differences may be largely independent of size in narrowly intraspecific or intrasexual data sets (eg, Native American anthropometrics) Log-transformations of shape variables are not always necessary or desirable We hope our findings enciourage other workers to question the assumptions and utility of residuals as size-adjusted data and to explore shape and relative size within Mosimann's explicitly geometric framework © 1995 Wiley-Liss, Inc
702 citations
TL;DR: Results indicate that a long femoral neck increases mediolateral bending of the femoral diaphysis and decreases gluteal abductor and hip joint reaction forces, and suggests that biacetabular breadth as well as Femoral neck length was relatively large in early Homo.
Abstract: A complex of traits in the femur and pelvis of Homo ereclus and early “erectus-like” specimens has been described, but never satisfactorily explained. Here the functional relationships between pelvic and femoral structure in humans are explored using both theoretical biomechanical models and empirical tests within modern samples of diverse body form (Pecos Amerindians, East Africans). Results indicate that a long femoral neck increases mediolateral bending of the femoral diaphysis and decreases gluteal abductor and hip joint reaction forces. Increasing biacetabular breadth along with femoral neck length further increases M-L bending of the femoral shaft and maintains abductor and joint reaction forces at near “normal” levels. When compared to modern humans, Homo erectus and early “erectus-like” specimens are characterized by a long femoral neck and greatly increased M-L relative to A-P bending strength of the femoral shaft, coupled with no decrease in hip joint size and a probable increase in abductor force relative to body size. All of this strongly suggests that biacetabular breadth as well as femoral neck length was relatively large in early Homo. Several features preserved in early Homo partial hip bones also indicate that the true (lower) pelvis was very M-L broad, as well as A-P narrow. This is similar to the lower pelvic shape of australopithecines and suggests that nonrotational birth, in which the newborn's head is oriented transversely through the pelvic outlet, characterized early Homo as well as Australopithecus. Because M-L breadth of the pelvis is constrained by other factors, this may have limited increases in cranial capacity within Homo until rotational birth was established during the late Middle Pleistocene. During or after the transition to rotational birth biacetabular breadth decreased, reducing the body weight moment arm about the hip and allowing femoral neck length (abductor moment arm) to also decrease, both of which reduced M-L bending of the proximal femoral shaft. Variation in femoral structural properties within early Homo and other East African Early Pleistocene specimens has several taxonomic and phylogenetic implications. © 1995 Wiley-Liss, Inc.
310 citations
TL;DR: The distribution of the four founding lineage haplogroups in Native Americans from North, Central, and South America shows a north to south increase in the frequency of lineage B and a North to South decrease in the frequencies of lineage A.
Abstract: The distribution of the four founding lineage haplogroups in Native Americans from North, Central, and South America shows a north to south increase in the frequency of lineage B and a North to South decrease in the frequency of lineage A. All four founding lineage haplogroups were detected in North, Central, and South America, and in Greenberg et al.'s ([1986] Curr. Anthropol. 27:477-497) three major linguistic groups (Amerind, NaDene, and Eskaleut), with all four haplogroups often found within a single population. Lineage A was the most common lineage in North America, regardless of language group. This overall distribution is most parsimonious with a single wave of migration into the New World which included multiple variants of all four founding lineage types. Torroni et al.'s ([1993a] Am. J. Hum. Genet. 53:563-590) report that lineage B has a more recent divergence time than the other three lineages can best be explained by multiple variants of lineages A, C, and D, and fewer variants of lineage B entering the New World. Alternatively, there could have been multiple waves of migration from a single parent population in Asia/Siberia which repeatedly reintroduced the same lineages to the New World.
297 citations
TL;DR: The proximal half of a hominid femur was recovered from deep within a paleokarst feature at the Berg Aukas mine, northern Namibia, and is fully mineralized, but it is not possible to place it in geochronological context.
Abstract: The proximal half of a hominid femur was recovered from deep within a paleokarst feature at the Berg Aukas mine, northern Namibia. The femur is fully mineralized, but it is not possible to place it in geochronological context. It has a very large head, an exceptionally thick diaphyseal cortex, and a very low collodiaphyseal angle, which serve to differentiate it from Holocene homologues. The femur is not attributable to Australopithecus, Paranthropus, or early Homo (i.e., H. habilis sensu lato). Homo erectus femora have a relatively longer and AP flatter neck, and a shaft that exhibits less pilaster than the Berg Aukas specimen. Berg Aukas also differs from early modern femora in several features, including diaphyseal cortical thickness and the degree of subtrochanteric AP flattening. The massive diaphyseal cortex of Berg Aukas finds its closest similarity within archaic H. sapiens (e.g., Castel di Guido) and H. erectus (e.g., KNM-ER 736) samples. It has more cortical bone at midshaft than any other specimen, although relative cortical thickness and the asymmetry of its cross-sectional disposition at this level are comparable with those of other Pleistocene femora. The closest morphological comparisons with Berg Aukas are in archaic (i.e., Middle Pleistocene) H. sapiens and Neandertal samples.
263 citations
TL;DR: This study found that party size, social rank, and tree structure all influence an animal's substrate choice and subsequent positional activities and should be considered essential components of body-sized based interpretations of the behavior of fossil or extant species.
Abstract: The objectives of this 27 month study were to document the positional behaviors used by lowland gorillas (Gorilla gorilla gorilla) in the Central African Republic and to compare the effects of body size dimorphism on the use of arboreal substrates. During this study, despite their great size, all gorillas used trees regularly. Predictions concerning the relationship of body size to arboreal behavior were generally upheld. Small branch and suspensory activities were rare for silverbacks. Females used smaller and multiple substrates and suspensory postures more frequently than males. Although females foraged in the periphery of trees, males stayed close to the cores and rarely used terminal branches.
In addition to body size, this study found that party size, social rank, and tree structure all influence an animal's substrate choice and subsequent positional activities. Lone males typically remained in the cores of trees where substrates are large. Group males may have been forced to use all parts of trees because others were present. Lone males used small crown trees which provided easy access to terminal branch foods. Males and females foraging together used larger trees (containing more feeding sites) than single sex groups. Female positional behavior may have been affected by the presence of males. When apart from males, females used the cores of trees and larger substrates more than when foraging with males. As habitat and social context both influence substrate use, they should be considered essential components of body-sized based interpretations of the behavior of fossil or extant species. © 1995 Wiley-Liss, Inc.
208 citations
TL;DR: The authors explored the process of differentiation of modern populations in Asia and argued for morphological discontinuities in the late Pleistocene populations in the region, concluding that the evolution of the Mongoloid population complex may result from a process of differentiations, expansions, and dispersals, resulting in the development of regional morphological patterns.
Abstract: The study of modern human origins and the study of the origins of modern human diversity are intimately linked. The evolutionary models employed have implications both for interpreting the significance of morphological variation and evolutionary trends, and in terms of the processes that gave rise to such variation. Although controversial, available evidence is taken to indicate a single, recent origin of modern humans.
This paper explores the process of differentiation of modern populations in Asia and argues for morphological discontinuities in the late Pleistocene populations in the region. The intensely studied population history of Eastern Asia suggests that the evolution of the Mongoloid population complex may result from a process of differentiations, expansions, and dispersals, resulting in the development of regional morphological patterns. The relatively late appearance of regional morphological differentiation, especially in Northeast Asia, opens the possibility of the earliest Amerindians not being a typical “Mongoloid” population.
A more generalized Mongoloid morphology has been described for both North and South American Paleoindian remains. In this paper, the morphology of a robust, not typically Mongoloid, population in South America is investigated, and its implications for the homogeneity of Amerindians discussed. Since a derived, typically Mongoloid morphology cannot be attributed to the early Amerindian and Fueguian-Patagonian populations, it is argued either that the sinodont dental pattern was acquired in parallel in Asia and the Americas or that at least two migratory waves ancestral to Amerinds took place. © 1995 Wiley-Liss, Inc.
180 citations
TL;DR: Observations of positional behavior and habitat use were recorded on focal individuals of five species of Old World monkeys at Kibale Forest, Uganda, through the dry season of 1990 and 1991, revealing few consistent trends with respect to body size or habitat use across primates.
Abstract: Observations of positional behavior and habitat use were recorded on focal individuals of five species of Old World monkeys at Kibale Forest, Uganda, through the dry season of 1990 and 1991. Cercopithecus ascanius, Cercopithecus mitis, Cercocebus albigena, Colobus badius, and Colobus guereza commonly utilize five similar types of positional behavior (i.e., quadrupedalism, leaping, climbing, sitting, and standing), but in varying frequencies and situations. As a group, colobines use oblique supports and leap more often, and cover greater linear distances during leaps than do cercopithecines. Colobines also prefer to sit (about 90% of all postures), while cercopithecines stand more frequently. Body size differences between the sexes of a species are not reflected in positional behavior. The two small-bodied species climb more and leap less often than the three larger species, which is the reverse of what we would expect. Leaping is the most common method of crossing open spaces within the canopy; but most spatial gaps and leaps are over short distances, usually one meter or less. All five species, regardless of body size or the availability of forest supports, prefer medium-sized supports. Incorporating our work from Uganda with previous investigations of positional behavior reveals few consistent trends with respect to body size or habitat use across primates.
175 citations
TL;DR: It is argued that hominids do not strictly obey the trend for basicranial flexion to increase with increasing relative brain size because of constraints on the amount of flexion that do not allow it to decrease much below 90 degrees.
Abstract: Comparative work among nonhominid primates has demon- strated that the basicranium becomes more flexed with increasing brain size relative to basicranial length and as the upper and lower face become more ventrally deflected (Ross and Ravosa (19931 Am J Phys Anthropol 91:305- 324) In order to determine whether modern humans and fossil hominids follow these trends, the cranial base angle (measure of basicranial flexion), angle of facial kyphosis, and angle of orbital axis orientation were measured from computed tomography (CT) scans of fossil hominids (Sts 5, MLD 37/38, OH9, Kabwe) and lateral radiographs of 99 extant humans Brain size relative to basicranial length was calculated from measures of neurocranial volume and basicranial length taken from original skulls, radiographs, CT scans, and the literature Results of bivariate correlation analyses revealed that among modern humans basicranial flexion and brain sizehasicranial length are not significantly correlated, nor are the angles of orbital axis orientation and facial kyphosis However, basicranial flexion and orbit orientation are significantly positively correlated among the humans sampled, as are basicranial flexion and the angle of facial kyphosis Relative to the comparative sample from Ross and Ravosa (1993), all hominids have more flexed basicrania than other primates: Archaic Homo sapiens, Homo erectus, and Australopithecus afri- canus do not differ significantly from Modern Homo sapiens in their degree of basicranial flexion, although they differ widely in their relative brain size Comparison of the hominid values with those predicted by the nonhominid reduced major-axis equations reveal that, for their brain sizehasicranial length, Archaic and Modern Homo sapiens have less flexed basicrania than predicted H erectus and A africanus have the degree of basicranial flexion predicted by the nonhominid reduced major-axis equation Modern humans have more ventrally deflected orbits than all other primates and, for their degree of basicranial flexion, have more ventrally deflected orbits than pre- dicted by the regression equations for hominoids All hominoids have more ventrally deflected orbital axes relative to their palate orientation than other primates It is argued that hominids do not strictly obey the trend for basicra- nial flexion to increase with increasing relative brain size because of con-
172 citations
TL;DR: A segment of DNA unique to Mycobacterium tuberculosis was identified in an extract from the vertebral lesion of a 12-year-old girl with Pott's disease from about A.D. 1000, establishing the pre-Columbian presence of tuberculosis with the most specific evidence currently available.
Abstract: Analysis of 483 skeletons from Arica (Chile) and review of mummy dissection records demonstrates an overall 1% prevalence rate for tuberculosis between 2000 B.C. and A.D. 1500. Tuberculosis cases cluster in the period A.D. 500-1000 which correlates with fully agropastoral societies. Considering only these agropastoral societies, about 2% of their members show tuberculosis lesions. A segment of DNA unique to Mycobacterium tuberculosis was identified in an extract from the vertebral lesion of a 12-year-old girl with Pott's disease from about A.D. 1000, establishing the pre-Columbian presence of tuberculosis with the most specific evidence currently available.
159 citations
TL;DR: In this article, five aspects of competitive alliances are reviewed: 1) the evolutionary and ecological conditions favoring the occurrence of alliances among females, among males, and between males and females, 2) the dynamics of the three main categories of competitive alliance, called bridging, revolutionary, and conservative, 3) the developmental processes that may account for the initial formation of alliances, 4) the cognitive abilities involved in two major aspects of alliances and 5) the value of functional explanations of alliance behavior, namely kin selection, reciprocal altruism and mutualism.
Abstract: Nonhuman primates commonly compete for mates, physical resources and dominance status. Competition is manifest in one-to-one contests or in more complex, multipartite aggressive interactions involving the formation of alliances. In this paper, five aspects of competitive alliances are reviewed: 1) the evolutionary and ecological conditions favoring the occurrence of alliances among females, among males, and between males and females, 2) the dynamics of the three main categories of competitive alliances, called bridging, revolutionary, and conservative, 3) the developmental processes that may account for the initial formation of alliances, 4) the cognitive abilities involved in two major aspects of alliances, the recognition of one's allies and of the allies of other individuals, and 5) the value of functional explanations of alliance behavior, namely kin selection, reciprocal altruism and mutualism. © 1995 Wiley-Liss, Inc.
146 citations
TL;DR: Although bone strontium quantitatively reflects the average dietary Sr/Ca ratio, it is disproportionately sensitive to high-calcium foods and can be easily affected by minor dietary constituents and culinary practices.
Abstract: Strontium in archaeological human bones is widely, almost paradigmatically, used as a measure of the relative dietary abundances of plants and meat. Quantitative modeling reveals, however, that there is not a simple proportional relationship between bone strontium and the dietary plant/meat ratio. While knowledge of specific foods and their compositions may permit accurate calculation of average bone strontium levels, knowledge of bone strontium does not inversely allow accurate calculation of specific foods. Although bone strontium quantitatively reflects the average dietary Sr/Ca ratio, it is disproportionately sensitive to high-calcium foods and can be easily affected by minor dietary constituents and culinary practices. Bone strontium, and by analogy, barium, should be seen as a reflection of the high-mineral dietary components rather than a quantitative index of trophic position. © 1995 Wiley-Liss, Inc.
TL;DR: Results from dust collection studies conducted at the primate research stations at Ketambe in Indonesia, and Hacienda La Pacifica in Costa Rica indicate that grit collects throughout the canopy in both open country and tropical rain forest environments.
Abstract: Dental microwear researchers consider exogenous grit or dust to be an important cause of microscopic wear on primate teeth. No study to date has examined the accumulation of such abrasives on foods eaten by primates in the forest. This investigation introduces a method to collect dust at various heights in the canopy. Results from dust collection studies con- ducted at the primate research stations at Ketambe in Indonesia, and Haci- enda La Pacifica in Costa Rica indicate that 1) grit collects throughout the canopy in both open country and tropical rain forest environments; and 2) the sizes and concentrations of dust particles accumulated over a fixed period of time differ depending on site location and season of investigation. These results may hold important implications for the interpretation of microwear on primate teeth. o 1995 Wiley-Liss, Inc.
TL;DR: The takeoff forces are higher than the landing forces when using compliant supports, indicating that the takeoff rather than the Landing may be critical in interpreting leaping behavior and related aspects of musculoskeletal design.
Abstract: Our current knowledge about the forces leapers generate and absorb is very limited and based exclusively on rigid force platform measurements. In their natural environments, however, leapers take off and land on branches and tree trunks, and these may be compliant. We evaluated the influence of substrate properties on leaping kinetics in prosimian leapers by using a combined field and laboratory approach. Tree sway and the timing of takeoffs relative to the movements of trees were documented for animals under natural conditions in Madagascar. Field data collected on three species (Indri indri, Propithecus diadema, Propithecus verreauxi) indicate that in the majority of takeoffs, the substrate sways and the animals takeoff before the elastic rebound of the substrate. This implies that force is "wasted" to deform supports. Takeoff and landing forces were measured in an experimental setting with a compliant force pole at the Duke University Primate Center. Forces were recorded for 2 Propithecus verreauxi and 3 Hapalemur griseus. Peak takeoff forces were 9.6 (P. verreauxi) and 10.3 (H. griseus) times body weight, whereas peak landing forces were 6.7 (P. verreauxi) and 8.4 (H. griseus) times body weight. As part of the impulse generated does not translate into leaping distance but is used to deform the pole, greater effort is required to reach a given target substrate, and, consequently, takeoff forces are high. The landing forces, on the other hand, are damped by the pole/substrate yield that increases the time available for deceleration. Our results contrast with previous studies of leaping forces recorded with rigid platform measuring systems that usually report higher landing than takeoff forces. We conclude that 1) Leapers generate and are exposed to exceptionally high locomotory forces. The takeoff forces are higher than the landing forces when using compliant supports, indicating that the takeoff rather than the landing may be critical in interpreting leaping behavior and related aspects of musculoskeletal design. 2) Large-bodied vertical clingers and leapers do not usually take advantage of the elastic energy stored in substrates. Rather, force (and energy) is wasted to deform compliant supports. 3) A compliant force pole approximates the conditions faced by large-bodied vertical clingers and leapers in the wild more closely than do rigid force platforms.
TL;DR: Much variation recorded by this study remains unexplained, providing additional evidence of the need to specially examine female ontogeny before primate body size dimorphism can be satisfactorily explained.
Abstract: This study examines statistical correlations between socioecological variables (including measures of group composition, intermale competition, and habitat preference) and the ontogeny of body size sexual dimorphism in anthropoid primates A regression-based multivariate measure of dimorphism in body weight ontogeny is derived from a sample of 37 species Quantitative estimates of covariation between socioecological variables and this multivariate measure are evaluated Statistically significant covariation between the ontogeny of dimorphism and socioecological variables, with the possible exception of habitat preference, is observed Sex differences in ontogeny are lacking in species that exhibit low levels of intermale competition and are classifiable as species with monogamous/polyandrous mating systems Among dimorphic species, two modes of dimorphic growth are apparent, which seem to be related to different kinds of group compositions Multimale/multifemale species tend to become dimorphic through bimaturism (sex differences in duration of growth) with minimal sex differences in growth rate Single-male/multifemale species tend to attain dimorphism through differences in rate of growth, often with limited bimaturism Measures of intermale competition may also covary with these modes of dimorphic growth, but the relations among these variables are sometimes ambiguous Correlations between dimorphic growth and behavioral variables may reflect alternative life history strategies in primates Specifically, the ways in which risks faced by subadult males are distributed and the relations of these risks to growth rates seem to influence the evolution of size ontogenies The absence of dimorphic ontogeny in some species can be tied to similar distributions of risk in each sex In taxa that become dimorphic primarily through rate differences in growth, the lifetime distribution of risks for males may change rapidly In contrast, males may face a pattern of uniformly changing or stable risk in species that become dimorphic through bimaturism Finally, much variation recorded by this study remains unexplained, providing additional evidence of the need to specially examine female ontogeny before primate body size dimorphism can be satisfactorily explained
TL;DR: The genetic structure of current populations speaking Indo-European languages seems to largely reflect a Neolithic expansion, consistent with the hypothesis of a parallel spread of farming technologies and a proto-Indo-European language in the Neolithic.
Abstract: Allele frequency distributions were generated by computer simulation of five models of microevolution in European populations. Genetic distances calculated from these distributions were compared with observed genetic distances among Indo-European speakers. The simulated models differ in complexity, but all incorporate random genetic drift and short-range gene flow (isolation by distance). The best correlations between observed and simulated data were obtained for two models where dispersal of Neolithic farmers from the Near East depends only on population growth. More complex models, where the timing of the farmers' expansion is constrained by archaeological time data, fail to account for a larger fraction of the observed genetic variation; this is also the case for a model including late Neolithic migrations from the Pontic steppes. The genetic structure of current populations speaking Indo-European languages seems therefore to largely reflect a Neolithic expansion. This is consistent with the hypothesis of a parallel spread of farming technologies and a proto-Indo-European language in the Neolithic. Allele-frequency gradients among Indo-European speakers may be due either to incomplete admixture between dispersing farmers, who presumably spoke proto-Indo-European, and pre-existing hunters and gatherers (as in the traditional demic diffusion hypothesis), or to founder effects during the farmers' dispersal. By contrast, successive migrational waves from the East, if any, do not seem to have had genetic consequences detectable by the present comparison of observed and simulated allele frequencies.
TL;DR: The mitochondrial evidence supports the morphologically and historically based hypothesis that the original founders came from Indonesia, and may support models of founder events in which rapid population growth prevents substantial loss of nuclear variation.
Abstract: Macaque monkeys (Macaca fascicularis) were introduced to the island of Mauritius approximately 400 years ago. This study compares the mitochondrial DNA of macaques on Mauritius with those from Indonesia and the Philippines. The goal is to measure the amount of evolutionary change that has occurred in this isolated population over 400 years, and to address questions regarding the origin of the Mauritian founders. Amplification of the control region of the mitochondrial genome via the polymerase chain reaction yielded an 1800 base pair DNA fragment which was surveyed for variation using restriction endonucleases. Fifty-two macaques were separated into 17 haplotypes by mapping the restriction sites. No haplotypes were shared among the three populations, and only two closely related haplotypes appeared in the Mauritian sample. Nucleotide variation in the mitochondrial DNA in the Mauritian sample was 10-fold less than the Indonesian and Filipino samples. In contrast, allozyme data estimates of genetic diversity on Mauritius are similar to populations from the ancestral range. The evidence of the more severe bottleneck as measured by mitochondrial data may be explained in part by almost exclusive male dispersal in this species, and may support models of founder events in which rapid population growth prevents substantial loss of nuclear variation. The mitochondrial evidence supports the morphologically and historically based hypothesis that the original founders came from Indonesia. © 1995 Wiley-Liss, Inc.
TL;DR: The regular occurrence of heel contact in a variety of arboreal primates, and the absence of a true biomechanical link between limb elongation, heel contact, and terrestriality, calls into question the claim that hominid foot posture was necessarily derived from a quadrupedal terrestrial ancestor.
Abstract: In this report we provide detailed data on the patterns and frequency of heel contact with terrestrial and arboreal supports in primates. These data can help resolve the question of whether African apes and humans are uniquely "plantigrade" (Gebo [1992] Am. J. Phys. Anthropol. 89:29-58; Gebo [1993a] Am. J. Phys. Anthropol. 91:382-385; Gebo [1993b] Postcranial Adaptation in Nonhuman Primates), or if plantigrady is common in other primates (Meldrum [1993] Am. J. Phys. Anthropol. 91:379-381). Using biplanar and uniplanar videotapes, we recorded the frequency and timing of heel contact for a variety of primates (32 species) walking on the ground and on simulated arboreal supports at a range of natural speeds. Our results indicate that Pongo as well as the African apes exhibit a "heel-strike" at the end of swing phase. Ateles and Hylobates make heel contact on all supports shortly after mid-foot contact, although spider monkeys do so only at slow or moderate speeds. Data available from uniplanar videotapes suggest that this pattern occurs in Alouatta and Lagothrix as well. No other New or Old World monkey or prosimian in this study made heel contact during quadrupedalism on any substrate. Thus, heel contact occurs in all apes and atelines, but only the great apes exhibit a heel-strike. We suggest that heel contact with the substrate is a by-product of an active posterior weight-shift mechanism involving highly protracted hindlimbs at touchdown. Force plate studies indicate that this mechanism is most extreme in arboreally adapted primate quadrupeds walking on arboreal supports. Although heel contact and heel-strike may have no evolutionary link, it is possible that both patterns are the result of a similar weight shift mechanism. Therefore, the regular occurrence of heel contact in a variety of arboreal primates, and the absence of a true biomechanical link between limb elongation, heel contact, and terrestriality, calls into question the claim that hominid foot posture was necessarily derived from a quadrupedal terrestrial ancestor.
TL;DR: While there is significant sexual dimorphism in the shape of the Sciatic notch, the amount of overlap between males and females is too great for the sciatic notch to be used as a reliable indicator of sex.
Abstract: Whether human fetal skeletal remains exhibit sexual dimorphism has been the subject of considerable debate. Most attention in this debate has focused on the greater sciatic notch of the ilium, since it is a gross morphological characteristic with known sex differences in the adult and is easily seen in fetal skeletal remains. Unfortunately, previous traditional morphometric analyses of the fetal sciatic notch have led to ambiguous results. The purpose of this study is to determine whether differences between the sexes can be discerned when modern morphometric techniques are applied to the fetal sciatic notch. Photographs of the ventral side of 133 fetal ilia of known age and sex from the Trotter Collection of Washington University were digitized, and the trace coordinates used for all subsequent analyses. The results of the analysis demonstrate that there is significant sexual dimorphism in the anterior to posterior location of the maximum depth of the sciatic notch, but that the depth of the notch itself is not dimorphic. While there is significant sexual dimorphism in the shape of the sciatic notch, the amount of overlap between males and females is too great for the sciatic notch to be used as a reliable indicator of sex. © 1995 Wiley-Liss, Inc.
TL;DR: Fossil assemblages from the Pliocene and Pleistocene of southern Africa were seriated to give a better idea of their relative chronology and calculation of the Faunal Resemblance Index.
Abstract: Fossil assemblages from the Pliocene and Pleistocene of southern Africa were seriated in order to give a better idea of their relative chronology. Time-sensitive mammals were selected for calculation of the Faunal Resemblance Index among 17 site units. On the basis of a logistical seriation and subsequent site analysis, the following sequence of sites was deemed most probable: Makapansgat Member 3, Makapansgat Member 4, Taung Dart deposits, Sterkfontein Member 4 and Taung Hrdlicka deposits, Sterkfontein Member 5 (in part) and Kromdraai B, Kromdraai A and Swartkrans Member 1, Swartkrans Member 2, Swartkrans Member 3, Plovers Lake, Cornelia, Elandsfontein Main Site, Cave of Hearths Acheulian levels, Florisbad and Equus Cave and Klasies River Mouth.
TL;DR: The purpose of this paper is to provide a method to obtain confidence intervals for form difference and growth difference estimators based on Euclidean distance matrix analysis using the model independent bootstrap method.
Abstract: Analysis of biological forms using landmark data has re- ceived substantial attention recently. Much of the statistical work in this area has concentrated on the estimation of average form, average form difference, and average growth difference. From the statistical, as well as the scientific point of view, it is important that any estimate of a scientifically relevant quantity be accompanied by a statement regarding its accuracy. Such a state- ment is contained in a confidence interval. The purpose of this paper is to provide a method to obtain confidence intervals for form difference and growth difference estimators. The estimators are based on Euclidean distance matrix analysis. The confidence intervals are calculated using the model independent bootstrap method. We illustrate the method by using three ex- amples: morphological differences between samples of craniofacial patients and normal controls using two dimensional data from head X-rays, sexual
TL;DR: It is suggested that a decrease of the rate of cell proliferation, which affected the later-forming crown regions to a greater extent, may be the biological process responsible for the general and differential dental size reduction that occurred during human evolution.
Abstract: In order to reassess previous hypotheses concerning dental size reduction of the posterior teeth during Pleistocene human evolution, current fossil dental evidence is examined. This evidence includes the large sample of hominid teeth found in recent excavations (1984-1993) in the Sima de los Huesos Middle Pleistocene cave site of the Sierra de Atapuerca (Burgos, Spain). The lower fourth premolars and molars of the Atapuerca hominids, probably older than 300 Kyr, have dimensions similar to those of modern humans. Further, these hominids share the derived state of other features of the posterior teeth with modern humans, such as a similar relative molar size and frequent absence of the hypoconulid, thus suggesting a possible case of parallelism. We believe that dietary changes allowed size reduction of the posterior teeth during the Middle Pleistocene, and the present evidence suggests that the selective pressures that operated on the size variability of these teeth were less restrictive than what is assumed by previous models of dental reduction. Thus, the causal relationship between tooth size decrease and changes in food-preparation techniques during the Pleistocene should be reconsidered. Moreover, the present evidence indicates that the differential reduction of the molars cannot be explained in terms of restriction of available growth space. The molar crown area measurements of a modern human sample were also investigated. The results of this study, as well as previous similar analyses, suggest that a decrease of the rate of cell proliferation, which affected the later-forming crown regions to a greater extent, may be the biological process responsible for the general and differential dental size reduction that occurred during human evolution.
TL;DR: Calcanei and tali of 100 skeletons in the Hamann-Todd Collection at the Cleveland Museum of Natural History were measured to derive linear-regression equations for estimating stature.
Abstract: Calcanei and tali of 100 skeletons in the Hamann–Todd Collection at the Cleveland Museum of Natural History were measured. The skeletons represented 50 males and 50 females distributed equally by race, i.e., whites and blacks. Linear-regression equations, with standard errors ranging from 4.09 to 6.11 cm, were derived from these measurements for the purpose of estimating stature. Two independent control samples, including one comprised of remains of American servicemen lost in World War II and the Korea and Vietnam wars, were tested with relatively accurate results. © 1995 Wiley-Liss, Inc.
TL;DR: Stable isotopes of carbon and nitrogen from human bone are analyzed in order to compare the diets of the high- and low-status individuals at La Florida and there is no evidence for this based on the bone chemistry data from La Florida.
Abstract: Excavation at the Ecuadorian highland site of La Florida in suburban Quito revealed six deep shaft tombs yielding high-status individuals (n = 9) as well as apparent sacrifices and other low-status individuals (n = 23). Determination of sex and age at death of the recovered skeletal remains resulted in a sample of 32 individuals aged from approximately 7 to 50 years of age. The sample of 18 individuals over the age of 18 years included 14 females and 4 males. Temporally, the remains are assigned to the Chaupicruz Phase (circa 100 to 450 AD) of the Regional Developmental Period. In this study, we analyze stable isotopes of carbon and nitrogen from human bone in order to compare the diets of the high- and low-status individuals. Stable carbon isotope analyses were carried out on preserved protein and biological apatite (bioapatite), and stable nitrogen isotope analyses were carried out on preserved protein. There is a statistically significant difference in delta 13C between the two groups for both protein and mineral sources of carbon with evidence for the greater consumption of maize in the high-status group. There is no significant difference in delta 15N between the two groups, nor is there a significant difference in the spacing between protein and mineral delta 13C values between the two groups. Ethnohistorical evidence for the 16th century AD provides the expectation that the only dietary difference was the higher consumption of animal protein by the elite. There is no evidence for this based on the bone chemistry data from La Florida.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: Examination of ontological patterns of change in variation of the human pelvis as a means of identifying regions of differential growth, growth canalization and evidence of selection found a posterior-to-anterior gradient of increasing dimorphism within the inlet and midplane of the pelvic birth canal.
Abstract: This research examines ontological patterns of change in variation of the human pelvis as a means of identifying regions of differential growth, growth canalization and evidence of selection. Data were derived from pelvic radiogrammetry of 180 8-year-olds and 89 subjects at age 18 who were part of the Fels Longitudinal Growth Study. Coefficients of variation (CVs) and total growth increments were compared between sexes and between ages 8 and 18 for 14 pelvic measures. Sex-specific comparisons of mean size were tested per age using Student's t, whereas coefficients of variation were calculated and compared using the methods suggested by Sokal and Braumann ([1980] Syst. Zool. 29:50–66). The Mann-Whitney U-test was used to test median growth increments between ages 8 and 18.
Results of these comparisons show significant sex differences in breadth of the ischium and acetabular regions among 8-year-olds. Most of the sexual dimorphism in the pelvis at age 18, however, develops during the adolescent growth period, during which both male and female pelves undergo growth remodeling of the pelvic cavity. Over the same time period, males show significantly greater incremental growth in the acetabulum, and females show differentially greater growth in the pelvic cavity. At age 18, the pelvis demonstrates a posterior-to-anterior gradient of increasing dimorphism within the inlet and midplane of the pelvic birth canal.
As a means of interpreting the effects of natural selection on the pelvis, it is argued that appropriate comparisons are within-sample comparisons of CVs over time, rather than comparisons between sexes of adult coefficients as has been argued by others (Meindl et al. [1985] Am. J. Phys. Anthropol. 68:79–85). Analyses of change in coefficients of variation over time show evidence of concordantly reduced within-sample variation in 7 pelvic dimensions indicating canalization of growth. These results are attributed to the effects of stabilizing selection operating on both males and females and include transverse diameters of the sacrum, inlet, anterior inferior iliac spines, and breadths of the ilium and ischium.
Six pelvic dimensions show evidence of increased total sample CVs and discordant change in within-sex comparisons of CVs as well as differential growth between sexes over time. This pattern is indicative of the effects of disruptive selection on the pelvis for interacetabular diameter, breadths of the anterior superior and posterior inferior iliac spines, pubic length, and ilium height. © Wiley-Liss, Inc.
TL;DR: The skeleton of Apidium phiomense is the most primitive anthropoid postcranial skeleton known and shows greatest similarities to the same elements of small platyrrhines such as Saimiri and is also very similar to the hypothetical morphotype for ancestral platyr rhine.
Abstract: Apidium phiomense is the most common primate from the early Oligocene deposits of Fayum, Egypt. It is known from hundreds of dental remains and dozens of skeletal remains, including numerous representatives of the long bones of the forelimb and hindlimb. Apidium phiomense was a small (1,600 g) arboreal quadruped. The forelimb bones of this species show features characteristic of arboreal quadrupeds and lack characteristic features found in the forelimb bones of vertial clingers, terrestrial quadrupeds, or suspensory species. The pelvis and hindlimb bones show numerous adaptations for leaping from a quadrupedal position. In general, Apidium lacks characteristic features of either cercopithecoid monkeys or hominoid apes. Overall, the skeleton shows greatest similarities to the same elements of small platyrrhines such as Saimiri and is also very similar to the hypothetical morphotype for the ancestral platyrrhine. The skeleton of Apidium phiomense is the most primitive anthropoid postcranial skeleton known. © 1995 Wiley-Liss, Inc.
TL;DR: An investigation of a new set of morphometric characters of the scapula and proximal humerus suggested by EMG analyses of shoulder muscle function, which supports previous functional interpretations of each taxon's locomotor abilities based on a variety of other characters.
Abstract: The study of muscle function in nonhuman primates through the technique of electromyography (EMG) has facilitated the identification of specific functional roles for muscles in particular behaviors. This has led to a more complete understanding of the biomechanics of certain regions of the musculoskeletal system, and should facilitate our ability to identify morphological features useful in the functional interpretation of fossil material. The current paper represents one such investigation of a new set of morphometric characters of the scapula and proximal humerus suggested by EMG analyses of shoulder muscle function. A set of new metric variables were examined on the scapulae and proximal humeri of 25 species of extant anthropoid primates, as well as on casts of scapulae and humeri of three fossil primate taxa. The variables are primarily related to the line of action and attachments of the rotator cuff muscles. The position of the scapular spine, the degree of lateral expansion of the subscapular fossa, the size and shape of the subscapularis insertion facet on the lesser tubercle, and the orientation of the infraspinatus insertion facet on the greater tubercle all appear to successfully sort the extant taxa into locomotor groups. Their appearance on the fossil specimens generally supports previous functional interpretations of each taxon's locomotor abilities based on a variety of other characters, suggesting that these traits are equally applicable to fossil material.
TL;DR: The postcranial body weight estimates for the three species of Proconsul are compared to body weights estimated from M1 area in order to investigate possible differences in scaling between the teeth and limbs in these species.
Abstract: A distal tibia of Proconsul major from Napak, Uganda, is described. It is morphologically similar to other Proconsul tibiae, only much larger in size. This specimen and others are used to estimate the body weight of P. major from postcrania for the first time. Body weight is predicted from articular and diaphyseal dimensions using regression equations derived from a modern comparative sample of catarrhine primates. The estimated body weight of P. major based on the Napak tibia is 86.7 kg, whereas two other P. major specimens are smaller, giving a total range of 63.4-86.7 kg and an average of 75.1 kg. The regression equations are also used to predict the body weight of specimens from Rusingdfangano belonging to P. nyanzae and P. heseloni. As the body weight estimates generated here are consistent with previous postcranial-based estimates for Proconsul species, the two sets of estimates are pooled to give means of 10.9 kg for P. heseloni (n = 6) and 35.6 kg for P. nyanzae (n = 12). These findings support the traditional assignment of two species at Rusingdfangano. The postcranial body weight estimates for the three species of Proconsul are compared to body weights estimated from M1 area in order to investigate possible differences in scaling between the teeth and limbs in these species. Despite being based on a smaller sample size, the postcranial estimates clearly differentiate the three taxa, whereas the dental estimates form a more continuous distribution. Molar area overesti- mates body weight in P. heseloni, indicating that it is megadont compared to a large sample of modern anthropoid primates. In contrast, molar area under- estimates body weight in P. nyanzae and especially P. major, suggesting relative microdonty in these taxa. o 1995 Wiley-Liss, Inc.
TL;DR: The Ohalo II H2 specimen, dated to ca.
Abstract: The discovery of well-preserved human remains at the site of Ohalo II in the northern Jordan Valley substantially augments the meager fossil record of the Levantine late Upper Pleistocene. The Ohalo II H2 specimen, dated to ca. 19,000 B.P., is the most complete early Epipaleolithic hominid discovered in Israel and promises to contribute to the clarification of a number of problematic issues in the local evolution of anatomically modern humans. In addition to a description of the burial and its Kebaran context, a detailed anatomical description of the skeleton is offered and morphometric comparisons are made to other Upper Paleolithic hominids. Ohalo II H2 is shown to demonstrate affinities in the craniofacial skeleton to fossils from the early Upper Paleolithic and late Epi-Paleolithic of the Levant.
TL;DR: In this paper, the authors presented nucleotide sequence data for mitochondrial DNA extracted from ancient human skeletons of the Yayoi era (ca. 2,000 BP) excavated from the Takuta-Nishibun site in northern Kyushu of Japan.
Abstract: We present nucleotide sequence data for mitochondrial DNA extracted from ancient human skeletons of the Yayoi era (ca. 2,000 BP) excavated from the Takuta-Nishibun site in northern Kyushu of Japan. Nucleotide sequence diversity showed that the Yayoi people of the Takuta-Nishibun site were not a genetically homogeneous population. This site shows a diversity in the burial style. Phylogenetic analysis indicated a statistically significant correlation between burial style and the genetic background of the Takuta-Nishibun individuals, and revealed no discrete clustering patterns for the Yayoi individuals, for early modern Ainu, or for the Jomon people. © 1995 Wiley-Liss, Inc.
TL;DR: A comparison of NCMA to included angle, both calculated on manual and pedal proximal phalanges of humans, apes, some monkeys, and the Hadar fossils, revealed that these two different measures of curvature are highly correlated and result in very similar distributional patterns.
Abstract: It has been generally assumed and theoretically argued that the curvature of finger and toe bones seen in some nonhuman primates is associated with cheiridial use in an arboreal setting. Assessment of such curvature in fossil primates has been used to infer the positional behavior of these animals. Several methods of quantifying curvature of bones have been proposed. The measure most commonly applied to phalanges is that of in cluded angle, but this has come under some criticism. We consider various other approaches for quantifying phalangeal curvature, demonstrating that some are equivalent to use of included angle, but that one—normalized curva ture moment arm (NCMA)—represents a true alternative. A comparison of NCMA to included angle, both calculated on manual and pedal proximal phalanges of humans, apes, some monkeys, and the Hadar fossils, revealed that these two different measures of curvature are highly correlated and result in very similar distributional patterns. © 1995 Wiley-Liss, Inc.