Abstract: Jugular vein blood samples were collected from 23 young and sexual mature feral stallions to examine the relationship between plasma testosterone concentration and age, breeding season or harem size. Testosterone concentration increased with the age of the stallions until they formed their own harems, at about 4 to 6 years old. Seasonal variations in testosterone concentrations were observed, and found to be significantly higher (P<0.001) throughout the breeding season than non-breeding season, from 3 years of age. Testosterone levels were correlated with harem size for individual stallions. It can be inferred from these results that there is a relationship between plasma testosterone concentration and age, breeding season and harem size.

Abstract: The acoustic features of 216 baboon grunts were investigated through analysis of field-recorded calls produced by identified females in known contexts. Analyses addressed two distinct questions: whether the acoustic features of these tonal sounds could be characterized using a source-filter approach and whether the acoustic features of grunts varied by individual caller and social context. Converging evidence indicated that grunts were produced through a combination of periodic laryngeal vibration and a stable vocal tract filter. Their acoustic properties closely resembled those of prototypical human vowel sounds. In general, variation in the acoustic features of the grunts was more strongly related to caller identity than to the social contexts of calling. However, two acoustic parameters, second formant frequency and overall spectral tilt, did vary consistently depending on whether the caller was interacting with an infant or participating in a group move. Nonetheless, in accordance with the general view that identity cueing is a compelling function in animal communication, it can be concluded that much of the observed variability in grunt acoustics is likely to be related to this aspect of signaling. Further, cues related to vocal tract filtering appear particularly likely to play an important role in identifying individual calling animals.

Abstract: Maloney, SJ. The relationship between asymmetry and athletic performance: A critical review. J Strength Cond Res 33(9): 2579-2593, 2019--Symmetry may be defined as the quality to demonstrate an exact correspondence of size, shape, and form when split along a given axis. Although it has been widely asserted that the bilateral asymmetries are detrimental to athletic performance, research does not wholly support such an association. Moreover, the research rarely seeks to distinguish between different types of bilateral asymmetry. Fluctuating asymmetries describe bilateral differences in anthropometric attributes, such as nostril width and ear size, and are thought to represent the developmental stability of an organism. There is evidence to suggest that fluctuating asymmetries may be related to impaired athletic performance, although contradictory findings have been reported. Sporting asymmetries is a term that may better describe bilateral differences in parameters, such as force output or jump height. These asymmetries are likely to be a function of limb dominance and magnified by long-standing participation within sport. Sporting asymmetries do not seem to carry a clear influence on athletic performance measures. Given the vast discrepancy in the methodologies used by different investigations, further research is warranted. Recent investigations have demonstrated that training interventions can reduce sporting asymmetries and improve performance. However, studies have not sought to determine whether the influence of sporting asymmetry is independent of improvements in neuromuscular parameters. It may be hypothesized that the deficient (weaker) limb has a greater potential for adaptation in comparison to the strong limb and may demonstrate greater responsiveness to training.

Abstract: We studied the relationship of reciprocity, gender, and racial composition (Caucasian, African American, cross-race) of adolescent friendship dyads to similarity and proximity in 136 young adolescents. We found that adolescents selected friends who were of the same gender and race and that female dyads were more similar than male dyads on verbal achievement and several personality dimensions. Caucasian dyads were more similar than African American dyads on verbal achievement, mental alertness, and dominance. African American adolescents had more contact with their best friends outside school, whereas Caucasian adolescent friends had more in-school contact. African American students had fewer reciprocal relationships than the Caucasian students. Cross-race friendships were less reciprocal than same-race friendships. Race and gender were important in determining friendship patterns. Similarity and proximity were more important than reciprocity in understanding early adolescent friendships.