Todd C. Rae

Functional morphology of the cave bear (Ursus spelaeus) mandible: a 3D geometric morphometric analysis

The diet of the fossil cave bears (Ursus spelaeus group) has been debated extensively. Thought traditionally to be herbivorous, more recent studies have proposed more meat in the cave bear diet. To test this, the mandibular morphology of cave bears was analysed using 3D geometric morphometrics and compared to that of extant Ursidae. Landmarks for 3D digitisation of the mandible were chosen to reflect functional morphology relating to the temporalis and masseter muscles. Extant and extinct Pleistocene Ursidae were digitised with a MicroScribe G2. Generalised Procrustes superimposition was performed, and data were allometrically and phylogenetically corrected. Principal component analysis (PCA), two-block partial least squares analysis (2B-PLS), regression analysis and discriminant function analysis were performed. PCA and 2B-PLS differentiate between known dietary niches in extant Ursidae. The lineage of the cave bear runs parallel to that of the panda (Ailuropoda melanoleuca) in morphospace, implying the development of morphological adaptations for eating foliage. A regression of shape onto foliage content in the diet and a discriminant function analysis also indicate that the cave bear diet consisted primarily of foliage.

Long-term benzodiazepine and Z-drugs use in England: a survey of general practice

BACKGROUND Current British National Formulary (BNF) guidelines state that benzodiazepines and zolpidem, zopiclone, and zaleplon, commonly known as Z-drugs (BZD), be prescribed for no more than 4 weeks, although anecdotal data suggest that many patients are prescribed BZDs for much longer. As there are no recent, evidence-based estimates of long-term (>12 months) BZD use in the UK, the scale of this potential problem is unknown. AIM To produce the first reliable, evidence-based estimate of long-term BZD use in the UK. DESIGN AND SETTING Estimates of UK long-term BZD use were projected from data obtained from a survey conducted in 2014-2015 by the Bridge Project, a prescribed-drug withdrawal support charity in the North of England (Bradford). METHOD Percentages of long-term users of BZD were derived from the survey, by sampling primary care GP surgeries with around 100 000 registered patients, and these were applied to UK-wide NHS patient numbers. The data were filtered to exclude the very young and old, and those with other health issues. RESULTS The mean percentage of registered patients prescribed BZDs for more than a year in the survey sample is 0.69% (95% confidence interval [CI] = 0.54 to 0.84). Applying this value to national patient numbers yields a mean projection of 296 929 (95% CI = 232 553 to 361 305) long-term users of BZD in the UK. The data also suggest that as many as 119 165 of these patients may be willing to accept prescribed drug dependency withdrawal services. CONCLUSION More than a quarter of a million people in the UK are likely to be taking highly dependency-forming hypnotic medication far beyond the recommended time scales. As there is evidence that long-term use of BZDs causes adverse physiological and neurological effects, and protracted withdrawal (with associated complications), this represents a serious public health problem.

Computer simulations show that Neanderthal facial morphology represents adaptation to cold and high energy demands, but not heavy biting

Three adaptive hypotheses have been forwarded to explain the distinctive Neanderthal face: (i) an improved ability to accommodate high anterior bite forces, (ii) more effective conditioning of cold and/or dry air and, (iii) adaptation to facilitate greater ventilatory demands. We test these hypotheses using three-dimensional models of Neanderthals, modern humans, and a close outgroup (Homo heidelbergensis), applying finite-element analysis (FEA) and computational fluid dynamics (CFD). This is the most comprehensive application of either approach applied to date and the first to include both. FEA reveals few differences between H. heidelbergensis, modern humans, and Neanderthals in their capacities to sustain high anterior tooth loadings. CFD shows that the nasal cavities of Neanderthals and especially modern humans condition air more efficiently than does that of H. heidelbergensis, suggesting that both evolved to better withstand cold and/or dry climates than less derived Homo. We further find that Neanderthals could move considerably more air through the nasal pathway than could H. heidelbergensis or modern humans, consistent with the propositions that, relative to our outgroup Homo, Neanderthal facial morphology evolved to reflect improved capacities to better condition cold, dry air, and, to move greater air volumes in response to higher energetic requirements.

Relationship between foramen magnum position and locomotion in extant and extinct hominoids

From the Miocene Sahelanthropus tchadensis to Pleistocene Homo sapiens, hominins are characterized by a derived anterior position of the foramen magnum relative to basicranial structures. It has been previously suggested that the anterior position of the foramen magnum in hominins is related to bipedal locomotor behavior. Yet, the functional relationship between foramen magnum position and bipedal locomotion remains unclear. Recent studies, using ratios based on cranial linear measurements, have found a link between the anterior position of the foramen magnum and bipedalism in several mammalian clades: marsupials, rodents, and primates. In the present study, we compute these ratios in a sample including a more comprehensive dataset of extant hominoids and fossil hominins. First, we verify if the values of ratios can distinguish extant humans from apes. Then, we test whether extinct hominins can be distinguished from non-bipedal extant hominoids. Finally, we assess if the studied ratios are effective predictors of bipedal behavior by testing if they mainly relate to variation in foramen magnum position rather than changes in other cranial structures. Our results confirm that the ratios discriminate between extant bipeds and non-bipeds. However, the only ratio clearly discriminating between fossil hominins and other extant apes is that which only includes basicranial structures. We show that a large proportion of the interspecific variation in the other ratios relates to changes in facial, rather than basicranial, structures. In this context, we advocate the use of measurements based only on basicranial structures when assessing the relationship between foramen magnum position and bipedalism in future studies.

Continuous dental eruption identifies Sts 5 as the developmentally oldest fossil hominin and informs the taxonomy of Australopithecus africanus

The relatively small Australopithecus africanus specimen Sts 5 has figured prominently in taxonomic debates, and the determination of this specimen as a young male or an elderly female has the potential to offer a great deal of resolution on this question. Sts 5 has been argued to be either a small, immature male or a mature female based on a variety of characters. A proposed model of continuous root remodeling and angular change for heavily worn dentition may account for the extremely short tooth roots, particularly for the anterior dentition, that Sts 5 demonstrates. The anterior tooth roots of Sts 5 are oriented vertically (relative to the alveolar plane), unlike those found in most other apes, humans, and fossil specimens, in which the tooth roots are roughly parallel with the plane of the nasoalveolar clivus. Computed tomography (CT) data of adult apes were examined and a relationship between the angle of the anterior tooth roots and their length was discovered, caused by heavily worn anterior dentition continuing to erupt to maintain occlusion. The extremely short and vertically oriented anterior roots observed in Sts 5 thus suggest that the specimen represents an aged female specimen with extremely worn dentition. Interestingly, this reorientation of anterior tooth roots helps account for the unusual nasoalveolar contour of Sts 5. The remodeling associated with the heavily worn teeth and reoriented roots thus resolves the taxonomic question raised by analyses identifying unusual prognathism of this small specimen.

First Indications for Long-Term Benzodiazepine and Z-drugs use in the United Kingdom

Benzodiazepines and Z-drugs (BZDs), hypnotic drugs used for insomnia and anxiety, are prescribed millions of times a year in the UK. Although guidance from the relevant regulatory authorities (NICE and BNF) indicates them only for short-term use, the evidence suggests that many patients have been taking these drugs for much longer, often for decades. At present, there are no up-to-date, evidence-based estimates of the scale of long-term BZD use in the UK, which has prevented making a strong case for the need for withdrawal services. However, data obtained recently on BZD use from a number of GP surgeries (covering nearly 100,000 registered patients) in the North of England, allow such projections to be calculated. Scaling the results to a national level suggests that there are over a quarter of a million patients in the UK using BZDs for periods far longer than recommended. The projections also suggest that nearly half this number may be willing to accept help to stop their dependency on BZDs. These results indicate a serious problem, which should be addressed by more research into the harms associated with long-term BZD use, the provision of withdrawal services, and a national helpline to support patients with BZD dependency.