Close Kin Research Articles

Kinlessness at older ages: Prevalence and heterogeneity in 27 countries.

We provide recent and detailed estimates of the prevalence of kinlessness (i.e., people lacking [close] kin) among older individuals in 27 countries. We add to the literature by considering a broad range of kinship ties and examining within-country variabilities by age, sex, education, and rurality of the residential area. Using data from Wave 8 (2019-2020) of the Survey of Health, Ageing, and Retirement in Europe (SHARE), we estimated the prevalence of kinlessness among individuals aged 65 and over in 26 European countries and Israel. We considered different definitions of kinlessness, from a less restrictive (based on the absence of both a partner and children) to a more restrictive one (absence of partner, children, grandchildren, parents, and siblings). Kinlessness varied considerably across countries. The percentage of people aged 65 and over who lacked a partner and children ranged between 2-3.5% in the Czech Republic, Romania, Israel, and Bulgaria to more than 8% in Switzerland, Spain, Belgium, and Malta. The percentage of older people lacking all close kin considered (partner, children, grandchildren, parents, and siblings) ranged from 0.1 to 4.1%. In addition, there was substantial heterogeneity in kinlessness in some countries by age, sex, and rurality of the residential area, whereas, except for a few cases, we did not find significant differences by education. Understanding the prevalence of kinless older adults is critical for policymakers and healthcare providers to design appropriate support systems for this potentially vulnerable group of people.

‘I am afraid to fly there’: informal care in Polish migrants’ families immobilised by COVID-19

ABSTRACT This paper discusses the COVID-19 pandemic as a new external challenge to transnational family life that can undermine the care arrangements and intentions developed by the families of Polish migrants following the 2004 EU enlargement. The pandemic, associated lockdowns and travel restrictions raise questions about assumed transnationalism, building upon earlier concerns about taking for granted migrants’ cross-national mobility. Based on focus group discussions with Polish grandparents conducted in July 2020 and March 2021, we analyse the pandemic’s impact on intergenerational relations with both geographically close and distant kin. We point to perceptions of risks of COVID-19 associated with ethnicised stereotypes and evolving with time. While the pandemic caused temporary restrictions to mobility, it shows the immobilising side of “unsettling events”], the consequences of which, for privileged EU migrants, will unfold in time as their parents’ age and require personal care.

Access to kin, economic stress, and late-life mortality in North Orkney, Scotland, 1851–1911

This paper analyzes the effects of kin availability and short-term economic stress on mortality among older adults in North Orkney, Scotland in the mid-19th through early 20th century. The mortality of those aged 60+ is associated with high oatmeal prices lagged by one year, a delayed effect that may suggest that buffering mechanisms are less effective in the longer term or that relative to younger groups, older adults are better able to cope with the immediate effects of stress. Associations between mortality risk and indicators of kin availability vary by individual sociodemographic characteristics, but they are limited to close kin in both the spatial and genealogical sense. Benefits of nearby, but not coresident kin accrue only to ever-married men during times of high food prices. Coresident and nearby kin are associated with complex patterns of mortality risk, suggesting that family relationships may represent a resource in some circumstances, but a liability in others. There is limited evidence for the effects of expansive kin support for aging adults and support flows do not always favor the older generation.

Explaining mobilization for revolts by private interests and kinship relations. A comment on Armandola, Doehne and Rost

The authors study the role of kinship relationships in explaining mobilization for a revolt in Basel, Switzerland, in 1691; rebels consisted of a weaker fraction of the elite and individuals with citizen rights. The empirical section shows that revolts are mainly driven by the elite’s distant kin rather than the rebels’ close kin. Allowing for coalition formation, as in the new theory of corruption, conflict, and inequality proposed in this comment, can give an alternative explanation. In the first formal model, we assume “elite” corresponds to the term “enforcer” in the new theory. This is a nonproductive individual who is the strongest in terms of fighting against peasants over a prize in a contest. In this simple model, there are no other players. Thus, this framework predicts that the only rebels would come from within the elite. Historical evidence shows that the marginal elite got stronger relatively and, thus, excluded the oligarchy from the winning coalition to take over the government. The direct application of this model would imply that non-elite members were not part of the rebellion. However, the historical facts presented by Armandola et al. show that non-elite citizens also participated in the revolt. To match these facts in Armandola et al., we allow informally individuals with citizen rights to participate in the rebellion. Peasants, a term also used in the new theory, and marginalized groups (a term only used in the commented paper) in the cities did not participate. Kinship effects are discussed.

Social and genetic connectivity despite ecological variation in a killer whale network.

Philopatric kin-based societies encourage a narrow breadth of conservative behaviours owing to individuals primarily learning from close kin, promoting behavioural homogeneity. However, weaker social ties beyond kin, and across a behaviourally diverse social landscape, could be sufficient to induce variation and a greater ecological niche breadth. We investigated a network of 457 photo-identified killer whales from Norway (548 encounters in 2008-2021) with diet data available (46 mixed-diet individuals feeding on both fish and mammals, and 411 exclusive fish-eaters) to quantify patterns of association within and between diet groups, and to identify underlying correlates. We genotyped a subset of 106 whales to assess patterns of genetic differentiation. Our results suggested kinship as main driver of social bonds within and among cohesive social units, while diet was most likely a consequence reflective of cultural diffusion, rather than a driver. Flexible associations within and between ecologically diverse social units led to a highly connected network, reducing social and genetic differentiation between diet groups. Our study points to a role of social connectivity, in combination with individual behavioural variation, in influencing population ecology in killer whales.

Geographical distribution of close kin in southern right whales on feeding grounds.

This study investigated the close kinship structure of southern right whales on feeding grounds during austral summer seasons. The study was based on biopsy samples of 171 individual whales, which were genotyped with 14 microsatellite DNA loci. Kinship was investigated by using the LOD (Log Odds) score, a relatedness index for a pair of genotypes. Based on a cut-off point of LODPO > 6, which was chosen to balance false positives and negatives, a total of 28 dyads were inferred. Among these, 25 were classified as parent-offspring pairs. Additional genetic (mitochondrial DNA haplotypes) and biological (estimated body length, sex) data were used to provide additional information on the inferred close kin pairs. The elapsed time between sampling varied from 0 (close kin detected in the same austral summer season) to 17 years. All the kin pairs occurred within the Antarctic Indo sector (85°-135°E) and no pair occurred between whales within and outside of this sector. Six pairs were between individuals in high (Antarctic) and lower latitudes. Results of the present analysis on kinship are consistent with the views that whales in the Indo sector of the Antarctic are related with the breeding ground in Southwest Australia, and that whales from this population can occupy different feeding grounds. The present study has the potential to contribute to the conservation of the southern right whales through the monitoring of important population parameters such as population sizes and growth rate, in addition to assist the interpretation of stock structure derived from standard population genetic analyses.

Soroton Literatur Terhadap Wakaf Keluarga: Konsep, Perundangan dan Isu-Isu Berbangkit di Malaysia

Muslims' unclaimed property is estimated to be worth 70 billion ringgit at the moment. Ironically, it has been shown that the owner of this property still has close kin or family members. This study proposes adopting the waqf approach to migrate these properties into real estate for optimal utilization. The existing research on waqf in Malaysia encompasses research on Shariah law, legislation, and its application. Hence, this study focuses on literature review based on several themes, namely (i) the concept of family waqf; (ii) legislation related to family waqf in Malaysia and other countries; and (iii) issues related to family waqf in Malaysia. The primary sources of Islamic law, namely the Quran and Hadith, are used as references. Additionally, the collection of historical documentation is also referred to obtain interpretations, points of view, and examples of waqf instrument governance in Malaysia. The findings of this study, there is a lack of details on family waqf in terms of implementation and legislation in Malaysia. At the same time, Malaysia also has several states with specific legal provisions related to waqf. Therefore, this study focuses on family waqf according to current Islamic law, to benefit Muslims in particular in the future.

Sibling aggression is surprisingly common and sexually egalitarian

Two well-supported generalizations from aggression research are that: a) people are less likely to commit homicide against close kin compared to non-kin, and b) females are less likely to engage in direct aggression than are males. Aggression between siblings, however, is somewhat more complicated than one might surmise from those two generalizations. Data from 3 studies collected using undergraduate and Prolific samples (N = 1640) reveal classic sex differences in direct aggression between non-relatives, but not between sisters and brothers. Whereas only a small minority of females have hit a friend or an acquaintance, the majority of females, like the majority of males, have hit a sibling. Although reputational aggression is substantially less likely between siblings than between friends or acquaintances, mild forms of direct aggression (such as hitting) are quite frequent between siblings. Discussion considers several possible limitations of the findings reported here and considers results in light of Trivers' theory of parent-offspring conflict.

Alloparental Support and Infant Psychomotor Developmental Delay

Receiving social support from community and extended family has been typical for mothers with infants in human societies past and present. In non-industrialised contexts, infants of mothers with extended family support often have better health and higher survival through the vulnerable infant period, and hence shared infant care has a clear fitness benefit. However, there is scant evidence that these benefits continue in industrialised contexts. Better infant health and development with allocare support would indicate continued evolutionary selection for allocare. The research reported here used multiple logistic regression analysis to test whether a lack of family and other social support for mothers was associated with an increased risk of developmental delay in 9-month-old infants in the UK Millennium Cohort (analysis sample size, 15,696 infants). Extended family-based childcare during work hours and more maternal time spent with friends were the most influential kin and social support variables: infants of mothers with kin-based childcare versus all other childcare arrangements had a lower risk of developmental delay (OR = 0.61, 95% CIs: 0.46–0.82). Infants of mothers who spent no time with friends when compared with those who saw friends every day had double the odds of delay. Greater paternal involvement in infant care was associated with a lower odds of developmental delay. In conclusion, shared care of infants and social support for mothers may influence fitness-related traits in industrialised societies rather than being factors that influenced selection only in the past and in societies which retain close kin networks and a strong local community focus.

Kin Term Borrowings in the World’s Languages

Abstract The universality of kinship terms means they are regarded, like much basic vocabulary, as resistant to borrowing. Kin term borrowings are documented at varying frequencies, but their role in the dynamics of change in this core social domain is understudied. We investigated the dimensions and the sociolinguistic contexts of kinship borrowings with 50 kinship categories from a global sample of 32 languages, a subset extracted from the World Loanword Database. We found that more borrowings take place in affinal kin categories and in generations denoting relatives older than ego. Close kin categories also have borrowings, but the borrowed items usually coexist with other, presumably non-borrowed variants. Colonisation and the spread of cultures and religions were main inducing forces for kin term borrowings; new terms often enter a language via bilingualism. These tentative patterns can be studied further with larger datasets in future systematic studies of kinship borrowings.

HOUSING CONCERNS AND TRAJECTORIES OF KINLESS OLDER ADULTS WITH DEMENTIA

Abstract Housing preferences of older adults (e.g., to remain in residence, or relocate), housing options available, and housing needs related to changing physical and cognitive abilities are common concerns of aging. The challenges are possibly more complex for those living with dementia, who may have difficulty articulating housing preferences, and whose housing needs may include supportive care. For those with dementia who lack close kin, these challenges are likely significantly compounded. This paper focuses on the intersection of housing concerns for 64 participants in the Adult Changes in Thought (ACT) study who were kinless (no living spouse or children) when they developed dementia. All the ACT participants were 65+ when recruited. Everyone in this sample had received a research diagnosis, and their mean age at dementia onset (estimated at the midpoint between the research study that triggered the diagnostic evaluation, and the last research study before that -- usually one year before diagnosis) was 87 (Standard Deviation [SD] 7 years), with a median age of 86 and a range of 71-103.We present an analysis of their housing trajectories, as captured in chart notes from their medical records. We highlight multiple themes illustrating how housing intersects with health and social well-being and conclude by commenting on the potential of medical records for understanding and documenting issues related to housing.

Sample contamination explains evidence of close kin proximity in yellowfin tuna (Thunnus albacares) in the Western and Central Pacific Ocean

Anderson et al.’s 2019 paper ‘Close Kin Proximity in Yellowfin Tuna (Thunnus albacares) as a Driver of Population Genetic Structure in the Tropical Western and Central Pacific’ provided observations of genetically related individuals among sampled yellowfin tuna. Resampling of some individuals from the original study produced very different sequencing results when compared with the original dataset, one possible explanation of which is cross-contamination among the original samples. Re-analyses produced no indication of strong population structure, including a very slightly and consistent heterozygosity deficit with only one statistically significant pairwise FST value of 0.002. We identified only one pair of genetically similar individuals that could still be an artefact of lingering contamination. These new results therefore support a highly connected population of yellowfin tuna in the study area, although we do not rule out the potential for local adaptation driven by non-observed loci or genetic sub-structure operating at more contemporary scales.

Retraction: Close kin proximity in yellowfin tuna (Thunnus albacares) as a driver of population genetic structure in the tropical Western and Central Pacific Ocean

Retraction: Close kin proximity in yellowfin tuna (Thunnus albacares) as a driver of population genetic structure in the tropical Western and Central Pacific Ocean

Determinants of hyena participation in risky collective action.

Collective action problems arise when cooperating individuals suffer costs of cooperation, while the benefits of cooperation are received by both cooperators and defectors. We address this problem using data from spotted hyenas fighting with lions. Lions are much larger and kill many hyenas, so these fights require cooperative mobbing by hyenas for them to succeed. We identify factors that predict when hyena groups engage in cooperative fights with lions, which individuals choose to participate and how the benefits of victory are distributed among cooperators and non-cooperators. We find that cooperative mobbing is better predicted by lower costs (no male lions, more hyenas) than higher benefits (need for food). Individual participation is facilitated by social factors, both over the long term (close kin, social bond strength) and the short term (greeting interactions prior to cooperation). Finally, we find some direct benefits of participation: after cooperation, participants were more likely to feed at contested carcasses than non-participants. Overall, these results are consistent with the hypothesis that, when animals face dangerous cooperative dilemmas, selection favours flexible strategies that are sensitive to dynamic factors emerging over multiple time scales.

Multiple mechanisms for inbreeding avoidance used simultaneously in a wild ape.

Mating with close kin can have considerable negative fitness consequences, which are expected to result in selective pressure for inbreeding avoidance mechanisms, such as dispersal, mate choice and post-copulatory biases. Captive studies have suggested that inbreeding avoidance through mate choice is far less widespread than expected and may be absent where other mechanisms already limit inbreeding. However, few studies have examined multiple mechanisms of inbreeding avoidance simultaneously, particularly in the wild. We use 13 years of detailed dispersal, copulation and paternity data from mountain gorillas to examine inbreeding avoidance. We find that partial dispersal of both sexes results in high kinship in multimale groups, but that copulations between close kin occur 40% less than expected. We find strong kin discrimination in mate choice, with significant avoidance of maternal kin but more limited avoidance of paternal kin. We find no evidence for post-copulatory inbreeding avoidance. Our analyses support familiarity-based mechanisms of kin identification and age-based avoidance that limits mating between fathers and daughters in their natal group. Our findings demonstrate that multiple complementary mechanisms for inbreeding avoidance can evolve in a single species and suggest that inbreeding avoidance through mate choice may enable more flexible dispersal systems to evolve.

Novel multilayer network analysis to assess variation in the spatial co-occurrences of close kin in wild caribou populations

Understanding how individuals within populations are connected genetically and through shared space-use is critical to understanding the demographic patterns of at-risk populations. In recent years, non-invasive genetic sampling methods have allowed us to begin addressing these questions. Using a network analysis framework, we examined the spatial co-occurrence and genetic relatedness of boreal and central mountain caribou (Rangifer tarandus) in populations varying in sizes and trend from across western Canada. Using 15 microsatellites loci and a sex-specific marker, we developed pedigree networks for each population, including first to third order relationships. We constructed networks of individual spatial co-occurrence, and using multilayer network analysis, we determined the degree to which caribou that co-occurred spatially were related. Caribou populations varied in the extent and classes of familial relationships which co-occurred in space. In most populations, spatial co-occurrences were greater than expected only for parent-offspring relationships. A sex-specific analysis of the longest sampled population revealed that this was driven by a significant overlap between mothers and their offspring. Whereas in populations where very few parent-offspring relationship were detected, no significant overlap was found between any relationship categories. The lack of overlap in these populations may be an indication of poor calf survival. On the other hand, the higher degree of overlap with more distant relations (i.e., grandparents) seen in some populations may indicate a population that lacks mobility. Our research presents a new approach to explore both spatial and genetic overlap at the individual level in support of the conservation of threatened populations.

Why do Hymenopteran workers drift to non-natal groups? Generalized reciprocity and the maximization of group and parental success.

Eusocial Hymenoptera are often characterized by having facultatively or obligately sterile worker castes. However, findings across an increasing number of species are that some workers are non-natal-they have 'drifted' away from where they were born and raised. Moreover, drifters are often indistinguishable from natal workers in the work and benefits provided to joined groups. This seems an evolutionary paradox of providing benefits to potentially unrelated individuals over close kin. Rather than being mistakes, drifting is proposed to be adaptive if joiners either gain inclusive fitness by preferentially moving to other kin groups or through generalized reciprocity in which exchanging workers across groups raises group-level genetic diversity and creates social heterosis. It is unclear, however, if reciprocity is unlikely because of a susceptibility to cheating. In resolving this question, a series of evolutionary simulations show: (1) Reciprocity can persist under a range of genetic assumptions and scenarios of cheating, (2) cheating almost always evolves, but can be expressed in a variety of ways that are not always predictable, (3) the inclusive fitness hypothesis is equally or more susceptible to cheating. Moreover, existing data in Hymenoptera (although not extensive) are more consistent with generalized reciprocity. This supports a hypothesis that drifting, as a phenomenon, may more often reflect maximization of group and parental fitness rather than fitness gains for the individual drifters.

Family Ties and Older Adult Well-Being: Incorporating Social Networks and Proximity.

This paper examines the family ties of older adults in the United States and how they are associated with mental health and social activity. We compare older adults with 4 types of family ties: adults "close" to family in proximity and social network, "kinless" older adults without a partner or children, "distanced" adults who live far from close kin, and "disconnected" older adults who do not report kin in their social network or do not report a location for some kin. Using pooled data from the National Health and Aging Trends Study 2015-2019 for older adults aged 70 and older (N = 24,818 person-waves), we examine how family ties are associated with mental health and social activity, and whether lacking family is tied to poor well-being because older adults' needs are not being met. Kinless older adults and disconnected older adults have poorer outcomes (lower mental health scores and less social activity), compared to those close to their family. These findings suggest that both the presence and quality of the connection, as measured here via both location and social network, are critical for understanding which older adults are "at risk." Older adults who were not geographically proximate to their close kin (i.e., distanced) were not disadvantaged relative to those close to their families. Unmet needs do not help explain these patterns. Our results highlight that family ties are important for older adults well-being, not just through their existence but also their quality and strength.

The Care Gap in Later Life Across European Countries.

Do adults without kin experience a care gap where they need help with activities of daily living but get no help from any source? We examine the prevalence of the care gap across Europe, and test whether those without partners or children substitute for their lack of close kin with help from broader networks, or whether they disproportionately experience care gaps. Using data from the Survey on Health, Ageing and Retirement in Europe, we estimate the care gap in 28 European countries and Israel, how it varies, and who provides help for respondents with different family structures. The care gap is substantial, with 6.1% of all respondents ages 50 and above reporting a gap. It is highest in Western and Eastern Europe and lowest in Southern Europe and Israel. Respondents without partners or children are significantly more likely to have care gaps than those with close kin. However, respondents without close kin draw more often on more diverse networks of friends and relatives and use nursing home care. Our study introduces the concept of the care gap and shows that although it is most common among unpartnered adults without children it is also quite common for those with immediate family. A broader network partially but not completely substitutes for care gaps among those without immediate family. Our results offer new insights into the demand for public care services in countries with diverse welfare states.

Paternity data reveal high MHC diversity among sires in a polygynandrous, egalitarian primate.

Evidence from human and nonhuman primates suggests that females avoid breeding with close kin and may choose mates based on MHC diversity, which can improve offspring survival. In despotic societies, female mate choice may be hindered by male sexual coercion, but in egalitarian societies, females may be less constrained. Among northern muriquis-an egalitarian, polygynandrous primate with male philopatry-analyses of new data on paternity and variation at microsatellite and MHC loci, combined with behavioural and life-history data, revealed that sires showed higher MHC diversity than expected by chance and were never close kin of dams, consistent with predictions of female mate choice and close inbreeding avoidance. However, females did not differentially reproduce with males who were more distantly related to them or more dissimilar at the MHC than expected by chance, nor with those who had more MHC alleles distinct from their own. The lack of male dominance may permit females to identify and reproduce preferentially with non-offspring males and with males who are more diverse at the MHC. Nonetheless, the absence of disassortative mating at the MHC and neutral loci suggests that female mate choice may be limited by other factors impacting male fertilization success.