Marital circles

Software makes analysis of matrimonial practices among indigenous South American peoples possible.

By Mônica Pileggi

Agência FAPESP – The matrimonial practices within a culture are guided by customs, beliefs or a series of variables like demographics or political interests. But each marriage is also determined by already existing factors that define the matrimonial possibilities and impossibilities of a society.

This is the premise of a study developed by Márcio Ferreira da Silva, professor of Anthropology in the School of Philosophy, Letters and Human Sciences (FFLCH) at the Universidade de São Paulo (USP) with FAPESP funding through its Regular Research Awards program.

The study, entitled “The union of marriage in tropical South America: study of two empirical networks” aimed to understand the complex network formed by family relations and resulted in the development of a computational tool to aid in this understanding. Two systems of marital unions were studied: that of the Waimiri-Atroari, located in the states of Roraima and Amazonas, and the Enawenê-Nawê, in Mato Grosso State.

Silva says that the two indigenous populations studied have different matrimonial norms. The Waimiris allow marriage between cousins while the Enawenês, even though they don’t have a set of formulated rules, prohibit marriage between members of the same clan or near relatives of different clans. 

 “All societies have rules for marriage and sexual relations. The system adopted by the Enawenês, for example, closely resembles that of the Brazilian Civil Code, disallowing marriage between close blood relatives,” he told Agência FAPESP.

Motivated to understand the way in which these peoples shape their family relations differently, the researcher developed software called MaqPar together with João Dal Poz Neto, professor at the Universidade Federal de Juiz de Fora (UFJF). Poz Neto received funding from the Minas Gerais Research Foundation (FAPEMIG).

The program’s mechanism finds marital circles, or real family relationships between married people in a given network, which multiply with every new marriage. The researchers swept the relations network in batches and organized the marital circles found, each with a set of parameters that allowed researchers to measure, calculate and classify the phenomena found.

According to Silva, in the two native populations studied, a marriage only really begins after the birth of the first child. Cohabitation with an active sexual life and reciprocal economic obligations can change if the woman doesn’t give birth.

Aside from love and affinity, a series of variables interferes with the formation of family ties. Demography, history, standard of marital preference, individual and familial strategies, economic and political interests, passions and personal likes are some of the elements that form family structures when they mix together.

“In order to have an idea of the complexity, the Waimiri-Atroari network analyzed by MaqPar comprises just 245 people including children. In this network, 33,160 marital circles were found. When a woman marries a man from the same indigenous tribe, for example, and she has a sister that marries his brother, they don’t marry with relatives, but rather as relatives,” he said.

“There are many types of mechanisms for closing circles and this is just one of them. The circles form multiple interconnections between people and families, in other words, an alliance between familial segments, connecting families with each marriage,” he explained.

In the Enawenê-Nawês network, which has 734 people, the number of marital rings found and analyzed by MaqPar was 81,079.  “This marital circle system, aside from being new, is dynamic and develops over time, as a network is formed with each marriage and also changes every time there is a death,” said the FFLCH-USP professor.

“The MaqPar software is free and can be used by anyone at http://maqpar.zip.net, using the visitor’s password ‘maqpar’,” said Silva.