Biosocial Worlds. Группа авторов
largely on animal models, but increasingly in humans, substantiates these findings and broadens their significance. Since the 1990s, a literature has accrued showing a strong relationship between ‘childhood maltreatment’ and negative mental health outcomes ranging from aggressive and violent behaviour to suicide. Current investigations are gradually exposing how the ‘biological embedding’ of childhood maltreatment comes about (Jaffee and Christian 2014). The overall conclusion drawn from this research is that the ‘epigenome is responsive to developmental, physiological and environmental cues’ that bring about so-called ‘epigenetic marks’.
In 2011 Moshe Szyf titled a presentation he gave at a Montreal gathering ‘DNA methylation: A molecular link between nurture and nature’. At the time this talk was given, evidence for such a link had accrued primarily from animal research and from one human study based on a sample of 25 individuals who had suffered severe abuse as children and later committed suicide. At autopsy, the donated brains of these individuals showed a significantly different pattern of DNA methylation than did those of a control group of 16 ‘normal’ individuals. A second control group of 20 individuals who had committed suicide but where no known abuse had taken place was also included in the study. The findings are presumed to substantiate a mechanism whereby nature and nurture meld as one. In this particular case, childhood adversity is associated with sustained modifications in DNA methylation across the genome, among which are epigenetic alterations in hippocampal neurons that may well interfere with processes of neuroplasticity (McGowan et al. 2009).
The researchers acknowledge that the sample was small, and that the study cannot be validated. The absence of a control group that experienced early life abuse and did not die by suicide is another shortcoming. Furthermore, the abuse that the subjects experienced was exceptionally severe. Szyf and colleagues readily agree that understanding of these processes remains rudimentary. Even so, given that epigenetic markers have been shown to play important roles in learning and memory that may be transmitted intergenerationally, these findings suggest how the effects of trauma associated with events such as colonisation, slavery, war, displacement, abuse and neglect may be transmitted through time. It is also the case that they bring about insights into resilience in connection with such events (Hughes 2012).
In the remainder of this chapter, I discuss the epigenetic effects brought about by the impact of stress, malnutrition, environmental toxins and social isolation on human wellbeing. Certain populations and individuals are of course more pervasively exposed to such variables than are others. The concept of local biologies posits that the material body is everywhere inseparably entangled with specific historical, economic and socio/political variables that are deeply implicated in bringing about epigenetic changes in individual bodies. However, it is also evident, given the extent of human migration today, voluntary or forced, that local biologies must be subsumed under broader, inclusive concepts of ‘situated’ and/or ‘emerging’ biologies and that epigenetic changes can be widely distributed across vast swaths of people.
Epigenetics and miniaturised environments
It has been demonstrated repeatedly that prenatal exposure to ‘maternal stress, anxiety, and depression’ can have lasting effects on infant development associated with the appearance of psychopathology later in life. A review of 176 articles, based on findings from both animal and, to a lesser extent, human research, notes: ‘the in utero environment is regulated by placental function and there is emerging evidence that the placenta is highly susceptible to maternal distress and is a target of epigenetic dysregulation’ (Monk et al. 2012, 1361). In addition to which a large body of research suggests that postnatal maternal care can induce further disruptions. Such findings are based largely on correlations, but researchers are beginning to map segments of the pathways whereby environmentally induced epigenetic marks are apparently associated with behavioural outcomes pre- and postnatally (Monk et al. 2012). Antenatal depression and anxiety symptoms are picked out for particular attention as signs of an in utero environment that brings about dysregulation. In other words, the environment is effectively scaled down to molecular activity inside a single organ of the body – the uterus and its fetal contents.
In an article published in BioSocieties, Ilina Singh (2012) comments on a warning sent out to its members by the American Academy of Paediatrics in 2011 cautioning about the harm caused to children by ‘toxic stress’. Singh interprets this warning as a move towards increased monitoring of families, notably pregnant women and young mothers who, she suggests, are likely to be targeted for observation – their behaviour subjected to surveillance designed to avoid fetal and infant stress. Medical and social support for young childbearing women is to be lauded but, as Singh states, the possibility that home visits to pregnant women, such as those being carried out through a partnership of nurses and family practitioners in New York, might well become, in effect, ‘womb visits’ (as seems likely to be the case in the many other cities in North America where home visits during pregnancy are the practice). The poverty and often violent living conditions of many mothers-to-be may well be virtually ignored, and attention light almost exclusively on the pregnant belly and its contents (Singh 2012). Research findings from the Mapping of the Human Brain project are providing remarkable insights into the singularity and complexity of genes that appear to put a fetus at risk for autism following birth, and it appears that epigenetic changes in utero are implicated.
As this research unfolds, the womb and its environments will be monitored yet more closely (Semeniuk 2014). It is clear that if molecularised findings are not systematically embedded in broader socio/political contexts, there is a distinct danger that accounting for epigenetic changes will be reduced to the presumed habitual behaviours of named populations, social groups and parents – notably mothers – who disproportionally fall into disadvantaged, impoverished and stigmatised populations.
Agent Orange: Lasting effects in time and space
Based on many years of fieldwork that commenced in 2003 in Hanoi, Vietnam, the Danish anthropologist Tine Gammeltoft has documented the devastating effects on reproduction caused by the chemical defoliant Agent Orange that persist more than 40 years after the war (Gammeltoft 2014). The US military conducted an aerial defoliation programme throughout the war that was part of a ‘forced urbanisation’ strategy designed to force peasants to leave the countryside where they helped sustain the guerrillas, and move to the cities dominated by US forces. Nearly 20 million gallons of chemical herbicides and defoliants was sprayed onto Vietnam, eastern Laos, and parts of Cambodia, destroying all plant material in 2 days. In some areas, toxic concentrations in soil and water became hundreds of times greater than the levels considered safe in the US (Schmidt 2016).
Agent Orange contains the highly toxic chemical dioxin, known to have long-lasting effects on the environment and human tissue. Gammeltoft documents a widespread fear about the so-called ‘dioxin gene’, widely believed by many people living in Vietnam today to be increasing in the population. It is estimated that at least 3 million Vietnamese citizens suffer from serious health problems due to exposure to defoliants, and the rate of severe congenital abnormalities in herbicide-exposed people is reckoned at 2.95 per cent higher than unexposed individuals. The media has reported cases of third-generation Agent Orange victims, in which individuals exposed during the war have produced apparently healthy children whose children are born severely disabled. Animal research has shown that, following fetal exposure, dioxin reprogrammes epigenetic developmental processes, the effects of which may become manifest throughout life and intergenerationally.
Vietnam was given membership in the World Trade Organization in 2007, one result of which was heightened concern by the Vietnamese government about the international visibility of the health of the population as a whole. It was at this juncture that extensive use of ultrasonography was introduced – a political tool designed to ensure the birth of healthy children. Ultrasound is now used repeatedly during pregnancy as part of antenatal care, even though the Vietnam Ministry of Health does not recommend this practice. Reaching a decision to have an abortion if a deformity is detected by ultrasound is not easy, particularly because many affected families think that abortion is an evil act. Everyone involved knows that it can be difficult to assess the extent of a deformity from ultrasound images, although it is equally the case that