The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology This is an RSS file. You can use it to subscribe to this data in your favourite RSS reader or to display this data on your own website or blog.

Pelvic Morphology in Homo erectus and Early Homo
ABSTRACT The evolution of the hominin pelvis is generally seen as involving two broad stages: the establishment of bipedal pelvic morphology by the mid‐Pliocene (or earlier), followed by architectural changes necessary to enlarge the birth canal in response to increased encephalization in Pleistocene members of the genus Homo. Pelvic and proximal femoral morphology in early Homo (namely H. erectus) has been seen as transitional between these stages, reflecting structural changes necessitated by greater body size (and perhaps moderate increases in brain size) overlain upon a basically primitive pelvic architecture. Here w...
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Steven Emilio Churchill, Caroline Vansickle Tags: Special Issue Article Source Type: research

Measuring Lateral Iliac Flare by Different Methods Risks Obscuring Evolutionary Changes in the Pelvis
ABSTRACT The orientation and morphology of the hominin ilium is functionally important for locomotion, yet no standard method exists for quantifying its lateral flare. This lack of standardization stems from fossil preservation issues and morphological differences between hominin species. Many techniques have been developed to measure flare based on what is preserved on a single fossil, but this makes comparisons between fossil species challenging. In some cases, methods developed based on australopith morphology are not appropriate for measuring the morphology in genus Homo. Lateral iliac flare is the angle between the il...
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Caroline Vansickle Tags: Special Issue Article Source Type: research

Mechanical Constraints on the Hominin Pelvis and the “Obstetrical Dilemma”
ABSTRACT The “obstetrical dilemma” posits that increases in birth canal dimensions during hominin evolution were constrained by mechanical factors associated with bipedal gait. This model has recently been challenged, in part on the basis of experimental data showing little association between pelvic and proximal femoral dimensions and locomotor costs among human experimental subjects. However, complete rejection of the model is premature, for two reasons: (1) it is difficult to extrapolate experimental results to naturalistic conditions and the much more varied body form and possibly locomotor style of early hominins....
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Christopher Ruff Tags: Special Issue Article Source Type: research

Hominin Hip Biomechanics: Changing Perspectives
This article reviews traditional approaches for understanding hip abductor function, shows how they have been applied to the fossil hominin record, and discusses new techniques that integrate the dynamic nature of mediolateral balance during human locomotion. Anat Rec, 300:932–945, 2017. © 2017 Wiley Periodicals, Inc. (Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology)
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Anna G. Warrener Tags: Special Issue Article Source Type: research

How Did the Pelvis and Vertebral Column Become a Functional Unit during the Transition from Occasional to Permanent Bipedalism?
We present an in vivo EOS study of eight spino‐pelvic parameters describing the sagittal balance in 131 adults. We observe a chain of correlations between the six angular parameters and discuss the functional significance of these results. We show that pelvic incidence increases and lumbar lordosis develops when the infant learns to walk, leading to a correlation between these parameters. This process of association between pelvis and spine might have acquired a solid genetic basis during hominid evolution by natural selection acting on both pelvis and spine. We suggest that this process of functional integration was onl...
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Christine Tardieu, Kazuhiro Hasegawa, Martin Haeusler Tags: Special Issue Article Source Type: research

Evolution of Spinopelvic Alignment in Hominins
We examined spinopelvic alignment of a single representative from each of the following hominin groups: Australopithecus, Homo erectus (H. erectus), H. neanderthalensis, and early H. sapiens. Pelvic incidence, lumbar lordosis, thoracic kyphosis, and cervical lordosis for each representative was estimated and compared with that of modern humans. Three basic spinopelvic alignments were found: (1) the sinusoidal alignment with moderate to high spinal curvatures and pelvic incidence found in H. erectus and H. sapiens; (2) the straight alignment with small spinal curvatures and small pelvic incidence found in Neandertal lineage...
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Ella Been, Asier G ómez‐Olivencia, Sara Shefi, Michalle Soudack, Markus Bastir, Alon Barash Tags: Special Issue Article Source Type: research

Neonatal Shoulder Width Suggests a Semirotational, Oblique Birth Mechanism in Australopithecus afarensis
ABSTRACT Birth mechanics in early hominins are often reconstructed based on cephalopelvic proportions, with little attention paid to neonatal shoulders. Here, we find that neonatal biacromial breadth can be estimated from adult clavicular length (R2 = 0.80) in primates. Using this relationship and clavicular length from adult Australopithecus afarensis, we estimate biacromial breadth in neonatal australopiths. Combined with neonatal head dimensions, we reconstruct birth in A. afarensis (A.L. 288‐1 or Lucy) and find that the most likely mechanism of birth in this early hominin was a semi‐rotational oblique birth in whic...
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Jeremy M. DeSilva, Natalie M. Laudicina, Karen R. Rosenberg, Wenda R. Trevathan Tags: Special Issue Article Source Type: research

Dimorphism in the Size and Shape of the Birth Canal Across Anthropoid Primates
This study shows that birth canal dimorphism is common among anthropoids regardless of cephalopelvic proportions, but taxa with large cephalopelvic proportions have a higher magnitude of dimorphism than those that give birth to relatively small‐headed neonates. Furthermore, humans have exceptionally high levels of dimorphism that cannot be explained based on our large cephalopelvic proportions alone. Anat Rec, 300:870–889, 2017. © 2017 Wiley Periodicals, Inc. (Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology)
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Elizabeth A. Moffett Tags: Special Issue Article Source Type: research

Development of Pelvic Sexual Dimorphism in Hylobatids: Testing the Obstetric Constraints Hypothesis
ABSTRACT Pelvic sexual dimorphism in primates is typically seen as the result of female‐specific adaptations to obstetric constraints, which arise from the tight fit between the neonate head and the maternal pelvis. However, it remains debated to which extent pelvic dimorphism is a correlate of obstetric constraints, of body size dimorphism, and/or of other factors. Also, little is known on how pelvic dimorphism develops. Here we use methods of biomedical imaging and geometric morphometrics to address these questions in two hylobatid species, Hylobates lar and Symphalangus syndactylus. These species differ markedly in bo...
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Christoph P.E. Zollikofer, Marc Scherrer, Marcia S. Ponce de Le ón Tags: Special Issue Article Source Type: research

Ischial Form as an Indicator of Bipedal Kinematics in Early Hominins: A Test Using Extant Anthropoids
In this study, we tested the hypothesis that ischial length and orientation are functionally linked with hip extension during bipedalism among these taxa. As expected, humans have the shortest ischia, followed by gibbons, spider monkeys, chimpanzees, and macaques. Our predictions for ischial orientation are not supported, however: macaques, gibbons, and spider monkeys do not vary in this trait, and they have ischia that are less dorsally angled than that of the chimpanzee. The results for ischium length provide limited support for the idea that the early hominin Ardipithecus ramidus, with its long, caudally oriented ischiu...
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Kristi L. Lewton, Jeremiah E. Scott Tags: Special Issue Article Source Type: research

Lower Ilium Evolution in Apes and Hominins
This study examines the variation in relative lower ilium height between and within living and fossil hominoid species (and other anthropoids), and models its evolution using available fossil hominoids as calibration points. We find nuanced differences in relative lower ilium height among living hominoids, particularly in regards to gorillas, which do not have elongate lower ilia (because they are likely to represent the plesiomorphic hominoid condition for this trait). We also show that differences in relative lower ilium height among hominoid taxa are not readily explained by differences in size between species. Our maxi...
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Ashley S. Hammond, Sergio Alm écija Tags: Special Issue Article Source Type: research

Determinants of Iliac Blade Orientation in Anthropoid Primates
ABSTRACT Orientation of the iliac blades is a key feature that appears to distinguish extant apes from monkeys. Iliac morphology is hypothesized to reflect variation in thoracic shape that, in turn, reflects adaptations for shoulder and forearm function in anthropoids. Iliac orientation is traditionally measured relative to the acetabulum, whereas functional explanations pertain to its orientation relative to the cardinal anatomical planes. We investigated iliac orientation relative to a median plane using digital models of hipbones registered to landmark data from articulated pelves. We fit planes to the iliac surfaces, m...
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Emily R. Middleton, Zachariah J. Winkler, Ashley S. Hammond, J. Michael Plavcan, Carol V. Ward Tags: Special Issue Article Source Type: research

Sacral Variability in Tailless Species: Homo sapiens and Ochotona princeps
This study uses the comparative method to test the hypothesis that sacral variability in H. sapiens is associated with absence of a tail. Three species of lagomorphs are studied: Ochotona princeps (N = 271), which is tailless, and Lepus californicus (N = 212) and Sylvilagus audubonii (N = 206), which have tails. Results show that O. princeps has (1) higher diversity index for number of sacral vertebrae (0.49) compared to L. californicus (0.25) and S. audubonii (0.26) and (2) significantly higher percentage of individuals with the species‐specific nonmodal number of sacral vertebrae (43.9%) compared to L. cali...
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Robert G. Tague Tags: Special Issue Article Source Type: research

Evolution of the Human Pelvis
ABSTRACT No bone in the human postcranial skeleton differs more dramatically from its match in an ape skeleton than the pelvis. Humans have evolved a specialized pelvis, well‐adapted for the rigors of bipedal locomotion. Precisely how this happened has been the subject of great interest and contention in the paleoanthropological literature. In part, this is because of the fragility of the pelvis and its resulting rarity in the human fossil record. However, new discoveries from Miocene hominoids and Plio‐Pleistocene hominins have reenergized debates about human pelvic evolution and shed new light on the competing roles ...
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Karen R. Rosenberg, Jeremy M. DeSilva Tags: Special Issue/Commentary Source Type: research

How We Came to Be: Evidence from Primate Relatives and Fossil Ancestors Offer Clues to How Human Capabilities for Birth, Posture, and Walking Evolved
(Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology)
Source: The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology - April 12, 2017 Category: Molecular Biology Authors: Jeffrey T. Laitman Tags: Special Issue/Commentary Source Type: research