While in many Western societies kinship systems are no longer important in our everyday lives, this has not been the case historically, nor is it presently the case for many parts of the developing world. There has been growing interest in understanding how variation in social structures such as kinship systems shape a wide variety of outcomes, including individual psychology, conflict, and the well-being of women.
Kinship Systems and the Western Church
In a recent Science article, Schulz et al. (2019) explore the effects of the Western Church’s (what would eventually become the Roman Catholic Church) efforts to undermine kinship systems in Europe. The authors note that kinship systems are a primary social structure for most of the world’s societies. They determine residence, marriage patterns, alliance formation, and norms. These kin-based institutions have had important consequences for individual psychology, encouraging cooperation and in-group loyalty, at the expense of individualism and impersonal fairness and cooperation.
The authors are interested in understanding how the Western Church’s ban on cousin marriage and related policies of marriage by choice and requiring neo-local residence affected the intensity of kin-based institutions and subsequent psychology. They find that globally, countries with longer exposure to the Western Church are more individualistic and more cooperative with strangers. Examining variation within countries in Europe, they find similar patterns. Finally, they also examine adult children of immigrants in European countries and find that greater intensity of exposure to the Western Church of the parents’ home countries is associated with more individualistic behavior and greater fairness and trust in strangers. The authors’ findings suggest that some of the so-called WEIRD – Western, Educated, Industrialized, Rich, and Democratic – psychology is a product of the policies pursued by the Church to undermine kin-based institutions.
Segmentary Lineages and Conflict
One form of organizing kinship is through segmentary lineages. Segmentary lineage societies are characterized by unilineal descent (tracing group membership through either the male or female line) and the presence of subsets of a full lineage that have political functions. Anthropologists had hypothesized that this form of social organization may lead to more conflict because it facilitates the mobilization of men to fight when there is a conflict. When there is conflict between various segments of a lineage, those within that segment and related segments are obligated to mobilize on behalf of those involved in the conflict. A Bedouin proverb illustrates the logic: “I against my brothers; my brothers and I against my cousins; my cousins, my brothers, and I against the world”. See the figure below for an illustration of various lineage segments.
This hypothesis is explored in Moscona, Nunn, and Robinson (2020) for sub-Saharan Africa. They code various ethnic groups as belonging to segmentary lineage societies or not. They pair this data geo-coded data on conflict. They find that there is a positive and significant relationship between practicing segmentary lineage and greater incidence of conflict, duration of conflict, and number of fatalities. The result is present across all types of conflicts (e.g. civil conflict, within-group conflicts). They find evidence that the effects of segmentary lineage on conflict are particularly strong for retaliatory conflicts – which suggests that segmentary lineages may facilitate the escalation of small disputes to larger-scale conflicts.
Matrilineal Kinship and the Well-Being of Women
Another form of variation in kinship structure is whether lineage and descent are traced through male or female members. In matrilineal systems, group membership is determined through women, rather than through men as in patrilineal systems. This may have important implications for the well-being of women and children. Anthropologists had highlighted how matrilineal systems may both empower women but undermine spousal cooperation. This is due to particular features of matrilineal systems. First, in matrilineal systems husbands and wives have so-called split allegiances, as they each retain strong ties with their own kin group. Women retain stronger ties with their family members, since their children are part of their kin group, and men are responsible for providing for their sisters’ children. Second, husbands have less authority over their wives, as the wife can more easily leave a spouse to return to her kin group. See the figure below for a comparison of matrilineal relative to patrilineal kinship.
In Lowes (2018), I explore the implications of matrilineal kinship relative to patrilineal kinship for spousal cooperation and the well-being of women and children. I examine this in the context of the matrilineal belt, which describes the distribution of matrilineal kinship systems across the center of Africa. I take two strategies to explore this question. First, I collect survey and experimental data from couples living in a town near the matrilineal belt border in the Democratic Republic of Congo (DRC). Couples participate in a public goods game where they are paired with a spouse or with a stranger of the opposite sex. I find that matrilineal individuals are less cooperative with their spouse when there is plausible deniability about the initial size of their endowment in the game. I do not find an equivalent effect for when spouses are paired with strangers of the opposite sex. These results are consistent with matrilineal systems leading to less spousal cooperation.
Second, I examine outcomes related to investment in children and women’s empowerment. I use the survey data from my sample in DRC as well as data from the Demographic and Health Surveys for countries along the matrilineal belt. I find that children of matrilineal women are healthier and better educated in both my sample and in the DHS. I also find that women are less likely to have experienced domestic violence and are less supportive of domestic violence. These results suggest matrilineal systems improve outcomes for women and children.
The papers discussed are just a few examples of the growing literature connecting variation in development outcomes to social structures. Other work, such as Enke (2019), explores how kinship tightness affects cooperation and moral systems (note, the map at the top of this post is from this paper). The papers tie social organization to variation in cooperation at various scales and highlight the importance of understanding how social structures shape incentives for cooperation.
Enke, Ben. “Kinship, Cooperation, and the Evolution of Moral Systems.” Quarterly Journal of Economics, 2019, vol. 134(2), pp. 953-1019.
Lowes, Sara. “Matrilineal Kinship and Spousal Cooperation: Evidence from the Matrilineal Belt”. 2018.
Moscana, Jacob, Nathan Nunn, and James A. Robinson. “Segmentary Lineage Organization and Conflict in Sub-Saharan Africa.” Econometrica. Volume 88. Number 5. September 2020, 1999-2036.
Schulz, Jonathan F., Duman Bahrami-Rad, Jonathan P. Beauchamp, and Joseph Henrich. “The Church, intensive kinship and global psychological variation.” Science. Volume 366. Number 707. November 2019.