Social class and survival on the SS Titanic

Passengers' chances of surviving the sinking of the S.S. Titanic were related to their sex and their social class: females were more likely to survive than males, and the chances of survival declined with social class as measured by the class in which the passenger travelled. The probable reasons for these differences in rates of survival are discussed as are the reasons accepted by the Mersey Committee of Inquiry into the sinking

<i>Zygomaticus major</i> muscle bony attachment site:a Thiel-embalmed cadaver study

Objective: Thezygomaticus major is a principal muscle of facial expression which is engaged when smiling. The zygomaticus major origin of the zygomatic bone is often discussed relevant to its importance in the field of plastic surgery. In addition, the zygomaticus major attachment site is also significant for forensic craniofacial reconstruction, separating the cheek into frontal and lateral surfaces. However, there are discrepancies amongst published articles regarding the precise origin of the zygomaticus major muscle. The aim of this study is to investigate more distinctive and palpable landmarks as the bony attachment of the zygomaticus major. Methods: This project is the first zygomaticus major dissection study utilising Thiel embalmed cadavers. Fifty-two facial dissections were investigated in 26 Thiel embalmed bodies, bequeathed to the Centre for Anatomy and Human Identification at The University of Dundee between 2013 and 2015. Results: This study found that the origin of zygomaticus major muscle was located at the superior margin of the temporal process on the lateral surface of zygomatic bone. Moreover, the zygomaticus major muscle overlapped the anterosuperior border of the masseter muscle. One out of 52 zygomaticus major muscles presented bifurcation. Conclusion: The origin site of zygomaticus major is considered important to increase resemblance in forensic craniofacial reconstruction. Furthermore, since zygomaticus major is a salient muscle involved in facial expression, the potential effects for cosmetic/surgical procedures are also relevant to the medical field and successful surgical outcomes. The current study provided easily palpable landmarks of zygomaticus major origin site which is beneficial for both surgeons and forensic craniofacial reconstruction practitioners. © 202

Evolution of the muscles of facial expression in a monogamous ape: evaluating the relative influences of ecological and phylogenetic factors in hylobatids

Facial expression is a communication mode produced by facial (mimetic) musculature. Hylobatids (gibbons and siamangs) have a poorly documented facial display repertoire and little is known about their facial musculature. These lesser apes represent an opportunity to test hypotheses related to the evolution of primate facial musculature as they are the only hominoid with a monogamous social structure, and thus live in very small groups. Primate species living in large groups with numerous social relationships, such as chimpanzees and rhesus macaques, have been shown to have a complex facial display repertoire and a high number of discrete facial muscles. The present study was designed to examine the relative influence of social structure and phylogeny on facial musculature evolution by comparing facial musculature complexity among hylobatids, chimpanzees, and rhesus macaques. Four faces were dissected from four hylobatid species. Morphology, attachments, three‐dimensional relationships, and variation among specimens were noted and compared to rhesus macaques and chimpanzees. Microanatomical characteristics of the orbicularis oris muscle were also compared. Facial muscles of hylobatids were generally gracile and less complex than both the rhesus macaque and chimpanzee. Microanatomically, the orbicularis oris muscle of hylobatids was relatively loosely packed with muscle fibers. These results indicate that environmental and social factors may have been important in determining morphology and complexity of facial musculature in the less social hylobatids and that they may not have experienced as strong selection pressure for mimetic muscle complexity as other, more social primates

The evolution of active vibrissal sensing in mammals: evidence from vibrissal musculature and function in the marsupial opossum Monodelphis domestica

Facial vibrissae, or whiskers, are found in nearly all extant mammal species and are likely to have been present in early mammalian ancestors. A sub-set of modern mammals, including many rodents, move their long mystacial whiskers back and forth at high speed whilst exploring in a behaviour known as ‘whisking’. It is not known whether the vibrissae of early mammals moved in this way. The grey short-tailed opossum, Monodelphis domestica, is considered a useful species from the perspective of tracing the evolution of modern mammals. Interestingly, these marsupials engage in whisking bouts similar to those seen in rodents. To better assess the likelihood that active vibrissal sensing was present in ancestral mammals, we examined the vibrissal musculature of the opossum using digital miscroscopy to see whether this resembles that of rodents. Although opossums have fewer whiskers than rats, our investigation found that they have a similar vibrissal musculature. In particular, in both rats and opossums, the musculature includes both intrinsic and extrinsic muscles with the intrinsic muscles positioned as slings linking pairs of large vibrissae within rows. We identified some differences in the extrinsic musculature which, interestingly, matched with behavioural data obtained through high-speed video recording, and indicated additional degrees of freedom for positioning the vibrissae in rats. These data show that the whisker movements of opossum and rat exploit similar underlying mechanisms. Paired with earlier results suggesting similar patterns of vibrissal movement, this strongly implies that early therian (marsupial and placental) mammals were whisking animals that actively controlled their vibrissae

Development of mandibular, hyoid and hypobranchial muscles in the zebrafish: homologies and evolution of these muscles within bony fishes and tetrapods

BackgroundDuring vertebrate head evolution, muscle changes accompanied radical modification of the skeleton. Recent studies have suggested that muscles and their innervation evolve less rapidly than cartilage. The freshwater teleostean zebrafish (Danio rerio) is the most studied actinopterygian model organism, and is sometimes taken to represent osteichthyans as a whole, which include bony fishes and tetrapods. Most work concerning zebrafish cranial muscles has focused on larval stages. We set out to describe the later development of zebrafish head muscles and compare muscle homologies across the Osteichthyes.ResultsWe describe one new muscle and show that the number of mandibular, hyoid and hypobranchial muscles found in four day-old zebrafish larvae is similar to that found in the adult. However, the overall configuration and/or the number of divisions of these muscles change during development. For example, the undivided adductor mandibulae of early larvae gives rise to the adductor mandibulae sections A0, A1-OST, A2 and Aω, and the protractor hyoideus becomes divided into dorsal and ventral portions in adults. There is not always a correspondence between the ontogeny of these muscles in the zebrafish and their evolution within the Osteichthyes. All of the 13 mandibular, hyoid and hypobranchial muscles present in the adult zebrafish are found in at least some other living teleosts, and all except the protractor hyoideus are found in at least some extant non-teleost actinopterygians. Of these muscles, about a quarter (intermandibularis anterior, adductor mandibulae, sternohyoideus) are found in at least some living tetrapods, and a further quarter (levator arcus palatini, adductor arcus palatini, adductor operculi) in at least some extant sarcopterygian fish.ConclusionAlthough the zebrafish occupies a rather derived phylogenetic position within actinopterygians and even within teleosts, with respect to the mandibular, hyoid and hypobranchial muscles it seems justified to consider it an appropriate representative of these two groups. Among these muscles, the three with clear homologues in tetrapods and the further three identified in sarcopterygian fish are particularly appropriate for comparisons of results between the actinopterygian zebrafish and the sarcopterygians