Social Selection Hypotheses Research Articles

Models of animal coalitions and their implications for human evolution.

Social interaction is a prime driver for the evolution of animal behaviour. Dyadic interaction, in particular, has been the focus of intensive research on the evolution of mutualistic, altruistic, selfish or spiteful behaviours. Meanwhile, triadic interaction has been the minimal framework for the study of animal coalition as observed in some species of primates, as well as in carnivores and cetaceans, where two or more individuals act jointly against a third party in a competitive context. Previous mathematical models of animal coalition have either failed to explain the observed diversity in the configuration of coalition or presumed fine-tuned decision-making that may be unrealistic for non-human animals. To approach these issues, the present study develops a new model that is fairly simple, but still able to account for the observed diversity in animal coalitions. Analysis of the model specifies key parameters affecting the predicted types of coalition: the nature of the benefit being contested, the cost-to-benefit ratio associated with fighting and the synergistic effect in coalition formation. Additionally, the model is used to evaluate the social selection hypothesis, which claims that coalition formation induced social selection favouring reduced aggression and lower fighting abilities during human evolution.

Sexual selection, feather wear, and time constraints on the pre-basic molt explain the acquisition of the pre-alternate molt in European passerines.

Avian feathers need to be replaced periodically to fulfill their functions, with natural, social, and sexual selection presumably driving the evolution of molting strategies. In temperate birds, a common pattern is to molt feathers immediately after the breeding season, the pre‐basic molt. However, some species undergo another molt in winter‐spring, the pre‐alternate molt. Using a sample of 188 European passerine species, Bayesian phylogenetic mixed models, and correlated evolution analyses, we tested whether the occurrence of the pre‐alternate molt was positively associated with proxies for sexual selection (sexual selection hypothesis) and nonsexual social selection (social selection hypothesis), and with factors related to feather wear (feather wear hypothesis) and time constraints on the pre‐basic molt (time constraints hypothesis). We found that the pre‐alternate molt was more frequent in migratory and less gregarious species inhabiting open/xeric habitats and feeding on the wing, and marginally more frequent in species with strong sexual selection and those showing a winter territorial behavior. Moreover, an increase in migratory behavior and sexual selection intensity preceded the acquisition of the pre‐alternate molt. These results provide support for the feather wear hypothesis, partial support for the sexual selection and time constraints hypotheses, and no support for the social selection hypothesis.

Does Social Class Matter Equally for the Timely Transition Into and Out of College? Evidence from the NLSY97

Although the positive relationship between social determinants and college attainment is well established, less is known about how social class specifically relates to the linear and timely completion of postsecondary degrees. In this paper, we empirically examine on-time completion of bachelor’s degrees using social class proxies for a national sample of U.S. high school graduates, using the life course perspective and social selection hypothesis to contextualize social effects on the two key transitions—timely full-time enrollment and timely degree completion—that bound the traditional 4-year college pathway. We find strongly positive associations between several social indicators and attainment of both transition events, although effects are larger and more numerous for the initial transition, indicating social selection may be more influential in launching the 4-year college pathway than in completing it. Gradients of social advantage also appear more complexly gendered and racialized at the start of the college pathway than at the end. Finally, we confirm that parenthood is highly incompatible with a 4-year path to a degree regardless of social class and conspicuously more likely to interfere with the timely completion of a bachelor’s degree than other major life transitions.

Conspicuous female plumage is common among open cup-nesting passerine birds

Alfred Russel Wallace hypothesized that the use of cavity or dome nests releases incubating birds from predation risk, and that this allows the evolution of conspicuous coloration in females. By this hypothesis, females that use open nests are subject to strong selection for crypsis. Here, we test the validity of Wallace’s proposed evolutionary correlation between nest type and conspicuous coloration in females across the largest avian radiation, the Passeriformes, using phylogenetic comparative methods. We also test an alternate hypothesis that cavity-nesting results in greater conspicuousness because competition for cavities is stronger than for other nest sites, and such competition can drive social selection on female plumage. By this hypothesis, dome-nesting females should generally be less conspicuous than cavity-nesting species. We found no support for Wallace’s hypothesis that concealed nests yield conspicuous plumage while open nests yield dull plumage, and some support for the social selection hypothesis in smaller-bodied, gregarious species. While our analyses do not support the core part of Wallace’s hypothesis, they corroborate his contention that evolutionary transitions in nest type are rare, indicating that nest types may influence macroevolutionary selective regimes for other traits.

Understanding the association between material hardship and posttraumatic stress disorder: a test of the social selection and social causation hypotheses and an exploration of gender differences.

There is a well-established association between poverty and posttraumatic stress disorder (PTSD); however, little research has tested the temporality of the association. Using data from Waves IV (2008; N = 14,800) and V (2016-2018; N = 10,685) of the National Longitudinal Study of Adolescent to Adult Health, we examined temporal associations between material hardship (a specific operationalization of poverty) and PTSD, as well as assessed for potential gender differences in associations. We conducted logistic regression and generalized structural equation modeling to examine associations between material hardship and PTSD and assess for mediation and moderation by gender. Prior PTSD diagnoses were associated with an increased likelihood of material hardship (OR = 1.64; 95% CI 1.21, 2.21). The indirect effect of gender on material hardship through PTSD diagnoses was significant. Prior material hardship was associated with an increased likelihood of PTSD diagnoses (OR = 1.81; 95% CI 1.35, 2.42). The indirect effect of gender on PTSD diagnoses through material hardship was significant. There was no evidence of moderation by gender for either association. Results suggest reciprocal associations between material hardship and PTSD. Economic policies, as well as improved access to evidence-based PTSD treatments, may reduce the burden of both material hardships and PTSD.

Carotenoids-based reddish pelvic spines in nonreproducing female and male sticklebacks (Gasterosteus aculeatus) - Signalling social dominance?

Conspicuous ornaments are often considered a result of evolution by sexual selection. According to the social selection hypothesis, such conspicuous traits may also evolve as badges of status associated with increased boldness or aggression toward conspecifics in conflicts about ecological resources. This study tested predictions from the social selection hypothesis to explain evolution of conspicuous red color of the pelvic spines of the three‐spine stickleback (Gasterosteus aculeatus). Wild nonreproducing sticklebacks were presented to pairs of dummies which differed at their pelvic spines, having either (i) normal‐sized gray or red pelvic spines or (ii) normal‐sized gray or large red pelvic spines. The experimental tank was illuminated by white or green light, since green light impedes the sticklebacks’ ability to detect red color. The dummies moved slowly around in circles at each end of the experimental tank. We quantified the parameters (i) which of the two dummies was visited first, (ii) time taken before the first visit to a dummy, (iii) distribution of the focal sticklebacks in the two zones close to each of the two dummies and in the neutral zone of the tank, (iv) close to which of the two dummies did the focal fish eat its first food‐piece, and (v) time spent until the first piece of food was eaten. This was carried out for 22 females and 29 males sticklebacks. The results suggested no effect of the color or size of the dummies’ pelvic spines, on none of the five behavioral parameters. Moreover, neither the color of the pelvic spines of the focal sticklebacks themselves (as opposed to redness of the dummies’ spines) nor their body length was associated with behavior toward the dummies. Thus, this study did not support predictions from the social selection hypothesis to explain evolution of red pelvic spines in sticklebacks.

Social determination, health selection or indirect selection? Examining the causal directions between socioeconomic status and obesity in the Chinese adult population.

Using nationally representative longitudinal data from 2010 to 2016 in China, this paper aims to systematically investigate the dynamic relationship between socioeconomic status (SES) and obesity in the Chinese adult population. We apply maximum likelihood estimations of dynamic panel models with fixed effects to evaluate the causal directions between SES and obesity, thus providing empirical evidence of the relative importance of the "social determination" hypothesis (SES determines obesity), the "health selection" hypothesis (obesity influences SES) and the "indirect selection" hypothesis (some third factors cause obesity and SES). All analyses were conducted for women and men separately. Our analyses mostly support the contention that after two years, there are no significant causal effects of either lagged SES on Body Mass Index (BMI) or BMI on SES, after controlling for time-invariant unobserved confounders. While there is weak evidence of social determination among men, non-manual workers tend to have a higher BMI than those who are unemployed. We conclude that the indirect selection hypothesis may be the most important explanation in understanding the relationship between SES and obesity in China.

A mathematical model of social selection favoring reduced aggression

Emergence of characteristically human traits, including extensive collaboration, prosociality, and cooperative communication, has presumably necessitated evolution toward lower aggression. While empirical studies have provided evidence for evolutionary reduction in human aggression, such as canine teeth reduction in hominins and craniofacial feminization in Homo sapiens, the underlying mechanisms for the reduction in human aggression are virtually unknown. A promising hypothesis is social selection by partner choice; that is, individuals’ choice of collaborative partners may have induced selection against exceedingly aggressive individuals. However, it is thus far unclear whether partner choice can give unaggressive individuals a fitness benefit that more than compensates for the lost advantage of being aggressive in interindividual conflict. This study explores the plausibility of the social selection hypothesis, using a game-theoretic model of coalition formation. Analysis of the game shows that partner choice can induce selection favoring reduced fighting ability if individuals are ecologically demanded to collaborate, they can be viewed as rational fitness maximizers, and they have communicative skills to bring a synergy in collaboration. The model also suggests a possible feedback loop between reduction of fighting ability and a correlated enhancement of communicative skills. Domesticated animals often share a suite of morphological, physiological, and cognitive characteristics, called the domestication syndrome, that are distinct from their wild ancestors. Experimental studies have shown that the domestication syndrome can arise as a by-product of selection against aggressiveness. A similar process may occur in wild animals; in particular, it has been suggested that “self-domestication” through selection against aggression may have played a major role in human evolution. Despite the proposed role of reduced aggression, however, it is thus far unclear in what ecological context less aggressive individuals can be selectively favored over more aggressive ones. This study provides a theoretical foundation for the social selection hypothesis for the evolution of reduced aggression, using a game-theoretic model of coalition formation, and specifies the conditions under which individuals’ choice of collaborative partners can induce selection favoring reduced aggression.

Social Causation, Social Selection, or Common Determinants? Examining Competing Explanations for the Link Between Young Adult Unemployment and Nicotine Dependence.

Unemployment has been related to smoking, yet the causal nature of the association is subject to continued debate. Social causation argues that unemployment triggers changes in smoking, whereas the social selection hypothesis proposes that pre-existing smoking behavior lowers the probability of maintaining employment. The present study tested these competing explanations while accounting for another alternative explanation-common liability. Data were from the Christchurch Health and Development Study, a longitudinal cohort followed from birth to age 35. Odds were generated for having nicotine dependence in models for social causation and being unemployed in models for social selection. These models were extended to include possible common liability factors during childhood (eg, novelty seeking) and young adulthood (eg, major depression). In the model testing social causation, coefficients representing the impacts of unemployment on nicotine dependence remained statistically significant and robust (odds ratio [OR] = 1.55; 95% confidence interval [CI] = 1.20, 2.00), even after accounting for common determinant measures. In contrast, a reverse social selection model revealed that coefficients representing the impacts of nicotine dependence on unemployment substantially attenuated and became statistically nonsignificant as childhood factors were added (OR = 1.14; 95% CI = 0.90, 1.45). Unemployment may serve as inroads to nicotine addiction among young adults, not the other way, even in the context of nicotine dependence, a more impaired form of smoking that may arguably hold higher potential to generate social selection processes. This social causation process cannot be completely attributable to common determinant factors. It is critical to clarify whether unemployment triggers changes in smoking behaviors (ie, social causation) or vice versa (ie, social selection)-the answers to the question will lead to public health strategies with very different intervention targets to break the linkage. The current study findings favor social causation over social selection, regardless of gender, and support a needed shift in service profiles for unemployed young adults-from a narrow focus on job skills training to a more holistic approach that incorporates knowledge from addiction science in which unemployed young adults can find needed services to cope with job loss.

한국사회 우울과 소득의 종단적 상호관계 : 사회 원인가설과 선택가설 검증을 중심으로

이 연구는 정신건강과 사회경제적 지위의 관계를 한국사회 내 성인들을 대상으로 한 우울과 소득 관계에 초점을 두고 상호간의 종단적 영향을 검증하는데 목적이 있다. 이를 위해 한국복지패널자료(Korean Welfare Panel Data) 및 다변량잠재성장모형 분석방법을 활용하여 우울과 소득궤적의 동시적 영향력에 대한 사회적 원인가설과 선택가설을 실증적으로 검증하였다. 분석 과정에는 연령 집단에 따른 특성이 반영되는지를 확인하기 위해 다중집단분석을 실시하였다. 분석 결과는 다음과 같다. 첫째, 우울증상은 전체적으로 매해 감소하는 궤적을 나타내었고 소득수준은 매해 증가하는 궤적을 나타내었다. 둘째, 우울과 소득궤적의 종단적 상호관계는 양방향의 동시적 영향력이 확인되었다. 즉 초기 우울증상이 높을수록 소득수준의 증가속도는 느려지고, 동시에 초기 소득수준이 높을수록 우울감소속도가 빨라지는 것으로 나타났다. 나아가 연령 집단의 차이를 분석한 결과, 두 연령 집단 모두 초기 우울증상이 소득수준의 변화율에 미치는 영향은 유의하게 나타났다. 그러나 초기 소득수준이 우울증상 변화에 미치는 영향은 청․장년기집단에서는 유의하지 않았고 노년기집단에서만 유의한 것으로 나타났다. 이를 통해 청‧장년기집단에서는 우울이 소득에 미치는 영향에, 노년기집단에서는 우울과 소득감소의 이중위험가능성에 보다 주목할 필요가 있음을 보여주었다. 결과를 바탕으로 우울과 소득궤적의 개선을 위한 실천적 정책적 함의를 제시하였다.

Pathways of Health and Human Capital from Adolescence into Young Adulthood.

Social inequalities in health and human capital are core concerns of sociologists, but little research examines the developmental stage when such inequalities are likely to emerge-the transition to adulthood. With new data and innovative statistical methods we conceptually develop, and empirically operationalize, pathways of physical health and human capital accumulation from adolescence into young adulthood, using an autoregressive cross-lagged structural equation model. Results reveal that pathways of health and human capital accumulate at differential rates across the transition to adulthood; evidence of cross-lagged effects lend support for both social causation and health selection hypotheses. We then apply this model to assess the presence of social inequality in metabolic syndrome-the leading risk factor of cardiovascular disease in the U.S. Findings document social stratification of cardiovascular health that is robust to both observed and unobserved social and health selection mechanisms. We speculate that this social stratification will only increase as this cohort ages.

Better late than early: Marital timing and subjective well-being in midlife.

Drawing on data from 405 Canadian adults surveyed as high school seniors (Age 18) and again in midlife (Age 43), the present study examined whether marital timing, a variable rooted in the age norm hypothesis (whether marriage was early, on time, or late in relation to peers), might contribute additional insight into the well-documented association between marital status and subjective well-being (SWB; happiness, symptoms of depression, and self-esteem). The analysis also considered 3 alternative explanations of the marriage-SWB link: the social selection hypothesis, social role theory, and the adaptation perspective. Path analysis results demonstrated marrying on time or late compared with marrying early predicted fewer symptoms of depression in midlife, offering some support for the age norm hypothesis. Little support was found for the social selection hypothesis, but getting married and divorcing were consistently linked with future SWB, in accordance with social role theory. Marrying at an older age predicted higher self-esteem in midlife for men, implying potential adaptation. (PsycINFO Database Record

The development of healthcare use among a cohort of Finnish social assistance clients: testing the social selection hypothesis.

This article examines the association between healthcare use and receipt of social assistance. It focuses on asking to what extent the use of healthcare (seen as a proxy for health status) leads to social assistance. This is answered by describing the use of healthcare services among a cohort of Finnish social assistance clients before, during and after the first receipt of benefit by means of fixed-effects logistic regression. Using register data, the study follows a group of social assistance recipients from 2005 to 2011 and compares their use of healthcare to those not claiming social assistance during this same period and analyses how their use of health services develops over time. The results show that recipients use public healthcare clearly more than non-recipients, but they do so already prior to the first social assistance receipt. This partly confirms the social selection hypothesis according to which health problems lead to low income. However, the results do not exclude the existence of social causation. The causality is most likely bi-directional. The findings of the descriptive analyses are corroborated by a fixed-effects logistic regression analysis: the use of healthcare services increases the probability of receiving social assistance in the following month.

The Relationship between Education and Mental Health: New Evidence from a Discordant Twin Study

Prior research has documented a strong and positive correlation between completed education and adults’ mental health. Researchers often describe this relationship using causal language: higher levels of education are thought to enhance people’s skills, afford important structural advantages, and empower better coping mechanisms, all of which lead to better mental health. An alternative explanation—the social selection hypothesis—suggests that schooling is a proxy for unobserved endowments and/or preexisting conditions that confound the relationship between the two variables. In this article, we seek to adjudicate between these hypotheses using a relatively large, US-based sample of identical adult twins. By relating within-twin-pair differences in education to within-twin-pair differences in mental health, we are able to control for the influence of genetic traits and shared family characteristics that may otherwise bias the estimates associated with educational attainment. Results from our analyses suggest that the observed association between education and mental health is attributable to confounding on unobserved variables. This finding holds across mental health conditions, is robust to several sensitivity checks, and survives a falsification test. Theoretical implications for the study of educational gradients in mental health are discussed.

Social and economic antecedents and consequences of adolescent aggressive personality: Predictions from the interactionist model.

The present study examined the development of a cohort of 279 early adolescents (52% female) from 1990 to 2005. Guided by the interactionist model of socioeconomic status and human development, we proposed that parent aggressive personality, economic circumstances, interparental conflict, and parenting characteristics would affect the development of adolescent aggressive personality traits. In turn, we hypothesized that adolescent aggressiveness would have a negative influence on adolescent functioning as an adult in terms of economic success, personality development, and close relationships 11 years later. Findings were generally supportive of the interactionist model proposition that social and economic difficulties in the family of origin intensify risk for adolescent aggressive personality (the social causation hypothesis) and that this personality trait impairs successful transition to adult roles (the social selection hypothesis) in a transactional process over time and generations. These results underscore how early development leads to child influences that appear to directly hamper the successful transition to adult roles (statistical main effects) and also amplify the negative impact of dysfunctional family systems on the transition to adulthood (statistical interaction effects). The findings suggest several possible points of intervention that might help to disrupt this negative developmental sequence of events.

Migraine and the social selection vs causation hypotheses

For decades, the question of social selection vs social causation has been raised by public health researchers and social scientists to explain the association between socioeconomic factors and mood disorders.(1,2) The social selection or "downward drift" theory postulates that the disease itself limits an individual's educational and occupational achievements, leading to a lower socioeconomic status (SES). In contrast, the social causation hypothesis suggests that factors associated with low SES (e.g., stressful life events, poor health care access) increase the likelihood of disease onset or prolonged disease duration.(3,4) Simply stated, the end result of each hypothesis is as follows:

Evolution of an ornament, the dewlap, in females of the lizard genus Anolis

Male ornaments have been the subject of numerous studies on sexual selection and communication, although female ornaments have garnered substantially less study, even though female ornaments are well developed in some species. The factors that have propelled the evolution of elaborate ornaments in females are poorly understood but may include genetic correlations between the sexes, social selection, sensory drive or species recognition. We used simulation-based comparative methods and a newly estimated phylogeny to test these four hypotheses to explain female ornamentation within the diverse neotropical lizard genus Anolis. We found support for the sensory drive hypothesis and the social selection hypothesis; the female dewlap was larger in species that use more arboreal habitats, as well as in species where the sexes were less dimorphic. We did not find support for the genetic correlation hypothesis or the species recognition hypothesis. We propose that the size of the female dewlap may evolve in response to sensory drive differentially affecting species in different habitats, as well as social selection such as male mate choice or intrasexual competition for territory among females. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106, 191‐201.

Gender, social engagement, and limitations in late life

This study examines gender differences in the pathways among social engagement, physical limitations and cognitive limitations among U.S. older adults. It improves upon previous literature by longitudinally testing both social benefit and selection hypotheses, examining gender differences in these relationships, gaining modeling advantages through structural equation modeling, and by incorporating the frequency of participation in social activities as an important source of social integration that may influence health among older adults. This study uses U.S. panel data of adults aged 60 and older from the Americans’ Changing Lives survey ( N = 1642) from 1986, 1989, and 1994 in a cross-lagged panel design to better understand these relationships. For women, the flow is from greater social engagement to lower levels of subsequent physical and cognitive limitations, whereas for men the flow is from greater physical and cognitive limitations to lower levels of subsequent social engagement.

Social Mobility and Psychiatric Disabilities: An Assessment of the Social Causation and Social Selection Hypotheses

Social mobility is the movement of individuals, families and groups from one social position to another. Researchers indicate that people with psychiatric disabilities tend to come from lower socioeconomic status groups, and that the causal relationship between lower socioeconomic status and mental illness occurs through social mobility process. The purpose of this study was to examine the occupational social mobility process of a sample of self-identified psychiatrically disabled individuals who have been active members of the labor force for most of their adult lives. A total of 200 participants were recruited from the customers of a One-Stop Career Center in Gloucester County, New Jersey. The social mobility pattern of persons with psychiatric disabilities was compared to that of persons without psychiatric disabilities (n = 100 for each group). That is, the social selection and the social causation hypotheses were applied to the social mobility patterns of people with psychiatric disabilities. It was revealed that the social class distribution for fathers of people with psychiatric disabilities was not different from that of people without psychiatric disabilities and also there was no significant social mobility difference between the two groups. These findings do not support the social causation and the social selection hypotheses. Specifically, the findings demonstrate that occupational capabilities and skills of people with psychiatric disabilities have been stabilized and are similar to those of people without psychiatric disabilities. Furthermore, these results may dispute several biases and prejudices with regard to social mobility process of persons with psychiatric disabilities.

Depressive Symptoms and Economic Outcomes of Low‐Income Women: A Review of the Social Causation, Social Selection, and Interactionist Hypotheses

We review research that connects depression and depressive symptoms to employment and economic factors for low‐income women. Women who have low incomes and are unemployed or underemployed are vulnerable to mental health distress. The strain of balancing work and family life can be exacerbated by poor psychological health or nonsufficient economic resources. Research on the barriers that impede self‐sufficiency can lead to policies that improve the economic and psychological health of low‐income populations. The discussion is framed by contrasting evidence for three theoretical perspectives: the social causation, social selection, and interactionist (bidirectional) hypotheses. The only causal relation reported is an effect of increased income on reduced depressive symptoms. Yet strong associations are found among psychological distress, earnings, employment stability, income, and job characteristics. The effects of programs to increase employment and the benefits of (and barriers to) depression treatment are also discussed. A bidirectional or interactionist perspective best conceptualizes the relationship between depression and economic factors. The reported negative effects of both poor mental well‐being and low‐quality employment suggest the need for stronger policies in the areas of mental health and work supports. We present policy recommendations addressing mental health treatment and outreach, employment placement, and workplace flexibility.