Descent Principles: Part 1


Kinship is reckoned in a number of different ways around the world, resulting in a variety of types of descent patterns and kin groups.  Anthropologists frequently use diagrams to illustrate kinship relationships to make them more understandable.  The symbols shown here are usually employed.  They may be combined, as in the example below on the right, to represent a family consisting of a married couple and their children.

Kinship diagram symbols--triangles for males, circles for females, equal signs for marriage bonds, vertical lines for descent bonds, and horizontal lines for codescent bonds

In kinship diagrams, one individual is usually labeled as ego click this icon to hear the preceding term pronounced.  This is the person to whom all kinship relationships are referred.   In the case below on the right, ego has a brother (Br), sister (Si), father (Fa), and mother (Mo).  Note also that ego is shown as being gender nonspecific--that is, either male or female.

Basic kinship diagram showing a man married to a woman and their three children


Unilineal Descent

Most cultures severely limit the range of people through whom descent is traced by using a unilineal click this icon to hear the preceding term pronounced descent principle.  This traces descent only through a single line of ancestors, male or female.  Both males and females are members of a unilineal family, but descent links are only recognized through relatives of one gender.  The two basic forms of unilineal descent are referred to as patrilineal click this icon to hear the preceding term pronounced and matrilineal click this icon to hear the preceding term pronounced.

With patrilineal descent, both males and females belong to their father's kin group but not their mother's.  However, only males pass on their family identity to their children.  A woman's children are members of her husband's patrilineal line.  The red people in the diagram below are related to each other patrilineally.

Diagram of patrilineal descent

The form of unilineal descent that follows a female line is known as matrilineal.  When using this pattern, individuals are relatives if they can trace descent through females to the same female ancestor.  While both male and female children are members of their mother's matrilineal descent group, only daughters can pass on the family line to their offspring.  The green people below are related to each other matrilineally.

Diagram of matrilineal descent

In societies using matrilineal descent, the social relationship between children and their biological father tends to be different than most people would expect due to the fact that he is not a member of their matrilineal family.  In the case of ego below, the man who would have the formal responsibilities that European cultures assign to a father would be his mother's brother (MoBr), since he is the closest elder male kinsmen.  Ego's father would have the same kind of responsibilities for his sister's children.

Diagram of matrilineal descent highlighting the importance of mother's brother's relationship to her son

 

Inheritance patterns for men in matrilineal societies also often reflect the importance of the mother's brother.  For example, in the Ashanti Kingdom of Central Ghana, a king traditionally passes his title and status on to his sister's son.  A king's own biological son does not inherit the kingship because he is not a member of the ruling matrilineal family group.  Women usually inherit status and property directly from their mothers in matrilineal societies.

Unilineal descent has been found most commonly, but not exclusively, among materially rich foragers, small-scale farmers, and nomadic pastoralists click this icon to hear the preceding term pronounced.  The common factors for these types of societies are small populations that usually have more than adequate food supplies.   Until the early 20th century, approximately 60% of all societies traced descent unilineally.  Since then, many of these societies have disappeared or have been absorbed by larger societies that follow other rules of descent.


Cognatic Descent

At least 40% of the societies around the world today trace descent through both the mother's and the father's ancestors to some degree.  They follow one of several nonunilineal or cognatic click this icon to hear the preceding term pronounced descent principles.  The result is usually more varied and complex family systems than are found in societies with patrilineal or matrilineal descent patterns.  Cognatic descent is known to occur in four variations: bilineal, ambilineal, parallel, and bilateral descent.  By far the most common pattern is bilateral descent, which is commonly used in European cultures.  It is described in the next section of this tutorial.

When both patrilineal and matrilineal descent principles are combined, the result is the bilineal click this icon to hear the preceding term pronounced, or double, descent pattern shown below.  With this rare hybrid system, every individual is a member of his or her mother's matrilineage click this icon to hear the preceding term pronounced and father's patrilineage click this icon to hear the preceding term pronounced.

Diagram of bilineal descent

As a result, everyone, except siblings click this icon to hear the preceding term pronounced, potentially have a unique combination of two unilineal family lines, as shown in the diagram below.  Note that parents only share either their children's matrilineal line or patrilineal line of descent.

Diagram of bilineal descent with more descent links shown

 

The Yško of southeastern Nigeria are an example of a society with bilineal descent.  Their important portable property, including livestock and money, are inherited matrilineally.  Fixed property, such as farm plots, pass down through the patrilinal line as do rights to trees and other forest products.   It is not surprising that they have patrilineally inherited obligations to cooperate in cultivating their fields.  Obligations to perform funerals and pay bride price for sons are inherited through the matrilineal line.

 

The Toda of southern India also follow bilineal descent.  Their property is inherited patrilineally and ritualistic privileges related to funerals are inherited matrilineally.

A similarly rare combination of unilineal descent patterns is known as parallel click this icon to hear the preceding term pronounced descent.  With this system, men trace their ancestry through male lines and women trace theirs through female lines.  Unlike bilineal descent, each individual is a member of only one descent group.

 

Diagram of parallel descent

Ambilineal click this icon to hear the preceding term pronounced descent  is still another unusual descent system that, in a sense, combines unilineal patterns.  Descent from either males or females is recognized, but individuals may select only one line to trace descent.  Since each generation can choose which parent to trace descent through, a family line may be patrilineal in one generation and matrilineal in the next.

Diagram of ambilineal descent

The reason for choosing one side over the other often has to do with the relative importance of each family.  In other words, ambilineal descent is flexible in that it allows people to adjust to changing family situations.   For instance, when a man marries a woman from a politically or economically more important family, he may agree to let his children identify with their mother's family line to enhance their prospects and standing within the society.

 

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This page was last updated on Tuesday, June 27, 2006.
Copyright © 1997-2006 by Dennis O'Neil. All rights reserved.
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