Showing papers in "American Journal of Physical Anthropology in 1987"

Late Pleistocene and Holocene population history of east Asia based on dental variation

Abstract: The purpose of this communication is to provide a summary description and analysis of 28 dental traits studied in a number of skeletal samples that originated in eastern Asia. The objectives of the analysis are to define the nature of Mongoloid dental variation, use it to measure Asian intergroup relationships, and develop in greater detail and with larger samples a dental anthropological model of the late Pleistocene and Holocene population history of eastern Asia.

Loading patterns and jaw movements during mastication in Macaca fascicularis: a bone-strain, electromyographic, and cineradiographic analysis.

Abstract: Rosette strain gage, electromyography (EMG), and cineradiographic techniques were used to analyze loading patterns and jaw movements during mastication in Macaca fascicularis. The cineradiographic data indicate that macaques generally swallow frequently throughout a chewing sequence, and these swallows are intercalated into a chewing cycle towards the end of a power stroke. The bone strain and jaw movement data indicate that during vigorous mastication the transition between fast close and the power stroke is correlated with a sharp increase in masticatory force, and they also show that in most instances the jaws of macaques are maximally loaded prior to maximum intercuspation, i.e. during phase I (buccal phase) occlusal movements. Moreover, these data indicate that loads during phase II (lingual phase) occlusal movements are ordinarily relatively small. The bone strain data also suggest that the duration of unloading of the jaw during the power stroke of mastication is largely a function of the relaxation time of the jaw adductors. This interpretation is based on the finding that the duration from 100% peak strain to 50% peak strain during unloading closely approximates the half-relaxation time of whole adductor jaw muscles of macaques. The EMG data of the masseter and medial pterygoid muscles have important implications for understanding both the biomechanics of the power stroke and the external forces responsible for the "wishboning" effect that takes place along the mandibular symphysis and corpus during the power stroke of mastication. Although both medial pterygoid muscles reach maximum EMG activity during the power stroke, the activity of the working-side medial pterygoid peaks after the balancing-side medial pterygoid. Associated with the simultaneous increase of force of the working-side medial pterygoid and the decrease of force of the balancing-side medial pterygoid is the persistently high level of EMG activity of the balancing-side deep masseter (posterior portion). This pattern is of considerable significance because the direction of force of both the working-side medial pterygoid and the balancing-side deep masseter are well aligned to aid in driving the working-side lower molars across the upper molars in the medial direction during unilateral mastication.(ABSTRACT TRUNCATED AT 400 WORDS)

Talocrural joint in african hominoids implications for australopithecus afarensis

Abstract: Talocrural joints of the African apes, modern humans, and A.L.288-1 are compared in order to investigate ankle function in the Hadar hominids. Comparisons between the hominids and African pongids clearly illustrate the anatomical and mechanical changes that occurred in this joint as a consequence of the evolutionary transition to habitual bipedality. Features which are considered include the obliquity of the distal tibial articular surface, the shape of the talar trochlea, and the location and functional implications of the talocrural axis. In every functionally significant feature examined the A.L.288-1 talocrural joint is fully bipedal. Moreover, the Hadar ankle complex also shows the functional constraints which are necessarily imposed by the adaptation to habitual bipedalism.

Hominid footprints at Laetoli: facts and interpretations.

Abstract: The history of discovery and interpretation of primate footprints at the site of Laetoli in northern Tanzania is reviewed. An analysis of the geological context of these tracks is provided. The hominid tracks in Tuff 7 at Site G in the Garusi River Valley demonstrate bipedality at a mid-Pliocene datum. Comparison of these tracks and the Hadar hominid foot fossils by Tuttle has led him to conclude that Australopithecus afarensis did not make the Tanzanian prints and that a more derived form of hominid is therefore indicated at Laetoli. An alternative interpretation has been offered by Stern and Susman who posit a conforming "transitional morphology" in both the Tanzanian prints and the Ethiopian bones. The present examines both hypotheses and shows that neither is likely to be entirely correct. To illustrate this point, a reconstruction of the foot skeleton of a female A. afarensis is undertaken, and the results are compared to the Laetoli tracks. We conclude that A. afarensis represents the best candidate for the maker of the Laetoli hominid trails.

Prevalence and age at development of enamel hypoplasias in Mexican children.

Abstract: Enamel hypoplasias, deficiencies in enamel thickness resulting from disturbances during the secretory phase of enamel development, are generally believed to result from nonspecific metabolic and nutritional disruptions. However, data are scarce on the prevalence and chronological distribution of hypoplasias in populations experiencing mild to moderate malnutrition. The purpose of this article is to present baseline data on the prevalences and chronological distributions of enamel hypoplasias, by sex and for all deciduous and permanent anterior teeth, in 300 5 to 15-year-old rural Mexican children. Identification of hypoplasias was aided by comparison to a published standard (Federation Dentaire Internationale: Int. Dent. J. 32(2):159−167, 1982). The location of defects, by transverse sixths of tooth crowns, was used to construct distributions of defects by age at development. One or more hypoplasias were detected in 46.7% (95% CI= 40.9−52.5%) of children. Among the unworn and completely erupted teeth, the highest prevalence of defects was found on the permanent maxillary central incisors (44.4% with one or more hypoplasias), followed by the permanent maxillary canine (28.0%) and the remaining permanent teeth (26.2 to 22.2%) Only 6.1% of the completely erupted and unworn deciduous teeth were hypoplastic. The prevalence of enamel defects on the permanent teeth was up to tenfold greater than that found in studies of less marginal populations that used the FDI method. The prevalence of defects in transverse zones suggests a peak frequency of hypoplasias during the second and third years for the permanent teeth, corresponding to the age at weaning in this group. In the deciduous teeth, a smaller peak occurs between 30 and 40 weeks post gestation. The frequency of defects after three years of age is slightly higher in females than males, suggesting a sex difference in access to critical resources.

Porotic hyperostosis: new evidence to support the anemia theory.

Abstract: The etiology of skull lesions known as porotic hyperostosis has long been a matter for speculation. The most widely accepted theory at present suggests that an anemia, either acquired or genetic, is responsible for lesion development. However, acceptance of this theory is not universal and the nature of the relationship between orbital and vault lesions remains a controversial issue. This paper provides a much broader field of supportive evidence on which to base the anemia theory. This involves a synthesis of information from the clinical and anthropological literature as well as new data from two skeletal collections: Poundbury Camp, a Romano-British series, and the Hodgson collection, a 19th century East Asian series. A comparison is made between clinical and anthropological data at the macroscopic, microscopic, radiographic, and demographic levels of analysis. This approach reveals the similarities in expression between clinically diagnosed anemias and porotic hyperostosis.

Life stresses of the free black community as represented by the First African Baptist Church, Philadelphia, 1823-1841.

Abstract: The congregation of the Reverend Henry Simmons (First African Baptist Church at 8th & Vine, Philadelphia) from 1823 to 1841 used a cemetery rediscovered through subway expansion which was carefully excavated by M. Parrington and S. Pinter in 1983–1984; currently 75 adults were available for study. As an overall health indicator, longevity at 38.9 years (N=39) female and 44.8 (N=36) male indicates more stress on females. Probable causes of stress are inadequate nutrition for the performance of arduous labor, pregnancy, and childrearing, unsanitary living conditions, limited exposure to sun, and extensive exposure to infectious diseases. Nutritional indicators of stature, dental lesions, skull base height, and pelvic brim index scarcely advance over 1790–1820 Catoctin Furnace, Maryland, slaves' indicators. Disease evidence includes limb-distorting rickets in one child who died at age 8, anemia, and arthritis; but the incidence of arthritis was less than at Catoctin. Genetic traits are chiefly. African. Family links show in details: os acromiale in about 30%. This plus less violence (fewer fractures) suggests community strength developing.

Kebara 2 Neanderthal pelvis: first look at a complete inlet.

Abstract: The renewed excavations at the Kebara Cave revealed a Neanderthal skeleton dated at about 50-55,000 years B.P. The pelvis of this individual is the most intact Neanderthal pelvis yet discovered, presenting for the first time a complete inlet. Although the superior pubic ramus is extremely long, as typically seen in the Neanderthals, the size of the pelvic inlet is comparable to that of modern Homo sapiens. The length of the superior pubic ramus is found to stem from a more externally rotated innominate bone and not, as generally assumed, from the larger pelvic inlet. It is suggested that the uniqueness of the Neanderthal pelvis may be attributable to locomotion and posture-related biomechanics rather than to obstetric requirements.

Genetics and history of sub‐Saharan Africa

Abstract: This paper aims to review the contribution of genetic data to the prehistory and history of sub·Saharan African peoples. The authors review briefly paleontologic data, which give limited information about modern Homo sapiens sapiens origins and isolation of present African gene pools. Most linguistic and archaeological theories about African peoples'prehistory are then confronted with the most informative genetic data available. Rhesus, Gm, HLA, and DNA data are analyzed. Their frequent haplotypes are compared between populations by means of genetic distances and average linkage clustering. Despite heterogeneities between the quality and the quantity of data provided by different genetic systems, some clear conclusions can be drawn. Genetic differentiation clearly paranels the clustering of major linguistic families. These families of populations seem genetically homogeneous, suggesting either relatively recent origins or long-term important and continuous intragroup migrations. The well-known divergence between the historical theories suggested by immunological and DNA data about the relationship between Africa and other gene pools is discussed. Decisive conclusions about African origins of modern humans either from fossil or from DNA data seem very premature. An alternative hypothesis issued from overall genetic variation is proposed.

Diagnosis and Differentiation of the Order Primates

Abstract: We contrast our approach to a phylogenetic diagnosis of the order Primates, and its various supraspecific taxa, with definitional proce- dures. The order, which we divide into the semiorders Paromomyiformes and Euprimates, is clearly diagnosable on the basis of well-corroborated informa- tion from the fossil record. Lists of derived features which we hypothesize to have been fixed in the first representative species of the Primates, Eupri- mates, Strepsirhini, Haplorhini, and Anthropoidea, are presented. Our clas- sification of the order includes both holophyletic and paraphyletic groups, depending on the nature of the available evidence. We discuss in detail the problematic evidence of the basicranium in Paleo- gene primates and present new evidence for the resolution of previously controversial interpretations. We renew and expand our emphasis on postcra- nial analysis of fossil and living primates to show the importance of under- standing their evolutionary morphology and subsequent to this their use for understanding taxon phylogeny. We reject the much advocated %ladograms first, phylogeny next, and scenario third" approach which maintains that biologically founded character analysis, i.e., functional-adaptive analysis and paleontology, is irrelevant to genealogy hypotheses. Unlike the cladistic rules of operations demand, we advocate and use a priori weighting of characters. We discuss the evidence for the various proposed relationships of the earli- est euprimates, the Adapidae and Omomyidae, and show that linking the former with living Strepsirhini and the latter with living Haplorhini does not depend on the assumption of the presence of soft-anatomical characters in the fossils. On the contrary, it is the sharing of derived hard anatomical features of the fossil taxa with the living groups which makes their possession of either strepsirhine or haplorhine "soft" attributes probable. We discuss the relative merits of the use of the grade concept (with its widely recognized implication of polyphyly) in attempts to group primates and maintain that there exists no evidence for either an "archaic primate" or a prosimian or an anthropoid grade. All the characters in the literature attributed to these are inherited from the first representatives of either the semiorder Paromomyiformes or the semiorder Euprimates or the semisubor- der Anthropoidea. Consequently, we find neither descriptive nor didactic merit in gradal arrangements, the goals of which can be much better served by a phylogenetic (not cladistic) classification.

Life stresses of slavery

Abstract: Skeletal evidence exists for life stresses of 120 Black individuals from 25 sites in Maryland, Virginia, and the Carolinas. Periods for statistical comparison are eighteenth century, 1690-1770; Catoctin Furnace, Maryland industrial slaves, 1790-ca.1820; 1800-ca.1860, nineteenth century; and a twentieth-century Black sample compiled from forensic (accidental deaths) cases. From these archaeological sources, skeletal age at death shifts from 36 years, female, and 30 years, male in eighteenth century (N = 29) to 34.8, female, and 36.3, male in nineteenth century (N = 56). Catoctin Furnace slaves' longevity may reflect special conditions for skilled males (34.6 years, female; 41.2 years, male (N = 16). Nutritional stresses are indicated by dental lesions, hypoplasias, stature, and skull base height and pelvic brim index. Occupational stress occurs in some adolescents and in many adults as exaggerated development of lifting muscles (deltoid and pectoral crests) and early vertebral and shoulder breakdown. Lead content of bone may reflect site of occupation. The most common pathology is anemia or sicklemia; parietal depressions and ulna fractures ("parry") indicate violence-related trauma.

Health and disease at a South Carolina plantation: 1840-1870.

Abstract: The analysis of 36 human skeletons (eight subadults, 13 males, 15 females) recovered during a cemetery relocation near Charleston, SC, provides data on health and disease for a 19th-century sample of Afro-Americans. The majority of the burials date from 1840-1870. Skeletal analysis verified some historical interpretations. Gender differential in mortality is evident with average age at death for males 35 and females 40 years. Females, besides living longer, had more missing and carious teeth but fewer abscesses. Both genders expressed childhood metabolic stress as indicated by linear enamel hypoplasias. Males, however, had a higher incidence (92%) than did females (70%). Age at occurrence was more widely distributed for females, but ages 2-4 were most critical for both genders. Postcranial indications of recovery from acute stress, Harris lines, occurred more frequently for males (45%) than for females (18%). Anemia, probably both genetic and acquired, was a significant health problem for both genders. Cribra orbitalia appeared in 35% of the adult crania, and 80% of the subadults had orbital lesions. Diplotic expansion of the cranial vault and infection were relatively common in the sample. Skeletal reaction to infections appeared in 69% of the males, 60% of the females, and 80% of the subadults. Skeletal changes associated with demanding physical labor were ubiquitous. The shoulder and hip were especially affected by degenerative changes, the cervical vertebrae frequently expressed osteophytosis, and males show a preponderance of Schmorl herniations and hypertrophy of the ulnar supinator crest. Skeletal trace elements indicate a relatively high exposure to lead, strontium concentrations indicative of a diet high in plant foods, and relatively low zinc and copper concentrations.

Brain lateralization in primates and its evolution in hominids

Abstract: Recent studies suggest that vocal communication and visuospatial processing are lateralized to left and right hemispheres respectively in monkeys of the genus Macaca, as they are in humans. The fundamental neurological substrate that forms the basis for complex cerebral asymmetries in Homo sapiens may therefore have been established remarkably early in anthropoid evolution. The tendency toward cortical lateralization has been greatly elaborated in human evolution, such that at least 90% of extant humans are right-handed. Numerous data support an association of the left human hemisphere with time-sequencing, language skills, certain neurochemical asymmetries, and specific psychiatric disorders. The right hemisphere, on the other hand, is associated with holistic processing, visuospatial and musical abilities, emotional processing, and its own neurochemical and psychiatric properties. Although a controversial topic, there appears to be slight but significant sexual dimorphism in certain skills associated with cortical lateralization in humans. Females excel at language and fine motor skills, as well as emotional decoding and expression; males are relatively adept at composing music and exhibit visuospatial and mathematical skills. Various scenarios that account for these differences are reviewed, and it is concluded that dimorphism in these behaviors may be due in part to hormonal priming involved in prenatal gender differentiation.

Demography and pathology of an urban slave population from New Orleans.

Abstract: Twenty-nine skeletons from the first cemetery in New Orleans provide significant new information about urban slavery in America. Dating as early as 1720 and used perhaps as late as 1810, the cemetery provided an identifiable sample of two whites, 13 blacks, one individual of possible Indian-white ancestry, and two possibly mulatto individuals. Numerous skeletal and dental lesions were noted in the series, and historical information was used in conjunction with the physical data to draw conclusions about rates and patterns of mortality. Pathological changes indicate that the cemetery contained individuals representing two slave occupational groups, house servants and laborers. This research provides information in the expanding area of Afro-American biohistorical research.

Nut-like oil seeds: food for monkeys, chimpanzees, humans, and probably ape-men.

Abstract: The hypothetical hyperrobust australopithecine gnathic nutcracker adaptation is reexamined in light of ecobotanical information on edible wild nuts provided by the flora of tropical and subtropical Africa. The nut producing species are tree-forms. Those of the forest region do not as a rule produce fruits with edible mesocarps. In contrast, the woodland savanna species (particularly in the Zambezian region) characteristically provide an important whole fruit, i.e., a nutritious mesocarp in addition to edible oil-rich nut seeds. These fruits drop from the tree before they are fully mature and go through the final ripening phase on the ground. They are important seasonal foods for a variety of vertebrates, including primates, elephants, and antelope. Altogether the nuts exhibit a broad range of toughness values, measured here as strength under compression. The woodland nuts are not as tough (177–934 kg force, breaking load) as those of the tropical forest (192–1,673 kg force). The seed-predators of the woodland species include squirrels, baboons, warthogs, and parrots. Paleoecological analyses indicate that it was the woodland nuts that were probably available to Australopithecus boisei and A. robustus. Preliminary estimates of adult male gnathic nut-cracking capabilities suggest that A. boisei could have orally cracked a significant portion of the woodland nuts. In spite of this, ecobotanical data indicate that we can probably reject the hypothesis that these hominids were year-round gnathic nut-cracking specialists. Both the indirect and direct evidence support this conclusion.

Evidence of spinal tuberculosis at the beginning of the fourth millennium BC from Arene Candide cave (Liguria, Italy).

Abstract: This paper describes tuberculosislike lesions affecting the spine of Neolithic skeleton found in Arene Candide cave (Liguria, Italy) and representing one of the earliest cases of this disease in Europe. The burial is attributed to middle Neolithic (square-mouthed pottery culture) whose layers date, by 14C, to the first half of the fourth millennium BC. The skeleton, well preserved in the postcranial portion, belongs to a male aged about 15 years having a very light body build. Resorptive lesions localized to the lower thoracic and upper lumbar vertebral bodies, collapse and angular kyphosis, resulting from complete destruction of T11 and T12 and partial destruction of T10 and L1, are the main pathologic features. The morphology of the lesions, sites involved, and age of the specimen are consistent with a diagnosis of tuberculous spondylitis (Pott's disease). The extreme gracility of the skeleton, along with other signs of stress (Harris lines, enamel hypoplasia) suffered during the last years of life, and the limited bony regeneration point to a disease process in its late phase having arisen at the beginning of adolescence. The funerary ritual suggests that the social integration of this adolescent was not prevented by the severe infirmity.

Evolution of the lumbosacral angle

Abstract: The lumbosacral angle (LSA) was studied in 131 children ranging in age from birth to 5 years. This angle increases from an average of 20 degrees at birth to an average of 70 degrees at the age of 5 years; it remains at that level thereafter. This study demonstrates that the formation of the LSA is not related to increasing age, height, or weight. Nor do obstetrical requirements seems to play any major role in the formation of the lumbosacral angle. Rather, it appears that the development of the LSA is related to the progressive acquisition of erect posture and the ontogeny of bipedal locomotion. This angle is almost nil in the nonprimate mammals (who only infrequently stand erect). It is minimal in monkeys who occasionally assume bipedal postures and increases somewhat in living apes who engage in facultative bipedal positional behavior. In the early australopithecines, the LSA is increased over that in apes, and it reaches its maximum in Homo sapiens. Deviations from normal and healthy erect posture in Homo sapiens result in corresponding changes in the lumbosacral angle. Lumbar and sacral angles (both forming the lumbosacral angle) are almost equal in all mammalian species. Since the sacral angle of Australopithecus afarensis is approximately 15 degrees, it can be implied that its lumbosacral angle was small, thus attesting to its "imperfect" erect posture and "primitive" form of bipedal locomotion.

Retromolar foramen of the human mandible

Abstract: Analysis of retromolar foramen (RMF) in a large series of mandibles (N 2500) was undertaken to provide descriptive statistics for this variant. RMF of diameter 0.5 mm or greater were scored. Consistent with other data on accessory canals in the facial skeleton, RMF was found to occur more commonly in native populations of North America than in other populations (Africa, Europe, India, northeast Asia). The ratio of bilateral to unilateral occurrences was shown to increase with population incidence, a pattern consistent with the theoretical model of an epigenetic (threshold "quasicontinuous") variant. Male-female differences were not found. Age profiles were characterized by a marked peak in the adolescent cohort. In some populations RMF showed a positive intertrait correlation with accessory mandibular foramen and with accessory mental foramen, but correlations with presence/absence of third molar and three-rooted first molar were not found. With refinements in scoring criteria and, ideally, better evidence of its heritability, RMF should be useful along with other minor cranial variants for ethnohistorical studies.

Body weights of wild chimpanzees (Pan troglodytes schweinfurthii) of the Mahale Mountains National Park, Tanzania.

Abstract: Ten male and nine female habituated chimpanzees (Pan troglodytes schweinfurthii) in the Kasoje area of the Mahale Mountains National Park, Tanzania, were weighed intermittently between December 1973 and March 1980 by luring them up a rope hung on a spring balance: six adult males averaged 42.0 kg and eight adult females 35.2 kg. Seasonal change in body weight was recognized at least partially; body weights tended to decrease in the later part of the wet season presumably because of food shortage in the middle of the wet season. Comparison of body weight among three populations of the same subspecies suggests that adult female chimpanzees of Mahale appear to be heavier than those of the Gombe National Park, Tanzania, and that they seem to be similar to the forest-living counterparts of eastern Zaire. On the other hand, body weights of adult male chimpanzees from the three populations do not show significant differences. Perhaps feeding competition among adult females in a small, isolated habitat is more severe than that among adult males, which may result in the body weight reduction among adult female chimpanzees at Gombe.

Stride length and its determinants in humans, early hominids, primates, and mammals.

Abstract: Primate stride lengths during quadrupedal locomotion are very long when compared to those of nonprimate quadrupedal mammals at the speed of trot/gallop transition. These exceptional lengths are a consequence of the relatively long limbs of primates and the large angular excursions of their limbs during quadrupedalism. When quadrupedal primates employ bipedal gaits they exhibit much lower angular excursions. Consequently their bipedal stride lengths do not appear to be exceptional in length when compared to other mammals. Angular excursions of the lower limbs of modern humans are not exceptionally large. However, when running, humans exhibit relatively long periods of flight (i.e., they have low duty factors) when compared to other mammals including primates. Because of these long periods of flight and their relative long lower limbs, humans have running stride lengths that are at the lower end of the range of stride lengths of quadrupedal primates. The stride length of the Laetoli hominid trails are evaluated in this context.

Interaction of nutritional and socioeconomic status as determinants of cognitive development in disadvantaged urban Guatemalan children.

Abstract: The relationship between nutritional status, measured by height for age, and cognition, measured by WISC full-scale IQ, was studied in a longitudinal sample of 459 urban Guatemalan children, aged 4–9 years, from a disadvantaged community of the fringe of Guatemala City, examined annually over a 3 year period. Socioeconomic status (SES) was controlled by developing a composite index for each home. The mean IQ differed significantly from the lowest to the highest quartiles of stature, the difference between the two extreme quartiles being approximately 0.3 SD of IQ. There was a significant interaction between SES and stature in their effects on IQ. Whereas nutritional status and SES affected IQ in an additive fashion in the upper three SES quartiles, there was no difference in IQ attributible to stature among children from the most disadvantaged homes. This analysis indicates that the mild-to-moderate protein-energy malnutrition (defined by height for age) that is prevalent among children from disadvantaged environments in developing countries is significantly related to cognitive development. However, in the poorest homes, SES is seen as a more important determinant of cognitive development than stature.

Effects of sexual dimorphism in body size on feeding postural behavior of Sumatran orangutans (Pongo pygmaeus)

Abstract: Male orangutans (Pongo pygmaeus) weigh about twice as much as females. Observations in northern Sumatra of adults of both sexes (one male, three females) feeding in the same trees reveal the effects of body size dimorphism on feeding behavior: The male tended to use larger branches than the females, and to employ above-branch postures (sitting and standing) with greater frequency. The females employed suspensory under-branch postures more often. When feeding techniques were variable, the male tended to pull in branches to detach food with the mouth, whereas the female plucked more fruit by hand. By controlling for postcranial morphology and habitat structure, these results provide the first rigorous quantitative test of predictions about the effects of body size on primate positional behavior, and raise further questions about sexual diethism in feeding postural behavior of primates of varying absolute size.

Evolution of the sacrum in hominoids.

Abstract: In order to study the formation of the sacrum during the primate evolution, a new way of numbering mammalian vertebrae is presented; this demonstrates that the thoracolumbosacral complex is fixed at 22 vertebrae in 80% and at 22 +/- 1 in 100% of the cases. The shift of a vertebra from one type to another occurs either at the thoracolumbar or at the lumbosacral junction and not at the cervicothoracic junction. Rarely does the shift take place at the sacrococcygeal junction. Data from 318 primates reveal that the seven original lumbar vertebrae of the Old World monkeys are reduced in the great apes by a caudad "thoracization" of one to two lumbar vertebrae and a cephalad sacralization of one to four lumbar vertebrae. In the apes, sacralization is not total and different stages that are intermediate between lumbar and sacral are described. In Homo sapiens there is a total sacralization of the last two original lumbar vertebrae. In addition, development of the sacral wings (alae) is minimal in apes and reaches its maximum in hominids. The tendency of the hominoid sacrum to incorporate the last lumbar vertebrae and to widen markedly provides for an enhanced articulation of the sacrum with the ilium and offers a firm base of support for the trunk during erect posture. This is necessary for the support of the weight of the trunk above the sacrum and for the stabilization of the body during bipedal posture and locomotion. Encephalization did not play any major role in the widening of the sacrum since the former by far preceded the latter.

Relative reliability of circumferences and skinfolds as measures of body fat distribution

Abstract: The question has arisen whether patterns of body fat distribution can be identified by body circumferences, a method which is said to be more reliable and simpler than skinfold thickness or like measures of subcutaneous fat (Ashwell et al., Int. J. Obes. 6: 143-152, 1982). Here we address the question of whether body circumferences are inherently more reliable than skinfold thicknesses in 77 intra- and 224 interexaminer replicates from the Health Examination Survey of 12 to 17-year-olds in the U.S.A. Reliability of six body circumferences (0.96) was significantly (P less than .01) higher than that of skinfold thicknesses at five sites (0.91), suggesting that circumferences are a more reliable method. However, the reliability of skinfolds is still high, and skinfolds may be used in studies which focus on preadults or other groups in which the validity of circumferences as measures of body fat distribution is unknown.

Mortuary practices at the Krapina Neandertal site

Abstract: It has often been reported that the Krapina Neandertal remains bear incised linear striations which appear to be cutmarks. Here, the plausibility of the striations as cutmarks is tested by comparing them to Mousterian butchery marks on large fauna and to cutmarks on modern human skeletons known to have been defleshed with stone tools. The anatomical location, gross appearance, and frequency of occurrence of the striations on the Krapina material do not resemble Mousterian butchery marks on reindeer. The Krapina striations do closely match authenticated cutmarks on 22 modern human skeletons defleshed with stone tools after partial decomposition, preparatory to secondary burial. Data are presented supporting the hypothesis that the striations on the Krapina Neandertal remains are consistent with postmortem processing of corpses with stone tools, probably in preparation for burial of cleaned bones.

Artificial grooves on the Krapina Neanderthal teeth.

Abstract: Gross and microscopic examination of the Krapina Neanderthal dental remains reveals the presence of artificial grooves along the cemento-enamel junction of 14 teeth representing ten different individuals. The grooves display distinct morphological features including their consistent location (primarily on the mesial and/or distal root walls), their troughlike appearance, striations and/or polishing in the channel, and the ridges of reactive cementum bordering the groove. These grooves occur only on erupted, permanent teeth, and except for a single occurrence on a lower I2, all are located on mandibular or maxillary P4-M3. The morphological nature of the grooves is distinct and has been used to distinguish these grooves from root caries and other pathological or natural causes. Based on the close resemblance between artificial grooves at Krapina and those which have been attributed to toothpick use in other fossil and recent populations, we argue the Krapina Neanderthals were habitually probing the interproximal dental spaces with tools.

A radiographic study of porotic hyperostosis.

Abstract: Skull lesions known as porotic hyperostosis have been of interest to researchers since the mid-19th century. The etiology of porotic hyperostosis has long been a matter for speculation yet there has never been complete acceptance or substantiation of any one of the many theories proposed. Today the most widely accepted theory suggests that anemias of either acquired or genetic origin are responsible for porotic hyperostosis. The present study tests this hypothesis using criteria which were chosen after the examination of clinical radiographs of patients with various types of anemia. These criteria are: the presence of "hair-on-end" trabeculation, outer table thinning, texture changes, diploic thickening, orbital roof thickening, orbital rim changes, and the underdevelopment of frontal sinuses. A comparison of these criteria from the clinical X-rays with X-rays of skulls with porotic hyperostosis provides a more rigorous, repeatable, and standardized method upon which to base a diagnosis. This approach enables radiography to provide the necessary link between the clinical and anthropological with which to investigate the origin of porotic hyperostosis.

Shape in morphometrics: Comparative analyses

Abstract: Comparative morphology has long been vexed by conflicting considerations of size and shape (relative size); a subsidiary consideration has been the effect of allometry (shape change with size) on results and interpretations. A review of history and opinion indicates the lack of universal acceptance of the following points: the inherent relatedness and/or separability of size and shape; the greater importance (anatomically, functionally, and/or taxonomically) of shape than size; the existence of residual size effects (allometry) after canceling the gross linear size factor from morphometric data; the failure of covariance matrix inversion to negate size always; the dimensionless quality of shape variables; the effect of logarithmic transformation; and the inadvisability of simple ratios. Two morphometric data sets (primate postcranial proportions, hominoid maxillary premolar odontometrics) encompassing significant size and taxonomic diversity in primates enable illustration and examination of these points. Although determination of optimum procedures is problematic, accuracy of classification and partition of variance among known morphogroups are criteria that can be applied. Intergroup distances generated after inversion of the covariance matrix show little improvement over raw size distances, unlike the shape distances expressed by shape vector (ratio), double-centered, Penrose, common part removed, and Q-mode correlation methods; very slight further improvement is accomplished using pooled within-group adjustment to remove residual size (allometric) effects. No improvement emanates solely from log transformation of measurements. Significant problems are indicated by the results obtained with interspecific regression residuals: particularly, large and small forms in the analysis become unrealistically similar. Also, regression-corrected distances still correlate with size even though the univariate residual values, by definition, do not.

Relationship between the mandibular condyle and the occlusal plane during hominid evolution: Some of its effects on jaw mechanics

Abstract: A selection of mandibles from recent higher primates, fossil hominids, and hominoids has been studied from photographs of skulls, reproductions, and material published by others, all viewed in the sagittal plane. Tracings of each mandible were constructed so that the dentitions were all scaled to the same length (d) and superimposed. The (scaled) positions of the articular surfaces of the condyles (J = joint point) were compared. The height of each J point above the scaled dentition (h = effective condyle height) and its distance behind the dentition (r = effective ramus width) were compared. With very few exceptions d greater than r greater than d/2. There was a poor correlation between r and the amount of prognathism. The position of the J point with respect to the occlusal plane was different for different groups within the material analysed and could prove to be a useful tool to help improve the reconstruction of fragmented fossil material. Some examples are given. A. afarensis and Homo habilis shared a low and anterior J point (r approximately d/2). The later australopithecines evolved a high and anterior J point, whereas that of Homo erectus was raised and displaced posteriorly (r approximately 3d/4). The value of r was increased to d in the Neanderthals, and recent man has moved the J point forward again. The effect of the position of the J point, the slope of the preglenoid plane, and the curve of Spee on the relationship between upper and lower postcanines when the jaw is opened and then closed to process food have been analysed. The results show that the position of the J point affects the way in which the mandible moves, and this may be related to changes in diet during evolution.

Short and plump physique of Mexican-American children.

Abstract: Mexican-American children are shorter but relatively heavier than non-Hispanic whites and blacks. The objectives of this paper are to assess the extent to which this "short and plump" physique occurs in data collected in two national surveys (HANES I and II); to determine variations by age, sex, and socioeconomic status; and to investigate the anthropometric characteristics that may account for the overweight. Three groups, defined on the basis of reported ancestry and observed race, are studied: Mexican-Americans (MEXAME), non-Hispanic Whites, (EURAME), and blacks (BLACK). Short stature was clearly associated with the poverty index (PI) in all three groups. MEXAMEs with a PI greater than 1.6 were similar in stature to EURAMEs at the same income level at ages 1-11 years but not at 12-17 years. On the other hand, MEXAMEs were shorter than BLACKs at all ages and income levels. The body mass index (kg/cm2) and poverty were unrelated. With respect to the anthropometric characteristics examined that are related to the body mass index, MEXAMEs and EURAMEs were similar in sitting height as a proportion of total height, arm muscle and fat areas, and triceps skinfold but different in the following ways: MEXAMEs had narrower elbow but broader bitrochanteric breadths and larger chest circumferences and subscapular skinfolds. Greater upper body dimensions and fatfolds seem to best describe the physique of MEXAMEs. However, in multiple regressions, these anthropometric characteristics failed to account fully for the greater relative weight of MEXAMEs as compared to EURAMEs.