The present study investigates the impact of northern pike (Esox Lucius) on the growth of juvenile burbot (Lota lota) in northern lake ecosystems. It is hypothesized that the presence of pike will positively affect the growth of juvenile burbot by reducing interspecific competition and increasing the abundance of benthic invertebrates. To test this hypothesis, electrofishing for juvenile burbot was conducted in the littoral zones of lakes with and without pike in the region Jämtland Härjedalen, Sweden. Data on length and age of the captured burbot were used to compare growth between the two lake types. Contrary to the initial hypothesis, the results show that juvenile burbot were significantly larger at a given age in lakes where pike was absent. This outcome suggests that juvenile burbot may reduce their foraging activity in lakes with pike to minimize predation risk. Since adult burbot has shown to be of greater size in lakes with pike, future research could investigate whether the shift towards piscivory in burbot leads to changes in how they are affected by pike.

Yes / The skeletal remains of infants and children are a poignant reminder of the perilous nature of childhood in the past, yet they offer valuable insight into the life histories of individuals and into the health of populations. Many osteoarchaeological and bioarchaeological analyses are dependent on two vital pieces of information: the age-at-death and sex of the individual(s) under study. This chapter will outline how age-at-death and sex can be estimated from the skeletal remains and dental development of non-adults, and how these are easier or more difficult to determine than for adults, and will discuss the complexities and controversies surrounding different methods.

No / Recent advances in the methods of skeletal age estimation have rekindled interest in their applicability to paleodemography. The current study contributes to the discussion by applying several long established as well as recently developed or refined aging methods to a subsample of 121 adult skeletons from the early medieval cemetery of Lauchheim. The skeletal remains were analyzed by 13 independent observers using a variety of aging techniques (complex method and other multimethod approaches, Transition Analysis, cranial suture closure, auricular surface method, osteon density method, tooth root translucency measurement, and tooth cementum annulation counting). The age ranges and mean age estimations were compared and results indicate that all methods showed smaller age ranges for the younger individuals, but broader age ranges for the older age groups. / Max Planck Institute for Demographic Research

Yes / Context: Adult age-at-death is presented in a number of different ways by anthropologists. Ordinal categories predominate in osteoarchaeology, but do not reflect individual variation in ageing, with too many adults being classified as ‘middle adults’. In addition, mean ages (derived from reference samples) are overly-relied upon when developing and testing methods. In both cases, ‘age mimicry’ is not adequately accounted for. Objectives: To highlight the many inherent biases created when developing, testing and applying age-estimation methods without fully considering the impact of ‘age mimicry’ and individual variation. Methods: The paper draws on previously published research (Web of Science, Pub Med, Google Scholar) on age estimation methods and their use in anthropology. Results and Conclusions: There is a lack of consistency in the methods used to estimate age, and for the mode of combining them. Ordinal categories are frequently used in osteoarchaeology, whereas forensic anthropologists are more likely to produce case-specific age ranges. Mean ages reflect the age structure of reference samples, and should not be used to estimate age for individuals from populations with a different age-at-death structure. Individual-specific age ranges and/or probability densities should be used to report individual age. Further research should be undertaken on how to create unbiased, combined method age estimates.

Yes / We analyzed the trabecular bone changes in the pubic bone (PB) and in the auricular surface (AS) of the ilium using 319 CT scans of cadavers to estimate the age. Although the sharpness of the trabecular structure decreases in CT images when soft tissues are present, we identified four phases for the changes in PB and five in AS; a juvenile trait in PB and a senile trait in AS helped narrow the age range. High correlation with age was identified for both sexes in PB (F 0.89; M 0.75) and in AS (F 0.85; M 0.71) used independently or combined (F 0.91; M 0.78). The old adults (>60 years) could be evaluated with better accuracy and discriminated in several phases. We found low inter-observer error and low inaccuracy (about 6 years, mean for all age ranges). The method is robust with respect to slice thickness, display window and kernel within the tested ranges.

Yes / Assessing and interpreting dental and skeletal age-related changes in both the living and the dead is of interest to a wide range of disciplines (e.g. see Bittles and Collins 1986) including human biology, paediatrics, public health, palaeodemography, archaeology, palaeontology, human evolution, forensic anthropology and legal medicine. ... This special issue of Annals of Human Biology arises from the 55th annual symposium of the Society for the Study of Human Biology in association with the British Association for Biological Anthropological and Osteoarchaeology held in Oxford, UK, from 9–11 December 2014. Only a selection of the presentations are included here which encompass some of the major recent advances in age estimation from the dentition and skeleton.

No

No / Research in facial age estimation has been active for over a decade. This is due to its numerous applications. Recently, convolutional neural networks (CNNs) have been used in an attempt to solve this age old problem. For this purpose, researchers have proposed various CNN architectures. Unfortunately, most of the proposed techniques have been based on relatively ‘shallow’ networks. In this work, we leverage the capability of an off-the-shelf deep CNN model, namely the VGG-Face model, which has been trained on millions of face images. Interestingly, despite being a simple approach, features extracted from the VGG-Face model, when reduced and fed into linear regressors, outperform most of the state-of-the-art CNNs. e.g. on both FGNET-AD and Morph II benchmark databases. Furthermore, contrary to using the last fully connected (FC) layer of the trained model, we evaluate the activations from different layers of the architecture. In fact, our experiments show that generic features learnt from intermediate layer activations carry more ageing information than the FC layers.

Cette étude teste l’hypothèse que le remodelage osseux dans le deuxième métacarpe peut être utilisé pour estimer l’âge à la mort. Les métacarpes utilisés dans cette analyse proviennent d’un cimetière d’Ontario, incluant des individus d’origine européenne (n=63; 34 hommes; 29 femmes). Leur âge varie de 19 à 61 ans (moyenne: 41,1±11,6). L’âge était connu ou a été estimé indépendamment à partir de la morphologie générale du squelette. À partir de lames minces coupées à la mi-diaphyse, la densité de population des ostéons (OPD; ostéons/mm2 intacts et fragmentaires) a été calculée pour huit colonnes du périoste à l’endoste, deux par quadrant anatomique. Les régressions par calibration classique ont produit une série d’équation pour les estimations de l’âge pour chaque sexe, sexes combinés, et en fonction de la latéralité. La méthode utilisée diminue l’efficacité des estimations mais elle a l’avantage de réduire les biais. Quand les sexes sont combinés, l’OPD est corrélé modérément mais significativement avec l’âge (droit r2= 0,35; gauche r2=0,28). Cependant, quand les hommes et les femmes sont analysés séparément, la corrélation entre l’OPD et l’âge dans l’échantillon féminin est meilleure (droit r2=0,48; gauche r2=0,39) alors que celle des hommes est réduite (droit r2=0,29; gauche r2=0,22). Ce résultat a déjà été observé dans d’autres études, mais n’est pas expliqué. Les résultats démontrent aussi une meilleure corrélation entre l’OPD et l’âge du côté droit que du côté gauche. Tous les résultats présentés ici supportent l’hypothèse que l’OPD du métacarpe est corrélé avec l’âge effectif (c’est-à-dire connu ou estimé), les régressions de l’OPD sur l’âge (droit-gauche combinés ou séparés, sexes combinés ou séparés) étant toutes significatives. / This preliminary study tests the hypothesis that evidence of bone remodeling in the second metacarpal can be used to estimate age at death. The metacarpals used in this analysis originated from an historic European sample from Ontario, Canada (n=63, 34 males and 29 females). They range in age from 19 to 61 years (mean=41.1±11.6). Age was known or independently estimated from gross morphology. For each right and left second metacarpal, Osteon Population Density (OPD; intact and fragmentary osteons/mm2) was recorded on four quadrants (anterior, posterior, medial, lateral), sampling two periosteal to endosteal columns separated by one column width. Classical calibration analysis produced a series of equations for estimates of age for each sex, sexes combined, and according to laterality. The method reduces the efficiency of estimates but has the advantage of reducing bias. When the sexes were combined, OPD correlated moderately but significantly with age (right r2=0.35, left r2= 0.28). However, when males and females were analyzed separately, the correlation between OPD and age in the female sample was improved (right r2=0.48, left r2=0.39) while the correlation in males was reduced (right r2=0.29, left r2=0.22). It remains unclear why the correlation is better in females than males, but similar results have been obtained in other studies. These results also indicate that there is a better correlation between OPD and age in the right second metacarpal than in the left. The results presented here support the hypothesis that the OPD of the metacarpal is correlated with chronological age (known or estimated) as all regressions of the OPD on age (right-left combined and separate, sexes combined and separated) are significant.

La morphométrie géométrique permet la visualisation dynamique 3D de la base du crâne et une prévision de leurs variations liées à la croissance. Le but de ce travail est de proposer des méthodes fiables et précises pour estimer l’âge fœtal et caractériser un stade de développement par sa conformation osseuse. Les os temporal, occipital et sphénoïde de 33 fœtus âgés de la 19ème à la 24ème semaine d’aménorrhée (S.A.) ont été reconstruits en 3D et 44 landmarks ont été positionnés. L’étude par morphométrie géométrique a permis de déterminer les maxima de variation morphologique, ainsi que d’étudier les trajectoires ontogénétiques. Les formules établies permettent l’estimation de l’âge à ±2,44 semaines. Les points de césure classiquement utilisés en anthropologie ont été confirmés. Nous avons établi une chronologie des conformations entre la 19ème, la 27ème et la 41ème S.A. L’os sphénoïde et occipital présentent un rythme de croissance commun alors que l’os temporal diffère. Nous avons confirmé ces structures anatomiques comme étant des critères indirects de maturation permettant d’estimer l’âge. / Geometric morphometric techniques allow the 3D visualization of the skull base and a forecast of their related growth variations. The aim of this work is to provide reliable and accurate methods to estimate fetal age and stage of development characterized by bone conformation. The temporal bone, occipital and sphenoid in 33 fetuses aged from the 19th to the 24th week of amenorrhea (W.A) were reconstructed in 3D and 44 landmarks were positioned. Geometric morphometrics was used to determine the maxima of morphological variation and ontogenetic trajectories. The established formulas allow the estimation of age at ±2.44 weeks. Hyphenation points conventionally used in anthropology have been confirmed. We have established a chronology of the conformations between 19th, 27th and 41st WA. The sphenoid and the occipital bone have a common growth rate, while the temporal bone differs. We confirmed these anatomical structures as indirect criteria of maturation to estimate age.