Adaptive Human Behavior and Physiology最新文献

Objectives

The male warrior hypothesis suggests that men have evolved psychological mechanisms to form aggressive coalitions against members of outgroups, which may explain men’s propensity to engage in warfare, as well as team sports. We examined gender differences in skin conductivity and attitudes toward war after exposing participants to video imagery depicting sports and war from a sample of young adults from Slovakia.

Methods

We measured skin conductivity responses using electrodermal activity (EDA) when participants watched three short videos: Football, World War II, and Control. Then, implicit and explicit attitudes toward war and subjective arousal of the three videos were examined using questionnaires.

Results

Men showed higher maximal skin conductivity when watching a team sport video, compared to a control video. Skin conductivity during a war video did not significantly differ from a sport or control video. In contrast, women showed highest maximal skin conductivity when watching a war video, followed by the sport and control videos, but these differences were not statistically significant. When the videos were subjectively rated by the same participants, men rated team sports and war as similarly arousing, but ratings of these videos were not significantly different for women.

Conclusions

These results suggest that visual cues of warfare and team sports influence skin conductivity, but we did not find support for the hypothesis that sport is a substitute for war. Because this study was based exclusively on visual cues, we discuss additional possibilities that could influence future investigations.

Energy is a finite resource that is competitively distributed among the body’s systems and biological processes. During times of scarcity, energetic “trade-offs” may arise if less energy is available than is required to optimally sustain all systems. More immediately essential functions are predicted to be prioritized, even if this necessitates the diversion of energy away from – and potential downregulation of – others. These concepts are encompassed within life history theory, an evolutionary framework with considerable potential to enhance understanding of the evolved biological response to periods of energy deficiency. Skeletal muscle is a particularly interesting tissue to investigate from this perspective, given that it is one of the largest and most energetically costly tissues within the body. It is also highly plastic, responsive to a broad range of stimuli, and contributes to many essential bodily functions, e.g., mechanical, regulatory and storage. These functions may be traded off against each other during periods of energy deficiency, with the nature of the trade-off’s dependent on the characteristics of the individual and the circumstances within which the deficit occurs. In this review, we consider the skeletal muscle response to periods of energy deficiency from a life history perspective, along with how this response may be influenced by factors including sex, age, body composition, training and nutritional status.

Objectives

This review will describe how human exercise performance at the highest level is exquisitely orchestrated by a set of responses by all body systems related to the evolutionary adaptations that have taken place over a long history. The review will also describe how many adaptations or features are co-opted (exaptations) for use in different ways and have utility other than for selective advantage.

Methods

A review of the literature by relevant search engines and reference lists in key published articles using the terms, performance, limitations, regulation, trade-offs as related to exercise, indicates that there are at least three areas which could be considered key in understanding the evolutionary basis of human exercise performance.

Results

First, there is a basic assumption that exaptations have limitations or capacities which cannot be exceeded which in turn will limit our physical performance. Second, it is thought that some biological systems and tissues have additional capacity which is rarely fully accessed by the organism; referred to as a safety factor. Third, there are biological trade-offs which occur when there is an increase in one trait or characteristic traded for a decrease in another.

Conclusions

Adaptations have resulted in safety factors for body systems and tissues with trade-offs that are most advantageous for human performance for a specific environment.

Objective

A suite of adaptations facilitating endurance running (ER) evolved within the hominin lineage. This may have improved our ability to reach scavenging sites before competitors, or to hunt prey over long distances. Running economy (RE) is a key determinant of endurance running performance, and depends largely on the magnitude of force required to support body mass. However, numerous environmental factors influence body mass, thereby significantly affecting RE. This study tested the hypothesis that alternative metabolic strategies may have emerged to enable ER in individuals with larger body mass and poor RE.

Methods

A cohort of male (n = 25) and female (n = 19) ultra-endurance runners completed submaximal and exhaustive treadmill protocols to determine RE, and V̇O_2Max.

Results

Body mass was positively associated with sub-maximal oxygen consumption at both LT1 (male r=0.66, p<0.001; female LT1 r=0.23, p=0.177) and LT2 (male r=0.59, p=0.001; female r=0.23, p=0.183) and also with V̇O_2Max (male r=0.60, p=0.001; female r=0.41, p=0.046). Additionally, sub-maximal oxygen consumption varied positively with V̇O_2Max in both male (LT1 r=0.54, p=0.003; LT2 r=0.77, p<0.001) and female athletes (LT1 r=0.88, p<0.001; LT2 r=0.92, p<0.001).

Conclusions

The results suggest that, while individuals with low mass and good RE can glide economically as they run, larger individuals can compensate for the negative effects their mass has on RE by increasing their capacity to consume oxygen. The elevated energy expenditure of this low-economy high-energy turnover approach to ER may bring costs associated with energy diversion away from other physiological processes, however.

Objectives

The potential differences between phylogenetic threats (e.g., snakes) and ontogenetic threats (e.g., guns) can have a wide-ranging impact on a variety of theoretical and practical issues, from etiology of specific phobias to stimulus selection in psychophysiological studies, yet this line of research has not been systematically reviewed.

Methods

We summarize and synthesize findings from fear conditioning, illusory correlation, attention bias, and neuroimaging studies that have compared these two types of threats to human survival.

Results

While a few brain imaging studies reveal preliminary evidence for different brain networks involved in the processing of phylogenetic and ontogenetic threats, attention bias studies tentatively show faster reaction time for modern threats, illusory correlation bias is evident for both types of threats, and fear conditioning studies are far from conclusive.

Conclusions

The results of behavioral experiments, especially attention bias research, pose a challenge to established theories like biological preparedness and fear module, as they show faster reaction time to modern threats, which is the opposite of what some evolutionary theories predict. We discuss the findings in terms of other theories that might explain the same results and conclude with potential future directions.

Objectives

Our objective was to study performance trade-offs in elite athletes competing in a multi-event sport requiring a combination of aptitudes that might conflict each other. Swimmers competing in the individual medley, in particular, might face trade-offs as they have to swim (in this specific order) a quarter of the distance in butterfly, backstroke, breaststroke, and freestyle within a single race.

Methods

We applied multivariate mixed models to analyse 28 years (1991–2019) of publicly available data on men (N = 121) and women (N = 131) swimmers competing for the 200 m individual medley in the semi-final and final rounds of Olympics and world championships.

Results

At the among-individual level, performance in the backstroke and breaststroke were negatively correlated in both men (r_ind = −0.264 ± 0.126) and women (r_ind = −0.453 ± 0.103). At the within-individual level, there was a negative correlation between performance in the first and final 50 m of the race in men (r_e = −0.181 ± 0.055), but not in women (r_e = 0.001 ± 0.058).

Conclusions

To our knowledge, this is the first demonstration of a trade-off between backstroke and breaststroke swimming styles. Such a trade-off might be caused by various extrinsic (e.g., allocation of training time across the four strokes) and intrinsic (e.g., body morphology and muscle physiology) constraints on human performance. The difference in the pattern of within-individual correlations between men and women aligns with pacing strategies described in the literature. Further research is required to better understand the nature of the trade-offs detected here, which could potentially help improving training strategies for the “generalist” individual medley swimmer.

Objectives

The purpose of this study is to provide a descriptive account of salivary testosterone levels in women in relation to being an athlete, sporting level, competitive context, and oral contraceptive (OC) use and, to explore the relationship between testosterone levels and performance in a task of competitive persistence.

Methods

Saliva samples were collected from teams of women athletes at the recreational, collegiate varsity, and elite-international levels, and a university participant-pool sample of athletes and non-athletes (N = 253). Among the elite athletes, additional saliva samples were collected before and after on- and off-field training sessions and competition. University participants competed in a timed weight-holding competition in the laboratory.

Results

Testosterone levels were highest in elite athletes compared to university students (η² = .07) and were elevated in the context of competitive training (+13–51%) and formal competition (69%) contexts. OC users had significantly lower testosterone levels than non-users (η² = .14). For university athletes, testosterone levels were positively correlated with performance in a task of competitive persistence (R² = .23). OC use was associated with lower competitive persistence (d = .42) – a relationship explained by OC users’ lower testosterone levels relative to non-users (d = 1.32).

Conclusions

Results suggest that salivary testosterone levels in women may depend on sport participation and OC use, are malleable to competitive contexts, and among athletes, are positively related to competitive task persistence. Given the testosterone suppressing effects of OC use, this study provides insight on psychophysiological risks of OC use that could be relevant to sport performance.

Objectives

There is evidence suggesting that in martial arts competitions athletes characterized by higher anxiety and harm avoidance may be more likely to lose a fight. This psychological profile has been hypothesized to explain in part the observation that cortisol is higher in losers before and in response to a competition. An important research target that needs further exploration is the identification of phenotypic traits that can be helpful in predicting athletes’ performance. Here we present a brief description of the theoretical bases that drives our research in the evolutionary psychobiology of sports and illustrate preliminary data on the relationship between the 5HTTLPR genotype, salivary cortisol, temperament and competition.

Methods

Sixty-five healthy male non-professional athletes provided saliva samples 10 min before and after a kumite session and filled out the Tridimensional Personality Questionnaire.

Results

Salivary cortisol levels 10 min before the competition were higher in losers and in athletes with the S allele. Temperament was associated with competition outcome and cortisol: losers were characterized by higher scores of harm avoidance and harm avoidance was positively correlated with cortisol levels.

Conclusions

The results confirm previous findings linking temperamental traits, pre-and post- competition physiological stress response with competition outcome in kumite fight. Moreover, they indicate an association between the 5HTTLPR polymorphism and pre-competition salivary cortisol, thus providing a preliminary but non-conclusive evidence on the role played by the 5HTTLPR genotype as a vulnerability factor in sport competition.

Objective

Although male relatives tend to sway people toward, and female relatives tend to sway people away from conservative political attitudes, there exist many ways in which family composition might cause these effects. Here we test several pathways whereby family might influence attitudes toward female veiling, gender stereotypes, and status-seeking in Pakistan.

Methods

Research assistants administered a survey to a diverse sample of 538 adults in Karachi neighborhoods of varying socio-economic status. Within each neighborhood we selected households and available adults within households randomly. Surveys captured socio-demographic data about the participant and their household, and their opinion on family structures, culture, gender roles, religion, and female attire.

Results

We find that likelihood of deriving future reproductive fitness from males increases status-seeking and stereotypes of women as warm and kind but decreases support for women having the right to choose whether to wear a veil in public. In contrast, deriving future fitness from females leads people to stereotype women as less warm but highly competent. Family effects were distinguishable from those deriving from an individual’s own sex.

Conclusions

Findings suggest that the inclusive fitness people gain through relatives of each gender may be one of the factors responsible for family effects, shifting dimensions of social cognition and swaying attitudes relevant to sexual conflict.