Marriage is found in virtually every human society, which suggests that it is adaptive. Three traditional explanations are offered: it lets men and women share the products of a gender division of labour, it provides for infants who are dependent for many years, and it reduces sexual competition. None of these shows that marriage is the only solution. Comparative evidence from birds and mammals points to a fourth explanation: the mother's difficulty in feeding herself and her infant at the same time.
This note examines why marriage is universal, weighing each explanation with evidence, for the UPSC Anthropology Optional. It falls under Paper I, topic 2.3 (marriage: definition and universality) of the Anthropology Optional syllabus.
The question
Humans can survive and reproduce without marriage. Yet almost all known societies have the custom. A custom so widespread is likely to solve a problem that all societies face. The test of any explanation is therefore strict: it must show not only that marriage solves the problem, but that marriage is the best or the only reasonable way of solving it.
The explanations at a glance
| Explanation | Argument | Weakness |
|---|---|---|
| Gender division of labour | Men and women do different work, so they need a way to share its products. | Sharing could be organised without marriage, through band-wide sharing or cooperation between brothers and sisters. |
| Prolonged infant dependency | The long dependence of the child burdens the mother, who needs a man's help. | A group of men and women could care for children together without marriage. |
| Sexual competition | Year-round female sexuality would cause rivalry among males unless it were regulated. | Greater availability should mean less competition; other rules could regulate it. |
| Postpartum feeding problem | A mother cannot feed herself and her infant at the same time, so a bonded male is needed. | Rests on analogy with other animals, which not all scholars accept. |
1. Gender division of labour
In every society known to anthropology, men and women perform different economic tasks. As long as this is so, society must provide a way for the two sexes to share what they produce. Marriage does this. G. P. Murdock made economic cooperation part of his definition of the family.
The difficulty. Marriage is not the only way to solve the problem.
- The hunter-gatherer rule of sharing meat could be extended to everything brought in by both men and women.
- A small group of men and women, such as brothers and sisters, could be pledged to cooperate economically.
2. Prolonged infant dependency
Humans have the longest period of infant dependency of any primate. The burden falls mainly on the mother, who is the chief caregiver in most societies. Child care may limit the kinds of work she can do, and she may need a man's help with tasks, such as hunting, that cannot be combined with it.
The difficulty. This is the division-of-labour argument in another form, and it has the same weakness. It is not clear why a group of men and women, such as a foraging band, could not provide for dependent children together without marriage.
3. Sexual competition
Unlike most other female primates, the human female may be sexually active throughout the year. Some scholars suggest that this created serious competition among males, and that society had to develop marriage to reduce the risk of destructive conflict.
The difficulties.
- Continuous sexuality should reduce competition, not increase it. Rivalry ought to be sharpest where there is only a brief breeding season.
- In many animal species, including some close primate relatives whose females are frequently receptive, males show little aggression over females.
- Competition could be regulated by rules other than marriage, such as a system in which partners changed at fixed intervals. Such a system might, however, break down if individuals formed preferences and jealousies.
Evidence from other mammals and birds
If the three theories were sound, the same factors should predict stable male-female bonding in other warm-blooded animals. Such bonding occurs in most species of birds and in some mammals, such as wolves and beavers. A comparative study of 40 mammal and bird species, reported by Melvin Ember and Carol Ember, tested this.
| Factor | What the theory predicts | What the comparison found |
|---|---|---|
| Division of labour | Bonding where the sexes do different work | These species have nothing like a human division of labour, yet many form bonds |
| Long infant dependency | More bonding | Less bonding |
| Greater female sexuality | More bonding | Less bonding |
None of the three factors predicts bonding in the expected direction.
4. The postpartum feeding problem
One factor does predict bonding. Species in which a mother can feed herself and her young at the same time after birth tend not to mate stably. Species in which she cannot do so typically form male-female bonds.
- Birds. The young cannot fly for some time. If the mother leaves the nest to find food, she risks losing them to predators. A bonded male can bring food or take his turn at the nest.
- Grazing animals. The young of horses can travel with the mother almost at once. There is no feeding problem and no stable bond.
- Baboons and kangaroos. The mother carries the young as she feeds. Again there is no stable bond.
The human case. The human mother, on this view, has a postpartum feeding problem. Once humans had lost most of their body hair, infants could not cling to the mother as she moved. Once humans came to depend on dangerous kinds of food-getting such as hunting, mothers could not safely take infants along.
Support from the Hadza
Frank Marlowe's research among the Hadza foragers of Tanzania supports this view.
- Women provide more berries and other plant foods; men provide more meat and honey.
- Hadza women could generally support themselves and their children without a mate.
- The exception is when a woman has a nursing infant, when her contribution of food falls.
- The father makes up the difference. Fathers of nursing children brought in significantly more food than fathers of older children.
Why marriage is the likely solution
| Alternative | Why it works less well |
|---|---|
| Two mothers take turns minding the children | Neither could collect enough food for two mothers and two sets of children. |
| A promiscuous group | A mother could not count on any particular male to watch her baby or bring her food, since none would think himself the father. |
| A mother and father | They share the same set of children, so each has reason to provide for them. |
Evaluation
- Strength. The postpartum feeding explanation is the only one tested against comparative evidence, and it explains why a particular man and woman, not just any group, should cooperate.
- Limitation. It argues from other animals to humans, and not everyone accepts that step. It explains the pair bond better than it explains marriage as an institution, with its rules, ceremonies and payments.
- Other views. Claude Lévi-Strauss saw marriage as an exchange that creates alliances between groups. Kathleen Gough and Notes and Queries stressed the legitimacy it gives to children. These explain what culture has added to the bond.
- How universal? The traditional Nayar of Kerala, where husband and wife did not live together, and the Na (Mosuo) of China, with their visiting relationships, are cited as limiting cases. The careful statement is that marriage is nearly universal.
For the distinction between the biological and the cultural sides of the union, see also our note on marriage and mating.
Using this topic in a UPSC answer
- Begin by stating that marriage is nearly universal and therefore presumed adaptive.
- Present the three traditional explanations, each followed at once by its weakness.
- Bring in the comparative study of 40 species and the postpartum feeding problem.
- Cite Marlowe's Hadza findings as ethnographic support.
- Add Lévi-Strauss on alliance, and the Nayar as a limiting case.
- Conclude that biology explains the bond and culture explains the institution.
For presentation, see our guide to anthropology answer writing with diagrams, thinkers and case studies.
Frequently asked questions
Why is marriage universal?
Marriage is nearly universal because it solves problems that every society faces: sharing the products of men's and women's work, caring for dependent infants, limiting sexual rivalry and, above all, supporting the mother while she nurses an infant.
What are the traditional explanations for the universality of marriage?
The three traditional explanations are the gender division of labour, prolonged infant dependency and sexual competition. Each shows a problem marriage solves, but none shows that marriage is the only possible solution.
What is the postpartum feeding problem?
It is the difficulty a mother has in feeding herself and her newborn at the same time. In species with this problem, including humans, males and females tend to form stable bonds so that the male can provide food or care.
What did the study of mammals and birds show?
A comparison of 40 species found that division of labour, long infant dependency and greater female sexuality do not predict male-female bonding. Only the mother's inability to feed herself and her young together predicted it.
What did Marlowe find among the Hadza?
Frank Marlowe found that Hadza women can usually support themselves, but their food contribution drops when they have a nursing infant. Fathers of nursing children then bring in significantly more food.
Is marriage found in every society?
Marriage is found in virtually all known societies. The traditional Nayar of Kerala and the Na of China are discussed as exceptions or limiting cases, so anthropologists usually call marriage nearly universal.
Why is the sexual competition theory criticised?
Critics note that year-round sexuality should reduce rivalry, that many primates with receptive females show little male aggression, and that rules other than marriage could regulate competition.