Systematic mapping of developmental milestones in wild chimpanzees

Postnatal development is protracted relative to lifespan in many primates, including modern humans (Homo sapiens), facilitating the acquisition of key motor, communication and social skills that can maximize fitness later in life. Nevertheless, it remains unclear what evolutionary drivers led to extended immature periods. While the developmental milestone literature is well established in humans, insight we can gain from one‐species models is limited. By comparing the timing of relatable developmental milestones in a closely related species, the chimpanzee (Pan troglodytes), we can gain further understanding of the evolution of such an extended developmental phase. To date, few studies have specifically attempted to estimate developmental milestones in a manner comparable to the human literature, and existing studies lack sufficient sample sizes to estimate which milestones are more plastic with higher inter‐individual variation in the timing of their emergence. Here, we describe the emergence of gross motor, fine motor, social interaction and communication traits from a longitudinal sample of 19 wild chimpanzee infants (8 females and 11 males), Taï National Park, Côte d’Ivoire. Gross motor traits emerged at a mean of 4 months, communication traits at 12 months, social interaction traits at 14 months and fine motor traits at 15 months, with later emerging milestones demonstrating greater inter‐individual variation in the timing of the emergence. This pattern of milestone emergence is broadly comparable to observations in humans, suggesting selection for a prolonged infantile phase and that sustained skills development has a deep evolutionary history, with implications for theories on primate brain development.     

Continuity in Problems of Social Functioning in Adulthood: A Cumulative Perspective

Based on an ongoing longitudinal study involving 145 women and 152 men, this study analyzed the continuity in and accumulation of problems of social functioning from age 27 (year 1986) to age 36 (year 1995), and studied sex differences in these processes. The accumulation of problems of social functioning (e.g., poor financial standing, poor intimate relationships, and drinking problems) was more common in men than in women at both ages. Sex differences, however, narrowed because problems increased only among women during the follow-up period. Continuity, both in accumulated problems and in good social functioning, was stronger than continuity in single problems, as assumed on the basis of the theory of problem gravitation. The proportion of individuals with either accumulated problems or with good social functioning did not, however, increase relative to individuals with single problems, as the theory of problem gravitation has suggested. Continuity in problems of social functioning was partly mediated by career instability among both sexes. There was also a tendency for the quality of partner to moderate the relation between problems of social functioning between the two ages; in particular, a problematic partner was likely to add to women's problems.     

Crossover between work and home in dyadic partner relationships

This study aimed at providing insight into the processes underlying crossover between "work" and "home" in dyadic partner relationships. Specifically, we examined to what extent husbands' work demands (work load and overtime hours) and psychological health (fatigue and depressive symptoms) "cross over" to their wives' home demands (home load) and psychological health. These associations were investigated among three couple groups, based on wives' working hours (i.e., more than 20 hours per week, from 1 to 20 hours per week, and not engaged in paid work) (253 couples in total). All husbands worked for at least 35 hours a week. Three possible crossover mechanisms were hypothesized: (i) time-based, (ii) strain-based, and (iii) empathy-based crossover. The results partially supported mechanisms (i) and (ii): when husbands reported higher work load (mechanism i) and more psychological health complaints (mechanism ii), their wives experienced higher home load. The results further supported mechanism (iii) that wives' and husbands' psychological health were associated. It is concluded that crossover from husbands to wives may occur through various mechanisms.     

Long-Term Development of Employee Well-Being: A Latent Transition Approach

The long-term development of employee well-being is still poorly understood. Consequently, in this three-wave 10-year longitudinal study among Finnish managers (n = 402) the development of employee well-being was examined in in detail. Specifically, the long-term development of job-related affective well-being was investigated at the intra-individual level, simultaneously taking into account positive and negative indicators of well-being, the level of well-being, and the direction of change. Further, the issue how (changes in) job resources and employee well-being were related across time was examined. By applying a novel person-centered methodology, factor mixture modeling and latent transition analysis, the results revealed that the development of favorable job-related affective well-being was eight times more probable than that of unfavorable development across the 10-year study period. Job resources predicted a high level of job-related well-being and, also, job resources increased along with favorable changes in well-being. Overall, the findings contribute to knowledge in the area of positive occupational health psychology by offering a detailed picture of the level of job-related affective well-being and its development over time.     

Should I stay or should I go? Initiation of joint travel in mother–infant dyads of two chimpanzee communities in the wild

It is well established that great apes communicate via intentionally produced, elaborate and flexible gestural means. Yet relatively little is known about the most fundamental steps into this communicative endeavour—communicative exchanges of mother–infant dyads and gestural acquisition; perhaps because the majority of studies concerned captive groups and single communities in the wild only. Here, we report the first systematic, quantitative comparison of communicative interactions of mother–infant dyads in two communities of wild chimpanzees by focusing on a single communicative function: initiation of carries for joint travel. Over 156 days of observation, we recorded 442 actions, 599 cases of intentional gesture production, 51 multi-modal combinations and 80 vocalisations in the Kanyawara community, Kibale National Park, Uganda, and the Taï South community, Taï National Park, Côte d’Ivoire. Our results showed that (1) mothers and infants differed concerning the signal frequency and modality employed to initiate joint travel, (2) concordance rates of mothers’ gestural production were relatively low within but also between communities, (3) infant communicative development is characterised by a shift from mainly vocal to gestural means, and (4) chimpanzee mothers adjusted their signals to the communicative level of their infants. Since neither genetic channelling nor ontogenetic ritualization explains our results satisfactorily, we propose a revised theory of gestural acquisition, social negotiation, in which gestures are the output of social shaping, shared understanding and mutual construction in real time by both interactants.     

Sport competition anxiety and sex role

Competitive trait anxiety scores, measured by the Sport Competition Anxiety Test, were obtained from subjects of both sexes. Subjects also were classified into one of five sex-role endorsement categories according to scores on the Bem Sex Role Inventory. It was predicted that greater endorsement of a feminine sex role, regardless of sex of the subject, would be associated with high levels of competitive trait anxiety. Analysis of variance showed no significant difference for sex of subject, but significant differences for both sex-role endorsement and sex × endorsement interaction. Both differences were attributed to male subjects' responses. Generally, masculine males were less anxious than other subjects, while feminine males were more anxious. There were no significant differences among female groups.The author expresses thanks to Elizabeth Y. Poland and Robert E. Hill, Jr., for their numerous helpful comments during the preparation of this article.     

A comparison of general and illness-related locus of control in Russians, ethnic German migrants and Germans

General and illness-related locus of control play an immensely important role in the adherence and cooperation of patients in their therapy. Until now, culture-specific aspects of these subjective theories have rarely been investigated. However, in view of the growing proportion of migrants in the German population, they are becoming increasingly significant. In a project supported by the Volkswagenstiftung (Volkswagen Foundation), a total of 607 healthy people were surveyed. The sample includes 307 ethnic German migrants from the successor states of the former Soviet Union (descendents of German origin who had emigrated to Russia during the 18th and 19th centuries) and 300 native Russians in Russia. They were compared with 100 Germans (matched from a previous study). The data were collected using questionnaires entitled "Multidimensional Health Locus of Control (MHLC)" and "Illness-related Locus of Control". The ethnic German migrants differed from the Russian sample in their health beliefs and attitudes towards medicine. However, in the first 18 months after migration, hardly any changes were observed. Fatalistic factors played only a minor role. Locus of health control was associated with beliefs about recovery from myocardial infarcts and tumours. Socio-demographic variables were of varying significance in the individual cultures. Gender influences on health beliefs were different in the subsamples. The level of education had only a minor influence on health attitudes. For those individuals who were acquainted with an ill person, internal factors in treatment of myocardial infarct and external psychosocial factors in cure of cancer played a larger role.     

Job demands and resources as antecedents of work engagement: A longitudinal study

By utilizing a 2-year longitudinal design, the present study investigated the experience of work engagement and its antecedents among Finnish health care personnel (n = 409). The data were collected by questionnaires in 2003 (Time 1) and in 2005 (Time 2). The study showed that work engagement—especially vigor and dedication—was relatively frequently experienced among the participants, and its average level did not change across the follow-up period. In addition, the experience of work engagement turned out to be reasonably stable during the 2-year period. Job resources predicted work engagement better than job demands. Job control and organization-based self-esteem proved to be the best lagged predictors of the three dimensions of work engagement. However, only the positive effect of job control on dedication remained statistically significant after controlling for the baseline level of work engagement (Time 1).     

The factor structure and factorial invariance of the 12-item General Health Questionnaire (GHQ-12) across time: evidence from two community-based samples

This study provides new knowledge about the factor structure of the 12-item General Health Questionnaire (GHQ-12; D. Goldberg, 1972) through the application of confirmatory factor analysis to longitudinal data, thereby enabling investigation of the factor structure, its invariance across time, and the rank-order stability of the factors. Two community-based longitudinal adult samples with 1-year (n = 640) and 6-year (n = 330) follow-up times were studied. As a result, the correlated 3-factor model (i.e., Anxiety/Depression, Social Dysfunction, and Loss of Confidence) showed a better fit with both samples than the alternative models. The correlated 3-factor structure was also relatively invariant across time in both samples, indicating that the scale has good construct validity. The rank-order stabilities of the factors were low across time, which suggests that the GHQ-12 measures temporal mental state.