A model explaining the matrilateral bias in alloparental investment.

Maternal grandmothers invest more in childcare than paternal grandmothers. This bias is large where the expression of preferences is unconstrained by residential and lineage norms, and is detectable even where marriage removes women from their natal families. We maintain that the standard evolutionary explanation, paternity uncertainty, is incomplete, and present an expanded model incorporating effects of alloparents on the mother as well as on her children. Alloparenting lightens a mother's load and increases her residual nepotistic value: her expected fitness from later investments in personal reproduction and in her natal relatives. The mother's mother derives fitness from all such investments, whereas her mother-in-law gains only from further investment in children sired by her son, and thus has less incentive to assist the mother even if paternity is certain. This logic extends to kin other than grandmothers. We generate several hypotheses for future research.

The importance of being explicit.

Van Lange et al. propose that climate affects violence via its effects on life history. That much is reasonable (and not novel), but their theory lacks causal specificity. Their foundational claim of an association between heat and violence is not well documented, and several findings that the authors themselves cite seem inconsistent with their model, rather than supportive.

The behavioural constellation of deprivation: Compelling framework, messy reality.

Pepper & Nettle's (P&N's) argument is compelling, but apparently contradictory data are easily found. Associations between socioeconomic status (SES) and substance abuse are sometimes positive, the poor are sometimes eager to educate their children, and perceptions of local mortality risk can be so distorted as to constitute an implausible basis for contextually appropriate responding. These anomalies highlight the need for more psychological work.

Investment by maternal grandmother buffers children against the impacts of adverse early life experiences.

Exogenous shocks during sensitive periods of development can have long-lasting effects on adult phenotypes including behavior, survival and reproduction. Cooperative breeding, such as grandparental care in humans and some other mammal species, is believed to have evolved partly in order to cope with challenging environments. Nevertheless, studies addressing whether grandparental investment can buffer the development of grandchildren from multiple adversities early in life are few and have provided mixed results, perhaps owing to difficulties drawing causal inferences from non-experimental data. Using population-based data of English and Welsh adolescents (sample size ranging from 817 to 1197), we examined whether grandparental investment reduces emotional and behavioral problems in children resulting from facing multiple adverse early life experiences (AELEs), by employing instrumental variable regression in a Bayesian structural equation modeling framework to better justify causal interpretations of the results. When children had faced multiple AELEs, the investment of maternal grandmothers reduced, but could not fully erase, their emotional and behavioral problems. No such result was observed in the case of the investment of other grandparent types. These findings indicate that in adverse environmental conditions the investment of maternal grandmothers can improve child wellbeing.

Parental Investment by Birth Fathers and Stepfathers : Roles of Mating Effort and Childhood Co-residence Duration.

This study investigates the determinants of paternal investment by birth fathers and stepfathers. Inclusive fitness theory predicts higher parental investment in birth children than stepchildren, and this has consistently been found in previous studies. Here we investigate whether paternal investment varies with childhood co-residence duration and differs between stepfathers and divorced birth fathers by comparing the investment of (1) stepfathers, (2) birth fathers who are separated from the child's mother, and (3) birth fathers who still are in a relationship with her. Path analysis was conducted using cross-sectional data from adolescents and younger adults (aged 17-19, 27-29, and 37-39 years) from the German Family Panel (pairfam), collected in 2010-2011 (n = 8326). As proxies of paternal investment, we used financial and practical help, emotional support, intimacy, and emotional closeness, as reported by the children. We found that birth fathers who were still in a relationship with the mother invested the most, and stepfathers invested the least. Furthermore, the investment of both separated fathers and stepfathers increased with the duration of co-residence with the child. However, in the case of financial help and intimacy, the effect of childhood co-residence duration was stronger in stepfathers than in separated fathers. Our findings support inclusive fitness theory and mating effort theory in explaining social behavior and family dynamics in this population. Furthermore, social environment, such as childhood co-residence was associated with paternal investment.

"Cinderella effects" in lethal child abuse are genuine and large: A comment on Nobes et al. (2019).

Nobes et al. (2019) combined novel analyses of homicide victimization of British preschool children with a critique of previous research reporting large Cinderella effects (excess risk to stepchildren) in this domain. Whereas Nobes and colleagues' empirical contribution is useful, the critique contains factual errors and misrepresentations of the literature in support of their conclusion that the magnitude of such effects has been greatly exaggerated. It has not, as I show by addressing Nobes et al.'s many misstatements and reviewing relevant literature that they ignored. Fatal baby batterings, in particular, have been found to exhibit Cinderella effects on the order of 100-fold or more in many studies in several countries, including Britain. Nobes et al.'s efforts to deny this reality are misguided. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Sexual Selection and the Treatment of Predecessors' Progeny by Replacement Mates.

Darwin's theory of sexual selection provides a useful framework for understanding the behavior of stepparents. A non-human animal whose new mate has dependent young may kill, ignore, or adopt the predecessor's progeny. The third option has been interpreted as courtship ("mating effort"), and whether selection favors such investment over killing or ignoring the young apparently depends on aspects of the species-typical ecology and demography. The tripartite categorization of responses is a simplification, however, There is variability both within and between species along a continuum from rejection to "full adoption." The average stepparent invests less than the average birth parent, but more than nothing. Human stepparents have often been found to kill young children at higher rates than birth parents, but stepparental infanticide cannot plausibly be interpreted as a human adaptation, both because it is extremely rare and because it is almost certainly more likely to reduce the killer's fitness than to raise it. How sexual selection theory remains relevant to human stepparenting is by suggesting testable hypotheses about predictors of the variability in stepparental investment.

Grandparental partnership status and its effects on caring for grandchildren in Europe.

Grandparents are important childcare providers, but grandparental relationship status matters. According to several studies, caregiving is reduced after grandparental divorce, but differential responses by grandmothers versus grandfathers have often been glossed over. To explore the effects of relationship status on grandparental care, we analysed data from the Survey of Health, Ageing and Retirement in Europe (SHARE) comparing four grandparental relationship statuses (original couple, widowed, divorced, and repartnered) with respect to grandmothers' and grandfathers' provision of care to their birth children's children. When proximity, kinship laterality, and grandparents' age, health, employment, and financial status were controlled, divorced grandmothers without current partners provided significantly more childcare than grandmothers who were still residing with the grandfather, those who had new partners unrelated to the grandchildren, and widows without current partners. Grandfathers exhibited a very different pattern, providing substantially less grandchild care after divorce. Grandfathers in their original partnerships provided the most grandchild care, followed by widowers, those with new partners and finally those who were divorced. Seemingly contradictory findings in prior research, including studies using SHARE data, can be explained partly by failures to distinguish divorce's effects on grandmothers versus grandfathers, and partly by insufficient controls for the grandmother's financial and employment statuses.

In-Law Relationships in Evolutionary Perspective: The Good, the Bad, and the Ugly.

In-laws (relatives by marriage) are true kin because the descendants that they have in common make them "vehicles" of one another's inclusive fitness. From this shared interest flows cooperation and mutual valuation: the good side of in-law relationships. But there is also a bad side. Recent theoretical models err when they equate the inclusive fitness value of corresponding pairs of genetic and affinal (marital) relatives-brother and brother-in-law, daughter and daughter-in-law-partly because a genetic relative's reproduction always replicates ego's genes whereas reproduction by an affine may not, and partly because of distinct avenues for nepotism. Close genetic relatives compete, often fiercely, over familial property, but the main issues in conflict among marital relatives are different and diverse: fidelity and paternity, divorce and autonomy, and inclinations to invest in distinct natal kindreds. These conflicts can get ugly, even lethal. We present the results of a pilot study conducted in Bangladesh which suggests that heightened mortality arising from mother-in-law/daughter-in-law conflict may be a two-way street, and we urge others to replicate and extend these analyses.

Inconsistent reports of risk behavior among Brazilian middle school students: National School Based Survey of Adolescent Health (PeNSE 2009/2012).

This study assessed the consistency of self-reports of risk behavior (overall and within four specific domains: alcohol use, tobacco use, drug use, and sexual activity) in two editions of the Brazilian National School Based Survey of Adolescent Health (PeNSE): 2009 and 2012. The overall proportion of cases with at least one inconsistent response in the two editions was 11.7% (2.7% on the alcohol items, 2.1% for drug use, 4.3% for cigarette use, 3% for sexual activity) and 22.7% (12.8% on alcohol items, 2.5% for drug use, 4.3% for cigarette use, 4.1% for sexual activity), respectively. Such inconsistency was more prevalent among males, delayed students, those who reported having experimented with drugs, and those who did not have a cellphone. Because inconsistent responses were more prevalent among the students who claimed to have engaged in risky activities, removing inconsistent responders affected the estimated prevalence of all risk behaviors in both editions of the survey. This study supports the importance of performing consistency checks of self-report surveys, following the growing body of literature on this topic.

The role of city income inequality, sex ratio and youth mortality rates in the effect of violent victimization on health-risk behaviors in Brazilian adolescents.

This study integrates insights from evolutionary psychology and social epidemiology to present a novel approach to contextual effects on health-risk behaviors (unprotected sex, drunkenness episodes, drugs and tobacco experimentation) among adolescents. Using data from the 2012 Brazilian National Survey of Adolescent Health (PeNSE), we first analyzed the effects of self-reported violent victimization on health-risk behaviors of 47,371 adolescents aged 10-19 nested in the 26 Brazilian state capitals and the Federal District. We then explored whether the magnitude of these associations was correlated with cues of environmental harshness and unpredictability (youth external mortality and income inequality) and mating competition (sex ratio) from the city level. Results indicated that self-reported violent victimization is associated with an increased chance of engagement in health-risk behaviors in all Brazilian state capitals, for both males and females, but the magnitude of these associations varies in relation to broader environmental factors, such as the cities' age-specific mortality rates, and specifically for females, income inequality and sex ratio. In addition to introducing a novel theoretical and empirical approach to contextual effects on adolescent health-risk behaviors, our findings reinforce the need to consider synergies between people's life experiences and the conditions where they live, when studying health-risk behaviors in adolescence.

On function, cause, and being Jerry Hogan's student.

Jerry Hogan has forcefully maintained that cause and function are distinct questions, and that attempts to integrate them are conceptually muddled. I dissent from his view, maintaining that causal analysis is conducted in the shadow of premises about function, and that bringing functional ideas out of the shadows facilitates the generation of fruitful causal hypotheses. This is not to suggest, however, that cause-function muddles are non-existent; I agree with Hogan that they are both common and mischievous. This article is part of a Special Issue entitled: In Honor of Jerry Hogan.

Do pretty women inspire men to discount the future?

Organisms 'discount the future' when they value imminent goods over future goods. Optimal discounting varies: selection should favour allocations of effort that effectively discount the future relatively steeply in response to cues promising relatively good returns on present efforts. However, research on human discounting has hitherto focused on stable individual differences rather than situational effects. In two experiments, discounting was assessed on the basis of choices between a smaller sum of money tomorrow and a larger sum at a later date, both before and after subjects rated the 'appeal' of 12 photographs. In experiment 1, men and women saw either attractive or unattractive opposite-sex faces; in experiment 2, participants saw more or less appealing cars. As predicted, discounting increased significantly in men who viewed attractive women, but not in men who viewed unattractive women or women who viewed men; viewing cars produced a different pattern of results.

Food caching and differential cache pilferage: a field study of coexistence of sympatric kangaroo rats and pocket mice.

Ecologists studying sympatric heteromyid rodents have sought evidence for species differences in primary foraging abilities and preferences and/or behavioural responses to predation risk in order to explain coexistence. The present field study was conducted to test the hypothesis that another factor may be involved, namely differences in caching patterns, which may result in differences in vulnerability to pilferage. We examined differences between kangaroo rats (Dipodomys merriami) and pocket mice (Chaetodipus spp.) in foraging, caching and pilferage behaviour. Specifically, we examined interactions at food patches, differential food caching patterns, and differential vulnerability to cache pilferage. Observations conducted at artificial seed patches showed that kangaroo rats dominated access to the patches by arriving and foraging first and by chasing pocket mice away. Individually provisioned pocket mice stored most seeds in underground burrows (larder hoarding), whereas kangaroo rats predominantly cached seeds in small, spatially dispersed caches in shallow pits in the surface of the sand (scatter hoarding). Pocket mice pilfered from each other as well as from the kangaroo rats, but the kangaroo rats rarely pilfered, and the only instance was from another kangaroo rat. Kangaroo rats and pocket mice were both vulnerable to cache pilferage. The results suggest that coexistence of kangaroo rats and pocket mice may be facilitated by a trade-off between primary harvest ability and the ability to exploit a resource that has been processed by another species, namely pilferage ability.

Inconsistent reports of risk behavior among Brazilian middle school students: National School Based Survey of Adolescent Health (PeNSE 2009/2012) / Inconsistências no relato de comportamentos de risco entre estudantes brasileiros: Pesquisa Nacional de Saúde do Adolescente (PeNSE 2009/2012) / Informes inconsistentes de comportamientos de riesgo entre los estudiantes de secundaria de Brasil: Encuesta Nacional de Salud del Adolescente (PeNSE 2009/2012)

Abstract: This study assessed the consistency of self-reports of risk behavior (overall and within four specific domains: alcohol use, tobacco use, drug use, and sexual activity) in two editions of the Brazilian National School Based Survey of Adolescent Health (PeNSE): 2009 and 2012. The overall proportion of cases with at least one inconsistent response in the two editions was 11.7% (2.7% on the alcohol items, 2.1% for drug use, 4.3% for cigarette use, 3% for sexual activity) and 22.7% (12.8% on alcohol items, 2.5% for drug use, 4.3% for cigarette use, 4.1% for sexual activity), respectively. Such inconsistency was more prevalent among males, delayed students, those who reported having experimented with drugs, and those who did not have a cellphone. Because inconsistent responses were more prevalent among the students who claimed to have engaged in risky activities, removing inconsistent responders affected the estimated prevalence of all risk behaviors in both editions of the survey. This study supports the importance of performing consistency checks of self-report surveys, following the growing body of literature on this topic.

Resumo: O presente estudo avaliou as inconsistências no autorrelato de comportamentos de risco (geral e em quatro domínios específicos: uso de álcool, tabaco, drogas e atividade sexual) em duas edições da Pesquisa Nacional de Saúde do Adolescente (PeNSE): 2009 e 2012. Nas duas edições, a proporção de casos com ao menos uma resposta inconsistente foi de 11,7% (2,7% nos itens sobre consumo de álcool, 2,1% para uso de drogas, 4,3% para uso de tabaco, 3% para atividade sexual) e 22,7% (12,8% nos itens sobre consumo de álcool, 2,5% para uso de drogas, 4,3% para uso de tabaco, 4,1% para atividade sexual), respectivamente. Tal inconsistência foi mais prevalente entre participantes do sexo masculino, estudantes com atraso escolar, participantes que relataram ter experimentado drogas e participantes que não possuíam telefone celular. Dado que as inconsistências foram mais prevalentes entre os estudantes que declararam ter se engajado nos comportamentos de risco, remover os casos com inconsistência afetou as estimativas de prevalência destes comportamentos em ambas as edições da pesquisa. Este estudo ressalta a importância de testes para a checagem da consistência dos dados autorrelato em pesquisas, acompanhando a crescente literatura na área.

Resumen: Este estudio evaluó las inconsistencias en las conductas de riesgo de auto-reporte (general y cuatro áreas específicas: el alcohol, el tabaco, las drogas y la actividad sexual) en dos ediciones de la Encuesta Nacional de Salud del Adolescente (PeNSE): 2009 y 2012. En dos ediciones, la proporción de casos con al menos una respuesta inconsistente fue 11,7% (2,7% en alcohol, 2,1% en drogas, 4,3% en tabaco, 3% en actividad sexual) y 22,7% (12,8% en alcohol, 2,5% en drogas, 4,3% en tabaco, 4,1% en actividad sexual), respectivamente. Tal inconsistencia era más frecuente entre los participantes masculinos, los alumnos con retraso escolar, los participantes que reportaron haber consumido drogas y participantes probado que no tenían teléfono celular. Dado que las inconsistencias fueron más prevalentes entre los estudiantes que reportaron haber participado en comportamientos de riesgo, eliminar los casos de inconsistencia afectó a las estimaciones de la prevalencia de estas conductas en las dos ediciones de la encuesta. Este estudio pone de relieve la importancia de las pruebas para comprobar la coherencia de los datos de auto-informe sobre la investigación, a raíz de la creciente literatura en la zona.

Has the child welfare profession discovered nepotistic biases?

A major trend in foster care in developed countries over the past quarter century has been a shift toward placing children with "kin" rather than with unrelated foster parents. This change in practice is widely backed by legislation and is routinely justified as being in the best interests of the child. It is tempting to interpret this change as indicating that the child welfare profession has belatedly discovered that human social sentiments are nepotistic in their design, such that kin tend to be the most nurturant alloparents. Arguably, however, the change in practice has been driven by demographic, economic, and political forces rather than by discovery of its benefits. More and better research is needed before we can be sure that children have actually benefitted.

Cues of paternal uncertainty and father to child physical abuse as reported by mothers in Rio de Janeiro, Brazil.

OBJECTIVE: Paternity is uncertain, so if paternal feelings evolved to promote fitness, we might expect them to vary in response to variables indicative of paternity probability. We therefore hypothesized that the risk of lapses of paternal affection, including abusive assaults on children, will be exacerbated by cues of non-paternity. METHODS: Cross-sectional study of 331 Brazilian mothers, interviewed about 1 focal child (age 1-12) residing with her and the putative father. Child physical abuse was assessed using the Conflict Tactic Scales: Parent Child (CTSPC). Two potential cues of (non) paternity were (1) whether the parents co-resided when the child was conceived, and (2) whether third parties allegedly commented on father-child resemblance. Data were analyzed through multiple logistic regressions. RESULTS: Mothers reported child physical abuse by 15.9% (95% CI 4.6-27.1) of fathers who had not cohabited with them at conception, compared to 5.9% (95% CI 3.1-8.7) of those who had. The odds ratio for abuse by fathers who had not cohabited at conception in relation to those who had-adjusted for income, education, age, sex of child, whether child was first born, household size, time father spent with child, and alcohol abuse and drug use by father-was 4.3 (95% CI 1.4-13.8). Mothers reported abuse of 7.0% (95% CI 4.0-10.0) of children who purportedly resembled their fathers, versus 8.7% (95% CI 0.2-17.1) of those who did not. CONCLUSION: According to maternal reports, not having co-resided at conception quadrupled the chance of child physical abuse by currently co-residing Brazilian fathers. The reported prevalence of abuse was unrelated to reported allegations of father-child resemblance.

Homicide and impunity: an ecological analysis at state level in Brazil.

OBJECTIVE: To assess a new impunity index and variables that have been found to predict variation in homicide rates in other geographical levels as predictive of state-level homicide rates in Brazil. METHODS: This was a cross-sectional ecological study. Data from the mortality information system relating to the 27 Brazilian states for the years 1996 to 2005 were analyzed. The outcome variables were taken to be homicide victim rates in 2005, for the entire population and for men aged 20-29 years. Measurements of economic and social development, economic inequality, demographic structure and life expectancy were analyzed as predictors. An 'impunity index', calculated as the total number of homicides between 1996 and 2005 divided by the number of individuals in prison in 2007, was constructed. The data were analyzed by means of simple linear regression and negative binomial regression. RESULTS: In 2005, state-level crude total homicide rates ranged from 11 to 51 per 100,000; for young men, they ranged from 39 to 241. The impunity index ranged from 0.4 to 3.5 and was the most important predictor of this variability. From negative binomial regression, it was estimated that the homicide victim rate among young males increased by 50% for every increase of one point in this ratio. CONCLUSIONS: Classic predictive factors were not associated with homicides in this analysis of state-level variation in Brazil. However, the impunity index indicated that the greater the impunity, the higher the homicide rate.