Remember that humans are born (at full term—42 weeks gestation) with only 25% of the brain developed, with next to no immune system, and with all sorts of other brain and body systems to be established and interconnected. Most of this occurs in the first 6 years of life, co-constructed by caregivers and a built-in biological timetable that co-evolved with particular parenting practices (Trevathan, 2011).
For example, the baby's brain is growing so rapidly that human milk is designed for frequent ingestion (thin, not thick) which washes the brain with thousands of chemicals needed to build well-functioning systems.
How do we know that caregiving practices influence self-control?
Here are three examples how self-control capacities are shaped by early caregiving.
(1) Self-regulation is affected by experiences at birth.
Bystrova (2009) and colleagues conducted an experiment with newborn babies in the first hour after birth with four conditions. Some were placed on mother's chest skin to skin immediately after birth. A second group was wrapped up and placed in mother's arms. A third group was wrapped up and placed in a bed nearby and a fourth group was wrapped up and taken to another room. The experimenters observed the mothers and babies a year later. Although skin-to-skin babies did best, all those who had been placed on mother had a better relationship with mother and more self-regulation.
Separating mom and baby at birth (or any time in the first years) is a violation of evolved expected care. Yet hospital practices in the USA routinely separate mom and baby after birth, which if it occurs for too long can trigger a depressive reaction in the mother (whose body assumes the baby has died) (Trevathan, 2011). We have a epidemic of post-partum depression so great that it is now considered to be "normal"(Dawson et al., 2000).
(2) Parents shape self-regulation mechanisms, like vagal tone.
Vagal tone is a physiological mechanism highly related to social functioning. It is calculated from measuring heart rate variability, a rough measure of how well the vagus nerve controls resting heart rate. Vagal tone function is highly affected by caregiving, particularly touch, in early life (Porges, 2011). The degree of variability between breath inspiration and expiration is higher among those with good vagal tone, found among those with secure attachment. The myelinated vagus, along with cranial nerves, regulate facial expression and together constitute a social engagement system. Those with little variability have more difficulty handling negative emotions, as exhibited through behavioral inhibition to novel situations. This process represents the immobilization of the unmyelinated vagus, a self-protective mechanism that takes over when the other vagal functions were poorly developed during early life.
Letting babies cry is a common practice in the USA. Such experiences will foster poor vagal tone and poor health. Vagal function is related to most systems in the body and when poorly functioning can lead to numerous detrimental health outcomes (digestive—e.g., irritable bowel; neuronal communication—e.g., seizures; mental health-depression; see Ghanem et al. 2006; Groves et al., 2005). The vagus nerve can even prevent inflammation, an instigator of many diseases.
(3) Parenting turns genes off and on, shaping functioning for life-e.g., for anxiety.
Meaney and colleagues have documented differences in gene expression within the brain-body pituitary-adrenal stress axis, based on extent of maternal care soon after birth (Weaver, Szyf, & Meaney, 2002). Examining only one of hundreds of genes affected, Meaney and colleagues found that rats with high-caring (high licking, which translates to high touch) mothers in the first ten days of life had elevated gene expressions for glucocorticoid receptor proteins. (For humans, a corresponding critical period would be the first 6 months of life.)
Glucocorticoid hormones produced in all mammals in response to stress need to be switched off to prevent excessive stress, hippocampal dysfunction, and eventual depression. Rats with little maternal care had weaker feedback systems, resulting in more anxiety and lifelong heightened responses to stress across a diversity of brain and behavioral measures (Champagne & Meaney, 2001).
Moreover, there were spiraling generational effects. A low-nurturing mother bred low-nurturing daughters, compounding the effects of poor care on brain system development over generations (Weaver et al., 2002). Cross-foster studies show that the effect is environmental and not genetic (Francis, Diorio, Liu & Meaney, 1999).
Meaney and colleagues have now demonstrated the same mechanism occurring in the brains of human adults abused as children who subsequently committed suicide (McGowan et al., 2009).
Self Control Needs a Good Beginning
At a very basic level, self-control involves mechanisms that control stress reactivity and negative emotions. When a person's basic biology has been neglected in terms of evolved expected care in early life, he or she is set up to be stress reactive. See table. It is hard to remedy later.
These findings all have moral implications. If one does not feel at ease, how can one face new people, think outside the box and socially succeed? Instead, new things (e.g., people who look or act differently) are threatening and lead to immobilized thinking, feeling, relating, or worse, reactive aggression.
So come on, adults, let's get back to the wisdom of our ancestors-it matters how you support babies and young children. Ignore their needs, mistreat them, and you raise a troubled and troublesome human being.
Table. Early Life Childrearing Practices that Co-evolved with Needs of Young Child
(Hewlett & Lamb, 2005; Konner, 2010; Narvaez, in press)
Natural childbirth (no interference with timing, no separation, no induced pain)
Breastfeeding 2-5 years (among foraging hunter gatherers, average weaning age is 4)
Responsivity (needs met promptly, limbic resonance)
Nearly constant touch with movement
Multiple (close, caring) adult caregivers
Free play in nature with multi-aged mates
Deep social support of mom and baby
Positive social climate
Companionship care (mutual reciprocal relationship between caregiver and child)
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