Socially Imposed Monogamy

By Kevin MacDonald

There are strong associations between wealth and reproductive success in traditional societies from around the world. Wealthy, powerful males are able to control very large numbers of females. The elite males of the vast majority of the traditional urban societies of the world, including those of China, India, and Muslim and New World civilizations, often had hundreds and even thousands of concubines. The children from these relationships were legitimate. They could inherit property and they were not scorned by the public.

Intensive polygyny by wealthy, powerful males is an optimal male strategy (i. e., it is behavior that optimizes individual male reproductive success). Males benefit from multiple mates, so males with wealth and power should use their wealth and power to secure as many mates as possible, and for the most part they have done so. The Emperor of China had thousands of concubines, and the Sultan of Morocco is in the Guinness Book of World records as having 888 children. Nevertheless, not all societies have been characterized by intensive polygyny by wealthy, powerful males.


1. Richard Alexander's Theory of SIM

As societies encounter larger and larger social groups, they are forced to impose rules that result in a leveling of reproductive opportunities in order to obtain cooperation and solidarity within the society in opposition to these external groups. In other words, high ranking males give up their added wives in order to get lower ranking males to cooperate.

Critique. The vast majority of traditional stratified societies were in fact highly polygynous, and they often covered vast areas with very large populations. Therefore, there is no need to have monogamy to have large political groups.

Nevertheless, it is certainly reasonable that egalitarian political and reproductive institutions may be one type of adaptive response to external pressure. Herlihy (1991) suggests that competition among the small, diffuse city-states of ancient Greece and Italy may have resulted in socially imposed monogamy:

Under conditions of acute competition, it was necessary to maintain the moral commitment and physical energies of the citizens. Such conditions favored the development of democratic and republican, rather than despotic institutions. The citizens whose moral commitment was essential for the welfare of the state had to be granted some participation in it. But another, equally crucial means of maintaining commitment and morale was to offer all citizens access to marriage. Not only would they gain the satisfactions of sexual union, but the rearing of the family and the acquisition of heirs would give them a large stake in the welfare of the society (pp. 14-15).

2. A Perspective on SIM in Western Europe

Males within a society have conflicts of interest over the regulation of reproduction. In general wealthy males benefit by being able to maximize their control of females. However, their doing so opposes the interests of non-wealthy males, since these non-wealthy males would benefit from establishing a more egalitarian mating system.

Evolutionary theory can't predict the outcome of this conflict any more than it can predict the winner of a battle. Evolutionary theory can only say that there are conflicts, not how they will be resolved. If wealthy males win the conflict, there will be polygyny. If lower ranking males win, then monogamy might be enforced. Low ranking males benefit by cooperating in an egalitarian group. High ranking males benefit by having non-egalitarian society with themselves at the top.

Evolutionary theory fails to predict the outcome of this conflict. From an evolutionary perspective, it is not the least surprising that conflicts of interest regarding the regulation of mating or economic activity occur in human societies. Social controls supporting mating or economic systems can vary from egalitarian to despotic, and these different types of social controls are in the interests of different individual members of human societies. Both despotisms and monogamous societies are maintained by SOCIAL CONTROLS on behavior: Despotisms control the behavior of the lower orders; monogamous societies must control the behavior of elite males. If the Czar had won the war of the Bolshevik Revolution, no evolutionary/ecological laws would have been broken, and there would be no violation of any of the principles of Darwinian psychology. However, the success of the revolution resulted in a very different type of society, with very different types of SOCIAL CONTROL (communism) than would have occurred had the Czar won.

The general finding that wealthy males in stratified societies tend to be intensively polygynous is not surprising given the evolutionary theory of sex (men benefit from multiple mates). Although it is expected that wealthy, powerful males will indeed attempt to be polygynous and may often have the power to do so, their ability to do so may conflicts with the interests of other members of the society. So the mating system is not determined by theory.

Here evidence will be provided for the importance of the following mechanisms:

  1. Political activity by lower or middle status males aimed at preventing wealthy males from being polygynous.
  2. Political activity by females or their relatives aimed at preventing polygyny. For example, a woman's relatives might insist that the husband not be allowed to have another wife. This was common in Jewish marriage contracts. (Jewish religious law does not prohibit polygyny. The Old Testament is full of polygyny.)
  3. The power of the Catholic Church which was able to impose monogamy on elite.
This last one is the most difficult to understand. Monogamy in Western Europe originated as a result of conflict between the ecclesiastical authorities and the lay aristocracy. The Church was 'the most influential and important governmental institution [of Europe] during the medieval period', and a major aspect of this power over the secular aristocracy involved the regulation of sex and reproduction. The result was that the same rules of sexual conduct were imposed on both rich and poor. This 'required above all that laymen, especially the most powerful among them, should submit to the authority of the Church and allow it to supervise their morals, especially their sexual morals. It was by this means, through marriage, that the aristocracy could be kept under control. All matrimonial problems had to be submitted to and resolved by the Church alone."

Can the Actions of the Church be Understood in terms of evolutionary psychology?

1. A main goal of the Church was to become a wealthy, powerful institution by superseding the nobility. The concerns with power and wealth are certainly comprehensible from an evolutionary perspective, even if they are unrelated to increased reproductive success. We evolved to want high social status because high social status was linked to reproductive success. But the link with reproductive success need not occur in any particular environment. In the same way we evolved to like sweets and fat, but these desires may not be linked with reproductive success in current environments.

2. At times Churchmen used their position to increase their reproductive success. Nepotism played a role of varying importance in ecclesiastical politics throughout the medieval period until the 19th century. During the early medieval period bishops gave Church properties to their relatives who provided them with their office. A common saying had it that 'the Lord has taken away our sons and has given us so many nephews." However, there were reforms during the high Middle Ages (12th and 13th centuries) that prevented nepotism from getting out of hand.

3. Popular acceptance of ecclesiastical power was facilitated by the Church's manipulation of evolved systems of dominance and subordination. For example, during the peak of ecclesiastical control over secular authorities, the papacy adopted symbols associated with secular Roman political power (the tiara, porphyry, imperial purple, burial in imperial sarcophagi) and developed ceremonies emphasizing the subordinate role of kings.

4. Popular acceptance of ecclesiastical influence was aided by the image (and reality) that the Church was altruistic -- that it wasn't concerned with or competing over reproduction. Before the reforms of the Middle Ages, many priests had wives and concubines. Writing of the French Church in 742, Saint Boniface complained to the pope about 'so-called deacons who have spent their lives since boyhood in debauchery, adultery, and every kind of filthiness, who entered the diaconate with this reputation, and who now, while they have four or five concubines in their beds, still read the gospel."

Nevertheless, reform among the clergy was real. No English prelate of the 13th century is known to have had a wife or family. Married clergy even at lower levels were exceptional during this period in England, and low levels of clerical incontinence continued into the Reformation period. The Church therefore projected the image of chastity and altruism. Whatever power and wealth it had was not directed at reproductive success.

True reproductive altruism appears to have been a factor in the very widespread attraction of extremely ascetic monastic lifestyles which provided an important aspect of the public's perception of the Church during the high middle ages. During the 11th and 12th centuries thousands of monasteries were founded. Composed of celibate and ascetic males and recruited mainly from the more affluent classes these societies 'set the tone in the spirituality of the whole church, in education and in art, [and] in the transmission of culture...'. The image of monastic altruism was also fostered by an ideology in which the prayers of monks were believed to aid all Christians. These orders provided a very popular public image of the Church.

During the 13th century, mendicant friars (Dominicans, Franciscans) were instrumental in reforming the Church to extend the power of the Pope over the Church, to enforce rules on clerical celibacy, to prevent nepotism and simony (the buying and selling of Church offices), and to make the Church supreme over secular powers and not subject to their influence.

"The voluntary poverty and self-imposed destitution that identified the early Mendicants with the humblest and most deprived sections of the population, in loud contrast to the careerism and ostentation of the secular clergy and the corporate wealth and exclusiveness of the monasteries, moved the conscience and touched the generosity of commercial communities.'

It is one of the most remarkable phenomena in the whole of history that in the high middle ages ... many members of the highest and wealthiest or at least prosperous strata of society, who had the best chances of enjoying earthly pleasures to the full, renounced them.... The flow of new candidates was particularly impressive in those places where the rules of monastic life had been restored to their ancient strictness, imposed more rigorously or even redefined more severely.... We must assume that the main motive for the choice of a monastic life was always the eschatological ideal of monasticism, even if this may have lost something of its driving force in the course of a long life or was mixed with other motives from the start. (Tellenbach, 1993; p. 103)
During the 13th century, the mendicant friars, who were typically recruited from the aristocracy, the landed gentry, and other affluent families, often had parents who disapproved of their decision'an indication that they often did not view the celibacy of their children in positive terms: 'It was a nightmare for well-to-do families that their children might become friars'. These families began to avoid sending their children to universities because of well-founded fears that they would be recruited into a religious life. Eventually, for the clergy, 'not to follow these models was increasingly a matter for silent or even noisy reproach.'

At the center of society was an institution with an ideology that people ought to be altruistic, that they ought to be celibate even when they were born to wealth. This explains popular acceptance of the authority of the church in matters of marriage and sex, but it still makes one wonder why these well-off people were entering monasteries and becoming celibate in the first place.


In Western Europe the Church adopted an ecclesiastical model of marriage which was diametrically opposed to the reproductive interests of the aristocracy. As a direct result of these efforts, there was a transformation of family structure and the social imposition of monogamy by the Christian Church by the end of the 12th century. The following factors appear to have been most important in the imposition and maintenance of SIM:

Prohibitions on Divorce

Wealthy males benefit most by being able to divorce easily because they can more easily remarry. While divorce was common in other Eurasian societies and was legal among the pre-Christian tribes of Europe, the Church's point of view was that marriage was monogamous and indissoluble. Divorce became ever more restricted under the Christian Roman emperors, and between the 9th and the 12th century the Church engaged in a successful conflict with the aristocracy centering around a series of divorce cases involving the nobility. For example, the King Phillip of France was prevented from divorcing his wife even though he disliked her and she was infertile. The king had to apologize to a group of religious personnel at an abbey in Paris.

At times divorce was allowed, but only if the goal was to obtain a male heir in cases where the first marriage had failed to produce one (e. g., Louis VII and Eleanor of Aquitaine in Medieval France). (But the Pope did not allow Henry VIII to divorce his wife even though they did not produce a son.) Divorce 'was virtually impossible except for a handful of the very rich' in England until the reform of 1857.

After the decline of ecclesiastical control in England, elite and middle class women were important interest groups favoring no basic change from the traditional anti-divorce customs. These women feared that divorce would result in desertion and economic loss. (Working class wives remained suspicious of divorce throughout this period, but had no influence on the political process.) Other women's interest groups focussed on recognition of women's economic interests during separation or divorce.

There is also some indication of a role for male interests in controlling the reproductive behavior of females and other males. Males feared that allowing divorce would lessen male authority in the family and worried that wealthy males would have a succession of wives. The fear of large scale serial monogamy was apparently groundless, at least until very recent times'a finding which attests to the inertia of anti-divorce customs in Western Europe: 'In those parts of Europe that had legalized divorce in the sixteenth century, it was three hundred years and more before any line of divorce could be distinguished from the horizontal axis of a graphic depiction of divorce rates.' In England the divorce rate remained at less than 0.1/1000 marriages until 1914 and less than 1/1000 until 1943 (Stone 1990); in 1910 no European country had a divorce rate higher than .5/1000 population.

Penalties for Illegitimacy

From an evolutionary perspective, the most crucial aspect of social controls related to reproduction is the control of concubinage. Controls on illegitimacy oppose the reproductive interests of wealthy males by making concubinage difficult or impossible and by affecting the prospects of illegitimate children by, e. g., preventing them from inheriting property. If illegitimate children can inherit property, then an important barrier to concubinage is removed. Wealthy males would be able to have a monogamous legitimate marriage but also sire other children who would be able to inherit property and even be the principal heir if there were no legitimate heirs.

The Church was actively opposed to concubinage, especially concubinage in the presence of a legitimate wife. It would appear that social controls on the abilities of illegitimate children to inherit were often effective. Church held the attitude that legitimate marriage produced legitimate children and that others had no legal standing, although in certain periods bastards had more standing than others (see below). Goody notes that the estates of bastards were subject to confiscation by the Church or the state, so that even if a man wanted to leave property to a bastard his wishes could be thwarted by the authorities. Bastards disappeared from wills altogether during the Puritan era in England.

Besides direct Church influence, there were a variety of other penalties attached to illegitimate birth arising from the secular authorities and public opinion. Being the father and especially the mother of an illegitimate child were causes for ostracism and jail, and it was common for the woman to take every effort to conceal the pregnancy, including leaving the area. These social controls had effects on mortality of illegitimate children. Infant mortality was higher for illegitimate children in both early modern England and France. Women often abandoned illegitimate children. Illegitimate children were often reported as stillborn, indicating infanticide, and women sometimes sought to avoid bearing illegitimate children via abortion.

Controls on Concubinage among the Elite

There is considerable evidence that controls on concubinage practiced by elite males became increasingly effective during the Middle Ages. The 12th century thus appears to be pivotal. There are good examples from this period of elite males who were able to avoid social and ideological controls favoring monogamy as well as examples where such individuals were entirely monogamous. The general patterns may be perceived by considering the illegitimate fertility of English rulers. 10 of the 18 kings who ruled England from 1066 to 1485 are known to have taken mistresses, and are known to have fathered 41 illegitimate offspring who can be identified with a fair degree of certainty. Henry I, who ruled from 1100 to 1135 sired 20 of these, and 5 more are listed as probable. No other Medieval king sired more than 3, and no certain illegitimate children are recorded for 8 of the kings. Henry I is unique in his apparent interest in obtaining large numbers of offspring to further his territorial ambitions. However, Henry treated his illegitimate children far less well than his legitimate children, the latter being pampered, tutored at court, and prepared for life as great nobles. Bastards, on the other hand, were excluded from inheriting the throne, and they were often not offered marriages.

Reflecting the general change in attitudes and practices related to marriage occurring in the 12th century, there is a decline in both the numbers and importance of illegitimate children in the following centuries.

Table 1. Illegitimate Fertility of Male English Rulers, 1485-1950

        Rulers                  Bastards 
        Henry VII               0  
        Henry VIII           1 son, died at age 17  
        James I                    0  
        Charles I                  0  
        Cromwell                  0  
        Charles II           14; 5 by one woman  
        James II                    6  
        William III                0  
        George I                   4; 3 by one woman  
        George II                 0  
        George III                0  
        George IV                3 acknowledged (by 3 different women); possibly 2 or 3 unacknowledged  
        William IV                11; 10 by one woman  
        Prince Albert              0  
        Edward VII                Possibly 1  
        George V                    0  
        Edward VIII                0  
        George VI                   0
Given the long term trends in bastardy within the royal family and the fact that much of this activity was publicly known in the era immediately following Puritan political power (during which adultery was declared a capital crime), the reproductive career of Charles II is truly remarkable. Nevertheless, there were limits on his power to control his own reproductive interests: Charles II did not have any legitimate children, and made an unsuccessful attempt to legitimize his oldest son, James, whom he nevertheless made the Duke of Monmouth and married off to a wealthy heiress.

While Charles II enjoyed a great deal of popularity early in his reign, his sexual behavior was considered scandalous and lowered public confidence in his regime. For example, Hutton (1989) notes that 'The regime had not regained the popularity which it had lost in 1661-2. His morals and those of this court remained the subjects of gossip and censure...' (p. 213). His last principle mistress, Louise (whom he made a duchess), was told by the Earl of Pembroke that 'she was the realm's greatest grievance' (p. 336). In 1675 a parody of the king's speech to Commons included a complaint that the money requested for the fleet would instead be used on 'cradles and swaddling clothes' (p. 338). Further, 'The king's habits continued to create a mixture of disgust and ribaldry, and to sap confidence in the government in general' (p. 338), and indeed, the court 'had become a byword for loose living' (Spurr 1990; p. 39). This indicates the existence of considerable social pressure on the king (albeit relatively ineffective) not to engage in concubinage.

Even during its peaks, however, the reproductive behavior of the English kings cannot be considered as maximizing reproductive success. The reproductive career of Charles II was truly polygynous, but certainly not maximally so given the enormous wealth available to a late-17th century monarch. Moreover, he was not able to pass the crown to his illegitimate offspring. Nor did he divorce his wife and sire legitimate children. In a society, such as traditional China where intensive polygyny and divorce were entirely legitimate, the emperor would have had much more control over the inheritance rights of his offspring, so that if a principal wife was barren, the offspring of a concubine could inherit (Ebrey 1986).

In addition, it is noteworthy that even though Charles II had a high degree of reproductive success, he fathered the same number of children as did the puritanical George III, all of whose children were legitimate. Thus Charles' polygyny did not really enable him to achieve higher reproductive success than would a monogamous relationship, or serial monogamy. (Recall Charles had no legitimate children and did not divorce his wife.) Moreover, since Charles' children were not legitimate, their marriage chances were far less than those of George III's legitimate brood. George III's children were all in the line of succession, and when George IV and the Duke of York died, William, the third son, inherited the crown. When William died with no legitimate heir, the crown passed to George III's granddaughter, Victoria, by yet another son, the Duke of Kent. Several of George III's other children were able to marry into the royal families of Protestant Europe. For Charles' brood, as well as for the children of William IV, the bar sinister would always be a liability in life. Even though public opinion was not able to prevent some English kings from behaving polygynously, there is no doubt that such behavior was viewed very negatively by the public and that this had effects on the prospects of the offspring.

Other Mechanisms of the Social Control of Sexual Behavior

One of the prime goals of the Medieval Church was to repress the pleasure of sexual intercourse even within marriage. Married couples 'were always being exhorted to continence. If they disregarded the admonition, they were threatened with begetting monsters or at best children who were sickly." Married couples were to have sex in the minimum number of times necessary for procreation, in a restricted number of positions, with the minimum amount of pleasure, and could only be engaged in on certain days and times.

Policing sexual violations was an important function of the ecclesiastical courts beginning in the Middle Ages and extending at least to the end of the 17th century. These courts were very active in 17th century England prosecuting cases of fornication, adultery, incest, and illicit cohabitation. Although the effectiveness of these ecclesiastical sanctions varied by region and period, there were examples of devastating consequences in which 'the victim was hounded by his fellows, deprived of his living by a community boycott, and treated as an outcast'. Indeed, Hill (1967; p. 349) notes that in the 17th century the ability of the High Commission of the Ecclesiastical Court system to impose sanctions, including sanctions for adultery, on the propertied who could expect to be immune from other judicial processes: 'This enforcement of equality before the law did not endear the court to those who mattered in seventeenth-century England'.

Moreover, the secular authorities, such as justices of the peace, also stood ready to prosecute such offenses, so that 'no one was at liberty to live a life of sexual freedom'. For example, pursuant to Elizabethan statutes, Justices of the Peace in the 16th and 17th centuries commonly sentenced sexual offenders of both sexes to a public whipping while stripped to waist (the woman 'until her back be bloody') and placed in the stocks (Marchant, 1969; p. 224). Powerful social controls on fornication, illegitimacy, 'promiscuous dancing', and extreme sanctions against adultery (including banishment) continued in Scotland throughout the 18th century. Indeed, capital punishment for adultery was only repealed in 1783 in Scotland, and the last recorded executions occurred in the 1690's.

The Puritan period is particularly interesting from an evolutionary perspective because of the evidence for middle and lower class support for social controls on sexual behavior. The main support of the Puritan religious movement which came to power during the 17th century in England was from the 'industrious sort of people' who were economically independent, including the yeomanry, artisans, and small and middling merchants and some few of the gentry. In Cambridgeshire this radical movement for conformity to monogamous sexual restraint represented a grass roots phenomenon not only among these classes, but also among many of the very humble, including women. The Puritans instituted very elaborate social controls on sexual behavior based mainly on their ability to exert economic pressure on the lower orders via their control of the poor relief and by exerting social pressure on all classes. Puritans criticized the Church courts because their sanctions on sexual crimes were insufficiently harsh, and Quaife (1979) details the extraordinary level of social control of individual's sex lives in 17th-century Somerset (England), including not only very aggressive magistrates made up mostly of the respectable yeomanry, but also a pervasive network of community informants who eagerly reported every aspect of sexual non-conformity to the authorities.

Ideologies Promoting Monogamy

Although ultimately relying on social controls, the Medieval Church developed elaborate ideological structures to promote monogamy and sexual restraint. In general these writings emphasized the moral superiority of celibacy, the sinfulness of extra-marital sex of any kind, and typically viewed sexual pleasure itself, even within marriage, as sinful. All sexual relationships apart from monogamous marriage were universally condemned by religious authority throughout the early modern period into contemporary times. Marital sex was viewed as a regrettable and sinful necessity, and excess passion towards one's wife was considered adultery. While there was a relative relaxation of attitudes during the 18th century, a powerful anti-hedonist religious sexual ideology rose to prominence in the 19th century.


These data indicate that beginning in the Middle Ages an elaborate system of social controls and ideologies resulted in the substantial imposition of monogamy in large areas of Western Europe. As Herlihy (1985) notes, 'The great social achievement of the early Middle Ages was the imposition of the same rules of sexual and domestic conduct on both rich and poor. The King in has palace, the peasant in his hovel: neither was exempt' (p. 157).

Nevertheless, the system was by no means completely egalitarian. There is evidence that for a positive association between wealth and reproductive success throughout pre-industrial Europe. Fertility rates of British ducal families remained above the average at least until the end of the 19th century and there was no general decline in fertility from the 14th to the 19th century, but rather an increase in fertility in the 18th century followed by a decline in the 19th century which paralleled trends occurring in the general population. British peers tended to have large families compared to commoners and that the fertility of dukes' daughters remained higher than commoners well into the 19th century.

As a result of institutionalized controls on reproduction, non-monogamous Western sexuality has been directed at obtaining psychological rewards deriving from evolved motivational systems (e. g., sexual pleasure, excitement, feelings of dominance, status, or intimacy) but that this non-monogamous sexuality has not typically been a major source of increased reproductive success. As a result, sexual behavior and attitudes have ranged between the extremes of Puritanism and libertinism, but have never approached the systems of legitimate intensive polygyny characteristic of other traditional stratified societies.

Thus during the Puritan era in England there was a pervasive suppression of sexual nonconformity while in the 18th century sexual promiscuity was more common. However, even this rather modest 18th-century libertinism appears rarely to have resulted in high reproductive success, and quite probably was often maladaptive. Despite the notorious sexual escapades of the French aristocracy in the 18th-century, many did not leave heirs or had very few legitimate children, and Coleman (1990) comes to the same conclusion regarding the British aristocracy in this period. Bernier (1984) notes that Louis XV of France (r. 1715-1774) had several maˆÆtresses declarˆ©s, as well as numerous short-lived affairs. Out of all of this illicit sexual activity, only one illegitimate child is mentioned. (One maˆÆtresse declarˆ© died in childbirth.) In this regard, his behavior was a far cry from that of his 13th-century predecessor, Louis IX (St. Louis), who ruled France while living like a monk and went on a Crusade to free the Holy Land. But the reproductive results were little different.

I suggest that the basic reason for this recurring gap between sexuality and reproduction even during periods of sexual tolerance in European societies is that, with the recent exception of serial monogamy made possible by divorce, European institutional structures surrounding reproduction have always discouraged non-monogamous reproduction. Unlike the institutionalized polygyny typical of the other stratified societies of Eurasia, Western non-monogamous sexuality has nearly always been limited, reproductively vacuous, and usually somewhat unrespectable.

The data also suggest that evolved male psychological predispositions are much more directed at sexual variety than at having large numbers of children (Fox 1986). Under conditions in which intensive polygyny is legitimate, these predispositions may be adequate to ensure large numbers of children and a similarly polygynous heir, but within Western institutional structures, the result tends to be a sterile libertinism. (e.g., Hugh Hefner)

Viewed from an evolutionary perspective there has been a remarkable continuity within a varied set of institutions which have uniformly penalized polygyny and channeled non-monogamous sexuality into non-reproductive outlets or suppressed it altogether. Despite changes in these institutions and despite vast changes in political and economic structures, Western family institutions deriving ultimately from Roman civilization have clearly aimed at the social imposition of monogamy. The thesis of this paper is that there has also been a significant degree of success in this endeavor.

Based on: MacDonald, K. B. (1995). The Establishment and Maintenance of Socially Imposed Monogamy in Western Europe. (This article was the subject of commentaries by Laura Betzig, Monique Borgerhoff Mulder, James A. Brundage, Ulrich Mueller, Frank Salter, John M. Strate, and David Sloan Wilson.) Politics and the Life Sciences, 14, 3-23. You may read the whole article here.

You may read an article on monogamy in animals here.