Monogamous Coupling and Polygamous Coordination
by Michael G. Heller
Published in Social Science Files, June 2, 2025
Home Again by Frederick McCubbin, 1884 Australia
Humans created utilitarian monogamy
Our polygamous primate ancestry reveals that early humans could not have been naturally monogamous. Monogamy is fairly common among the warm-blooded categories of animals such as mammals and birds. Some monkey species are monogamous. In at least one genus the male monkey spends more time with his infants than does their mother.1 Among apes, only gibbons exhibit a monogamous living pattern. For both sexes this requires the fierce defence of territory against all same sex competitors. The fact that infidelity is not unknown among gibbons in the wild simply shows how difficult it is for individuals to maintain such prohibitive defences against polygamy in the absence of a genetic predisposition for fidelity or without human-level language and discursive political institutions for rule-making.2
On the other hand, as a general rule of thumb monogamous animals tend to have larger brains than polygamous ones.3 Perhaps, the fierce individual territoriality of gibbons correlates with their greater aptitudes for Machiavellian Intelligence.4
Our probable nearest ancestors, the chimpanzees5, were and remain rampantly promiscuous and instinctively polygamous.6 For this reason alone we know that early humans were truly ‘going against their nature’ when they eventually did begin to couple-up in monogamous relationships. Changes in group-based organisation and social ordering would have been needed for conditions of monogamy to be maintained.
For any of this to happen there would have had to be material incentives to change customs, as well as cognitive and communicational advances that would enable decision making and implementation. These are the factors we must weigh in any evolutionary analysis of our hominoid transition from polygamy to monogamy.
It appears to be the case that polygamy has indeed been the norm among anatomically modern humans ever since the commencement of the hominid lineage.7 The great significance of coupling was that it was not the natural thing for humans to do.
There have always been short-run reasons in favour of polygamy that might have weighed the evolutionary balance against monogamy. This can be appreciated by making but a short digression into the future. Even today in various parts of the world some hunter gatherers (who remain our indispensable ‘proxy-primitives’ in any evolutionary analysis of society) still choose to remain polygamous.8 Although intrepid nineteenth century explorers of the then comparatively pristine ‘new world’ societies concluded that monogamy was more prevalent than polygamy, they also observed that rule-sanctioned polygamy often remained politically rational in the short term for the consolidation of centralised forms of rulership in warring militant societies. He who had most wives and the most children enhanced his status as the richest, the most powerful and the most favoured by the gods. In these ways, the claims for kinship-based forms of supreme rulership were greatly strengthened.9
Looking at the contemporary world it may be tempting to reach the conclusion that polygamy and monogamy are ‘cultural choices’. The relevant story is repeatedly told in relation to factors such as religious custom or convention, or the differentiations of belief systems that characterised both the absorptive empires and the determinedly isolated territories. However, from the longer run perspective of social science such short-term worldviews of differences between relatively recently manufactured creeds and constitutions belittles the world before rulership and hyper-organised militant competition for territory, and before centrally organised story telling and religion.
Far more fundamental are the points in time and space when the decision for monogamy over polygamy was driven by autonomous rational individual choice making that must have been perceived by each of the innumerable pioneering individuals as more of a revolution than an evolution. The uptake of any big new idea would have been imitative on a grand scale. Yet this is how evolution occurs.
When a similar or equivalent innovation is made over and over again unrelatedly in different places we may conclude that the historical process observed is both one of variation, selection, stabilisation and emulation over generations and territories, but also one that is a commonsensical ‘correct’ response to a commonplace obstacle.
It is from this perspective that the biological insight into growth of brain size from Neanderthals onwards makes such a dramatic difference to our analysis. Complex physiological drivers and psychological advances gave humans from at least two hundred thousand years ago onwards the sufficient cognitive capacity to rationally weigh up their environments against their calculative options for better managing these environments.10 They invented tools and elementary language, they learned to communicate while better controlling their emotions, they collaborated in shared calculative processes. But they also created similarly universal divisions of labour and notions of exclusive possession. With their improvements in cognition humans finally became competent enough to recognise the calculative logic that enabled creations of governed society. In this context, coupling was one very significant ‘pre-adaptation’ that enabled sociation. The choice of monogamy must have been made repeatedly in many different places. It was developmentally revolutionary for the first society.
After forms of rulership had been invented in the transitions between coordinated and administered societies some societies reverted for practical or ideological reasons to polygamy. But their organised and highly regulated polygamy bore no resemblance to the chimpanzee version. Therefore, there were two developmental discontinuities in reproductive rationality — the hominin evolution from polygamy to monogamy, and a later political-religious commandment to choose between monogamy and polygamy.
The presupposition of governed forms of polygamy in proxy-primitive societies is that advanced language provided sophisticated means for dickering over details. Paternity could be relatively certain, marriage or its equivalent was already almost universally institutionalised, social interaction was controlled, and the commonest sex-based divisions of labour were firmly established. Looking ahead with the advantage of complete historical hindsight, we can observe that effective monarchial rulership could eventually only be stabilised through laws of inheritance and primogeniture, which depended upon exclusive coupling.11 Thus, by the nineteenth century, a society’s choice for either polygyny and monogamy could be rationally made based on experience and circumstance. Such ideal conditions — of being able to experiment with combinations of known and tested alternatives — did not exist when Stone Age humans made their moves away from polygamy and toward monogamy. This ‘coupling revolution’ consisted in multiple radical innovations by large-brained individuals.
The pioneer by Frederick McCubbin, 1904 Australia
Crystal balls
[Social Science Files now takes a short unplanned detour into the future.]
As we will see presently when examining the pressures or impediments that provoked coupling choices from circa 150k-200k years ago, monogamy proved to be efficient in maximising human fitness for work and for social interaction. But in the richest countries today it is possible that monogamy may have become a hindrance to adaptation for fitness. The time might have arrived to evolve in the opposite direction, opening up to polygamy once again as part of a process of learning to sustain societies that reproduce themselves on the back of the latest waves of technological revolution.
The catalyst for change lies in falling birth and fertility rates in rich countries that either discourage or prohibit polygamy. On current trajectories these countries are not fully regenerating new generations.12 In itself a decline in birth rates in a wealthy society should not be a problem in the context of a self-adjusting free market economy with rapid endogenous technological change. In the ideal case, lower births per capita might reflect an economic adjustment to the moving equilibrium between the supply and demand for labour and continual technological advances that recalibrate the ratios of humans to machines and services. But if because of advances in medicine and new knowledge of life-extending lifestyles people are living longer, and if state subsidies, munificent state welfare provisioning, minimum wage laws, short working weeks, low retirement ages, and the wrong education and training priorities distort and hinder market-driven equilibrations between types of supply and demand for labour in the economy, then a falling birth rate can become a very serious problem.
The current method of coping with a ‘dysfunctional’ falling birth rate is to allow or attract cheap labour from very poor countries. The drawback of this strategy, if it is not carefully managed, is that it may easily erode the sociopolitical equilibrium, which depends on secure borders, shared bonds of beliefs, and binding common rules of behaviour. If societies become ‘islands of strangers’, clearly the cure is worse than the disease. Also, large migrant outflows can totally distort the development trajectories of poor societies. In an ideal world, when countries conform to more or less the same laws of property and the same rules for trade and investment, free flow of goods and services is desirable. Free flows of labour, on the other hand, too easily harm societies.
Although migrants are at present viewed as a way to mitigate the effects of declining fertility, the background long run technological trend is quite promising. Rapid and sustained progression in automation and artificial intelligence will eventually allow societies to maintain themselves at a higher level of quality with smaller populations.
Might polygamy help? The clear evidence is that countries which tolerate or encourage polygamous sexual unions have higher birth and fertility rates.13 For hundreds of years rich societies have engineered monogamy into their laws, customs and beliefs.14 Those who today worry about declining birth and fertility rates are also aspirant engineers. They would like to reengineer society all over again in ways they hope will revitalise the monogamous status quo, and with assistance from migrants.
Ross Douthat interviewed Alice Evans on this topic. They did not mention polygamy. First, they blamed the phone — “You’re living in a phone. You’re abstracted from your own body in a more profound way than usual” and “as people spend more time on their phones hooked on these echo chambers, polarising differently — not just by gender, but polarising — then the less time that we spend socialising with different other people, the less we develop understanding right across genders and across political groups”. Second, they advocated using “the tax system to give massive tax incentives to people who have children”. Third, they warned of competition for more migrants as birth rates in the rich countries fall further — “the U.S. may be better off because they’ll get all the world’s migrants, they’ll get the most productive migrants, they’ll get the most entrepreneurial migrants”. Fourth, they want Hollywood to make more romantic movies — “we’re ending on an agreement of a massive government program to subsidise a new revival of Jane Austen adaptations for the 21st century”.15
The problem is that social engineering almost always ends badly. If the aim is to make a society more encouraging of smart adaptive evolutionary change and more receptive to the consequences, then it would make sense — as an energising first step — to liberalise polygamy. This move could inject an exciting and potentially creative competitive dynamism into the currently stagnant trajectory of reproduction. A new spirit of individual reproductive enterprise could dovetail with the new technology.16
Polygamous communities could spread the various perceived burdens and risks of longterm bilateral intimacy — and the responsibilities of household management — among contemporary generations of well-educated and busy information-processing phone users, expanding mating choices and stimulating their instincts for copulation.
As society waits for robotics and AI to populate workplaces, reducing the demand for human labour, transforming administration, legal systems, welfare services, taxation regimes, monetary policymaking and other market and governmental activities that would benefit by employing super-intelligent rules-based non-discretionary decision making machines, young febrile and fertile adults could throw themselves into adventurous radical innovation and free experimentation, devising revolutionary philosophies of functional un-coupling and polygamous promiscuity. My own social science research suggests a new polygamous generation is likely gravitate toward communalistic and coordinated structures of decision making for household and childcare management.
FOOTNOTES
Examples are “the monogamous South American titi (Callicebus cupreus) and owl (Aotus azarae) monkeys in which fathers carry infants on their backs most of the day, spending more time with their babies than the mothers”, in David F. Bjorklund, Alyson J. Myers, and Ariel Bartolo-Kira, ‘Human child-rearing and family from an evolutionary perspective’ in W. Kim Halford and Fons van de Vijver (eds.), Cross-Cultural Family Research and Practice, Academic Press 2020:13.
“Even the gibbons—who were once viewed as partnered for life with their rare monogamous mating pattern—have recently been discovered “sleeping around” in some gibbon treetops. In the gibbon case, ‘conjugal’ fidelity is primarily maintained by keeping mated pairs physically and socially isolated in small, high canopy arboreal territories actively defended by both sexes.” Jonathan H. Turner and Alexandra Maryanski, On the Origin of Societies by Natural Selection, Routledge 2008:73.
See also: “In the case of gibbon pairs in neighbouring territories or pair-bonding birds that nest nearby other pairs, one aspect of maintaining the exclusive mating relationship may require that the female actively fends off other females and the male actively fends off other males that could be sexual competitors. This is only reliable when the mated pair tend to remain in the same vicinity.” Terrence W. Deacon, The Symbolic Species: The Co-evolution of Language and the Brain, W. W. Norton 1998:399
Dunbar RIM, Shultz S. 2017 ‘Why are there so many explanations for primate brain evolution?’ Phil. Trans. R. Soc. B 372: 20160244. http://dx.doi.org/10.1098/rstb.2016.0244
See the many fascinating primate examples cited by leading scholars in the classic collection — Andrew Whiten and Richard W. Byrne (eds.), Machiavellian Intelligence: II Extensions and Evaluations, Cambridge University Press 1997
For an important dissenting view that is nevertheless very informative about what can be learned from chimpanzees about prehistoric human capabilities in regard to technology, diet, shelter-building, and foraging diversity, see W. C. McGrew, ‘In search of the last common ancestor: new findings on wild chimpanzees’, Philos Trans R Soc Lond B Biol Sci. 2010 Oct 27;365(1556):3267–3276. 27 October 2010 doi:10.1098/rstb.2010.0067
Frans de Waal, Chimpanzee Politics: Power and Sex among Apes, Johns Hopkins University Press 2007; Jane Goodall, The Chimpanzees of Gombe: Patterns of Behavior, Belknap Press of Harvard University Press 1986.
Robin Dunbar, Human Evolution, Penguin Books 2014:130. However, Dunbar then also argues that “monogamy occurs only where it is socially enforced”, which is a much more contestable claim. There is no way of knowing the direction of causation. However, I believe that the reverse occurred. Men and women began to couple up before there existed governance mechanisms for enforcement, and it was to an extent because of their incipient sociation (illustrated by coupling) that governance patterns first began to take shape.
Robert L. Kelly, The Lifeways of Hunter-Gatherers: The Foraging Spectrum, Cambridge University Press 2013:36,272
Herbert Spencer, Principles of Sociology, Vol. I–IV, Complete Edition 1895:775-799
My understanding of the coevolution of larger brain size and new social relations is mainly informed by the pathbreaking hypotheses of Robin Dunbar. His publications are definitive on this topic. I also consult books by Jonathan H. Turner and Michael Tomasello [archive].
“Familial charisma may lead to wild palace intrigues and revolutions, particularly where polygamy is practiced and the wives’ struggle for the future of their children is added to the ruler’s interest in eliminating rival contenders. In such cases the only alternatives are to divide the realm among the descendants like any other property or to select a successor among them according to some regular procedure, such as combat among the sons or priestly oracles or public acclamation. All these methods are fraught with uncertainty, and royal power has become stabilised only where the principles of monogamy and primogeniture (inheritance by the first-born) prevailed, though even in such a case the rule of succession is jeopardised when a royal house dies out — like the Carolingian kings — or when the properly chosen successor proves himself too inept to rule.” Reinhard Bendix, Max Weber: An Intellectual Portrait, University of California Press [1960] 1977:308-313
Startling global maps — Total Fertility Rate and Birth Rate via Wikipedia.
References for this topic include:
Sophia Chae and Victor Agadjanian, ‘Polygyny and fertility: Continuity or change in sub-Saharan Africa’, IPC Conference Paper 2021.
Grant, Monica J. and Kohler, Hans-Peter, ‘Marriage Change and Fertility Decline in sub-Saharan Africa, 1991-2019’, Population Center Working Papers (PSC/PARC), Publication date: 2022-05-13.
Charlotte Greenbaum, Deborah Bitire, Roch Millogo, and Matè Labité, ‘Polygamy in West and Central African Countries: Implications for Fertility Intentions and Family Planning’, IPC Conference Paper 2021.
Miriam Koktvedgaard Zeitzen, Polygamy: A Cross-Cultural Analysis, Routledge 2008
References for this topic other than Wikipedia include:
World Population Review, Polygamy Legal States 2025
House of Commons Library, Research Briefing: ‘Polygamy’, Published 1 February, 2023
Before going to university I completed an apprenticeship as an antique furniture restorer. I well remember that when making a ‘dovetail joint’ we spoke of ‘mating’ the two surfaces. A thought occurs to me. AI might eventually be able to do good social science. ChatGPD is becoming very analytic and extremely argumentative. And, robots can already make chairs. But I am certain that antique furniture restoration will always remain the preserve of humans. The patina! Only human creativity can reproduce that. Replacing a section of a seventeenth or eighteenth century French or English chair leg and matching the colour, the depth and the opacity of the french polish on the new piece with the original? No, no robot will ever achieve that.