Issues in Interdisciplinarity 2020-21/Truth in Explanations for the Rise of Human Monogamy

Introduction
Historically, human relationship have taken various forms, but monogamy, the practice of having only one sexual, romantic relationship at once, has emerged as starkly dominant. Several disciplines have offered different explanations for the factors driving its pervasiveness, tensions which can be attributed to their approaches to truth. Biology subscribes to scientific realism, adopting a positivist, empirical correspondence theory of truth, in which the truth they seek to generate mirrors the natural world. In viewing the foundations of social life as biological, they posit that the current prevalence of monogamy is natural and driven by deterministic factors such as the genetic makeup of humans and evolutionary forces. Conversely, sociological approaches based on social theory assume a more constructivist approach to truth, recognising that monogamy arises from, and is constituted in, social and historical contexts, as a social norm and institution rather than an essentialist biological fact.

In this chapter, we will be exploring further exploring how these frictions between perspectives on truth lead the disciplines to conflicting conclusions.

Evolutionary Biology
As only 3-5% of the mammalian species are socially monogamous, evolutionary biologists deem the prevalence of human monogamy an anomaly. In seeking an explanation, academics have extrapolated ethological work to humans.

Research suggests that ecologically imposed monogamy may originate in early monogamous couples when population levels were low and scarce resources could only provide well for a couple and their offspring. Male and female partnerships thus emerged as the most effective way to utilise resources. This explanation is well-documented amongst biologists; Benshoof and Thornhill indicate that monogamy is mutually beneficial, citing the example of marmoset Callimico goeldii. The female’s reproductive success heavily depends on "the food and protection provided by the hunting male", while the male invests in his relationship to ensure "the survival of his young and thus his own reproductive success".

Whilst this explanation has been contested, the general consensus is that a monogamous mating system is more likely to survive within a population. Cooperative breeding details the differences in kin-based benefits between non-monogamous and monogamous mating systems. As kin-based benefits are diminished under female multiple mating, biologists predict that monogamy is key to increase relatedness within a system and receive the subsequent evolutionary advantages.

Neuroscience
Neuroscience treats social behaviour, such as monogamy, as a stable, scientifically explainable phenomena, which can be understood through manipulating neural circuits in the brain and observing their behavioural outcomes. Consequently, neuroscientists posit that monogamy in humans is the inevitable outcome of a linear chain of neurochemical reactions.

Neurological processes have been connected to genetic make-ups as modes of explanation. Research carried out by Larry Young in 1998 claims to have found a "monogamy gene", using vole species displaying diverging social behaviours, from those associated with promiscuity (Microtus montanus) to monogamy (Microtus ochragaster). The results were then used as a proxy for examining the human neural model for monogamy. A longer strand of a section of microsatellite DNA, changing the neuroanatomical distribution of the neuropeptides oxytocin and vasopressin receptors, has a positive causal relationship with monogamous social behaviours, such as "pair bonding, parental care and mate guarding." The distribution of these receptors triggers a neurochemical event with behavioural outcomes, ultimately determining whether the individual is monogamous or nonmonogamous.

Another neuroscientific study linked heightened brain activity in areas associated with social pain during conditions of jealousy, suggesting monogamy is maintained through neural negative reinforcement.

Marxist perspective
Marxism views societies as constructed in the historical materialist sense, in which social realities and truths about them are products of their material contexts. Consequently, Marxism recognises that family organisation is dynamic and susceptible to modification by material and social changes. Engels propagated that the shift from community to the monogamous nuclear family structure was driven by the move from "primitive" communism to capitalism.

Before "structured conjugal relations", society was organised in "primitive" community, characterised by unregulated sexual relations, matrilineality, and matriarchy. The introduction of husbandry and improvement in agricultural techniques created a newfound material surplus. As "[p]roduction of exchange eclipsed production for use", private property emerged. Men controlled private property due to the sexual division of labour, and it was therefore in their interests to ensure patriarchal hereditary rights. The institution of monogamy emerged as an enabler of patrilineality, as it ensured certainty in paternal relations.

As summed up by Engels, the monogamous family model emerged "not on natural but on economic conditions", systems of both exchange and power relations embedded in capitalism. Although this is not deterministic, ownership and control over means of production provide resources used to shape the reproduction of ideas; social institutions like monogamy are dependent on both.

Feminist perspective
The feminist perspective explains the rise of monogamy by similar factors as Engels, also considering the phenomenon as a social norm and institution built on capitalist notions of possession. However, as the field primarily emerged in the context of the 1960’s sexual revolution in the United States, a greater focus is placed on the emotional and personal sphere of sexual relationships, and the application of critical feminist analysis to previously deterministic psychological theories.

Feminists are generally critical of the essentialist explanations for emotions of jealousy that neuroscientific study offers; Toril Moi argues that “psychology becomes relevant only when jealousy has occurred; when and why somebody becomes jealous…are socially determined”. In seeking to explain the origins of jealousy, several feminists have theorised it as a socially constructed, rather than natural, emotion, framed as evidence for love in order to maintain the institution of monogamy. Some have also questioned why it is that jealousy, and the possessiveness it endorses, has come to be considered a desirable element in romantic and sexual relationships, when it is largely undesired in platonic relationships. Thus, they recognise that whilst certain phenomena may be natural, the arbitrary meanings attached to them are social, political and cultural.

Conclusion
The different ways in which biologists and sociologists perceive truth influences not only the nature of the explanations they offer to the rise of monogamy, but also the extent to which they are able to separate those causal explanations from justifications for its dominance. Biological explanations rely on human nature, and therefore become prescriptive and deterministic, insofar as what is natural must also be considered inevitable and true. Thus, explanations for why monogamy is pervasive become justifications for why it should be pervasive. Meanwhile, sociological explanations take on a more descriptive approach, recognising critically that the causal relationships between capitalist or patriarchal forces and the rise of monogamy are arbitrary and unessential. Aided by the rise of new materialism, which repositions the human within material matter, interdisciplinarity can help bridge these seemingly discrete explanations for monogamy. For example, the refutation of the nature-culture binary, claiming “monogamy’s normalised status cannot be disentangled from its scientific naturalisation”, exposes scientific truth as reliant upon sociopolitical “conceptualisations”. Moreover, tension between realism and social constructivism is eased by the concept of “agential realism”, where scientific study interacts with and influences the object, demanding the conception of science as a "material-discursive" practice.

Whilst an interdisciplinary approach may not directly determine which is the single true explanation for the rise of human monogamy, it facilitates a more holistic understanding of the phenomenon by illuminating the limitations of each discipline’s epistemological approaches and conceptions of truth.