Core Concept # 8
From
From Neurons to Neighborhoods:
The Science of Early Childhood Development
Human development is shaped by the ongoing interplay among sources of vulnerability and sources of resilience. Individual developmental pathways throughout the life cycle are influenced by interactions among risk factors that increase the probability of a poor outcome and protective factors that increase the probability of a positive outcome (Garmezy et al., 1984; Rutter, 2000; Werner, 2000). Risk factors may be found within the individual (e.g., a temperamental difficulty, a chromosomal abnormality) or the environment (e.g., poverty, family violence). Protective factors also may be constitutional (e.g., good health, physical attractiveness) or environmental (e.g., loving parents, a strong social network). The cumulative burden of multiple risk factors is associated with greater developmental vulnerability; the cumulative buffer of multiple protective factors is associated with greater developmental resilience. Sameroff, Seifer, Barocas, Zax, and Greenspan (1987) have demonstrated that the total number of risk factors in a child’s life is a better predictor of IQ scores than the specific nature of those factors. The double burden of both biological and environmental risk produces an unusually high level of vulnerability (Escalona, 1982; Parker et al., 1988; Shonkoff, 1982).
Some developmental pathways follow trajectories or patterns that are deeply ingrained and thus less amenable to influences that may deflect them in a positive or negative direction. Others are highly susceptible to such risks and protective influences. Waddington (1966) compared these pathways to the valleys and ridges that are formed by a ball rolling downhill. The further the ball rolls along a given path, the deeper are the valleys and the steeper are the ridges. Developmental characteristics that are embedded in deeply chiseled trajectories (e.g., basic motor capacities, such as crawling and walking) are less amenable to environmental modification and are described as canalized. Other trajectories have valleys that are more shallow or ridges that are less steep, which leave them more susceptible to change (e.g., basic self-care skills, early literacy). Ultimately, the extent to which any existing pathway can be modified or redirected is determined by both biological and environmental influences. The child’s own expectations, and those of the significant people in his or her life, often play an important role in maintaining or changing direction. These concepts are especially pertinent to the literature reviewed in Part III regarding the contexts for early development.
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