Early human development is an intricate dance between nature and nurture, genes and environment. Nurturing, stimulation and nutrition interact with genetic predispositions and “get under the skin.” Developing brains and biological systems adapt and influence learning, behaviour and physical and mental health for life.
All societies have better-off and less well-off citizens. As we look across large groups of individuals, socioeconomic status is a combination of material wealth and non-economic characteristics, such as social standing and education. Socioeconomic status is predictably associated with a gradient pattern. As socioeconomic circumstances improve on average, so do measures of better learning, behaviour and health. Conversely, as socioeconomic circumstances diminish, so do these same outcomes. When gradients are steeper, there is a larger gap between more and less affluent members of a society.
Gradients in how children are doing on average, start early and carry forward. Early childhood socioeconomic status is linked to learning, behaviour and health in early life and beyond.42 The gene–environment interactions and early brain and biological development set up lifelong trajectories. Later circumstances have an influence on how things turn out, but the trajectories launched in early childhood become part of our biology and carry forward. Socioeconomic gradient patterns in children’s early development are linked to several aspects of brain development, particularly within those areas of the brain that are tied most closely to the limbic and prefrontal cortex pathways.43
Socioeconomic status gradients are evident in language pathways. Canada’s National Longitudinal Survey for Children and Youth includes a measure of 4- and 5-year-old children’s vocabulary skills that are one aspect of language. Figures 2.9 and 2.10 shows the spread of children’s vocabulary skills by family income, which is organized by relationship to LICO (low income cut-off). The results are a gradient: children who are poor (that is below Canada’s LICO as determined by Statistics Canada) are more likely to have difficulties and less likely to be advanced than children in higher family income groups. Overall, children in the middle income groups do better than those in the lowest income group, but not as well as children in the most affluent group.
Learning, behaviour and health outcomes are associated with each other. Low literacy rates are associated with more health problems. Better outcomes at birth and in early childhood are related to better academic outcomes in school. Studies of populations reveal that a more equitable distribution of resources and improvements to the quality of the social environment improve the overall health and well-being of the population.44 Reducing inequality also reduces the learning, behaviour and health gap between the most and least affluent. Greater equality improves the well-being of the whole population and is key to national standards of achievement. If, for instance, a country wants higher average levels of educational achievement among its school children, it must address the underlying inequality that creates a steeper social gradient in educational achievement.
Gradient patterns are trends across the population. A minority of individuals at all points along the socioeconomic spectrum deviate. Affluent individuals, regions or countries may not do as well as expected, and those living in disadvantaged circumstances may do much better than expected. Socioeconomic status influences, but does not determine outcomes. Sometimes researchers can learn much by studying the outliers.
Figures 2.9 and 2.10
Figures 2.11 and 2.12
Cuba is one example. Cubans consistently do much better than other South American countries, even though Cuba is a poorer country. International assessments reveal Cuba has the lowest under age 1 mortality rate and under age 5 mortality rate, and the highest life expectancy of all South American countries.45 Cuban rates for under age 1 mortality are actually better than the United States and Canada. The language scores of Cuban students in grade 3 in 1998 and 2005 were higher than other Latin American countries participating in the UNESCO study.48
While Cubans may have low individual incomes, they have high levels of education and their government allocates significant resources to ensuring health, well-being and developmental opportunities across the population. The polyclinic program for pregnant mothers and mothers with young children is universally available in every neighbourhood, providing strong support for good early development in utero and in infancy.49 Children’s early development is also influenced by their parents’ level of education.50
In Canada, analyses of the international Adult Literacy and Life Skills Survey (ALLS), conducted by Statistics Canada in partnership with the OECD in 2003, confirms conclusions about socioeconomic gradients and learning and health reported in both earlier Early Years Studies.51 Overall, there was little change in literacy performance between 1994 and 2003. Forty-two percent of Canadian adults are estimated to have low literacy abilities. The established patterns of literacy proficiency continue to prevail, with higher performance among the young and the educated. Higher parental education levels as a marker of socioeconomic status were also associated with higher scores.
The ALLS establishes the link between health and literacy that is explained by early brain and biological development.52 In most jurisdictions, 16- to 65-year-olds in poor health have lower average literacy scores than those reporting better health. The gradients are strongest in Canada and the United States, where about 9 and 19 percent, respectively, of the gap between the lowest and highest group in literacy can be attributed to differences in parental education.
Literacy and numeracy skills are essential to full participation in a democratic, pluralistic society in the twenty-first century. How can citizens participate in decision-making about climate change and the future of the human species without the skills necessary to understand the complexity of the issue? Dismally low voter turnout in elections, a fundamental right and responsibility in a democratic society, is another outcome of low literacy. Figure 2.13 shows literacy levels on the civic engagement index reported in the ALLS study. The patterns suggest that the higher the literacy levels, the more likely it is that a respondent engages in various forms of civic activities.
Next: 8. Early adversity and later life
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