Impressionable Biologies

From the Archaeology of Plasticity to the Sociology of Epigenetics

Maurizio Meloni

• Publisher: Routledge
• Year: 2019
• ISBN:
  9781351689380
• Edition: 1
• Topic: Ciencias sociales
• Subtopic: Sociología

During the twentieth century, genes were considered the controlling force of life processes, and the transfer of DNA the definitive explanation for biological heredity. Such views shaped the politics of human heredity: in the eugenic era, controlling heredity meant intervening in the distribution of "good" and "bad" genes. However, since the turn of the twenty-first century, this centrality of genes has been challenged by a number of "postgenomic" disciplines. The rise of epigenetics in particular signals a shift from notions of biological fixedness to ideas of plasticity and "impressionability" of biological material.

This book investigates a long history of the beliefs about the plasticity of human biology, starting with ancient medicine, and analyses the biopolitical techniques required to govern such permeability. It looks at the emergence of the modern body of biomedicine as a necessary displacement or possibly reconfiguration of earlier plastic views. Finally, it analyses the returning of plasticity to contemporary postgenomic views and argues that postgenomic plasticity is neither a modernistic plasticity of instrumental management of the body nor a postmodernist celebration of potentialities. It is instead a plasticity that disrupts clear boundaries between openness and determination, individual and community, with important implications for notions of risk, responsibility and intervention.

1An archaeology of plasticity

Living in postgenomic times: Of imprinting and plasticity

Claims of a new entanglement of bodies and the environment are increasingly relevant in postgenomic models:¹ “the life sciences are generating a transformative view of the biological body not as fixed and innate but as permeable to its environment and, therefore, plastic” (Mansfield, 2017: 355). Since the early 1990s there has been much emphasis on the brain’s synapses and gross organization as sculpted by social and cultural influences, even in adult life (Clark, 1998; Glannon, 2002; Park and Huang, 2010; Overgaard and Jensen 2012; Rees, 2016). Now, fields like environmental epigenetics, developmental origins of health and disease (DOHaD) and microbiomics lead even wider arguments about the dynamism of biological matter (Charney, 2012; Majnik and Lane, 2015; Moore, 2015). These fields have shown how the human body is permeable to environmental effects (e.g. toxins, food and socioeconomic status) to its genomic core, entangled inseparably “with environmental forces (macro and micro) from the moment of conception on throughout life” (Lock, 2015: 151).

A wealth of evidence has accumulated since the early 2000s that not only is the human brain plastic, and hence changeable at the structural and functional level (Rubin, 2009; Rose and Abi-Rached, 2013), but also the microbiota and epigenome are moulded by the impact of food, lifestyle, toxins, chemicals, stressors and socioeconomic factors. Environmental or social epigenetics is the most well-known example of this emerging interest in the biological embedding of social experience and the appreciation of the power of the environment in explaining health trajectories, development and biological identity. By showing how various material instantiations of social life become literally embodied in the epigenome, epigenetics is said to illustrate how the environment gets inside the body and makes “the boundary of the skin of little significance” (Landecker and Panofsky, 2013: 339, referring to Michael Meaney’s work). Chiselled by the incessant workings of external forces, postgenomic bodies are described nowadays as fully absorbed in their surroundings (Solomon, 2016): the boundaries between the body and the outside world become uncertain. This is not quite the same as saying that genes and environment “interact”, as we have known for the whole of the twentieth century (Hogben, 1933; Tabery, 2014). In postgenomics the environment is no longer a mere container for gene expression (Stallins et al., 2016); it is increasingly seen as a productive, bioactive force (Landecker, 2011), an inducer and generator of phenotypes (West-Eberhard, 2003). Even in terms of biological capitalism, postgenomics introduces a different logic that makes not just DNA sequences alone but the “whole spatial and temporal contexts and circumstances surrounding DNA” a new potential source of biovalue (Stallins et al., 2016).

Changes in evolutionary thinking are also significant: the formative power of the environment is wielded not only via indirect selective pressures, as in the classical neo-Darwinian account; the emerging logic of epigenetics now implies that the environment directly instructs the organism (Jablonka and Lamb, 2014). This reconceptualization has an impact on the way in which bodies are rewritten: not just as “reacting to” or “withstanding” the environment but as “composed of transduced representations” of it (Landecker, 2016: 87). Since external conditions are understood as reflecting directly, at the molecular level, in the body’s “internal biological changes”, a model of imprint replaces one of random genetic mutation (Lappé and Landecker, 2015). Metaphors of writing, marking, coating and labelling, as well as notions of memory, scars and erasures, have nowadays become widespread in the epigenetic landscape.

If imprint is a key metaphor for conveying the notion that the environment leaves a durable mark on the genome, plasticity is probably the word that best captures the spirit of postgenomic times. Plasticity, which the Oxford English Dictionary defines as “the ability to be easily moulded or to undergo a permanent change in shape”, is a very complex notion. It is too often confused with its antonym,² elasticity. The difference between plasticity and elasticity is obvious in the science of matter. While elasticity is the capacity to regain an original form after the deforming pressure has ceased, plasticity is about undergoing a permanent change:

If a coiled spring is pulled beyond the limits of elasticity, it will be permanently elongated. Provided that the spring does not break, the change is plastic.

(Bateson and Gluckman, 2011: 31)

However, this distinction is more blurred in biology, where plasticity often flirts with elasticity or even polymorphism (the possibility to assume a nearly infinite number of forms), and is too often taken as equivalent to “change”, “malleability”, “reversibility” or “tractability”. Its multifarious history reveals, however, a more complex polysemy, and an association with ideas of stabilization and retaining of forms after a perturbation. This connotation of plasticity as continuous with stabilization (Bateson and Gluckman, 2011), which had been neglected in modern writings, is coming powerfully back to the fore nowadays. As I will argue in this book, this is mostly an effect of emerging claims in epigenetics and related programs such as DOHaD, which explains health trajectory as the durable result of in utero effects.

Contemporary plasticity

Plasticity is today a trendy catchall term “encompassing multiple processes regulated in a variety of different ways” (Bateson and Gluckman, 2011: 5). In contemporary life science, plasticity appears in many guises: synaptic, morphological, immunological, not to mention psychic, behavioural and mental. Plasticity spans a number of cutting-edge research programs, including cloning and stem cells (plasticity as reprogramming of cell fate), immunology (producing antibodies to pathogens not encountered before), neuroscience (plasticity as rewiring of synaptic connections, even in the adult brain), and epigenetics (malleability of genomic expression). Due to their impact on notions of corporeal plasticity, phenotypic and developmental plasticity are the two areas of major interest in this book. Phenotypic plasticity is “the ability of individual genotypes to produce different phenotypes when exposed to different environmental conditions” (Pigliucci et al., 2006; Nicoglou, 2015, 2018); developmental plasticity (which looks at the same phenomenon from a developmental angle and is often used as a synonym) is usually defined as the capacity of an organism or the body to react to an environmental input “with a change in form, state, movement, or rate of activity” (West-Eberhard, 2003: 34). Reference to these notions brings to the forefront the capacity of humans to adjust quickly and flexibly in “heterogeneous environments” (Gabriel et al., 2005; Kuzawa and Bragg, 2012), relying less on forms of “genetic commitment” (Wells, 2012: S470).

Given this multifaceted situation, the semantic “unity” of the term is by itself questionable. As scholars in Science and Technology Studies (STS) know, it is best in this case to understand scientific terms as the result of a complex negotiation across multiple scientific communities shaped by different “research questions, [and] practices of scientific measurement” (Pitts-Taylor, 2016: 36). Plasticity, therefore, ultimately comes in the plural, and genealogy is exactly what is needed to diffract this polysemy of the term into its multiple instantiations.

The flourishing status of plasticity in several scientific research programs and social science writings shows a significant discontinuity with last-century debates. One visible case is evolutionary biology. For a large part of the twentieth century, with few pioneering exceptions, the term was considered a simple “nuisance” (Forsman, 2015: 276; see alternatives in Weber and Depew, 2003; Morange, 2009; Nicoglou, 2018). A key text of twentieth-century neo-Darwinism, Ernst Mayr’s 800-page Growth of Biological Thought (1982), features the word “plastic” just twice, firstly to be criticized as an antiquated view and secondly in the sense of modern surgery. The contemporary scenario is very different. Plasticity research “has grown tremendously from ten papers published per year before 1983 to nearly 1300 papers in 2013” (Forsman, 2015: 282). This increase is paralleled only by that of epigenetics, which has escalated in the last decade by comparable figures (Meloni and Testa, 2014; Skinner, 2015). The two areas support each other and in several cases even overlap, with epigenetics offering a plausible molecular but non-genetic mechanism for biological plasticity and rapid adaptation to changing environments (Kuzawa and Bragg, 2012). In terms of its social translation, “plasticity” is currently used to describe the openness of the body and the brain to complex environmental interactions throughout life, and particularly in specific critical periods of heightened sensitivity (especially early-life experiences). It is invoked to mark a shift from premillennial notions of biological fixedness and genetic hardwiring. It is used as a powerful rhetorical platform drenched in hope to suggest that brains can reprogram and repair themselves and bodies are always open to forms of intervention to optimize biological fitness, enhance therapeutic potential and even correct past injustice (Duffau, 2006; Moller, 2006; Rubin, 2009; Rose and Abi-Rached, 2013; Lloyd, 2018; Lloyd and Raikhel, 2018).

Plasticity, especially in social science quarters, has a strong allure, and is very often captured into a discourse of social progress. Boas famously played the card of the “instability or plasticity” of human racial types (Boas, 1912: 557) against typological racists and American eugenists, inaugurating a long tradition of liberal anthropology based on plasticity against biological fixedness. The post-Boasian tradition further reinforced this association of values, neatly aligning a discourse of fixity with one of exclusion and a discourse of plasticity with one of emancipation. This polarized strategy was probably favoured by the specific research design that American anthropology privileged (Hulse, 1981): physical changes (such as increase in stature) in the descendants of poor or rural migrants moving to the USA (Shapiro and Hulse, 1939; Goldstein, 1943; see also Lasker, 1952, 1954). In her review, Bernice Kaplan (1954) discusses twenty-five studies on human plasticity, of which only a few referred overtly to its negative effects, one written by a non-American author (Ivanovsky, 1923, on the effects of inanition in Russia). This debate is so value-laden that nowadays, one century later, attacking Boas’ study (Sparks and Jantz, 2003) still has deep political implications.

However, this one-sidedly emancipatory use of the term “plasticity” is one of the most important obstacles to an appreciation of its plurality of meaning. Plasticity is an inherently dualistic term, caught between openness and determination, agency and vulnerability (Paillard, 1976; Malabou, 2005; Pitts-Taylor, 2016). Analogous to the Greek phármakon, which can cure and poison at the same time (Derrida, 1981), plasticity in emerging styles of epigenetic reasoning is the domain of a profound indecision compatible with conflicting social and ethical scenarios (Lloyd, 2018; Lloyd and Raikhel, 2018). This fundamental ambiguity of the concept of plasticity between creation, reception and annihilation of forms (Malabou, 2005; see also 2009, 2010) will be turned in this book into a heuristic for unpacking its rich polysemy across various epochs. A longue durée and non-linear history of the plastic body shows how each of its conceptual facets may have become prevalent in certain historical moments, at the expense of others. Its ambiguity becomes here the very source of its productiveness (Rheinberger, 2003).

Plasticity, etymology and history

Even a quick look at the etymology and recent history of the term aptly demonstrates some of the traps connected with it. As for its etymology, plasticity comes from the Greek plassein, which means to mould, shape or form, and by extension, to fabricate, forge, sculpt and train someone; hence the adjective plastikos, a thing to which a form can be assigned, but also all the arts and techniques by which a form can be produced:

“Plastic” as an adjective has two meanings. On the one hand, it means “to be susceptible to changes of form” or “to be malleable.” Clay, in this sense, would be “plastic.” On the other hand, it means “having the power to bestow form,” as in the expression “plastic surgeon” or “plastic art” understood as “the art of modelling” in the arts of sculpture or ceramics. Plasticity describes the nature of that which is plastic, being at once capable of receiving and of giving form.

(Malabou, 2005: 65)

A similar polarity arises when observing the nature of plastic matter. In his Meteorology, Aristotle highlights the singular nature of plasticity as located between two poles: a hardness that resists all modifications, and a softness or fluidity that does not retain any. Notably, this definition came many centuries before William James’ often cited and, in fact, derivative definition of plasticity as “semi-inertness” – “the possession of a structure weak enough to yield to an influence, but strong enough not to yield all at once” (1890: 105; my italics).³ Aristotle writes:

Some things, e.g. copper and wax, are impressible, others, e.g. pottery and water, are not. […] Those impressibles that retain the shape impressed on them and are easily moulded by the hand are called “plastic”; those that are not easily moulded, such as stone or wood, or are easily moulded but do not retain the shape impressed, like wool or a sponge, are not plastic. The last group are said to be “squeezable”.

(Book IV, part 9: Webster, 1923)

In another work, On Memory and Reminiscence, Aristotle offers the example of “running water”, on which no form could be implanted, as a case of a material too fluid to be considered “plastic” (2014).

Plasticity belongs, therefore, in this intermediate space between ability to change and capacity to retain a shape, “between the opposing moments of total immobility and vacuity”, fixedness and dissolution (Malabou, 2005: 12). It often overlaps with the apparently opposite notion of robustness (insensitivity to environmental changes), which is part of the same gradual continuum (Bateson and Gluckman, 2011). These semantic tensions, as we shall see, are inherent in the definition of plasticity and have not gone away in contemporary debates.

The modern historical trajectory of the term also presents a number of traps. From Aristotle’s definition to Herder’s eighteenth-century book Plastik (on plastic arts like sculpture) (1778 [2002]), plasticity belongs to the realm of inanimate matter, not living organisms. I will explore in the next pages a rare exception to this, in Renaissance embryological debates around the Neoplatonic notion of a vis plastica (plastic power: Smith, 2006; Hirai, 2007a). However, albeit not exclusive, the non-biological sense of plasticity remained predominant until Herder’s time, when the term started to significantly increase in all the many European languages.⁴ Besides re-elaborating some of the Greek themes about giving and receiving forms, Herder’s book adds a further twist to the meanings associated with plasticity. He uses the term in a strong polemic against the modern primacy of sight versus touch, painting versus sculpture. While sight has a destructive function, to transform everything “into planes and surfaces”, plastic arts like sculpture create an experience of the in-depth, of a three-dimensional body (1778 [2002]). Plastic is here the opposite not of fixed, but of flat, superficial, two-dimensional. So far, plasticity is not associated with modernistic ideas of continuous change, regeneration, tractability, improvement, or optimization.⁵

This is, instead, the meaning that plasticity would gradually acquire when it was imported since the nineteenth century into the biological and medical sciences. Here it was used to convey the idea of adaptability to environmental changes and, in medicine and neuroscience, renewal of tissues, memory formation, creation of new brain structures and potentiation of synaptic strengths (Stahnisch, 2003; Berlucchi and Buchtel, 2008; Overgaard and Jensen, 2012).

At the turn of the twentieth century, in the evolutionary writings of James Mark Baldwin, plasticity became a principle above natural selection to explain the evolution of intelligence and learning (Baldwin, 1902; Weber and Depew, 2003). Baldwin made plasticity a keystone of advancement toward higher stages of life (Spencer, a generation before, actually did the same, often with a racialist tinge). He posited that a correlation between

increasing plasticity of the nervous system and increasing mental endowment holds as we ascend from a lower to a higher stage [in the scale of life].

(1902: 36)

This association of plasticity with progress is even clearer in the work of another psychologist, Pavlov. In his 1930s neurological w...

Table of contents

• Cover
• Endorsement
• Half Title
• Title Page
• Copyright Page
• Contents
• Preface and acknowledgements: Problematizing the turn to plasticity
• 1 An archaeology of plasticity
• 2 Plasticity before plasticity: The humoralist body
• 3 Taming plasticity: Darwin, selectionism, and modern agency
• 4 Epigenetics or how matter returned to the genome
• 5 A sociology of the body after the genome
• References
• Index