Postmarital Residence and Bilateral Kin Associations among Hunter-Gatherers

Dispersal of individuals from their natal communities at sexual maturity is an important determinant of kin association. In this paper we compare postmarital residence patterns among Pumé foragers of Venezuela to investigate the prevalence of sex-biased vs. bilateral residence. This study complements cross-cultural overviews by examining postmarital kin association in relation to individual, longitudinal data on residence within a forager society. Based on cultural norms, the Pumé have been characterized as matrilocal. Analysis of Pumé marriages over a 25-year period finds a predominant pattern of natalocal residence. We emphasize that natalocality, bilocality, and multilocality accomplish similar ends in maximizing bilateral kin affiliations in contrast to sex-biased residential patterns. Bilateral kin association may be especially important in foraging economies where subsistence activities change throughout the year and large kin networks permit greater potential flexibility in residential mobility.     

Kin and Child Survival in Rural Malawi

This paper investigates the impact of kin on child survival in a matrilineal society in Malawi. Women usually live in close proximity to their matrilineal kin in this agricultural community, allowing opportunities for helping behavior between matrilineal relatives. However, there is little evidence that matrilineal kin are beneficial to children. On the contrary, child mortality rates appear to be higher in the presence of maternal grandmothers and maternal aunts. These effects are modified by the sex of child and resource ownership: female children and children in households where women, rather than men, own land suffer higher mortality rates in the presence of maternal kin. These modifiers suggest the detrimental effects of matrilineal kin may result from competition between such kin for resources. There are some positive effects of kin on child survival: the presence of elder siblings of both sexes is correlated with higher survival rates, and there is some weak evidence that paternal grandmothers may be beneficial to a child’s survival chances. There is little evidence that any male kin, whether matrilineal or patrilineal, and including fathers, affect child mortality rates. This study highlights the importance of taking social and ecological context into account when investigating relationships between kin.     

Dynamics of Postmarital Residence among the Hadza

When we have asked Hadza whether married couples should live with the family of the wife (uxorilocally) or the family of the husband (virilocally), we are often told that young couples should spend the first years of a marriage living with the wife's family, and then later, after a few children have been born, the couple has more freedom--they can continue to reside with the wife's kin, or else they could join the husband's kin, or perhaps live in a camp where there are no close kin. In this paper, we address why shifts in kin coresidence patterns may arise in the later years of a marriage, after the birth of children. To do so, we model the inclusive fitness costs that wives might experience from leaving their own kin and joining their husband's kin as a function of the number of children in their nuclear family. Our model suggests that such shifts should become less costly to wives as their families grow. This simple model may help explain some of the dynamics of postmarital residence among the Hadza and offer insight into the dynamics of multilocal residence, the most prevalent form of postmarital residence among foragers.     

Hamilton's rule and kin competition: the Kipsigis case

Evolutionary studies of human behavior have emphasized the importance of kin selection in explaining social institutions and fitness outcomes. Our relatives can nevertheless be competitors as well as sources of altruism. This is particularly likely when there is local competition over resources, where conflict can lead to strife among nondispersing relatives, reducing or even negating the effects of relatedness on promoting altruism. Here, I present demographic data on a land-limited human population, utilizing large within-population variation in land ownership to determine the interactions between local resource competition and the benefits of kin in enhancing child survival, a key component of fitness in this population. As predicted, wealth affects the extent of kin altruism, in that paternal relatives (specifically father's brothers) appear to buffer young children from mortality much more effectively in rich than in poor households. This interaction effect is interpreted as evidence that the extent of nepotism among humans depends critically on resource availability. Further unanticipated evidence that maternal kin play a role in buffering children from mortality in situations where paternal kin control few resources speaks to the important role that specific local circumstance plays in shaping kin contributions to child welfare.     

Aggregation,interregional interaction,and postmarital residence patterning: A study of biological variation in the late prehistoric middle Ohio Valley

This study examines a perennial problem in anthropology, changes in postmarital residence patterning. Cross‐cultural patterns related to shifts from patrilocal to matrilocal patterns have been attributed to changes in subsistence and/or the result of migrants entering a populated region. Shifts from matrilocal to multilocal patterns have been found to be related to depopulation. This study examines these possibilities in an archeological context through morphometric analyses of human dentition. Comparisons in variability among males and females are made at four Fort Ancient sites in the Middle Ohio Valley that date to sequential time periods between circa A.D. 1000 and 1650. Results show that the earliest site (Turpin) that was occupied during the transition to maize agriculture was patrilocal, whereas two subsequent sites (Anderson and SunWatch) that were occupied after the transition to a maize‐focused diet reflect a matrilocal pattern. The most recently occupied site (Madisonville), occupied during a time of depopulation of the region after a decline in levels of maize consumption and a marked population shuffling contains a multilocal pattern. These results fit well with the various cross‐cultural findings regarding shifts in postmarital residence patterns. Am J Phys Anthropol 154:270–278, 2014. © 2014 Wiley Periodicals, Inc.     

Postmarital residence and biological variation at Pueblo Bonito

Although the social organization of many of the present-day pueblos of the American Southwest is well-described in the anthropological literature, many aspects of prehistoric Puebloan social organization have received limited attention since initial investigations of postmarital residence in the 1960s and 1970s. This paper examines postmarital residence at the Chaco Canyon great house of Pueblo Bonito, using biological data. Our findings are inconsistent with the previously well-accepted hypothesis that the Pueblo II and Pueblo III occupants of the San Juan Basin conformed to a socially prescribed pattern of matrilocal residence with matrilineal descent. Univariate variance differences for nine craniometric variables indicate a pattern of increased female variability consistent with patrilocal/bilocal residence. The results of multivariate determinant ratio analyses are in agreement with the univariate results, suggesting the possibility of a patrilocal or bilocal residence preference at Pueblo Bonito. These findings are inconsistent with the notion that the female-based system of matrilocal residence with matrilineal descent observed among the present-day Western Pueblos was the ancestral Anasazi condition.     

Maternal grandmothers improve nutritional status and survival of children in rural Gambia

Hypotheses for the evolution of human female life-history characteristics have often focused on the social nature of human societies, which allows women to share the burden of childcare and provisioning amongst other members of their kin group. We test the hypothesis that child health and survival probabilities will be improved by the presence of kin using a longitudinal database from rural Gambia. We find that the only kin to improve the nutritional status of children significantly (apart from mothers) are maternal grandmothers, and that this is reflected in higher survival probabilities for children with living maternal grandmothers. There is also evidence that the reproductive status of the maternal grandmother influences child nutrition, with young children being taller in the presence of non-reproductive grandmothers than grandmothers who are still reproductively active. Paternal grandmothers and male kin, including fathers, have negligible impacts on the nutritional status and survival of children.     

Going Home

Humans have been called “cooperative breeders” because mothers rely heavily on alloparental assistance, and the grandmother life stage has been interpreted as an adaptation for alloparenting. Many studies indicate that women invest preferentially in their daughters’ children, but little research has been conducted where patrilocal residence is normative. Bangladesh is such a place, but women nevertheless receive substantial alloparental investment from the matrilateral family, and child outcomes improve when maternal grandmothers are alloparents. To garner this support, women must maintain contact with their natal families. Here, the visiting behavior of 151 interviewed mothers was analyzed. Despite the challenges of patrilocality and purdah, almost all respondents visited their own mothers, and mothers-in-law were visited far less. This contrast persists in analyses controlling for proximity, respondent age, postmarital residence, family income, and marital status. These results affirm the importance women place on matrilateral ties, even under a countervailing ideology.     

Female Mobility and Postmarital Kin Access in a Patrilocal Society

Across a wide variety of cultural settings, kin have been shown to play an important role in promoting women’s reproductive success. Patrilocal postmarital residence is a potential hindrance to maintaining these support networks, raising the question: how do women preserve and foster relationships with their natal kin when propinquity is disrupted? Using census and interview data from the Himba, a group of semi-nomadic African pastoralists, I first show that although women have reduced kin propinquity after marriage, more than half of married women are visiting with their kin at a given time. Mobility recall data further show that married women travel more than unmarried women, and that women consistently return to stay with kin around the time of giving birth. Divorce and death of a spouse also trigger a return to living with kin, leading to a cumulative pattern of kin coresidence across the lifespan. These data suggest that patrilocality may be less of a constraint on female kin support than has been previously assumed.     

Grandmaternal childcare and kinship laterality. Is rural Greece exceptional?

Grandmothers provide more childcare for their daughters' children than for those of their sons, almost everywhere. Exceptions occur where virilocal (patrilocal) postmarital residence makes the children of sons more accessible, but even under virilocality, preferential care of daughters' children, net of the effects of proximity, is often demonstrable. A unique counter-example has been reported by Pashos (2000, Evolution & Human Behavior, 21, 97–109) who found that rural Greek grandmothers cared more for their sons' children even when effects of proximity were controlled; however, this result was based on an analysis in which everything from living in the same household to living in nearby villages was treated as equally close.Here, we present new analyses that replicate Pashos's result, based on a large European survey with a finer differentiation of residential proximity. In interviews conducted in 2004–2007, rural, but not urban, Greek women indeed reported more care of sons' than of daughters' children, net of the effects of proximity and other variables, This rural reversal of the usual uterine (matrilateral) bias was not observed elsewhere in Europe. Greeks were not surveyed again until 2015, whereupon the pattern had disappeared, with rural women now exhibiting a strong uterine bias in grandchild childcare. It seems likely that the financial crisis of 2008–2009, which hit Greece especially hard, played some role in this dramatic change, but it cannot readily be traced to increases in either unemployment or multigenerational households.     

Flexible kinship: caring for AIDS orphans in rural Lesotho

HIV/AIDS has devastated families in rural Lesotho, leaving many children orphaned. Families have adapted to the increase in the number of orphans and HIV‐positive children in ways that provide children with the best possible care. Though local ideas about kinship and care are firmly rooted in patrilineal social organization, in practice, maternal caregivers, often grandmothers, are increasingly caring for orphaned children. Negotiations between affinal kin capitalize on flexible kinship practices in order to legitimate new patterns of care, which have shifted towards a model that often favours matrilocal practices of care in the context of idealized patrilineality.     

The effects of kin propinquity on infant mortality

This study tests the grandmother hypothesis and analyzes the effect of kin propinquity on infant mortality in a 19th century American frontier communal, polygynous population. The study shows that the presence of maternal grandmothers, aunts, uncles, and paternal aunts were significantly associated with increased infant survivorship while grandfathers, paternal grandmothers, and paternal uncles showed little effect. This study has implications for understanding the evolution of a long postreproductive life span, postmarital residential strategies, and behavioral strategies that enhance inclusive fitness.     

Kin and birth order effects on male child mortality: three East Asian populations, 1716–1945

Human child survival depends on adult investment, typically from parents. However, in spite of recent research advances on kin influence and birth order effects on human infant and child mortality, studies that directly examine the interaction of kin context and birth order on sibling differences in child mortality are still rare. Our study supplements this literature with new findings from large-scale individual-level panel data for three East Asian historical populations from northeast China (1789–1909), northeast Japan (1716–1870), and north Taiwan (1906–1945), where preference for sons and first-borns is common. We examine and compare male child mortality risks by presence/absence of co-resident parents, grandparents, and other kin, as well as their interaction effects with birth order. We apply discrete-time event-history analysis on over 172,000 observations of 69,125 boys aged 1–9 years old. We find that in all three populations, while the presence of parents is important for child survival, it is more beneficial to first/early-borns than to later-borns. Effects of other co-resident kin are however null or inconsistent between populations. Our findings underscore the importance of birth order in understanding how differential parental investment may produce child survival differentials between siblings.     

Fecundity of Paternal and Maternal Non-Parental Female Relatives of Homosexual and Heterosexual Men

A variety of social, developmental, biological and genetic factors influence sexual orientation in males. Thus, several hypotheses have attempted to explain the sustenance of genetic factors that influence male homosexuality, despite decreased fecundity within the homosexuals. Kin selection, the existence of maternal effects and two forms of balancing selection, sexually antagonistic selection and overdominance, have been proposed as compensatory mechanisms for reduced homosexual fecundity. Here, we suggest that the empirical support for kin selection and maternal effects cannot account for the low universal frequency and stability of the distribution of homosexuals. To identify the responsible compensatory mechanism, we analyzed fecundity in 2,100 European female relatives, i.e., aunts and grandmothers, of either homosexual or heterosexual probands who were matched in terms of age, culture and sampling strategy. Female relatives were chosen to avoid the sampling bias of the fraternal birth order effect, which occurs when indirectly sampling mothers though their homosexual sons. We observed that the maternal aunts and grandmothers of homosexual probands were significantly more fecund compared with the maternal aunts and maternal grandmothers of the heterosexual probands. No difference in fecundity was observed in the paternal female lines (grandmothers or aunts) from either of the two proband groups. Moreover, due to the selective increase in maternal female fecundity, the total female fecundity was significantly higher in homosexual than heterosexual probands, thus compensating for the reduced fecundity of homosexuals. Altogether, these data support an X-linked multi-locus sexually antagonistic hypothesis rather than an autosomal multi-locus overdominance hypothesis.     

Reply to Opler on Apachean Subsistence, Residence, and Girls' Puberty Rites

Archaeological evidence shows that Apaches occupied the central Plains area from A.D. 1525–1725 in Wyoming, South Dakota. Nebraska, Kansas, and Colorado. Toward the end of this period they were semi-sedentary farmers living in houses generically like those of the Plains-Prairies earth lodge. Because in their southward migration they contacted Plains-Prairies farmers earlier than those in the Southwest proper, and farming was women-dominated and residence matrilocal for the Hidatsa, Mandan, Arikara, Pawnee, and Wichita, it seems highly probable that these Plains Apaches acquired matrilocal residence and a female farming division of labor at this time before contacting Tanoans in the Southwest. The more western Apacheans, who may not have had contact with Plains tribes, could have acquired matrilocal residence from western Pueblos, including the Keresans, who were probably all matrilocal before Spanish contact. It is doubtful that the wild plant gathering of Apachean women was sufficient to cause matrilocal residence, because in parts of California and the Great Basin where women gathered a greater proportion of the diet than Apachean women, residence was vary rarely matrilocal.     

Genetic variation in Northern Thailand Hill Tribes: origins and relationships with social structure and linguistic differences

Background

Ethnic minorities in Northern Thailand, often referred to as Hill Tribes, are considered an ideal model to study the different genetic impact of sex-specific migration rates expected in matrilocal (women remain in their natal villages after the marriage and men move to their wife's village) and patrilocal societies (the opposite is true). Previous studies identified such differences, but little is known about the possible interaction with another cultural factor that may potentially affect genetic diversity, i.e. linguistic differences. In addition, Hill Tribes started to migrate to Thailand in the last centuries from different Northern areas, but the history of these migrations, the level of genetic legacy with their places of origin, and the possible confounding effects related to this migration history in the patterns of genetic diversity, have not been analysed yet. Using both original and published data on the Hill Tribes and several other Asian populations, we focused on all these aspects.

Results

Genetic variation within population at mtDNA is lower in matrilocal, compared to patrilocal, tribes. The opposite is true for Y-chromosome microsatellites within the Sino-Tibetan linguistic family, but Hmong-Mien speaking patrilocal groups have a genetic diversity very similar to the matrilocal samples. Population divergence ranges between 5% and 14% at mtDNA sequences, and between 5% and 36% at Y- chromosomes STRs, and follows the sex-specific differences expected in patrilocal and matrilocal tribes. On the average, about 2 men and 14 women, and 4 men and 4 women, are exchanged in patrilocal and matrilocal tribes every generation, respectively. Most of the Hill Tribes in Thailand seem to preserve a genetic legacy with their likely geographic origin, with children adoption probably affecting this pattern in one tribe.

Conclusion

Overall, the sex specific genetic signature of different postmarital habits of residence in the Hill Tribes is robust. However, specific perturbations related to linguistic differences, population specific traits, and the complex migratory history of these groups, can be identified. Additional studies in different populations are needed, especially to obtain more precise estimates of the migration parameters.

     

Household food group expenditure patterns are associated with child anthropometry at ages 5, 8 and 12 years in Ethiopia,India, Peru and Vietnam

Population-level analysis of dietary influences on nutritional status is challenging in part due to limitations in dietary intake data. Household expenditure surveys, covering recent household expenditures and including key food groups, are routinely conducted in low- and middle-income countries. These data may help identify patterns of food expenditure that relate to child growth.ObjectivesWe investigated the relationship between household food expenditures and child growth using factor analysis.MethodsWe used data on 6993 children from Ethiopia, India, Peru and Vietnam at ages 5, 8 and 12y from the Young Lives cohort. We compared associations between household food expenditures and child growth (height-for-age z scores, HAZ; body mass index-for-age z scores, BMI-Z) using total household food expenditures and the “household food group expenditure index” (HFGEI) extracted from household expenditures with factor analysis on the seven food groups in the child dietary diversity scale, controlling for total food expenditures, child dietary diversity, data collection round, rural/urban residence and child sex. We used the HFGEI to capture households’ allocations of their finances across food groups in the context of local food pricing, availability and pReferencesResultsThe HFGEI was associated with significant increases in child HAZ in Ethiopia (0.07), India (0.14), and Vietnam (0.07) after adjusting for all control variables. Total food expenditures remained significantly associated with increases in BMI-Z for India (0.15), Peru (0.11) and Vietnam (0.06) after adjusting for study round, HFGEI, dietary diversity, rural residence, and whether the child was female. Dietary diversity was inversely associated with BMI-Z in India and Peru. Mean dietary diversity increased from age 5y to 8y and decreased from age 8y to 12y in all countries.ConclusionHousehold food expenditure data provide insights into household food purchasing patterns that significantly predict HAZ and BMI-Z. Including food expenditure patterns data in analyses may yield important information about child nutritional status and linear growth.     

Girls' Puberty Rites and Matrilocal Residence

This paper challenges the view of Judith K. Brown (1961) and Peter Kloos (1969) that matrilocal residence tends to cause girls' puberty rites. It shows how improbable this hypothesis is for western North America, where data are plentiful, and suggests that it is unlikely for the rest of the world. Girls' puberty rites seem to be earlier in most localities because of much greater world frequency and dominance among hunters, gatherers, and fishers, while matrilocal residence appears mainly to have stemmed from female hand farming at a later date. [causality, evolution, puberty rites—female, matrilocal residence, migration as agent of culture spread]     

Mate selection and its impact on female marriage age, pregnancy wastages, and first child survival in Tamil Nadu, India

Marriage in Indian society is a religious duty. Consanguineous marriage is common, where individuals prefer to marry within their clan (a unilateral kin group based on either matrilineal or patrilineal descent). Keeping in mind that this form of marriage has certain disadvantages for social and biological as well as demographic aspects of individuals and families, the present study examines the influence of mate selection (i.e., close relatives, distant relatives, not related) on female age at marriage, pregnancy wastages, and survival status of the first child. The study was designed based on the information collected on a sample size of 3,948 married women aged 13-49 in Tamil Nadu, India, by the National Family Health Survey (NFHS), 1992. Results suggest that 48 per cent of women in Tamil Nadu marry their relatives. This practice of marrying relatives is high in rural areas, among Hindus, Scheduled Castes/tribes, and illiterate women as compared to urban areas, among non-Hindus, non-SC/ST, and educated women, respectively. The bivariate analysis reveals that women marrying their close relatives had low age at marriage and experienced a higher per cent of pregnancy wastage and child loss (first child) as compared to those women marrying their distant relatives or nonrelatives. The result is found to be consistent even after controlling for selected background variables through multivariate techniques (applied separately for age at marriage, pregnancy wastages, and the survival status of first child). Hence, this study suggests that steps should be taken to inform people about the problems of marrying close relatives through appropriate IEC programs in Tamil Nadu.     

Vervet monkey grandmothers: Interactions with infant grandoffspring

Social relationships of 30 infants with their maternal grandmothers were studied in a captive colony of vervet monkeys (Cercopithecus aethiops sabaeus).Grandmothers and grandinfants formed affiliative relationships with one another that could be distinguished from the infant’s relationships with nonkin adult females and with other adult female kin. The intensity of the grandmother—grandinfant relationship varied according to several factors which were related to the infant’s vulnerability to mortality and to the grandmother’s ability to provide effective social support. High-ranking grandmothers spent more time near their grandinfants, and initiated more grooming and caretaking of their grandinfants, than did lower-ranking grandmothers. Grandmothers spent more time near their daughter’s first surviving infant than near later-born infants, and when grandmothers had more than one adult daughter, they spent more time near the infant of the younger daughter. These results, combined with the fact that the presence of a maternal grandmother has been associated with a reduction in the rate of infant mortality in this colony (Fairbanks and McGuire, 1986), suggest that grandmothers are actively contributing to the reproductive success of their adult daughters and to the survival of their infant grandoffspring.