Comparative analysis of intragroup intermale relationships: a study of wild bonobos (Pan paniscus) in Wamba, Democratic Republic of Congo and chimpanzees (Pan troglodytes) in Kalinzu Forest Reserve, Uganda.

Although chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) share a multi-male/multi-female societal organization and form male-philopatric groups, disparities in terms of male aggression and stability of temporary parties are thought to exist among them. However, existing research in bonobos has mainly focused on the high social status, prolonged receptivity, and characteristic sexual behaviors of females, leaving the behaviors of males understudied. Moreover, prior comparative studies on Pan suffer from methodological inconsistencies. This study addresses these gaps by employing a uniform observation method to explore party attendance and aggressive interactions among male bonobos in Wamba and male chimpanzees in Kalinzu. Unlike male chimpanzees, which exhibit dispersion in the absence of receptive females in the group, male bonobos showed a lesser degree of such dispersion. Although the overall frequency of aggressive interactions per observation unit did not significantly differ between the two species, the nature of these interactions varied. Notably, severe aggressive behaviors such as physical confrontations among adult males were absent in bonobos, with most aggression occurring between the sons of the two highest-ranking females. Additionally, in bonobos, females actively engaged in polyadic aggressive behavior as aggressors, while all instances of coalitionary aggression in chimpanzees originated from male aggressors. These findings underscore the substantial impact of female behaviors on the observed distinctions in male aggressive interactions between the two species.

Mechanism for control of ball spin rate by the upper limb in baseball pitching based on singular value decomposition.

This study aims to examine the mechanism by which the ball spin rate during fastball pitching is controlled by synergistic joint torque. The participants were seven baseball players. The kinematics and kinetics of the fingers, wrist, elbow, and shoulder were calculated using the inverse dynamics method. The synergistic relationship between the joint torques was calculated using singular value decomposition. The similarity of the spatial pattern of the joint torque in each participant was evaluated using cosine similarity. The results indicated that there were three types of synergistic torque control: (1) two pitchers had a synergistic torque control that was primarily based on shoulder internal rotation torque, (2) two pitchers had a synergistic torque control that was primarily based on elbow extension torque, and (3) three pitchers had a synergistic torque control that was primarily based on shoulder horizontal adduction torque. In particular, pitchers with a high spin rate relative to the ball velocity (SPV) had a torque control of the shoulder internal rotation type. In contrast, pitchers with a low SPV had a torque control of the shoulder horizontal adduction type. It is considered that pitchers with a high SPV execute shoulder internal rotation torque, which has the same direction as that of ball spin, based on hierarchical control to increase the ball spin rate. These results suggest that pitchers with high and low SPVs exhibit different motor patterns. Pitchers and coach need to focus on the shoulder joint as well as the fingers when they throw fastball.

Estimation of tangential finger force and its relationship with the spin rate of pitched fastball.

This study had two objectives: (a) estimating the force exerted by pitchers in generating the spin of a fastball and (b) examining the factors that influence the spin rate of a fastball. Thirteen baseball pitchers participated in this study. The resultant forces acting on the ball was measured using an accelerometer placed in the baseball, and the force was decomposed into two frequency components using maximal overlap discrete wavelet transform. The intraclass correlation coefficients (ICC) between the integration of the high-frequency component of acceleration and the variation in the tangential velocity was high (ICC(3,1) = 0.64 ± 0.16). The ball spin per velocity (SPV) was significantly correlated with the peak value of the high-frequency component of the resultant forces (r = 0.66, p < 0.01). The high-frequency component of the resultant forces reflected the force in the tangential direction, and this force was one of the factors that adjusted the ball spin rate. The SPV did not significantly correlate with the peak value of the low-frequency component of the resultant forces (r = 0.50, p > 0.05). This indicates that decomposing the resultant forces into two frequency components is necessary to investigate the function of the finger during pitching.

Adaptive Party Choice of Low-Ranking Males in Fission-Fusion Dynamics of Chimpanzees in Kalinzu Forest Reserve, Uganda.

Several studies have examined factors that regulate fission-fusion dynamics (FFD) in chimpanzee communities, such as receptive females, predation risks, and food availability. However, the effects of these factors vary between populations. In this study, we conducted focal animal observations of adult males in the M group in Kalinzu to examine the influence of male dominance rank, aggression from other males, the presence of females exhibiting maximum sexual swelling (MS), and fruit abundance on male tendencies of party attendance. We found that low-ranking males spent more time alone than other males when females with MS were absent. In contrast, when females with MS were present, males of all ranks showed a similar tendency of party attendance. We also found that the aggressive interactions increased with the number of males irrespective of the presence or absence of females with MS, and low-ranking males attracted aggression more frequently than higher-ranking males. These results suggest that low-ranking males frequently ranged alone to avoid aggression from other males unless they attended parties to seek mating opportunities. We conclude that low-ranking males have alternative tactics to balance the costs and benefits incurred or gained when attending parties.

Do female bonobos (Pan paniscus) disperse at the onset of puberty? Hormonal and behavioral changes related to their dispersal timing.

Natal dispersal is a milestone in an animal's life history, but its timing in developmental trajectories may differ between species. Although the two Pan species exhibit a similar pattern of female-biased dispersal, female bonobos (P. paniscus) leave their natal groups at an earlier age than female chimpanzees (P. troglodytes). As a preliminary step to explore the dispersal strategies of female bonobos, this study aimed to determine the relations of sexual swelling development, behavioral and hormonal activation, and first ovulation relative to dispersal timing. We measured levels of urinary estrone conjugates (E1C) and pregnanediol glucuronide (PdG) from 14 nulliparous females in wild bonobo groups at Wamba in the Democratic Republic of the Congo, and recorded their copulations with mature males. When close to dispersal, female bonobos exhibited swelling of the sexual skin (labia minora and perianal region) that did not reach the mature stage. Urinary E1C levels and copulation rates increased slightly before dispersal and greatly increased after dispersal. Ovulatory or gestatory signs implied by daily hormone profiles were not detected until one to two years after dispersal. Our findings indicate that female bonobos disperse at an early pubertal stage before ovulatory cycling is established. This earlier dispersal than sexual maturation could allow female bonobos to postpone reproduction-related energy costs until they become familiar with their new group or gain more time finding the group more suitable for successful reproduction in the future before actually settling. Further demographic and genetic data from dispersal to reproduction will help clarify their dispersal strategies.

Kinetic Analysis of the Fingers Under Different Ball Velocities During Overarm Throwing.

The purpose of this study is to examine changes in the kinetic parameters of the fingers caused by differences in ball velocity during overarm throwing. Six baseball players participated in the study, and the kinetics of the wrist and metacarpophalangeal (MP) joint were calculated using an inverse dynamics method. The results of Tukey's multiple comparison tests showed that the torque and work of the wrist increased with increasing ball velocity (p < .05), indicating that wrist torque and work contributed to the adjustment of ball velocity. Peak MP joint torque also increased with ball velocity (p < .05), although the work of the MP joint remained relatively constant. We conclude that MP joint torque and work contribute to the achievement of stable ball release rather than adjusting ball velocity.

Kinetic analysis of the wrist and fingers during fastball and curveball pitches.

This study had two objectives: (a) revealing kinetic parameter differences at the fingers during a fastball and curveball, and (b) examining timing control between the wrist and finger torques. The participants were eight baseball pitchers. The kinetics of the wrist and fingers were calculated using an inverse dynamics method. The peak torque and work of finger adduction during the curveball was significantly larger than that during the fastball. During the fastball pitch, the maximal correlation coefficient between the wrist flexion torque and finger flexion torque was very high (r = 0.94 ± 0.05). The reasons for this result are twofold: (a) the extrinsic finger muscles cross the wrist (biarticular muscle) and (b) the wrist flexion torque during the fastball pitch acts in the direction of acceleration of the ball. During the curveball pitch, we found two typical types of wrist and finger torque control. Furthermore, the two pitchers exerted large wrist extension and radial torque, and finger adduction torque. Although the other six pitchers hardly exerted these torques, they exerted wrist flexion torque predominantly. It was considered that the six pitchers selected wrist flexion torque as the control for the fastball and curveball pitch to confuse the batter.

Kinetic Analysis of Fingers During Aimed Throwing.

This study had two objectives: (a) revealing the difference in finger segments between the conventional and finger models during aimed throwing and (b) examining the central nervous system's timing control between the wrist torque and finger torque. Participants were seven baseball players. Finger kinetics was calculated by an inverse dynamics method. In the conventional model, wrist flexion torque was smaller than that in the finger model because of the error in ball position approximation. The maximal correlation coefficient between the wrist torque and finger torque was high (r = .85 ± .10), and the time lag at maximal correlation coefficient was small (t = 0.36 ± 3.02 ms). The small timing delay between the wrist torque and finger torque greatly influenced ball trajectory. We conclude that, to stabilize release timing, the central nervous system synchronized the wrist torque and finger torque by feed-forward adjustments.

Overexpression of eukaryotic elongation factor eEF2 in gastrointestinal cancers and its involvement in G2/M progression in the cell cycle.

A high level protein synthesis is one of the characteristics of cancer cells. The aim of this study is to show the contribution of eukaryotic elongation factor 2 (eEF2), which plays an essential role in the polypeptide chain elongation step, in the tumorigenesis of gastrointestinal cancers. In the present study, we demonstrated by using immunohistochemistry that eEF2 protein was overexpressed in 92.9% (13 of 14) of gastric and 91.7% (22 of 24) of colorectal cancers. No mutations were found in any of the exons of the eEF2 gene in six gastric and six colorectal cancers. Knockdown of eEF2 by eEF2-specific short-hairpin RNA (shEF2) inhibited cancer cell growth in two gastric cancer cell lines, AZ-521 and MKN28, and one colon cancer cell line, SW620. Flow cytometric analysis showed that knockdown of eEF2 induced G2/M arrest and resulted in inactivation of Akt and cdc2 (a G2/M regulator) and activation of eEF2 kinase (a negative regulator of eEF2) in these cancer cells. Conversely, forced expression of eEF2 in AZ-521 cells significantly enhanced the cell growth through promotion of G2/M progression in cell cycle, activated Akt and cdc2, and inactivated eEF2 kinase. Furthermore, forced expression of eEF2 in these cancer cells enhanced in vivo tumorigenicity in a mouse xenograft model. These results showed that overexpressed eEF2 in gastrointestinal cancers promoted G2/M progression and enhanced their cell growth in vitro and in vivo. These results also suggested a novel linkage between translational elongation and cell cycle mechanisms, implying that the linkage might play an important role to orchestrate the deregulated translation and cell cycle mechanisms for promotion of the development of gastrointestinal cancers.