Showing papers in "American Journal of Physical Anthropology in 1984"

Patterns of molar wear in hunter–gatherers and agriculturalists

Abstract: Tooth wear records valuable information on diet and methods of food preparation in prehistoric populations or extinct species. In this study, samples of modern and prehistoric hunter-gatherers and agriculturalists are used to test the hypothesis that there are systematic differences in patterns of tooth wear related to major differences in subsistence and food preparation. Flatness of molar wear is compared for five groups of hunter-gatherers (N = 298) and five groups of early agriculturalists (N = 365). Hunter-gather- ers are predicted to develop flatter molar wear due to the mastication of tough and fibrous foods, whereas agriculturalists should develop oblique molar wear due to an increase in the proportion of ground and prepared food in the diet. A method is presented for the quantitative measurement and analysis of flatness of molar wear. Comparisons of wear plane angle are made between teeth matched for the same stage of occlusal surface wear, thus standardizing all groups to the same rate of wear. Agriculturalists develop highly angled occlusal wear planes on the entire molar dentition. Their wear plane angles tend to exceed hunter-gatherers by about 10" in advanced wear. Wear plane angles are similar within subsistence divisions despite regional differences in particular foods. This approach can be used to provide supporting evidence of change in human subsistence and to test dietary hypotheses in hominoid evolution. Tooth wear is one skeletal feature that pre- serves direct evidence of the masticatory be- havior of mammals. Mastication is inti- mately related to diet, and patterns of tooth wear can be used to make inferences about diet in prehistoric populations and extinct

Quantitative differences in dental microwear between primate species with different diets and a comment on the presumed diet of Sivapithecus

Abstract: Studies of dental microwear have been used to relate tooth form to function in a variety of recent and extinct mammals. Probably the most important aspect of microwear analysis is the possibility of using it to deduce the diet of extinct animals. Such deductions must be based on comparative studies of modern species with known diets, but to date, only qualitative studies have been attempted and all have been based on small samples. Here we report quantitative differences in dental microwear between primate species that are known to have different diets. Occlusal facets with different functions have previously been shown to exhibit different microwear patterns. However, the differences between facets of one species are shown to be far less than those between homologous facets of different species. Study of seven species of extant primates shows that enamel microwear can be used to distinguish between those with a mainly frugivorous diet and those with a mainly folivorous one. Microwear can also distinguish hard-object feeders from soft-fruit eaters. The microwear of Miocene Sivapithecus indicus cannot be distinguished statistically from that of the chimpanzee, but it is different from that of the other species. On this evidence S. indicus was not a hard-object feeder and the adaptive significance of its thick molar enamel is at present unknown.

Stress and strain in the mandibular symphysis of primates: a test of competing hypotheses.

Abstract: The primary purpose of this study was to test various hypotheses about symphyseal stress in primates. First, those patterns of symphyseal strain that would be associated with various hypothetical patterns of symphyseal stress were formulated. Then these hypothetical patterns of stress and strain were tested by comparing the formulated bone strain pattern with actual in vivo symphyseal bone strain patterns. Patterns of in vivo symphyseal bone strain were determined by bonding rosette and/or single-element strain gages to the midline of the middle and lower third of the labial aspect of the symphysis of six adult Macaca fascicularis. Following recovery from the anesthetic, bone strain was recorded during mastication, incision, and isometric biting. Symphyseal bone strain was also recorded during yawning, licking, and threat behaviors. The data suggest that during the power stroke of mastication, the macaque symphysis is predominately sheared dorsoventrally and/or twisted about a transverse axis and bent by lateral transverse bending of the mandibular corpora. During lateral transverse bending of the mandibular corpora, the labial aspect of the macaque symphysis experiences compressive bending stress, while the lingual aspect experiences tensile bending stress. During the opening stroke of mastication and during other jaw opening behaviors, the macaque symphysis is bent by medial transverse bending of the mandibular corpora. At this time the labial aspect of the symphysis experiences tensile bending stress, while its lingual aspect experiences compressive bending stress. During both the power and opening strokes of mastication, the macaque mandible is bent in the plane of its curvature, and therefore the mandible acts as a curved beam. This is important because it results in elevated levels of stress along the lingual aspect of the macaque symphysis, particularly during the power stroke of mastication. During the power stroke of incision, the local effects of the bite force are unknown; however, at this time the lower half of the macaque symphysis is both sheared dorsoventrally and bent due to twisting of the mandibular corpora about their long axes. The results of this stress analysis have implications for understanding the mechanical attributes of symphyseal structure. In order to counter dorsoventral shear, the most important symphyseal attribute is to have adequate cross-sectional area of bone in the plane of the applied stress. In contrast, both the cross-sectional area of bone and symphyseal shape is important in order to counter stress effectively during symphyseal torsion and the three symphyseal bending regimes.(ABSTRACT TRUNCATED AT 400 WORDS)

Metamorphosis at the Sternal Rib End: a New Method To Estimate Age At Death in White Males

Abstract: While the pubic symphysis and intracortical morphometry have provided successful results in estimating age at death, other methods and sites in the skeleton are needed to improve the accuracy of age estimation. This research is an attempt to develop a new age-determination technique by using the sternal extremity of the rib. The right fourth rib was collected at autopsy from 93 white males. The sternal extremity of each rib was analyzed in relation to the pit depth (component I), pit shape (component II), and rim and wall configurations (component III), each of which was divided into six stages. Results indicated that the age at death can be estimated from a rib within about 2 years in the second decade to about 7 years in the fifth and sixth decades of life. Pit shape and rim and wall configurations yielded better results than absolute pit depth alone. While this method has a potentially important contribution to skeletal anthropology, factors such as sex differences and biomechanical variation between individuals may affect the determination of age from the rib.

The ecological role of the callitrichidae: a review.

Abstract: The marmosets and tamarins fill a unique ecological role among the anthropoid primates, one that has not been fully recognized. Many misconceptions--that they are primitive, monogamous, territorial, and squirrellike--pervade the literature. These misconceptions are largely the result of misinterpreting laboratory studies which have not been confirmed with identified animals in natural habitats. Recent field studies, reviewed here, indicate that marmosets and tamarins have a highly derived ecological role, are not monogamous, feed largely on insects and plant exudates, and have uniquely specialized positional behavior involving clinging to vertical tree trunks in order to feed on exudates. Accompanying these behavioral traits are a number clawlike nails on all digits except the hallux, and a three-cusped upper molar morphology. These form a suite of characteristics unique among the living primates, many of which are related to their ecological role. We believe that the marmosets and tamarins are members of a guild of exudate feeders in which plant exudates are an important component of the diet. It is within this framework of a primate foraging guild that we can best understand many of their morphological and behavioral adaptations.

Structural changes in the femur with the transition to agriculture on the Georgia coast

Abstract: Structural characteristics of the femur are compared in preagricultural (2200 B.C.-A.D. 1150) and agricultural (A.D. 1150-1550) subsistence strategy groups from the Georgia coast. Using an automated technique, cross-sectional geometric properties used in structural analyses (areas, second moments of area) were determined at midshaft and distal to the lesser trochanter in 20 adults from each group. A significant decline in magnitude of almost every geometric property occurs in the agricultural group. The differences between groups are reduced but still significant for many properties after standardizing for bone length differences. In addition, a remodeling of the femoral cortex to one of relatively smaller medullary and subperiosteal diameter, as well as a more circular cross-sectional shape, is characteristic of agricultural femora. Thus, while the relative cross-sectional area of bone remains the same, the spatial distribution of bone area is different in the two groups. The results strongly suggest a relative reduction in mechanical loadings of the femur in the agricultural group, implying different levels and possibly types of activity involving the lower limb in the two groups. The data are also compared with similar data available for the Pecos Pueblo (agricultural) sample. The comparison indicates that types of activity may have been more similar in the two agricultural samples, but that general levels of activity were more similar in the Pecos Pueblo and Georgia coast preagricultural samples.

Cranial morphology of Australopithecus afarensis: a comparative study based on a composite reconstruction of the adult skull.

Abstract: The Pliocene hominid species Australopithecus afarensis is represented by cranial, dental, and mandibular remains from Hadar, Ethiopia, and Laetoli, Tanzania. These fossils provide important information about the cranial anatomy of the earliest known hominids. Because complete crania or skulls are not known, we produced a composite reconstruction of an adult male skull based on 13 specimens from the Hadar Formation. The reconstruction serves as a testable hypothesis regarding functional relationships in the A. afarensis skull and is the basis for the comparative study presented here. We examine six major aspects of cranial and mandibular anatomy. We combine our results with those of White et al. (1981) in a discussion of alternate hypotheses of early hominid phylogeny. In the cranium, jaws, and teeth A. afarensis exhibits a morphological pattern that we interpret as primitive for the Hominidae. Homo habilis retains a number of these primitive features for which A. africanus, A. robustus, and A. boisei share derived character states, particularly in the masticatory apparatus. Homo and "robust" species of Australopithecus share a suite of derived cranial base features. These shared traits may relate to upper facial orthognathium which is also common to these taxa and are probably indicative of parallelism rather than a close phylogenetic relationship. The cranial base characteristics of A.L. 333-45 do not, contrary to Olson's (1981) claims, provide evidence for an A. afarensis--"robust" Australopithecus sister group. When the range of mastoid variation in extant African pongids and A. afarensis is examined thoroughly, the Pliocene hominid appears to retain a primitive, rather than derived, morphology.

A new world syndrome of metabolic diseases with a genetic and evolutionary basis

Abstract: Currently, many Amerindian peoples, including European- Amerindian admixed groups such as Mexicans, are experiencing a major epidemic of a series of diseases which includes a tendency to become obese at an early adult age, adult onset diabetes mellitus, the formation of cholesterol gallstones, and gallbladder cancer, especially in females. Other cancer sites, and morbid consequences of these primary disorders, also occur at elevated rates. This epidemic has begun, or at least increased dramatically since World War II, and seems to be due to an interaction between susceptible Amerindian genotype(s) and some recently changed aspect of the environment, probably involving dietary components. This paper reviews the epidemiology of this New World Syndrome (NWS), quantifying incidence, prevalence, and risk in susceptible genotypes. This pattern is distinct from the rise of similar diseases associated around the world with “westernization.” The susceptible genes probably arose by virtue of a selective advantage during or before the initial peopling of the Americas.

Microscopic criteria for the determination of directionality of cutmarks on bone

Abstract: Shipman and Rose (1983) have recently attracted attention to the fact that the determination of directionality of cutmarks could possibly provide additional evidence for interpretation of early hominid butchering practices and handedness. They found no criteria of directionality, however. We have previously recognized directionality in cut dental tissues and more recently in bone, and so we undertook a study of over 200 experimentally produced cutmarks on bovine bone by scanning electron microscopy. Three criteria of directionality were observed: bone smears, oblique faulting, and oblique chipping. In our analysis we considered properties of bone as a relevant variable in the microscopic appearance of cutmarks, which has also led to the new finding that not all marks made by a single tool under similar conditions are the same. We observed that bone smears occurred in most specimens, relatively low density forming bone surfaces facilitated oblique fault production, whereas oblique chipping frequently occurred in plexiform bone tissue common to growing artiodactyls. In this study, handedness of the operator could be determined from cutmarks, but much further experimental work will be required in order to detail the criteria.

Rib lesions in chronic pulmonary tuberculosis

Abstract: The diagnosis of skeletal tuberculosis in human remains has traditionally been based upon the detection of secondary skeletal lesions which result from hemotogenous dissemination of tubercle bacilli (e.g., Pott's disease). Since such lesions develop in less than 7% of cases of human tuberculosis, the paleodemography and paleoepidemiology of this disease have been difficult to assess from skeletal remains. This study presents a new diagnostic approach to tuberculosis, focusing on the skeletal manifestations of chronic pulmonary disease (which comprises approximately 90% of human-form tuberculosis). Four hundred forty-five skeletal remains from persons dying of tuberculosis during the first half of the 20th century were examined. A total of 70/445 (16%) exhibited skeletal lesions in one or more locations as a response to infection. Of these 70, 39 (56%) were found to display a specific set of lesions restricted to the internal aspect of the ribs. These lesions take one of two forms: (1) diffuse periostitis or (2) localized abscess, and appear to correspond to areas of chronic pulmonary infection. The diffuse type of rib lesion is more commonly observed than the localized type. In our observations (and according to the natural history of tuberculosis) the occurrence of chronic pulmonary tuberculosis is usually mutually exclusive with hematogenous dissemination to secondary bone locations. Thus, the detection of rib lesions in cases of chronic pulmonary disease increases the absolute sample size of skeletal tuberculosis by a factor of two in this study.

The chronological distribution of enamel hypoplasias from prehistoric Dickson Mounds populations.

Abstract: The chronological distributions of enamel hypoplasias (indicators of nonspecific stress) are assessed for 111 individuals from two prehistoric populations from Dickson Mounds, Lewiston, Illinois. The earlier population (circa A.D. 950-1150) involves a transition from an indigenous gathering-hunting tradition to increasing adoption of Mississippian lifeways. The later population (circa A.D. 1150-1300) is fully Mississippian (MM). Based on the occurrence of hypoplasias on all permanent teeth except third molars, 14 half-year periods from birth to 7.0 years are graded for evidence of hypoplasia-stress. Both populations have a low frequency of hypoplasia which occur before 2 years of age and after 4 years of age. A common peak frequency of hypoplasias between 2.0 and 4.0 years is suggestive of an elevated degree of stress at weaning. The peak frequency of hypoplasias is earlier in the MM (2.5-3.0 years versus 3.0-3.5 years in the pre-Mississippian population). In addition, the rise to and decline from peak frequency occurs approximately 0.5 years earlier in the MM. The earlier and sharper rise to peak frequency suggests earlier and more severe weanling-related stress. Hypoplasias chronologies are undoubtedly influenced by age-related host resistance factors (Sarnat and Schour, 1941). Nevertheless, these data demonstrate that populations may vary in their chronological distribution of hypoplasias and that these variations may provide useful information on age-related patterns of exposure to environmental stressors.

Aspects of size and scaling in primate biology with special reference to the locomotor skeleton

Abstract: Scaling refers to the structural and functional consequences of differences in size (or scale) among organisms of more or less similar design. Investigations into such size-related phenomena in primates continue to be a primary concern of physical anthropologists, primatologists, and other vertebrate biologists. An overview of allometric studies, especially those of the last decade or so, documents the enormous impact of body size variation in primates for interpretations of comparative behavior and ecology, morphology and physiology, and evolutionary biology. Specific methodological issues are also discussed (the utility of the bivariate power function, regression models, and choice of body size variables). Distinctions are drawn between ontogenetic and static adult forms of intraspecific allometry, and the genetic assumptions about extrapolation of either type to evolutionary allometry are briefly reviewed. Ontogenetic allometries of the locomotor skeleton in African apes are used to illustrate the potential utility and limitations of this approach for our understanding of evolutionary mechanisms. Selected aspects of locomotor adaptation in primates are also explored through interspecific allometric analysis: an analysis of long bone size and shape with respect to competing biomechanical theories of functional equivalence; scaling of interlimb proportions and functional competence in climbing; and relative limb proportions and the reconstruction of locomotion and posture in fossil “hominoids”.

Determination of Sex from the Tibia

Abstract: Determination of sex from the tibial shaft as well as the entire bone itself has not been generally investigated by osteologists . This paper is an attempt to fulfill this need. The purpose is to determine sex from both the complete tibia and the shaft at the nutrient foramen level. The sample was obtained from the Terry Collection and included 159 specimens of whites and blacks. The tibial length, and circumference, anteroposterior, and transverse measurements at the nutrient foramen level were analyzed by means of step-wise discriminant function analysis. It was found that the circumference alone could give, on the average, 80% accuracy in determining sex. The addition of other dimensions to the function increased the accuracy by about 4%. Comparisons of this study with those on the femur indicated that sexual dimorphism in the tibia was a result not only of the general growth and musculo-skeletal activity, but also of the genetic structure of the population, i.e., racial variation.

Primate evolution: Evidence from the fossil record, comparative morphology, and molecular biology

Abstract: Our understanding of primate evolution is ultimately based on patterns of phyletic relationship and morphological change documented in the fossil record. Stratophenetic interpretation of living and fossil primates yields an objective alternative to the arbitrary scala naturae assumed implicitly in traditional comparative biology. Fossils provide an outline of primate history constraining comparative analyses incorporating taxa and morphological characteristics not represented in the fossil record. Extant taxa without known prehistoric relatives may be interpolated into this outline using deductive cladistic analysis of morphological characteristics and overall molecular similarity. Cladistic analysis provides a method for evaluating the relative strength of stratophenetic links between taxa. The phyletic node connecting Anthropoidea-Adapoidea-Lemuroidea is analyzed here as an example: the link between Eocene Adapoidea and primitive Anthropoidea appears stronger than that between Adapoidea and Lemuroidea because it is based on shared-derived rather than shared-primitive characteristics. Full integration of molecular results with morphological information requires a better understanding of rates of molecular change over geological time. Rates of molecular evolution can be studied using paleontologically documented divergence times for Prosimii-Anthropoidea (ca. 55 m.y.B.P.), Platyrrhini-Catarrhini (ca. 40 m.y.B.P.), and Hominoidea-Cercopithecoidea (ca. 25 m.y.B.P.). Immunological distances combined with these divergence times indicate that primate albumin, widely used as a molecular clock in primatology, has evolved nonlinearly over geological time. A nonlinear albumin clock yields divergence times of about 9 million years before present for humans and chimpanzees, and about 13 million years before present for humans and orangutans (compared with 4 m.y.B.P. and 7 m.y.B.P., respectively, based on a linear albumin clock). Apparent slowing of albumin evolution over time remains to be fully explained. Other proteins and nucleic acids may provide better clocks. Cladistic analysis of morphological characteristics and comparative study of molecular structure, interpreted in the context of the fossil record, promise to contribute to a more complete understanding of primate evolution.

Variation in the pattern of cranial venous sinuses and hominid phylogeny.

Abstract: In 1967 Tobias noted that Australopithecus boisei cranium O.H.5 exhibited a cranial venous sinus pattern in which the occipital sinus and the marginal sinuses of the foramen magnum appeared to have replaced the transverse-sigmoid sinuses as the major venous outflow track. Specimens of A. robustus and several more recently recovered A. boisei crania also show evidence of enlarged occipital-marginal sinuses. In contrast, A. africanus and H. habilis retain a dominant transverse-sigmoid system that characterizes the great majority of extant apes and modern human cadaver samples. Pliocene A. afarensis exhibits a high frequency of occipital-marginal drainage systems. An examination of several series of precontact North American Indian crania shows that the frequency distribution of the occipital-marginal sinus pattern is spatiotemporally disjunct , ranging from 7.5% to 28%. The Late Pleistocene sample from P redmost , Czechoslovakia, also shows a very high incidence of occipital-marginal sinus patterns (approximately 45%). These observations suggest that occipital-marginal and transverse-sigmoid sinus patterns are adaptively equivalent character states. This conclusion is supported by the fact that enlarged occipital-marginal and transverse-sigmoid sinus systems often coexist on the same and/or contralateral sides of the head. It is well known that the frequencies of such adaptively neutral traits are often heavily influenced by population-specific epistatic interactions. The utilization of such traits in phylogenetic reconstruction entails a substantial risk of mistaking parallelism for synapomorphy . It is concluded that using functional-adaptive criteria in the definition of morphologic characters is a more reliable method to guide phylogeny reconstruction. In light of this, the distribution of venous sinus variants in Plio -Pleistocene hominids gives little or no basis for revising the phylogenetic scheme of Johanson and White (1979), or the functional-adaptive interpretation offered by White et al. (1981).

Stride length and speed for adults, children, and fossil hominids

Abstract: Research workers studying the relationship between stride length (L) and speed (u) in human walking have often expressed their results as multiples of stature (h): they have given values of L/h and u/h They have claimed or implied that this takes account of differences of body size and that L/h should be the same function of u/h for people of all sizes It is shown that this is not true for comparisons of children with adults Further, it is argued by dimensional analysis that u/square root gh is a more appropriate speed parameter that u/h (g is the acceleration of free fall) It is shown that L/h is approximately the same function of u/square root gh for children aged 4 or more years as for adults The empirical relationship between L/h and u/square root gh is used to make new estimates of walking speed for the early hominid footprints found at Laetoli, Tanzania The speeds obtained are equivalent to mean speeds of human walking observed in small towns (ie, they give approximately equal values of u/square root gh)

A hominine hip bone, KNM-ER 3228, from East Lake Turkana, Kenya

Abstract: A male hominine partial hip bone, KNM -ER 3228, from East Lake Turkana , Kenya is described. In most of its features this specimen resembles modern human male hip bones. This is especially true for functional features related to weight transfer from the trunk to the pelvis and within the pelvis, and to the effective action of musculature arising from the pelvis during the performance of the modern human type of bipedalism . KNM -ER 3228 is very similar to the Olduvai Hominid 28 and the Arago XLIV hip bones, both attributed to Homo erectus .

Mechanisms of honing in the male baboon canine

Abstract: Male baboons use their sharp upper canines in aggressive interactions. These teeth are sharpened against specialized lower third premolars. The honing premolar is protected against wear by having very thick enamel and the upper canine having very thin enamel, not by structural or mineral differences between the two enamels. Evidence is presented which shows the interactions of enamel ultrastructure and both dentin and enamel wear in canine sharpening.

The diabetes alert study: Growth, fatness, and fat patterning, adolescence through adulthood in Mexican Americans

Abstract: Diabetes Alert is a multidisciplinary genetic and epidemiological study of Type II (non insulin-dependent) diabetes in Texas Mexican Americans. We report the anthropometry of 1,155 individuals 10 to 70 or more years with particular reference to overweight, fatness, and anatomical fat patterning in the sample. Children ages 10-18 of both sexes are growing at the 50th percentile of the reference data (U.S. Health and Nutrition Examination Survey-1) for height, Wt/Ht2, and triceps and subscapular skinfolds. Adults are well below median height but well above median Wt/Ht2 and skinfolds. Prevalence of obesity (Wt/Ht2 greater than or equal to 30) among adults is typically 30% or higher by age 30. Diabetics compared to age/sex-matched non diabetics have shorter sitting heights, have more upper body fat (subscapular skinfold), have less lower body fat (lateral calf skinfold), and were heavier at maximum weight and at age 18. The ratio of lower to upper body fat distribution decreases over the life cycle, being highest at adolescence and lowest at ages 40-50 in both sexes. Our results show a precipitous weight gain after maturity in the sample and an association of diabetes with differences in anatomical fat patterning. The age-related changes in fat patterning need to be explained in terms of their ecological and genetic influences.

Hemoglobin levels in a Himalayan high altitude population

Abstract: This report presents data on hemoglobin concentrations in a sample of Himalayan high altitude natives measured at their habitual altitude of residence. In this sample of 270 healthy Tibetan adults resident at 3250-3560 m in Upper Chumik , Nepal, the mean hemoglobin concentration is 16.1 +/- 1.2 gm/dl among adult males, 14.4 +/- 1.4 gm/dl among premenopausal and 15.0 +/- 1.1 gm/dl among postmenopausal adult females. 123 of 126 (98%) males, 96 of 100 (96%) premenopausal and 36 of 44 (82%) postmenopausal females have hemoglobin concentrations within two standard deviations of the sea level mean. These data demonstrate that a healthy population may reside at high altitude without the degree of elevation in hemoglobin widely known and cited for Andean highlanders. Comparing published data on mean hemoglobin concentrations of adult Himalayan and Andean samples residing between 3200 m and 4100 m reveals that Himalayan means are systematically lower. This in turn may account for the reported population differences in the prevalence of chronic mountain sickness ( Monge 's disease). It is hypothesized that Himalayan and Andean highlanders represent alternative patterns of high altitude hematological adaptation.

Interpretation of scanning electron microscopic images of abraded forming bone surfaces

Abstract: The experimental abrasion of forming bone surfaces was conducted so that such surfaces could be characterized. This is particularly important to bone remodeling studies utilizing scanning electron microscope (SEM) imaging of archeological material. Forming surfaces derived from subadult macaque cranial bone were treated by particle abrasion, water abrasion, sliding abrasion, brushing, manual rubbing, weight, exfoliation, chipping and replication. Acetic acid treatments were also performed. The effects of abrasive agents are specific but generally fall into rough (particle and water abrasion) and smooth (sliding abrasion, brushing, rubbing and weight) categories. Protohistoric human and Plio-Pleistocene hominid subadult craniofacial remains were observed with the SEM for comparison with experimental data. The more recent material appeared smooth, probably as a result of specimen preparation procedures using brushes. Surfaces were still interpretable as forming, however, using a more abrasion-resistant feature called intervascular ridging (IVR) described in this study. The IVR pattern is also recognized on the hominid sample, confirming the possibility of performing remodeling studies on abraded fossil material. The abrasion characteristics are somewhat more difficult to classify, however. Abrasion is defined and discussed relative to remodeling studies and taphonomy. The usefulness of the experimental data reported here, however, in paleoenvironmental reconstruction, has yet to be fully realized. Acid and mechanical preparation techniques are briefly addressed. It is concluded that it is possible to characterize a forming surface as abraded according to the findings of this study and that acid, if handled with care, will more likely preserve microanatomical surface detail. It would also be in everyone's interest to employ a less abrasive cleaning regime on archeological specimens.

Mechanism of intraoral transport in macaques.

Abstract: All mammals have the same divisions of cyclic movement of tongue and hyoid during mastication: a protraction or forward phase that begins at minimum gape, and a retraction or return phase. Nonanthropoid mammals transport food from the oral cavity to the oropharynx during the return phase; food on the dorsal surface of the tongue moves distally while the tongue is retracted. Macaques, however, transport food during the protraction phase of tongue/hyoid movement. Food is squeezed posteriorly by contact between the tongue surface and the palate anterior to the food. This mechanism of transport is occasionally seen in nonanthropoid mammals when they are transporting liquids from the oral cavity to the oropharynx. It has, however, not been seen when these mammals transport solid food. One morphological basis for this difference is the reduction in height of the rugae of the palate of macaques. In most mammals these rugae are pronounced ridges that are able to hold food in place during protraction as the tongue slides forward beneath the food. Anthropoids and other mammals differ in the way they store food prior to swallowing. When macaques transport food to the oropharynx, usually they swallow in the next cycle, but always in the next 2 or 3 cycles. Most mammals transport and store food in the oropharynx for several cycles before a swallow clears that region of food. This behavior is correlated with differences in morphology of the oropharynx; anthropoids have reduced valleculae, the area in which other mammals store food prior to swallowing.

Primate cortical bone microstructure: Relationship to locomotion

Abstract: Mechanical factors are implicated in the control of osteonal (Haversian) remodeling. Twenty primate species, representing a diverse range of locomotor behaviors, have been examined to determine whether the arrangement of secondary osteonal bone at femoral mid-diaphysis reflects behaviorally related biomechanical influences. The proportion of bone cortex occupied by secondary osteons (percent osteonal bone) is related to the biomechanical environment of these femora. Percent osteonal bone delineates groups which correspond to other skeletal and kinesiological categorizations of primate locomotion and distinguishes among arboreal quadrupedal, terrestrial quadrupedal, suspensory, and bipedal primates.

Long bone growth variation among Arikara skeletal populations

Abstract: Long bone growth variation among skeletal samples has had limited application to ecological studies of archaeological groups, in spite of its well-known sensitivity to health and nutritional status. In this study, long bone growth variation was examined among 10 samples of Arikara skeletal groups, all located in the Middle Missouri subarea of South Dakota and ranging in time from 1600 to 1832. The samples are analyzed by variant, an archaeological taxonomic unit below Tradition. Children's long bones between about 0. 5 and 11. 9 years of age were analyzed by means of regression using the model, bone length = b 0 + b 1 (age) + b 2 (log 10 age). The three variants, Extended Coalescent, Postcontact Coalescent, and Disorganized Coalescent, differ from one another with regard to health and nutritional status. Extended Coalescent groups probably experienced periods of undernutrition due to unfavorable climatic conditions prevailing at the time. Postcontact Coalescent groups experienced more favorable health and nutrition due to the improved climatic conditions and introduction of the horse. Disorganized Coalescent groups were exposed to undernutrition and high levels of morbidity, due to introduction of epidemic diseases, depopulation, and intertribal conflict. Analysis of slopes shows significant heterogeneity among variants for humerus, radius, and tibia, but not femur. In general, the Postcontact Coalescent is characterized by slightly greater rates of increase with age and longer bone lengths for each age than is Extended Coalescent. Disorganized Coalescent exhibits lower rates of increase, particularly in later childhood, with shorter bone lengths in late childhood. Disorganized Coalescent also presents longer radius and humerus lengths than the other two variants in early childhood, an unexpected finding. This may be partly, but not entirely, explained by differential bone response to stress along the lines of maturity gradients.

Allometry between length and cross-sectional dimensions of the femur and tibia in Homo sapiens sapiens.

Abstract: Allometric equations relating length and cross-sectional geometric properties of the femur and tibia are generated using skeletal remains from three recent human population samples. Approximate isometry, or geometric similarity, is found both within and between samples. Cross-sectional areas scale to approximately length2, while second moments of area scale to approximately length4. It is shown that this is consistent with the maintenance of equivalent mechanical stress in long bones of different length under dynamic loadings in vivo. Other evidence indicates that bending and torsional loadings are more critical than axial loadings in the determination of lower limb bone cross-sectional dimensions.

Genetic correlations between sides and heritability of asymmetry for nonmetric traits in rhesus macaques on Cayo Santiago

Abstract: The use of nonmetric traits for estimation of biological distance is a long-standing practice in biological anthropology. Nonmetric traits can be scored using either the individual or the side of the individual as the unit of measure. If sides of the individual are genetically correlated the use of sides would produce redundant genetic information. For this reason, Korey (Am. J. Phys. Anthropol. 53:19–23, 1980) argues for the use of individuals as the unit of measure for nonmetric traits. Ossenberg (Am. J. Phys. Anthropol. 54:471–479, 1981), however, argues that bilateral occurrence of nonmetric traits indicates greater genetic liability for the trait and that therefore the sides are the more biologically correct unit of measure. Genetic correlations for 13 cranial nonmetric traits are estimated for a sample of rhesus macaque skeletons from Cayo Santiago. In addition, heritability of asymmetry is estimated for these 13 traits as a test of Ossenberg's contention that asymmetry is genetically influenced. Significant genetic correlations between sides support Korey's contention that nonmetric traits should be scored by individual. Only two asymmetry heritabilities were significantly different from zero, providing no significant support for Ossenberg's contention that asymmetry is genetically determined. Our results support the theory that asymmetry represents a measure of the ability of an organism to buffer stresses. Therefore, a measure of the heritability of asymmetry is a measure of the heritability of the ability to buffer stresses. This ability does not appear to be heritable in this sample.

Primate mating systems, kin associations, and cooperative behavior: Evidence for kin recognition?

Abstract: The degree to which cooperative behavior is kin-correlated in different primate species is reviewed. The mechanisms whereby individuals might recognize related conspecifics are also considered. Different mating systems, in conjunction with dispersal behavior, are hypothesized to produce particular patterns of kin association in primate groups. These patterns determine what classes of kin are likely to be distinguished, as well as which mechanisms of recognition would be predicted. Association or familiarity during development is concluded to be the most important mechanism of kin discrimination in the primates.

The Taung endocast and the lunate sulcus: a rejection of the hypothesis of its anterior position.

Abstract: Using an independent method of direct tape-arc measurements on six chimpanzee brain casts, it is shown that Falk's (1980, 1983) claims regarding an anterior pongidlike placement of a lunate sulcus on the Taung specimen remain unconfirmed Thus Holloway's (1981) stereoplotting method of testing Falk's hypothesis is independently confirmed, using the actual specimens rather than photographs of them Falk's (1980) placement of a lunate sulcus falls at least 25 standard deviations anterior to a position expected on the basis of a Pan location

Computerized X‐ray tomography of fossil hominid skulls

Abstract: The newest generation of Computerized Tomography (CT) scanners appears to provide x-ray pictures of the internal structures of a rather heavily mineralized Homo erectus skull, i.e., Pithecanthropus IV, notably of its temporal bones, that reveal more details than traditional x-ray procedures. An analysis of the right temporal bone shows that it is extensively pneumatized, that the oval shape of the external meatus does not result from fractures as previously suggested, and that the middle ear and the internal auditory meatus have probably been damaged during restoration. Labyrinthine structures can be seen, and the facial nerve canal appears to be of a relative small size.

Incisor size and diet revisited: The view from a platyrrhine perspective

Abstract: Allometric relationships between incisor size and body size were determined for 26 species of New World primates. While previous studies have suggested that the incisors of Old World primates, and anthropoids in general, scale isometrically with body size, the data presented here indicate a negative allometric relationship between incisor size and body size among New World species. This negative allometry was exhibited by platyrrhines when either upper or lower incisor row length was regressed against body weight, and when either least-squares or bivariate principal axis equations were used. When upper incisor length was plotted against skull length, negative allometry could be sustained using both statistical techniques only when the full sample of 26 species was plotted. The choice of variables to represent incisor size and body size, and the choice of a statistical technique to effect the allometric equation, had a more pronounced impact on the location of individual species with regard to lines of best fit. Platyrrhines as a group have smaller incisors relative to body size than do catarrhines, regardless of diet. Among New World primates, small incisors represent a plausible primitive condition; species with relatively large incisors manifest a phyletic change associated with a dietary shift to foods that require increased incisal preparation. The opposite trend characterizes Old World primates. In spite of the taxonomic differences in relative incisor size between platyrrhine and catarrhine primates, inferences about diet derived from an allometric equation for all anthropoids should prove reliable as long as the species with unknown diet does not lie at the upper end of the body size range for platyrrhines or catarrhines.