Sex-related variation in compact bone microstructure of the femoral diaphysis in juvenile rabbits

<p>Abstract</p> <p>Background</p> <p>While gross morphological changes in the skeleton between males and females are well know, differences between sexes in the histomorphology are less known. It is important to have knowledge on the bone structure of rabbits, as this is a widely used species in biomedical research. A study was performed to evaluate the association between sex and the compact bone morphology of the femoral diaphysis in juvenile rabbits.</p> <p>Methods</p> <p>Seventeen clinically healthy 2–3 month-old rabbits (9 females, 8 males) were included in the study. The rabbits were euthanized and the right femur was sampled for analysis. 70–80 microns thick bone sections of the femoral diaphysis were prepared using standard histological equipment. The qualitative histological characteristics were determined according to internationally accepted classification systems while the quantitative parameters were assessed using the software Scion Image. Areas, perimeters, minimum and maximum diameters of primary osteons' vascular canals, Haversian canals and secondary osteons were measured. Additionally, blood plasma concentrations of progesterone, corticosterone, IGF-I, testosterone and estradiol were analyzed.</p> <p>Results</p> <p>Qualitative histological characteristics were similar for both sexes. However, variations of certain quantitative histological characteristics were identified. Measured parameters of the primary osteons' vascular canals were higher in males than for females. On the other hand, females had significant higher values of secondary osteons parameters. Differences in Haversian canals parameters were only significant for minimum diameter.</p> <p>Conclusion</p> <p>The study demonstrated that quantitative histological characteristics of compact bone tissue of the femoral diaphysis in juvenile rabbits were sex dependent. The variations may be associated with different growth and modeling of the femur through influence by sex-specific steroids, mechanical loads, genetic factors and a multitude of other sources. The results can be applied in experimental studies focusing on comparison of the skeletal biology of the sexes.</p

The evolutionary psychology of leadership trait perception

Knowles, Kristen K. - ORCID 0000-0001-9664-9055 https://orcid.org/0000-0001-9664-9055Many researchers now approach the understanding of how facial characteristics shape the perception of leadership ability through the lens of human evolution. This approach considers what skills and characteristics would have been valuable for leaders to possess in our evolutionary history, including dominance, masculinity, and trustworthiness. Moreover, it gives an understanding about why rapid categorisation of these social cues from faces is adaptive. In this chapter, I present evolutionary arguments for social inferences based on faces, and discuss how our understanding of this categorisation has shifted away from purely associative phenomena towards evolved, innate processes. I explain how the perception of leadership ability in faces is linked to variance in facial morphology, and how these morphologies tell us something about the individuals who carry them. Specific facial cues relating to leadership-relevant traits are discussed, as well as the underlying biological systems that accompany these traits. I also explain the importance of context and individual differences on the prioritisation of seemingly disparate facial cues to leadership: dominance and trustworthiness. I also discuss recent findings in this area which further extend these concepts to examine cues to leadership in women’s faces, generally overlooked by evolutionary psychologists, and how political ideology can interact with these effects.https://doi.org/10.1007/978-3-319-94535-4_5pubpu