recent journal articles: anthropology


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Recent Articles in Journal of Human Evolution

Rae TC
Paranasal pneumatization in extant and fossil Cercopithecoidea.
J Hum Evol. 2007 Dec 6;
Unlike most primates, extant cercopithecoids lack maxillary sinuses, which are pneumatic spaces in the facial skeleton lateral of the nasal cavity proper. Character state analysis of living cercopithecoids across well-supported topologies suggests that the sinus was lost at the origin of the superfamily, only to have evolved again convergently in extant macaques. Recent work has shown that a) the 'early loss' hypothesis is supported by the lack of any pneumatization in Victoriapithecus, a stem cercopithecoid, b) like extant macaques, the fossil cercopithecine Paradolichopithecus shows evidence of presence of the maxillary sinus (MS), and c) unlike extant colobines, the fossil colobine Libypithecus also possesses a maxillary sinus. To more fully assess the pattern of cercopithecoid sinus evolution, fossil taxa from both subfamilies (Colobinae, Cercopithecinae) were examined both visually and by computed tomography (CT). The observations were evaluated according to standard anatomical criteria for defining sinus spaces, and compared with data from all extant Old World monkey genera. Most taxa examined conformed to the pattern already discerned from extant cercopithecoids. Maxillary sinus absence in Theropithecus oswaldi, Mesopithecus, and Rhinocolobus is typical for all extant cercopithecids except Macaca. The fossil macaque Macaca majori possesses a well-developed maxillary sinus, as do all living species of the genus. Cercopithecoides, on the other hand, differs from all extant colobines in possessing a maxillary sinus. Thus, paranasal pneumatization has reemerged a minimum of two and possibly three times in cercopithecoids. The results suggest that maxillary sinus absence in cercopithecoids is due to suppression, rather than complete loss. [Abstract]

Barrickman NL, Bastian ML, Isler K, van Schaik CP
Life history costs and benefits of encephalization: a comparative test using data from long-term studies of primates in the wild.
J Hum Evol. 2007 Dec 6;
The correlation between brain size and life history has been investigated in many previous studies, and several viable explanations have been proposed. However, the results of these studies are often at odds, causing uncertainties about whether these two character complexes underwent correlated evolution. These disparities could arise from the mixture of wild and captive values in the datasets, potentially obscuring real relationships, and from differences in the methods of controlling for phylogenetic non independence of species values. This paper seeks to resolve these difficulties by (1) proposing an overarching hypothesis that encompasses many of the previously proposed hypotheses, and (2) testing the predictions of this hypothesis using rigorously compiled data and utilizing multiple methods of analysis. We hypothesize that the adaptive benefit of increased encephalization is an increase in reproductive lifespan or efficiency, which must be sufficient to outweigh the costs due to growing and maturing the larger brain. These costs and benefits are directly reflected in the length of life history stages. We tested this hypothesis on a wide range of primate species. Our results demonstrate that encephalization is significantly correlated with prolongation of all stages of developmental life history except the lactational period, and is significantly correlated with an extension of the reproductive lifespan. These results support the contention that the link between brain size and life history is caused by a balance between the costs of growing a brain and the survival benefits the brain provides. Thus, our results suggest that the evolution of prolonged life history during human evolution is caused by increased encephalization. [Abstract]

Lemelin P, Hamrick MW, Richmond BG, Godfrey LR, Jungers WL, Burney DA
New hand bones of Hadropithecus stenognathus: implications for the paleobiology of the Archaeolemuridae.
J Hum Evol. 2007 Dec 6;
A partial, associated skeleton of Hadropithecus stenognathus (AHA-I) was discovered in 2003 at Andrahomana Cave in southeastern Madagascar. Among the postcranial elements found were the first hand bones (right scaphoid, right hamate, left first metacarpal, and right and left fifth metacarpals) attributed to this rare subfossil lemur. These hand bones were compared to those of extant strepsirrhines and catarrhines in order to infer the positional adaptations of Hadropithecus, and they were compared to those of Archaeolemur in order to assess variation in hand morphology among archaeolemurids. The scaphoid tubercle does not project palmarly as in suspensory and climbing taxa, and the hamate has no hook at all (just a small tubercle), which also points to a poorly developed carpal tunnel. There is a distinctive, radioulnarly directed "spiral" facet for articulation with the triquetrum that is most similar in orientation to that of more terrestrial primates (i.e., Lemur catta, Papio, and Gorilla). The first metacarpal is very reduced and represents only 48% of the length of metacarpal V, as in Archaeolemur, which suggests that pollical grasping of arboreal supports was not important. Compared to Archaeolemur, the shaft of metacarpal V is gracile, and the head has no dorsal ridge and lacks characteristics functionally associated with digitigrade, extended metacarpophalangeal joint postures. Proximally, the articular facet for the hamate is oriented more dorsally. Thus, the carpometacarpal joint V appears to have a distinctive hyperextended set, which has no analog among living or extinct primates. The carpals of Hadropithecus are diagnostic of a pronograde, arboreal and terrestrial (although not digitigrade) locomotor repertoire that typifies Lemur catta and some Old World monkeys. No clinging, suspensory, or climbing specializations that characterize indriids or lorises can be found in the hand of this subfossil lemur. The hand of Hadropithecus likely had similar ranges of movement at the radiocarpal and midcarpal joints as of those of pronograde primates, such as lemurids, for which the hand is held in a more extended, pronated, and neutral (i.e., showing less ulnar deviation) position during locomotion in comparison to that of vertical clingers or slow climbers. Although highly autapomorphic, the hand of Hadropithecus resembles that of its sister taxon, Archaeolemur, in having a very reduced pollex and an articular facet on the scaphoid for a sizeable prepollex. These unusual hand features reinforce the monophyly of the Archaeolemuridae. [Abstract]

Gibert J, Gibert L, Ribot F, Ferrŕndez-Canadell C, Sánchez F, Iglesias A, Walker MJ
CV-0, an early Pleistocene human phalanx from Cueva Victoria (Cartagena, Spain).
J Hum Evol. 2007 Nov 29; [Abstract]

Balzeau A, Radov?i? J
Variation and modalities of growth and development of the temporal bone pneumatization in Neandertals.
J Hum Evol. 2007 Nov 28;
The temporal bone is used frequently to determine taxonomic affinities as it contains several features that differentiate Neandertals from anatomically modern Homo sapiens. However, only little information is available about temporal bone pneumatization in Neandertals. This study provides descriptions and comparisons of the disposition and the extensiveness of the pneumatization of the temporal bone in large samples of Neandertal specimens of different geological and developmental ages (25 individuals and 33 temporal bones from the sites of Engis, Krapina, La Chapelle aux Saints, La Ferrassie, La Quina, Pech de l'Azé, and Spy). Although temporal bone pneumatization shows some individual variability, a similar pattern of distribution is found in all adult Neandertal individuals from Krapina and Western Europe. Pneumatization is restricted mainly to most parts of the petromastoid areas. We also retrace for the first time the modalities of growth and development of this pneumatization in Neandertals. Finally, this study provides new information about possible correlations between the extension and position of temporal bone pneumatization and some of the morphological features used to characterize the temporal bone of the Neandertals. These latter features include the relatively low and short temporal squama, the robust zygomatic process with a relatively marked lateral projection, the strong supramastoid crest, the significant thickness of the tympanic part of the temporal bone, and the relatively small mastoid process and large juxtamastoid eminence. Our results suggest that the development of pneumatization in Neandertals is related to available space and to temporal bone morphology. Moreover, it appears that the development of pneumatization does not play an active role in determining the morphology of the apomorphic features of the temporal bone in Neandertals. [Abstract]

Skinner MM, Wood BA, Boesch C, Olejniczak AJ, Rosas A, Smith TM, Hublin JJ
Dental trait expression at the enamel-dentine junction of lower molars in extant and fossil hominoids.
J Hum Evol. 2007 Nov 27;
Discrete dental traits are used as proxies for biological relatedness among modern human populations and for alpha taxonomy and phylogeny reconstruction within the hominin clade. We present a comparison of the expression of lower molar dental traits (cusp 6, cusp 7, trigonid crest pattern, and protostylid) at the enamel-dentine junction (EDJ) in a variety of extant and fossil hominoid taxa, in order to assess the contribution of the EDJ to the morphology of these traits at the outer enamel surface (OES). Molars (n=44) were imaged nondestructively using high-resolution microCT, and three-dimensional surface models of the EDJ and OES were created to compare trait expression at each surface. Our results indicate that these dental traits originate at the EDJ, and that the EDJ is primarily responsible for their degree of expression at the OES. Importantly, variable trait morphology at the EDJ (often not easily recognizable at the OES) indicates that different developmental processes can produce traits that appear similar at the enamel surface, suggesting caution in intra- and intertaxonomic comparisons. The results also highlight the importance of the EDJ for understanding the morphological development of discrete traits, and for establishing graded scales of variation to compare trait frequency among groups for the purpose of taxonomic and/or phylogenetic analysis. Finally, this study demonstrates that imaging the EDJ of both worn and unworn fossil hominin teeth provides a novel source of information about tooth development and variation in crown morphology. [Abstract]

Smith TM, Hublin JJ
Dental tissue studies: 2D and 3D insights into human evolution.
J Hum Evol. 2007 Nov 26; [Abstract]

Tafforeau P, Smith TM
Nondestructive imaging of hominoid dental microstructure using phase contrast X-ray synchrotron microtomography.
J Hum Evol. 2007 Nov 26; [Abstract]

Dean MC, Vesey P
Preliminary observations on increasing root length during the eruptive phase of tooth development in modern humans and great apes.
J Hum Evol. 2007 Nov 26;
Ground sections of incisors, canines, and molars were selected that showed clear incremental markings in root dentine. The sample comprised 98 Homo sapiens, 53 Pan troglodytes, and a more limited combined sample of 51 Gorilla and Pongo sections. Daily rates of root dentine formation, together with the orientation of incremental markings in roots close to the cement-dentine junction (CDJ), were used to calculate root extension rates for the first 10mm of root formed beyond the buccal enamel cervix. Modern human anterior tooth roots showed a more regular pattern of increase in root length than those in great apes. In Pan, root growth rose quickly to higher rates but then flattened off. The fastest extension rates in modern humans were in incisor roots (10-12mum per day), followed by canines (8-9mum per day). Extension rates in Pan rose to slightly greater values in canines ( approximately 12-14mum per day) than in incisors ( approximately 10-11mum per day). Molar tooth roots in both modern humans and great apes grew in a nonlinear manner. Peak rates in molars reduced from M1 to M3 (8, 7, and 6mum per day, respectively). Like humans, root growth in Pan peaked earlier in M1s at rates of between 8 and 9mum per day, and later in M3s at rates of 7 to 8mum per day. The more limited data set for Gorilla and Pongo molars suggests that extension rates were generally higher than in Pan by approximately 1.0-1.5mum per day. There were greater differences in peak extension rates, with Gorilla and Pongo extension rates being between 2.5 and 4.5mum per day higher than those in Pan. These findings highlight for the first time that root growth rates differ between tooth types in both pattern and rate and between taxa. They provide the basis with which to explore further the potential comparative relationships between root growth, jaw growth, and the eruption process. [Abstract]

Olejniczak AJ, Tafforeau P, Feeney RN, Martin LB
Three-dimensional primate molar enamel thickness.
J Hum Evol. 2007 Nov 26;
Molar enamel thickness has played an important role in the taxonomic, phylogenetic, and dietary assessments of fossil primate teeth for nearly 90 years. Despite the frequency with which enamel thickness is discussed in paleoanthropological discourse, methods used to attain information about enamel thickness are destructive and record information from only a single plane of section. Such semidestructive planar methods limit sample sizes and ignore dimensional data that may be culled from the entire length of a tooth. In light of recently developed techniques to investigate enamel thickness in 3D and the frequent use of enamel thickness in dietary and phylogenetic interpretations of living and fossil primates, the study presented here aims to produce and make available to other researchers a database of 3D enamel thickness measurements of primate molars (n=182 molars). The 3D enamel thickness measurements reported here generally agree with 2D studies. Hominoids show a broad range of relative enamel thicknesses, and cercopithecoids have relatively thicker enamel than ceboids, which in turn have relatively thicker enamel than strepsirrhine primates, on average. Past studies performed using 2D sections appear to have accurately diagnosed the 3D relative enamel thickness condition in great apes and humans: Gorilla has the relatively thinnest enamel, Pan has relatively thinner enamel than Pongo, and Homo has the relatively thickest enamel. Although the data set presented here has some taxonomic gaps, it may serve as a useful reference for researchers investigating enamel thickness in fossil taxa and studies of primate gnathic biology. [Abstract]

Kupczik K, Dean MC
Comparative observations on the tooth root morphology of Gigantopithecus blacki.
J Hum Evol. 2007 Nov 26;
The extinct great ape Gigantopithecus blacki from the middle Pleistocene of China and Vietnam is known only from dental and mandibular remains, and its dietary specializations remain contentious. Here, for the first time, we describe the root morphology in G. blacki using computed tomography and three-dimensional image processing. We quantify the tooth root lengths and surface areas of the female G. blacki mandible No. 1 from the Liucheng Cave and compare it to a sample of extant great apes and humans, as well as the giant panda (Ailuropoda melanoleuca) and the American black bear (Ursus americanus). The results show that, in G. blacki, the pattern of mandibular root numbers-particularly that of the premolars-corresponds with that of Gorilla gorilla, Pan troglodytes, and Pongo pygmaeus. However, G. blacki can be distinguished from the extant hominids by having relatively higher values for postcanine root length and surface area, both absolutely and relative to mandibular size (except for premolar root lengths of humans). The relatively large postcanine root surface areas, which are most similar to A. melanoleuca, suggest that the dentition of G. blacki was adapted to sustaining relatively large occlusal forces needed to fracture mechanically resistant foods such as bamboo. [Abstract]

Guatelli-Steinberg D, Reid DJ
What molars contribute to an emerging understanding of lateral enamel formation in Neandertals vs. modern humans.
J Hum Evol. 2007 Nov 26;
Two hypotheses, based on previous work on Neandertal anterior and premolar teeth, are investigated here: (1) that estimated molar lateral enamel formation times in Neandertals are likely to fall within the range of modern human population variation, and (2) that perikymata (lateral enamel growth increments) are distributed across cervical and occlusal halves of the crown differently in Neandertals than they are in modern humans. To investigate these hypotheses, total perikymata numbers and the distribution of perikymata across deciles of crown height were compared for Neandertal, northern European, and southern African upper molar mesiobuccal (mb) cusps, lower molar mesiobuccal cusps, and the lower first molar distobuccal (db) cusp. Sample sizes range from five (Neandertal M(1)db) to 29 (southern African M(1)mb). Neandertal mean perikymata numbers were found to differ significantly from those of both modern human samples (with the Neandertal mean higher) only for the M(2)mb. Regression analysis suggests that, with the exception of the M(2)mb, the hypothesis of equivalence between Neandertal and modern human lateral enamel formation time cannot be rejected. For the M(2)mb, regression analysis strongly suggests that this cusp took longer to form in the Neandertal sample than it did in the southern African sample. Plots of perikymata numbers across deciles of crown height demonstrate that Neandertal perikymata are distributed more evenly across the cervical and occlusal halves of molar crowns than they are in the modern human samples. These results are integrated into a discussion of Neandertal and modern human lateral enamel formation across the dentition, with reference to issues of life history and enamel growth processes. [Abstract]

Smith TM
Incremental dental development: Methods and applications in hominoid evolutionary studies.
J Hum Evol. 2007 Nov 26;
This survey of dental microstructure studies reviews recent methods used to quantify developmental variables (daily secretion rate, periodicity of long-period lines, extension rate, formation time) and applications to the study of hominoid evolution. While requisite preparative and analytical methods are time consuming, benefits include more precise identification of tooth crown initiation and completion than conventional radiographic approaches. Furthermore, incremental features facilitate highly accurate estimates of the speed and duration of crown and root formation, stress experienced during development (including birth), and age at death. These approaches have provided insight into fossil hominin and Miocene hominoid life histories, and have also been applied to ontogenetic and taxonomic studies of fossil apes and humans. It is shown here that, due to the rapidly evolving nature of dental microstructure studies, numerous methods have been applied over the past few decades to characterize the rate and duration of dental development. Yet, it is often unclear whether data derived from different methods are comparable or which methods are the most accurate. Areas for future research are identified, including the need for validation and standardization of certain methods, and new methods for integrating nondestructive structural and developmental studies are highlighted. [Abstract]

Zhao L, Lu Q, Zhang W
Age at first molar emergence in Lufengpithecus lufengensis and its implications for life-history evolution.
J Hum Evol. 2007 Nov 23;
The late Miocene hominoid Lufengpithecus from Yunnan Province, China, is crucial for understanding hominoid evolution in Asia. Given that age at first permanent molar emergence is a key life-history trait in primates, the present study determined the age at death of the Lufengpithecus lufengensis juvenile PA868, which was in the process of erupting its first molar. Using a perikymata periodicity of 7-11 days, along with estimation of cusp formation time and the postnatal delay of crown mineralization, perikymata counts obtained from the permanent central incisor and canine germs indicate that the age at death of PA868 was 2.4-4.5 years based on the central incisor germ, and 2.5-4.7 years based on the canine germ. The age at the first molar emergence was actually slightly younger (by about 0.3 years), as demonstrated by tiny wear facets on this tooth, which indicate that gingival emergence had occurred sometime before death. The average age at first molar emergence of Lufengpithecus lufengensis PA868 is estimated to be 3.2-3.3 years, with a range of 2.1-4.4 years. In comparison to extant primates and other fossil hominoids, the life history of Lufengpithecus lufengensis is similar to that of extant great apes and the Miocene hominoids Afropithecus turkanensis and Sivapithecus parvada, as well as Plio-Pleistocene Australopithecus, and different from monkeys, gibbons, and modern humans. [Abstract]

Hardy BL, Bolus M, Conard NJ
Hammer or crescent wrench? Stone-tool form and function in the Aurignacian of southwest Germany.
J Hum Evol. 2007 Nov 20;
The early Upper Paleolithic of Europe is associated with the appearance of blade/bladelet technology (e.g., Aurignacian). These industries include a wider range of formal tool types than seen in the Middle Paleolithic. Greater diversity in tool types is often interpreted as specialized tools created for specific tasks. This, in turn, is said to reflect dramatic behavioral shifts between Neandertals and modern humans. In order to test previous interpretations, it is necessary to have a detailed understanding of early Upper Paleolithic stone-tool function. Toward this end, analyses of microscopic residue and use-wear were undertaken on 109 stone tools from three Aurignacian sites in southwest Germany (Hohle Fels, Geissenklösterle, and Vogelherd). These cave sites evidenced remarkable residue preservation, with approximately 82% of the sample showing some form of functional evidence. Residues observed included hair, feathers, bone/antler, wood, plant tissue, phytoliths, starch grains, and resin. The results suggest that tool typology is not strongly linked to the processing of specific materials. For example, endscrapers from the sample show evidence of processing wood, charred wood, plants, starchy plants, birds, bone/antler, and animals (hair). Hairs are found on tools typologically classified as blades, flakes, borers, pointed blades, and combination tools (nosed endscraper-borer, burin-laterally-retouched blade). In the early Upper Paleolithic of southwest Germany, a wide range of tool types appears to have been used to process a diverse array of materials. These results suggest that the interpretation of behavioral patterns from stone tools must consider more than tool typology. [Abstract]

Auerbach BM, Raxter MH
Patterns of clavicular bilateral asymmetry in relation to the humerus: Variation among humans.
J Hum Evol. 2007 Nov 20;
Studies of directional asymmetry in the human upper limb have extensively examined bones of the arm, forearm, and hand, but have rarely considered the clavicle. Physiologically, the clavicle is an integrated element of the upper limb, transmitting loads to the axial skeleton and supporting the distal bones. However, clavicles develop in a manner that is unique among the bones of the upper limb. Previous studies have indicated that the clavicle has a right-biased asymmetry in diaphyseal breadth, as in humeri, radii, ulnae, and metacarpals, but unlike these other elements, a left-biased length asymmetry. Few studies have assessed how clavicular asymmetry relates to these other bones of the upper limb. Bilateral directional asymmetry of the clavicle is examined in relation to the humerus in a large, geographically diverse human sample, comparing lengths and diaphyseal breadths. Dimensions were converted into percentage directional (%DA) and absolute (%AA) asymmetries. Results indicate that humans have same-side %DA bias in the clavicles and humeri, and contralateral length %DA between these elements. Diaphyseal breadths in both clavicles and humeri are more asymmetric-both in direction and amount-than lengths. Differences in diaphyseal asymmetry are shown to relate to variation in physical activities among groups, but a relationship between activity and length asymmetry is not supported. This further supports previous research, which suggests different degrees of sensitivity to loading between diaphyseal breadths and maximum lengths of long bones. Differences in lateralized behavior and the potential effects of different bone development are examined as possible influences on the patterns observed among human groups. [Abstract]

Quam R, Rak Y
Auditory ossicles from southwest Asian Mousterian sites.
J Hum Evol. 2007 Nov 20;
The present study describes and analyzes new Neandertal and early modern human auditory ossicles from the sites of Qafzeh and Amud in southwest Asia. Some methodological issues in the measurement of these bones are considered, and a set of standardized measurement protocols is proposed. Evidence of erosive pathological processes, most likely attributed to otitis media, is present on the ossicles of Qafzeh 12 and Amud 7 but none can be detected in the other Qafzeh specimens. Qafzeh 12 and 15 extend the known range of variation in the fossil H. sapiens sample in some metric variables, but morphologically, the new specimens do not differ in any meaningful way from living humans. In most metric dimensions, the Amud 7 incus falls within our modern human range of variation, but the more closed angle between the short and long processes stands out. Morphologically, all the Neandertal incudi described to date show a very straight long process. Several tentative hypotheses can be suggested regarding the evolution of the ear ossicles in the genus Homo. First, the degree of metric and morphological variation seems greater among the fossil H. sapiens sample than in Neandertals. Second, there is a real difference in the size of the malleus between Neandertals and fossil H. sapiens, with Neandertals showing larger values in most dimensions. Third, the wider malleus head implies a larger articular facet in the Neandertals, and this also appears to be reflected in the larger (taller) incus articular facet. Fourth, there is limited evidence for a potential temporal trend toward reduction of the long process within the Neandertal lineage. Fifth, a combination of features in the malleus, incus, and stapes may indicate a slightly different relative positioning of either the tip of the incus long process or stapes footplate within the tympanic cavity in the Neandertal lineage. [Abstract]

Griffin NL
Bone architecture of the hominin second proximal pedal phalanx: a preliminary investigation.
J Hum Evol. 2007 Nov 19; [Abstract]

Watson JC, Payne RC, Chamberlain AT, Jones RK, Sellers WI
The energetic costs of load-carrying and the evolution of bipedalism.
J Hum Evol. 2007 Nov 17;
The evolution of habitual bipedalism is still a fundamental yet unsolved question for paleoanthropologists, and carrying is popular as an explanation for both the early adoption of upright walking and as a positive selection pressure once a terrestrial lifestyle had been adopted. However, to support or reject any hypothesis that suggests carrying efficiency was an important selective pressure, we need quantitative data on the costs of different forms of carrying behavior, especially infant-carrying since reduction in the grasping capabilities of the foot would have prevented infants from clinging on for long durations. In this study, we tested the hypothesis that the mode of load carriage influences the energetic cost of locomotion. Oxygen consumption was measured in seven female participants walking at a constant speed while carrying four different 10-kg loads (a weighted vest, 5-kg dumbbells carried in each hand, a mannequin infant carried on one hip, and a 10-kg dumbbell carried in a single hand). Oxygen consumption was also measured during unloaded standing and unloaded walking. The results show that the weighted vest requires the least amount of energy of the four types of carrying and that, for this condition, humans are more efficient than would be predicted for mammals in general. The balanced load was carried with approximately the predicted energy cost. However, the asymmetrical conditions were considerably less efficient, indicating that, unless infant-carrying was the adaptive response to a strong environmental selection pressure, this behavior is unlikely to have been the precursor to the evolution of bipedalism. [Abstract]

Pucciarelli HM, González-José R, Neves WA, Sardi ML, Rozzi FR
East-West cranial differentiation in pre-Columbian populations from Central and North America.
J Hum Evol. 2007 Nov 16;
In a recent study we found that crania from South Amerindian populations on each side of the Andes differ significantly in terms of craniofacial shape. Western populations formed one morphological group, distributed continuously over 14,000km from the Fuegian archipelago (southern Chile) to the Zulia region (northwestern Venezuela). Easterners formed another group, distributed from the Atlantic Coast up to the eastern foothills of the Andes. This differentiation is further supported by several genetic studies, and indirectly by ecological and archaeological studies. Some authors suggest that this dual biological pattern is consistent with differential rates of gene flow and genetic drift operating on both sides of the Cordillera due to historical reasons. Here we show that such East-West patterning is also observable in North America. We suggest that the "ecological zones model" proposed by Dixon, explaining the spread of the early Americans along a Pacific dispersal corridor, combined with the evolution of different population dynamics in both regions, is the most parsimonious mechanism to explain the observed patterns of within- and between-group craniofacial variability. [Abstract]

Humphrey LT, Andrews P
Metric variation in the postcanine teeth from Pa?alar, Turkey.
J Hum Evol. 2007 Nov 16;
The coefficient of variation (CV) has frequently been used to evaluate variation in a morphologically homogeneous fossil assemblage and to make inferences about its species composition. Comparisons of coefficients of variation in single- and mixed-species assemblages have typically involved mixed-species assemblages made up of an equal number of data points from two or more different species, but in reality, a fossil assemblage may be biased in favor of one or more of the component species. In this paper, we evaluate the effects of unequal species composition in mixed-species assemblages on CV distributions by carrying out an extensive series of resampling experiments. The experiments were designed to replicate a paleontological situation in which the species affiliation of particular specimens is not known. We use this technique to explore the pattern of metric variation in the postcanine dental assemblage from the middle Miocene site of Pa?alar in a comparative context. The distributions of CVs from mixed assemblages that are heavily biased toward one species may be characterized by a greater range of CVs, increased skewing, and a tail of low values, but only heavily biased assemblages comprising species that differ markedly in size could be reliably identified on this basis. Evidence from the simulated CV distributions supports nonmetric evidence in indicating that the Pa?alar assemblage represents a heavily biased assemblage of two species that are similar in size but not entirely overlapping in the size distributions of their postcanine teeth. [Abstract]

Chaimanee Y, Yamee C, Tian P, Chavasseau O, Jaeger JJ
First middle Miocene sivaladapid primate from Thailand.
J Hum Evol. 2007 Nov 15;
Sivaladapids are a group of Asian adapiform primates that were previously documented from deposits dating to the middle Eocene through the late Miocene in Pakistan, India, Myanmar, Thailand, and China. The group is notable for the persistence of three genera, Sivaladapis, Indraloris and Sinoadapis, into the late Miocene. In Thailand, sivaladapids were previously documented only from late Eocene deposits of the Krabi mine. Here, we describe the first Southeast Asian Miocene sivaladapid, Siamoadapis maemohensis gen. et sp. nov. from a 13.3 to 13.1 Ma lignite layer from the Mae Moh coal mine, Thailand. It differs from other Miocene sivaladapids by its distinctly smaller size and in features of the dentition. This discovery enhances the paleoecological diversity of the middle Miocene primate fauna of Thailand, which now includes sivaladapids, a loris, tarsiids, and hominoids. In this respect, the fossil primate community from the middle Miocene of Thailand is similar in its composition to roughly contemporaneous assemblages from southern China, India, and Pakistan. However, the Thai fossils represent a distinct genus, suggesting a different biogeographic province with distinctive paleoenvironments. [Abstract]

Kay RF, Fleagle JG, Mitchell TR, Colbert M, Bown T, Powers DW
The anatomy of Dolichocebus gaimanensis, a stem platyrrhine monkey from Argentina.
J Hum Evol. 2007 Nov 12;
Dolichocebus is known from the type skull encased in a concretion, numerous isolated teeth, parts of two mandibles, and a talus. The specimens come from the Trelew Member (early Miocene, Colhuehuapian South American Land Mammal Age) of the Sarmiento Formation near the village of Gaiman, Chubut Province, Argentina, dated to about 20Ma. We describe all Dolichocebus fossil material using conventional surface anatomy and micro-CT data from the cranium. The new material and newly imaged internal anatomy of the skull demonstrate that anatomical characters hitherto supposed to support a phyletic link between Dolichocebus and either callitrichines (marmosets, tamarins, and Callimico) or Saimiri (squirrel monkeys) are either indeterminate or absent. To more fully explore the phyletic position of Dolichocebus, we undertook a comprehensive phylogenetic analysis. We examined 268 characters of the cranium and dentition of 16 living platyrrhine genera, some late Oligocene and early Miocene platyrrhines, Tarsius, some Eocene and Oligocene stem anthropoids, and several extant catarrhines. These analyses consistently indicate that Dolichocebus is a stem platyrrhine, as are late Oligocene Branisella and early Miocene Tremacebus, Soriacebus, and Carlocebus. Platyrrhine evolution often is conceived of as a single ancient adaptive radiation. Review of all available phyolgenetic data suggests a more layered evolutionary pattern, with several independent extinct clades filling modern platyrrhine niche space, and modern platyrrhine families and subfamilies appearing over a nine-million-year interval in the Miocene. The outcome of these analyses highlights the pervasiveness of homoplasy in dental and cranial characters. Homoplasy is a real evolutionary phenomenon that is present at all levels of biological analysis, from amino-acid sequences to aspects of adult bony morphology, behavior, and adaptation. [Abstract]

Harvati K, Gunz P, Grigorescu D
Cioclovina (Romania): affinities of an early modern European.
J Hum Evol. 2007 Dec;53(6):732-46.
The current modern human origins debate centers on the possibility and degree of admixture between indigenous archaic humans and modern human populations migrating out of Africa into Europe and Asia in the Late Pleistocene. Evidence for such admixture must be sought in the earliest fossil record of modern humans outside Africa, as it is those populations that would have encountered, and possibly interbred with, archaic hominins. In the case of Europe, the recent application of direct dating techniques has eliminated several specimens from the Upper Paleolithic fossil record, while confirming early ages for others. Among these earliest reliably dated specimens is the Cioclovina calvaria from Romania. This individual is of highest importance for the understanding of modern human origins in Europe, and has recently been proposed to represent a Neanderthal-modern human hybrid. We present a short description and a three-dimensional (3D) geometric morphometric analysis of the Cioclovina specimen using a large geographic sample of recent humans, Neanderthals and Middle and Late Pleistocene fossil hominins from Europe, Africa, and the Levant, in order to establish its phenetic affinities and to evaluate its morphology for evidence of admixture between Neanderthals and early modern Europeans. Our results show Cioclovina to be entirely modern in its cranial shape, and do not support the hypothesis that it represents a hybrid. [Abstract]

Marivaux L, Beard KC, Chaimanee Y, Jaeger JJ, Marandat B, Soe AN, Tun ST, Aung HH, Htoon W
Anatomy of the bony pelvis of a relatively large-bodied strepsirrhine primate from the late middle Eocene Pondaung Formation (central Myanmar).
J Hum Evol. 2007 Nov 7;
Recent survey of the fossiliferous variegated mudstones of the PK1 locality (Sabapondaung) in the late middle Eocene Pondaung Formation (central Myanmar) has led to the recovery of a partial right innominate of a relatively large-bodied primate. Given its size and provenance, this bone probably belongs to the same individual represented by the NMMP 20 primate partial skeleton described previously from the same locality. The new fossil, which preserves the region around the acetabulum and the adjacent part of the ilium, clearly exhibits strepsirrhine rather than anthropoid affinities. This addition to our knowledge of the NMMP 20 partial skeleton allows us to reassess the different locomotor interpretations that have been proposed for this specimen. Aspects of pelvic morphology suggest that the NMMP 20 partial skeleton documents a primate that probably engaged in active arboreal quadrupedalism similar to that practiced by medium-sized Malagasy lemurids rather than lorislike slow moving and climbing. Given the conflicting phylogenetic signals provided by NMMP 39 (a talus showing anthropoid affinities) and NMMP 20 (a partial skeleton bearing adapiform affinities), it appears that two higher-level taxonomic groups of relatively large-bodied primates are documented in the Pondaung Formation. The recent discovery of two taxa of sivaladapid adapiforms from the Pondaung Formation indicates that the assumption that the NMMP 20 partial skeleton belongs to an amphipithecid can no longer be sustained. Instead, this specimen apparently documents a third large-bodied sivaladapid species in the Pondaung Formation. [Abstract]

Martínez-Navarro B, Palmqvist P, Shabel AB, Pérez-Claros JA, Lorenzo C, Claret A
Reply to on the supposed human phalanx from Cueva Victoria (Cartagena, Spain).
J Hum Evol. 2007 Nov 5; [Abstract]

Ruff C
Femoral/humeral strength in early African Homo erectus.
J Hum Evol. 2007 Oct 29;
Lower-to-upper limb-bone proportions give valuable clues to locomotor behavior in fossil taxa. However, to date only external linear dimensions have been included in such analyses of early hominins. In this study, cross-sectional measures of femoral and humeral diaphyseal strength are determined for the two most complete early Homo erectus (or ergaster) associated skeletons-the juvenile KNM-WT 15000 and the adult KNM-ER 1808. Modern comparative samples include an adult human skeletal sample representative of diverse body shapes, a human longitudinal growth series, and an adult chimpanzee sample. When compared to appropriately age-matched samples, both H. erectus specimens fall very close to modern human mean proportions and far from chimpanzee proportions (which do not overlap with those of humans). This implies very similar mechanical load-sharing between the lower and upper limbs, and by implication, similar locomotor behavior in early H. erectus and modern humans. Thus, by the earliest Pleistocene (1.7 Ma), completely modern patterns of bipedal behavior were fully established in at least one early hominin taxon. [Abstract]

Trauth MH, Maslin MA, Deino AL, Strecker MR, Bergner AG, Dühnforth M
High- and low-latitude forcing of Plio-Pleistocene East African climate and human evolution.
J Hum Evol. 2007 Nov;53(5):475-86.
The late Cenozoic climate of East Africa is punctuated by episodes of short, alternating periods of extreme wetness and aridity, superimposed on a regime of subdued moisture availability exhibiting a long-term drying trend. These periods of extreme climate variability appear to correlate with maxima in the 400-thousand-year (kyr) component of the Earth's eccentricity cycle. Prior to 2.7Ma the wet phases appear every 400kyrs, whereas after 2.7Ma, the wet phases appear every 800kyrs, with periods of precessional-forced extreme climate variability at 2.7-2.5Ma, 1.9-1.7Ma, and 1.1-0.9Ma before present. The last three major lake phases occur at the times of major global climatic transitions, such as the onset of Northern Hemisphere Glaciation (2.7-2.5Ma), intensification of the Walker Circulation (1.9-1.7Ma), and the Mid-Pleistocene Revolution (1.0-0.7Ma). High-latitude forcing is required to compress the Intertropical Convergence Zone so that East Africa becomes locally sensitive to precessional forcing, resulting in rapid shifts from wet to dry conditions. These periods of extreme climate variability may have provided a catalyst for evolutionary change and driven key speciation and dispersal events amongst mammals and hominins in East Africa. [Abstract]

Weinstein KJ
Thoracic morphology in Near Eastern Neandertals and early modern humans compared with recent modern humans from high and low altitudes.
J Hum Evol. 2007 Oct 17;
Paleoanthropologists have long noted the unique "hyper-barrel-shaped" Neandertal thorax as inferred from fragmentary ribs, clavicles, and sterna. Yet scholars disagree whether the Neandertal thorax represents an adaptation to cold climates or elevated activity levels. Given the difficulties of reconstructing overall chest shape from isolated and fragmentary thoracic skeletal elements, it is worthwhile comparing Neandertals and contemporaneous early modern human fossils from the same geographic region to recent modern human skeletons that are known to have enlarged chests. This study compares thoracic skeletal morphology in two Near Eastern Neandertals (Tab?n C1 and Shanidar 3) and two early modern humans from the same region (Skh?l IV and V) with four samples of recent modern human skeletons from the Andes (n=347): two coastal groups and two groups from high altitudes. The two highland groups, similar to their living descendants, exhibit morphological evidence of anteroposteriorly deep and mediolaterally wide chests as part of respiratory adaptations to high-altitude hypoxia. I calculated the percentage of deviation of each Neandertal and early modern human fossil from the means of the four recent modern human samples for clavicle and rib lengths and curvatures. Shanidar 3 and Tab?n C1 exhibit ribs that are slightly larger and less curved than the Andean samples, indicating slightly larger thoracic skeletons than modern humans who are known to have enlarged chests in response to increased respiratory demands. Skh?l IV and V have significantly shorter ribs with greater curvature suggesting especially narrow thoracic skeletons. Comparisons with Andean populations suggest that the enlarged thoraces of Neandertals may reflect high activity levels, although results from this study do not exclude cold adaptation as an explanatory factor. [Abstract]

Hopley PJ, Marshall JD, Weedon GP, Latham AG, Herries AI, Kuykendall KL
Orbital forcing and the spread of C(4) grasses in the late Neogene: stable isotope evidence from South African speleothems.
J Hum Evol. 2007 Nov;53(5):620-34.
Reconstructing Plio-Pleistocene African paleoenvironments is important for models of early hominin evolution, but is often hampered by low-resolution or discontinuous climatic data. Here, we present high-resolution stable oxygen and carbon isotope time series data from two flowstones (secondary cave deposits) from the South African hominin-bearing Makapansgat Valley. The age of the older of the two flowstones (Collapsed Cone) is constrained by magnetostratigraphy to approximately 4-5Ma; the younger flowstone (Buffalo Cave) grew between 2.0-1.5Ma, as determined by magnetostratigraphy and orbital tuning of the isotopic data. The carbon isotope data is used as a proxy for the proportion of C(4) grasses in the local environment and the oxygen isotope data reflects monsoon rainfall intensity. The carbon isotope evidence indicates that in the late Miocene/early Pliocene, the local environment was dominated by C(3) vegetation, whereas, in the Plio-Pleistocene, it was composed of a mixture of C(3) and C(4) vegetation. This suggests that C(4) grasses became a significant part of the Makapansgat Valley ecosystem at approximately 4-5Ma, towards the end of the late Neogene global expansion of C(4) grasses. After this initial expansion, South Africa experienced further fluctuations in the proportion of C(3) and C(4) vegetation during the Plio-Pleistocene, in response to regional and global climatic changes. Most notably, the Buffalo Cave flowstone provides evidence for C(4) grass expansion at ca. 1.7Ma that we suggest was a response to African aridity caused by the onset of the Walker Circulation in the Pacific Ocean at this time. [Abstract]


Recent Articles in American Journal of Physical Anthropology

Kappelman J, Alçiçek MC, Kazanc? N, Schultz M, Ozkul M, Sen S
First Homo erectus from Turkey and implications for migrations into temperate Eurasia.
Am J Phys Anthropol. 2007 Dec 7; .
Remains of fossil hominins from temperate regions of the Old World are rare across both time and space, but such specimens are necessary for understanding basic issues in human evolution including linkages between their adaptations and early migration patterns. We report here the remarkable circumstances surrounding the discovery of the first fossil hominin calvaria from Turkey. The specimen was found in the Denizli province of western Turkey and recovered from within a solid block of travertine stone as it was being sawed into tile-sized slabs for the commercial natural stone building market. The new specimen fills an important geographical and temporal gap and displays several anatomical features that are shared with other Middle Pleistocene hominins from both Africa and Asia attributed to Homo erectus. It also preserves an unusual pathology on the endocranial surface of the frontal bone that is consistent with a diagnosis of Leptomeningitis tuberculosa (TB), and this evidence represents the most ancient example of this disease known for a fossil human. TB is exacerbated in dark-skinned peoples living in northern latitudes by a vitamin D deficiency because of reduced levels of ultraviolet radiation (UVR). Evidence for TB in the new specimen supports the thesis that reduced UVR was one of the many climatic variables presenting an adaptive challenge to ancient hominins during their migration into the temperate regions of Europe and Asia. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]

Coleman MN
What does geometric mean, mean geometrically? Assessing the utility of geometric mean and other size variables in studies of skull allometry.
Am J Phys Anthropol. 2007 Dec 7;
This study investigated the effects of using different size variables for interpretations of relative orbit size and mandibular robusticity. Thirty-three skull measurements taken on 385 platyrrhines representing 12 of 16 New World monkey genera (in addition to body mass and total body length) were used singly and in combinations (by taking the geometric mean of all measurements) as size variables to produce relative size indices of orbit area and mandibular thickness. These indices were then compared to investigate which size variables proved effective at differentiating nocturnal from diurnal taxa and hard object from soft object feeders based upon results from previous biomechanical studies.It was found that certain groups of size variables consistently produced the a priori expectations and resulted in lower coefficients of variation. The general principles shared by these size variables were that they sampled anatomically remote regions of the skull that appear to be functionally independent from the trait being evaluated and they were nearly always geometric mean combinations composed of a relatively high number (>/=12) of large measurements. Suggestions are also presented for amending these principles for use with incomplete material such as fossils. Am J Phys Anthropol, 2008. (c) 2007 Wiley-Liss, Inc. [Abstract]

Carter ML, Pontzer H, Wrangham RW, Peterhans JK
Skeletal pathology in Pan troglodytes schweinfurthii in Kibale National Park, Uganda.
Am J Phys Anthropol. 2007 Dec 7;
The ecological pressures shaping chimpanzee anatomy and behavior are the subject of much discussion in primatology and paleoanthropology, yet empirical data on fundamental parameters including body size, morbidity, and mortality are rare for wild chimpanzees. Here, we present skeletal pathology and body size data for 20 (19 crania, 12 postcrania) chimpanzees (Pan troglodytes schweinfurthii) from Kibale National Park, Uganda. We compare these data with other East African populations, especially Gombe National Park. Estimated body size for Kibale chimpanzees was similar to other East African populations and significantly larger than Gombe chimpanzees. The high rates of trauma and other skeletal pathology evident in the Kibale chimpanzee skeletons were similar to those in the Gombe skeletal sample. Much of the major skeletal trauma in the Kibale skeletons was attributable to falls, although other pathologies were noted as well, including apparent injuries from snares, degenerative arthritis, and minor congenital abnormalities. Am J Phys Anthropol, 2008. (c) 2007 Wiley-Liss, Inc. [Abstract]

Shang H, Trinkaus E
An ectocranial lesion on the middle Pleistocene human cranium from Hulu Cave, Nanjing, China.
Am J Phys Anthropol. 2007 Dec 7;
The earlier Middle Pleistocene human partial cranium from Hulu Cave, Tangshan, Nanjing (Hulu 1) exhibits an ectocranial lesion which covers most of the anterior neurocranium, largely between the temporal lines and extending from the supratoral sulcus to the anterior parietal bone. The endocranial surfaces and the remainder of the cranium (upper facial skeleton, lateral frontal bone, posterior parietal bones, and mid-occipital bone) are normal. The healed lesion exhibits both resorption and the laying down of new bone. Differential diagnosis suggests that the lesion was caused by either trauma (broad compressive trauma, tensile trauma to the scalp, or partial scalp removal) or burning (with damage to scalp and superficial neurocranium). Dietary deficiencies, infection, and neoplastic disorders do not fit the lesion characteristics. The Hulu 1 specimen therefore joins a growing sample of Pleistocene Homo remains with nonfatal and nontrivial disorders. Am J Phys Anthropol, 2008. (c) 2007 Wiley-Liss, Inc. [Abstract]

Kingston JD
Shifting adaptive landscapes: progress and challenges in reconstructing early hominid environments.
Am J Phys Anthropol. 2007;Suppl 45
Since Darwin situated humans in an evolutionary framework, much discussion has focused on environmental factors that may have shaped or influenced the course of human evolution. Developing adaptive or causal perspectives on the morphological and behavioral variability documented in the human fossil record requires establishing a comprehensive paleoenvironmental context. Reconstructing environments in the past, however, is a complex undertaking, requiring assimilation of diverse datasets of varying quality, scale, and relevance. In response to these difficulties, human evolution has traditionally been interpreted in a somewhat generalized framework, characterized primarily by increasing aridity and seasonality periodically punctuated by pulses or intervals of environmental change, inferred largely from global climatic records. Although these broad paradigms provide useful heuristic approaches for interpreting human evolution, the spatiotemporal resolution remains far too coarse to develop unambiguous causal links. This challenge has become more acute as the emerging paleoenvironmental evidence from equatorial Africa is revealing a complex pattern of habitat heterogeneity and persistent ecological flux throughout the interval of human evolution. In addition, recent discoveries have revealed significant taxonomic diversity and substantially increased the geographic and temporal range of early hominids. These findings raise further questions regarding the role of the environment in mediating or directing the course of human evolution. As a consequence, it is imperative to critically assess the environmental criteria on which many theories and hypotheses of human evolution hinge. The goals here are to 1) compile, review, and evaluate relevant paleoecological datasets from equatorial Africa spanning the last 10 Ma, 2) develop a hierarchical perspective for developing and evaluating hypotheses linking paleoecology to patterns and processes in early hominid evolution, and 3) suggest a conceptual framework for modeling and interpreting environmental data relevant to human evolution in equatorial Africa. [Abstract]

Martin RD
The evolution of human reproduction: a primatological perspective.
Am J Phys Anthropol. 2007;Suppl 45
Successful reconstruction of any aspect of human evolution ideally requires broad-based comparisons with other primates, as recognition of general principles provides a more reliable foundation for inference. Indeed, in many cases it is necessary to conduct comparisons with other placental mammals to test interpretations. This review considers comparative evidence with respect to the following topics relating to human reproduction: (1) size of the testes, sperm, and baculum; (2) ovarian processes and mating cyclicity; (3) placentation and embryonic membranes; (4) gestation period and neonatal condition; (5) brain development in relation to reproduction; and (6) suckling and age at weaning. Relative testis size, the size of the sperm midpiece, and perhaps the absence of a baculum indicate that humans are adapted for a mating system in which sperm competition was not a major factor. Because sizes of mammalian gametes do not increase with body size, they are increasingly dwarfed by the size of the female reproductive tract as body size increases. The implications of this have yet to be explored. Primates have long ovarian cycles and humans show an average pattern. Menstruation is completely lacking in strepsirrhine primates, possibly weakly present in tarsiers and variably expressed in simians. The only other mammals reliably reported to show menstruation are bats. Three hypotheses have been proposed to explain the evolution of menstruation (eliminating sperm-borne pathogens; reducing the metabolic cost of a prepared uterine lining; occurrence as a side-effect of physiological changes), but no consensus has emerged. Copulation at times other than the periovulatory period is not unique to humans, and its occurrence during pregnancy is widespread among mammals. Although the human condition is extreme, extended copulation during the ovarian cycle is the norm among simian primates, in stark contrast to prosimians, in which mating is typically restricted to a few days when the female is in oestrus. The model of regular mid-cycle ovulation in simians is questionable. Gestation periods calculated on that basis show greater variability than in other mammals, and evidence from laboratory breeding colonies indicates that an extended mating period is matched by an extended period in which conception can occur. New evidence indicates that the noninvasive placentation found in strepsirrhine primates is not primitive after all. Furthermore, comparative studies reveal that such noninvasive placentation is not "inefficient". Evolution of highly invasive placentation in haplorhine primates is probably linked instead to immunological factors. Primates have relatively long gestation periods, and humans are average in this respect. However, there is evidence that humans show greater maternal investment during pregnancy in comparison with apes. Although the human neonate matches the typical precocial pattern of primates in most respects, a fetal pattern of brain growth continues for a year after birth, such that the human infant is "secondarily altricial" in terms of its dependence on parental care. Nevertheless, the "natural" lactation period of humans is probably about 3 years, fitting the expectation in comparison to other hominoids. [Abstract]

Wells JC, Stock JT
The biology of the colonizing ape.
Am J Phys Anthropol. 2007;Suppl 45
Hominin evolutionary history is characterized by regular dispersals, cycles of colonization, and entry into novel environments. This article considers the relationship between such colonizing capacity and hominin biology. In general, colonizing strategy favors rapid rates of reproduction and generalized rather than specialized biology. Physiological viability across diverse environments favors a high degree of phenotypic plasticity, which buffers the genome from selective pressures. Colonizing also favors the capacity to access and process information about environmental variability. We propose that early hominin adaptive radiations were based upon the development of such capacities as adaptations to unstable Pliocene environments. These components came together, along with fundamental changes in morphology, behavior, and cognition in the genus Homo, who exploited them in subsequent wider dispersals. Middle Pleistocene hominins and modern humans also show development of further traits, which correspond with successful probing of, and dispersals into, stressful environments. These traits have their precursors in primate or ape biology, but have become more pronounced during hominin evolution. First, short interbirth intervals and slow childhood growth allow human females to provision several offspring simultaneously, increasing the rate of reproduction in favorable conditions. This allows rapid recovery from population crashes, or rapid population growth in new habitats. Second, despite high geographical phenotypic variability, humans have high genetic unity. This is achieved by a variety of levels of plasticity, including physiology, behavior, and technology, which reduce the need to commit to genetic adaptation. Hominin behavior may increasingly have shaped both the ecological niches occupied and the selective pressures acting back on the genome. Such selective pressures may have been exacerbated by population dynamics, predicted to both derive from, and favor, the colonizing strategy. Exposure to ecological variability is likely to have generated particular selective pressures on female biology, favoring increasing steering of offspring ontogeny by maternal phenotype. We propose that the concept of hominins as "colonizing apes" offers a novel unified model for interpreting the suite of traits characteristic of our genus. [Abstract]

Lynnerup N
Mummies.
Am J Phys Anthropol. 2007;Suppl 45
Mummies are human remains with preservation of nonbony tissue. Mummification by natural influences results in so-called natural mummies, whereas mummification induced by active (human) intervention results in so-called artificial mummies, although many cultures practiced burial rites, which to some degree involved both natural and artificial mummification. Since they are so uniquely well-preserved, mummies may give many insights into mortuary practices and burial rites. Specifically, the presence of soft tissues may expand the scope of paleopathological studies. Many recent mummy studies focus on the development and application of nondestructive methods for examining mummies, including radiography, CT-scanning with advanced three-dimensional visualizations, and endoscopic techniques, as well as minimally-destructive chemical, physical, and biological methods for, e.g., stable isotopes, trace metals, and DNA. This article discusses mummification and gives a presentation of various key mummy finds and a brief history of mummy studies. A description of the extant key technologies of natural and medical science that are applied in mummy studies is given; along with a discussion of some of the major results in terms of paleopathology. It is also shown how mummy studies have contributed much to the knowledge of the cultural habits and everyday life of past populations. Finally the impact of mummy studies on analyses of mortuary practices and cultural history is discussed. [Abstract]

Xing J, Witherspoon DJ, Ray DA, Batzer MA, Jorde LB
Mobile DNA elements in primate and human evolution.
Am J Phys Anthropol. 2007;Suppl 45
Roughly 50% of the primate genome consists of mobile, repetitive DNA sequences such as Alu and LINE1 elements. The causes and evolutionary consequences of mobile element insertion, which have received considerable attention during the past decade, are reviewed in this article. Because of their unique mutational mechanisms, these elements are highly useful for answering phylogenetic questions. We demonstrate how they have been used to help resolve a number of questions in primate phylogeny, including the human-chimpanzee-gorilla trichotomy and New World primate phylogeny. Alu and LINE1 element insertion polymorphisms have also been analyzed in human populations to test hypotheses about human evolution and population affinities and to address forensic issues. Finally, these elements have had impacts on the genome itself. We review how they have influenced fundamental ongoing processes like nonhomologous recombination, genomic deletion, and X chromosome inactivation. [Abstract]

McKenna JJ, Ball HL, Gettler LT
Mother-infant cosleeping, breastfeeding and sudden infant death syndrome: what biological anthropology has discovered about normal infant sleep and pediatric sleep medicine.
Am J Phys Anthropol. 2007;Suppl 45
Twenty years ago a new area of inquiry was launched when anthropologists proposed that an evolutionary perspective on infancy could contribute to our understanding of unexplained infant deaths. Here we review two decades of research examining parent-infant sleep practices and the variability of maternal and infant sleep physiology and behavior in social and solitary sleeping environments. The results challenge clinical wisdom regarding "normal" infant sleep, and over the past two decades the perspective of evolutionary pediatrics has challenged the supremacy of pediatric sleep medicine in defining what are appropriate sleep environments and behaviors for healthy human infants. In this review, we employ a biocultural approach that integrates diverse lines of evidence in order to illustrate the limitations of pediatric sleep medicine in adopting a view of infants that prioritizes recent western social values over the human infant's biological heritage. We review what is known regarding infant sleeping arrangements among nonhuman primates and briefly explore the possible paleoecological context within which early human sleep patterns and parent-infant sleeping arrangements might have evolved. The first challenges made by anthropologists to the pediatric and SIDS research communities are traced, and two decades of studies into the behavior and physiology of mothers and infants sleeping together are presented up to the present. Laboratory, hospital and home studies are used to assess the biological functions of shared mother-infant sleep, especially with regard to breastfeeding promotion and SIDS reduction. Finally, we encourage other anthropologists to participate in pediatric sleep research using the unique skills and insights anthropological data provide. By employing comparative, evolutionary and cross-cultural perspectives an anthropological approach stimulates new research insights that influence the traditional medical paradigm and help to make it more inclusive. That this review will potentially stimulate similar research by other anthropologists is one obvious goal. That this article might do so makes it ever more possible that anthropologically inspired work on infant sleep will ultimately lead to infant sleep scientists, pediatricians, and parents becoming more informed about the consequences of caring for human infants in ways that are not congruent with their evolutionary biology. [Abstract]

Wood B, Constantino P
Paranthropus boisei: fifty years of evidence and analysis.
Am J Phys Anthropol. 2007;Suppl 45
Paranthropus boisei is a hominin taxon with a distinctive cranial and dental morphology. Its hypodigm has been recovered from sites with good stratigraphic and chronological control, and for some morphological regions, such as the mandible and the mandibular dentition, the samples are not only relatively well dated, but they are, by paleontological standards, reasonably-sized. This means that researchers can trace the evolution of metric and nonmetric variables across hundreds of thousands of years. This paper is a detailed review of half a century's worth of fossil evidence and analysis of P. boisei and traces how both its evolutionary history and our understanding of its evolutionary history have evolved during the past 50 years. [Abstract]

Parra EJ
Human pigmentation variation: evolution, genetic basis, and implications for public health.
Am J Phys Anthropol. 2007;Suppl 45
Pigmentation, which is primarily determined by the amount, the type, and the distribution of melanin, shows a remarkable diversity in human populations, and in this sense, it is an atypical trait. Numerous genetic studies have indicated that the average proportion of genetic variation due to differences among major continental groups is just 10-15% of the total genetic variation. In contrast, skin pigmentation shows large differences among continental populations. The reasons for this discrepancy can be traced back primarily to the strong influence of natural selection, which has shaped the distribution of pigmentation according to a latitudinal gradient. Research during the last 5 years has substantially increased our understanding of the genes involved in normal pigmentation variation in human populations. At least six genes have been identified using genotype/phenotype association studies and/or direct functional assays, and there is evidence indicating that several additional genes may be playing a role in skin, hair, and iris pigmentation. The information that is emerging from recent studies points to a complex picture where positive selection has been acting at different genomic locations, and for some genes only in certain population groups. There are several reasons why elucidating the genetics and evolutionary history of pigmentation is important. 1) Pigmentation is a trait that should be used as an example of how misleading simplistic interpretations of human variation can be. It is erroneous to extrapolate the patterns of variation observed in superficial traits such as pigmentation to the rest of the genome. It is similarly misleading to suggest, based on the "average" genomic picture, that variation among human populations is irrelevant. The study of the genes underlying human pigmentation diversity brings to the forefront the mosaic nature of human genetic variation: our genome is composed of a myriad of segments with different patterns of variation and evolutionary histories. 2) Pigmentation can be very useful to understand the genetic architecture of complex traits. The pigmentation of unexposed areas of the skin (constitutive pigmentation) is relatively unaffected by environmental influences during an individual's lifetime when compared with other complex traits such as diabetes or blood pressure, and this provides a unique opportunity to study gene-gene interactions without the effect of environmental confounders. 3) Pigmentation is of relevance from a public health perspective, because of its critical role in photoprotection and vitamin D synthesis. Fair-skinned individuals are at higher risk of several types of skin cancer, particularly in regions with high UVR incidence, and dark-skinned individuals living in high latitude regions are at higher risk for diseases caused by deficient or insufficient vitamin D levels. [Abstract]

Rapoff AJ, Rinaldi RG, Hotzman JL, Daegling DJ
Elastic modulus variation in mandibular bone: A microindentation study of Macaca fascicularis.
Am J Phys Anthropol. 2007 Nov 30;
We characterized the heterogeneous anisotropic elastic properties of mandibular bone in an adult female specimen of Macaca fascicularis using the technique of microindentation. This approach used an indenter of known mass and geometry to sample bone hardness at a spatial resolution in the order of 100 mum. Hardness values were converted to elastic modulus using empirically derived regression. We determined properties in alveolar, midcorpus, and basal regions of coronal and transverse sections taken from multiple locations along the corpus and ramus. Within sections, we determined properties from endosteal, midcortical, and periosteal regions. We found regional variations in bone structure, including bands of orthotropic circumferential lamellar bone at the endosteal and periosteal corpus base, angular region, and ramus. Transversely isotropic osteonal bone characterizes the midcortices of alveolar and basal regions, with many resorption spaces in alveolar regions restricting sampling opportunities. Regional variations in elasticity include relatively compliant bone in the anterior corpus and ramus. Basal cortical bone is stiffer longitudinally than transversely or superoinferiorly, while the evidence for directional dependence in alveolar bone is equivocal. Alveolar bone appears to be relatively compliant with respect to bone found in midcorpus or basal regions. Considerable variation exists in structure and material properties on a highly localized scale, more so than is discernible through conventional approaches for determining material property variation. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]

Pinhasi R, Eshed V, Shaw P
Evolutionary changes in the masticatory complex following the transition to farming in the southern Levant.
Am J Phys Anthropol. 2007 Nov 28;
A post-Pleistocene reduction trend in the dimensions of the masticatory complex followed the transition to agricultural lifestyle in several world regions. A major limitation of previous studies is large temporal gaps between the analyzed skeletal populations, which do not allow the detection and analysis of a diachronic morphological transition. In this work, we analyze a large number of specimens from the southern Levant, where agriculture first emerged in situ and for which there is a good diachronic sequence of the shift from a hunting-gathering way of life to a food producing, farming economy (12,000-7,000 uncalibrated bp). Changes in the masticatory complex are examined in the context of three prevailing dental reduction models: the Probable Mutation Effect (Brace,1963; Brace and Mahler,1971), Increasing Population Density Effect (Macchiarelli and Bondioli,1986) and Selective Compromise Effect (SCE) (Calcagno,1989). A series of linear regressions of dimension vs. time and coefficients of variation for each dimension are analyzed. Our results indicate significant reduction in the buccolingual but not mesiodistal dental dimensions and in the ramus breadth and anterior height dimensions of the mandible but not in its overall size. These findings, taken together with low coefficients of variation for the buccolingual dimensions, suggest selective pressure resulting in reduction of specific dimensions. The observed trend is in partial accordance with the SCE but differs from the trends observed in other regions, and is therefore best explained as a region-specific variant of the SCE. Am J Phys Anthropol, 2008. (c) 2007 Wiley-Liss, Inc. [Abstract]

Thompson ME, Wrangham RW
Diet and reproductive function in wild female chimpanzees (Pan troglodytes schweinfurthii) at Kibale National Park, Uganda.
Am J Phys Anthropol. 2007 Nov 28;
Human female reproductive function is highly sensitive to current energetic condition, indicating adaptation to modulate reproductive effort in accordance with changing ecological conditions that might favor or disfavor the production of offspring. Here, we test the hypothesis that reproductive capacity in female chimpanzees is likewise limited by current energetic condition. We used 12 years of data on wild chimpanzees (Pan troglodytes schweinfurthii) in the Kanyawara community of Kibale National Park, Uganda, to examine the relationship of dietary quality, as assessed by fruit components of the diet, to the occurrence of sexually receptive females, concentrations of ovarian steroid hormones, and timing of conception. We found that the frequency of females having sexual swellings was positively related to the consumption of drupe fruits. Estrogen levels of both cycling and noncycling females increased during seasonal peaks in the consumption of drupe fruits. When average fruit consumption remained high across months, females conceived more quickly. These results support the hypothesis that cycling and conception in chimpanzees are contingent upon high energy balance, and they indicate that the availability of fruit is a key variable limiting reproductive performance in chimpanzees. Chimpanzees appear to share with humans a reproductive system that is primed to respond to proximate levels of energy acquisition. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]

Hadley C, Patil CL
Seasonal changes in household food insecurity and symptoms of anxiety and depression.
Am J Phys Anthropol. 2007 Nov 28;
There is growing awareness that common mental health disorders are key contributors to the burden of disease in developing countries. Studies examining the correlates of mental health have primarily been carried out in urban settings and focused on the burden rapid economic change places on individuals. In these settings, poverty and low education are consistent predictors of anxiety and depressive symptoms. We argue here that these variables are proxies for insecurity, and that a more general model of symptoms of depression and anxiety should focus on locally salient forms of insecurity. Building on previous work in a seasonal subsistence setting, we identify food insecurity as a potent source of insecurity in a rural African setting, and then test whether seasonal changes in food insecurity are correlated with concomitant changes in a measure of symptoms of anxiety and depression among 173 caretakers. Results indicate that food insecurity is a strong predictor of symptoms of anxiety and depression (P < 0.0001), that changes in food insecurity across the seasons predict changes in symptoms of anxiety and depression (P < 0.0001), and that this is robust to the inclusion of covariates for material assets and household production. These results hold for individuals in both ethnic groups studied (Pimbwe and Sukuma); however, at the group level the burden falls disproportionately on Pimbwe. The results add to the growing literature on the causes of population level differences in mental health disorders and suggest new research avenues and strategies to link mental health disorders with variation in physical and biosocial outcomes. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]

Martin SA, Guatelli-Steinberg D, Sciulli PW, Walker PL
Brief communication: Comparison of methods for estimating chronological age at linear enamel formation on anterior dentition.
Am J Phys Anthropol. 2007 Nov 28;
Linear enamel hypoplasia (LEH) is an enamel defect that records the effects of physiological stress on tooth formation. Estimating the age at which LEH defects form is integral to the reconstruction of population health in bioarcheological studies. Two principal methods for aging LEH defects have been introduced in the literature. The conventional approach employs regression equations based on a linear model of tooth growth. The newer, Reid and Dean [Am J Phys Anthropol 113 (2000) 135-139] approach, is based upon a histologically derived curvilinear model of enamel development and therefore likely provides more accurate age estimates. However, the extent to which the Reid and Dean method produces estimated ages at defect formation differing from those of the regression equations has not, until now, been determined. This study quantifies the differences between these two methods. Evaluating the degree to which these methods differ is essential for interpreting the accuracy of LEH age estimates given in previous bioarcheological studies. Age estimates of LEH defects on 338 anterior teeth from the Hamann-Todd osteological sample were calculated using both methods. The resulting estimated ages were compared through a randomized block ANOVA. However, the mean differences between the estimated ages yielded by both methods range from 4 months or less depending on the tooth type with an overall average of 2.63 months. The discussion focuses on the degree to which this difference affects answers to bioarcheological questions. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]

Proctor DJ, Broadfield D, Proctor K
Quantitative three-dimensional shape analysis of the proximal hallucial metatarsal articular surface in Homo, Pan, Gorilla, and Hylobates.
Am J Phys Anthropol. 2007 Nov 28;
Multidimensional morphometrics is used to compare the proximal articular surface of the first metatarsal between Homo, Pan, Gorilla, Hylobates, and the hominin fossils A.L. 333-54 (A. afarensis), SKX 5017 (P. robustus), and OH 8 (H. habilis). Statistically significant differences in articular surface morphology exist between H. sapiens and the apes, and between ape groups. Ape groups are characterized by greater surface depth, an obliquely curved articular surface through the dorso-lateral and medio-plantar regions, and a wider medio-lateral surface relative to the dorso-plantar height. The OH 8 articular surface is indistinguishable from H. sapiens, while A.L. 333-54 and SKX 5017 more closely resemble the apes. P. robustus and A. afarensis exhibit ape-like oblique curvature of the articular surface. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]

Melchior L, Gilbert MT, Kivisild T, Lynnerup N, Dissing J
Rare mtDNA haplogroups and genetic differences in rich and poor Danish Iron-Age villages.
Am J Phys Anthropol. 2007 Nov 28;
The Roman Iron-Age (0-400 AD) in Southern Scandinavia was a formative period, where the society changed from archaic chiefdoms to a true state formation, and the population composition has likely changed in this period due to immigrants from Middle Scandinavia. We have analyzed mtDNA from 22 individuals from two different types of settlements, Břgebjerggĺrd and Skovgaarde, in Southern Denmark. Břgebjerggĺrd (ca. 0 AD) represents the lowest level of free, but poor farmers, whereas Skovgaarde 8 km to the east (ca. 200-270 AD) represents the highest level of the society. Reproducible results were obtained for 18 subjects harboring 17 different haplotypes all compatible (in their character states) with the phylogenetic tree drawn from present day populations of Europe. This indicates that the South Scandinavian Roman Iron-Age population was as diverse as Europeans are today. Several of the haplogroups (R0a, U2, I) observed in Břgebjerggĺrd are rare in present day Scandinavians. Most significantly, R0a, harbored by a male, is a haplogroup frequent in East Africa and Arabia but virtually absent among modern Northern Europeans. We suggest that this subject was a soldier or a slave, or a descendant of a female slave, from Roman Legions stationed a few hundred kilometers to the south. In contrast, the haplotype distribution in the rich Skovgaarde shows similarity to that observed for modern Scandinavians, and the Břgebjerggĺrd and Skovgaarde population samples differ significantly (P approximately 0.01). Skovgaarde may represent a new upper-class formed by migrants from Middle Scandinavia bringing with them Scandinavian haplogroups. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]

Hunley KL, Spence JE, Merriwether DA
The impact of group fissions on genetic structure in Native South America and implications for human evolution.
Am J Phys Anthropol. 2007 Nov 28;
In a series of publications beginning in the 1960s, Neel and colleagues suggested that genetically nonrandom, or "lineal", population fissions contributed to genetic structure in ancient human groups. The authors reached this conclusion by studying the genetic consequences of village fissions among the Yanomamo, a Native South American group thought to have been relatively unaffected by European contact and, therefore, representative of the human past. On the basis of ethnographic accounts and pedigree data, they further concluded that patrilineal relationships were particularly important in shaping the genetic structure of villages following fissions. This study reexamines the genetic consequences of village fissions using autosomal STRs, Y-chromosome STRs, and mitochondrial DNA sequences collected from large samples of individuals from multiple Yanomamo villages. Our analyses of the autosomal STRs replicate the previous finding that village fissions have produced substantial genetic structure among the Yanomamo. However, our analyses of Y-chromosome STRs and mtDNA d-loop polymorphisms suggest that other population processes, including village movements, inter-village migration, and polygynous marriage, affect genetic structure in ways not predicted by a simple model of patrilineal fissions. We discuss the broader implications of population fissions for human evolution and the suitability of using the Yanomamo as a model for the human past. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]

Cardoso HF
Epiphyseal union at the innominate and lower limb in a modern Portuguese skeletal sample, and age estimation in adolescent and young adult male and female skeletons.
Am J Phys Anthropol. 2007 Nov 28;
This study documents the timing of epiphyseal union at the innominate, femur, tibia, and fibula in a sample of modern Portuguese skeletons. The sample was taken from the Lisbon documented skeletal collection and it is comprised of 57 females and 49 males between the ages of 9 and 25. Individuals are mostly representative of the middle-to-low socioeconomic segment of the early 20th century Lisbon population. A total of 18 anatomical locations were examined for epiphyseal union using a three-stage scheme: 1) no union; 2) partial union; and 3) completed union, all traces of fusion having disappeared. Results show that females are ahead of males by 1-2 years and provide similar age ranges for the stages of union than previous studies. Some variations between studies can be explained by methodological differences between dry bone and radiographic observations. However, a review of the literature indicates that socioeconomic status of a given population seems to be of decisive importance to the rate of ossification and most of the differences in skeletal maturation across studies and populations can probably be ascribed to different levels of social and economic development of the societies in which the individuals lived. Although the effects of socioeconomic status in skeletal maturation are greater during childhood than in adolescence, as to make the timing of epiphyseal union a reliable estimate of age at death, they are not negligible and age estimates should take into account the likely socioeconomic status of the individual, whose remains are under examination. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]

Gordon AD, Green DJ, Richmond BG
Strong postcranial size dimorphism in Australopithecus afarensis: Results from two new resampling methods for multivariate data sets with missing data.
Am J Phys Anthropol. 2007 Nov 28;
There is considerable debate over the level of size dimorphism and inferred social behavior of Australopithecus afarensis. Most previous studies have analyzed size variation in single variables or multiple variables drawn from single elements. These approaches suffer from small sample sizes, underscoring the need for new techniques that incorporate measurements from multiple unassociated elements, reducing the influence of random sampling on size variation in fossil samples. One such technique, the template method, has recently been proposed but is limited to samples with a template specimen and is sensitive to a number of assumptions. Here we present two new resampling methods that do not require a template specimen, allow measurements from multiple unassociated elements to be included in a single analysis, and allow for significance tests between comparative and fossil multivariate data sets with missing data. Using these new methods, multivariate postcranial size dimorphism is measured using eight measurements of the femur, tibia, humerus, and radius in samples of A. afarensis, modern humans, chimpanzees, gorillas, and orangutans. Postcranial dimorphism in A. afarensis is similar to that of gorillas and orangutans, and significantly greater than in modern humans and chimpanzees. Because studies in living primates have examined the association of behavior with dimorphism in body mass and craniodental measurements, not postcrania, relationships between postcranial dimorphism and social behavior must be established to make robust behavioral inferences for A. afarensis. However, the results of this and past studies strongly suggest behavioral and mating strategies differed between A. afarensis and modern humans. Am J Phys Anthropol, 2008. (c) 2007 Wiley-Liss, Inc. [Abstract]

Caillaud D, Levréro F, Gatti S, Ménard N, Raymond M
Influence of male morphology on male mating status and behavior during interunit encounters in western lowland gorillas.
Am J Phys Anthropol. 2007 Nov 28;
The western lowland gorilla (Gorilla gorilla gorilla) is one of the most sexually dimorphic primate species. Mature males are twice the size of females and have grey fur on their backs and a fibrous, adipose crest on their heads. Such traits are likely to have evolved by sexual selection, either because they confer advantages during male-male fights or because females prefer males with more dimorphic traits. We developed photogrammetric methods for distance collection of morphological data from silverback males frequenting the Lokoué forest clearing in Odzala-Kokoua National Park, Republic of the Congo. Body length, head-crest size, musculature development, and extent of the grey color on the back were assessed in 87 nonbreeding and breeding mature males. Behavioral data were also collected during 312 male-male encounters involving 67 mature males in order to estimate their level of aggressiveness. The number of females belonging to a mature male positively correlated with the male crest size, body length, and musculature. Whereas morphological variables did not significantly affect the intensity of male-male encounters, the number of females attending male-male encounters strongly affected the number of agonistic displays by the two males. We discuss the mechanisms through which males with more exaggerated traits could obtain a mating advantage, namely male-male fights or female mate choice. Am J Phys Anthropol, 2008. (c) 2007 Wiley-Liss, Inc. [Abstract]


Books received.
Am J Phys Anthropol. 2007 Nov 13; [Abstract]

Trinkaus E, Biglari F, Mashkour M, Monchot H, Reyss JL, Rougier H, Heydari S, Abdi K
Late Pleistocene human remains from Wezmeh Cave, western Iran.
Am J Phys Anthropol. 2007 Nov 13;
Paleontological analysis of remains from Wezmeh Cave in western Iran have yielded a Holocene Chalcolithic archeological assemblage, a rich Late Pleistocene carnivore faunal assemblage, and an isolated unerupted human maxillary premolar (P(3) or possibly P(4)). Species representation and U-series dating of faunal teeth place the carnivore assemblage during oxygen isotope stages (OIS) 3 and 2, and noninvasive gamma spectrometry dating of the human premolar places it at least as old as early OIS 2. The human premolar crown morphology is not diagnostic of late archaic versus early modern human affinities, but its buccolingual diameter places it at the upper limits of Late Pleistocene human P(3) and P(4) dimensions and separate from a terminal Pleistocene regional sample. Wezmeh Cave therefore provides additional Paleolithic human remains from the Zagros Mountains and further documents Late Pleistocene human association with otherwise carnivore-dominated cave assemblages. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]

Sylvester AD, Kramer PA
Stand and shuffle: When does it make energetic sense?
Am J Phys Anthropol. 2007 Nov 13;
Many reasons for the emergence of bipedalism have been proposed, including postural arguments which highlight that a sub-optimal form of bipedalism ("shuffling") might have been used by protohominids to cover short distances between resources that require bipedal standing. Bipedal shuffling may have been employed because it avoids the cost of raising the trunk from the quadrupedal orientation, which we assume is the habitual locomotor stance of protohominids. To date, these postural proposals have not been analytically assessed, a lack we rectify herein. Our model seeks to specify a threshold distance, below which bipedal shuffling uses less energy than quadrupedalism. Parameters for the model include the mechanical cost of transport, the ratio of bipedal to quadrupedal cost, and the cost associated with raising the trunk. We found that, using reasonable model parameters, open distances of approximately 9-16 m support the use of bipedal shuffling. Protohominids may have used shuffling as an energetically effective way to traverse between resource patches. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]

Schilling AF, Kummer T, Marshall RP, Bauerochse A, Jopp E, Pueschel K, Amling M
Brief communication: Two and three-dimensional analysis of bone mass and microstructure in a bog body from the Iron Age.
Am J Phys Anthropol. 2007 Nov 13;
Human remains from peat bogs, called "bog bodies," have yielded valuable insights into human history because of their excellent preservation of soft tissue. On the other hand, the acidic environment of the peat leads to an extensive demineralization of skeletal elements, complicating their analysis. We studied the skeleton of the bog body "Moora" dated to approximately 650 B.C. Nondestructive evaluation of the bone was made using contact X-rays, peripheral quantitative computed tomography (pQCT) analysis, multislice computed tomography (CT) and high resolution micro computed tomography (muCT) imaging. Two thousand seven hundred years in the acidic environment of the bog led to a loss of 92.7% of bone mineral density. Despite this demineralization and in contrast to other bog bodies, the spatial structure of the bones of "Moora" is exceptionally well preserved. We found Harris lines and were able to obtain the first three-dimensional data on the trabecular microstructure of the bone of a young woman from the early Iron Age. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]

Ibarra-Rivera L, Mirabal S, Regueiro MM, Herrera RJ
Delineating genetic relationships among the Maya.
Am J Phys Anthropol. 2007 Nov 13;
By 250 AD, the Classic Maya had become the most advanced civilization within the New World, possessing the only well-developed hieroglyphic writing system of the time and an advanced knowledge of mathematics, astronomy and architecture. Though only ruins of the empire remain, 7.5 million Mayan descendants still occupy areas of Mexico, Guatemala, Belize, El Salvador, and Honduras. Although they inhabit distant and distinct territories, speak more than 28 languages, and have been historically divided by warfare and a city-state-like political system, and they share characteristics such as rituals, artistic, architectural motifs that distinguish them as unequivocally Maya. This study was undertaken to determine whether these similarities among Mayan communities mirror genetic affinities or are merely a reflection of their common culture. Four Mayan populations were investigated (i.e., the K'iche and Kakchikel from Guatemala and the Campeche and Yucatan from Mexico) and compared with previously published populations across 15 autosomal STR loci. As a whole, the Maya emerge as a distinct group within Mesoamerica, indicating that they are more similar to each other than to other Mesoamerican groups. The data suggest that although geographic and political boundaries existed among Mayan communities, genetic exchanges between the different Mayan groups have occurred, supporting theories of extensive trading throughout the empire. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]

Boldsen JL
Leprosy in the early medieval Lauchheim community.
Am J Phys Anthropol. 2007 Nov 13;
Leprosy was a well-recognized and dreaded disease in medieval Europe (5th-15th century AD). It is reported to have reached Germany with the Roman invasion. A much larger fraction than previously assumed appears to have been affected by leprosy in the medieval period. This article estimates the frequency (i.e., the prevalence at death) of leprosy among adult people buried in the Lauchheim early medieval cemetery. Seven different dichotomous osteological lesions indicative of leprosy are analyzed, and it is possible to score at least one of these conditions on 110 adult skeletons (aged 15 or more). The scores were transformed to a statistic-lambda (lambda)-indicating the likelihood that the person to whom the skeleton belonged suffered from leprosy. The analyses indicate that 16% (95% confidence interval: 9-23%) of adult people in Lauchheim died with osteological signs of leprosy. Leprosy was significantly more prevalent among men than women. The lambda statistic indicates that people who died with signs of leprosy did not differ in the distribution of age at death from those who did not have such signs. Some of the leprosy-related lesions had a statistically significant nonrandom dispersal on the cemetery; but there is no clear pattern to this and the significant results could be easily attributed to a type-1 error in the statistical analysis. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]

Galtés I, Jordana X, Cos M, Malgosa A, Manyosa J
Biomechanical model of pronation efficiency: New insight into skeletal adaptation of the hominoid upper limb.
Am J Phys Anthropol. 2007 Nov 13;
Despite considerable literature on the functional anatomy of the hominoid upper limb, there are no quantitative approaches relating to bone design and the resulting muscular-activity enhancement. The purpose of this study is to quantitatively analyze the relationship between the rotational efficiency of the pronator teres muscle and the design of the skeletal structures on which it acts. Using conventional scan images of a human forearm for three rotational positions, this study develops an original biomechanical model that defines rotational efficiency as a mathematical function expressing a geometrical relationship between the origin and insertion muscular sites. The results show that this parameter varies throughout the entire pronation range, being maximal when the forearm lies around its functional position. Moreover, the rotational-efficiency formula allows us to demonstrate, by several simulation conditions, that an improvement in pronation efficiency is derived from a large shaft radius curvature, a large humeral medial epicondyle, and a more proximal pronator teres radial attachment. The fact that forearm pronation efficiency can be inferred, even quantified, throughout the entire rotational range, by applying the biomechanical model developed here allows us to undertake anatomical approaches in the field of Evolutionary Anthropology, to interpret more precisely how skeletal design is related to upper-limb function in extant and fossil primate taxa. Am J Phys Anthropol, 2007. (c) 2007 Wiley-Liss, Inc. [Abstract]