Guide: A World of Differences: The Science of Human Variation Can Drive Early Childhood Policies and Programs to Bigger Impacts

May 2024

It is widely accepted that investing in early childhood development helps build the foundations of a healthy, productive, and equitable society. Guided by that knowledge, a range of broad-based programs and targeted services clearly make a significant difference for millions of young children, yet a closer look at program evaluation research shows that some children benefit greatly, some benefit less, and some not at all. Within this variation lies opportunity. Increasing the effects for all children—especially those who currently benefit the least—may be the key that unlocks greater impacts for society.

This working paper from the National Scientific Council on the Developing Child examines within-group variations and between-group differences, and it highlights the urgency of supporting the healthy development of young children in a way that addresses and evaluates both kinds of variation.

The paper calls for a significant shift in the way we conceive, implement, and evaluate policies and programs—one that recognizes the significance of disparities between groups associated with demographic variables, but also expects and designs for individual variation within each of those groups. Intentionally incorporating this flexibility into the core architecture of all early childhood policies and services would offer tremendous promise for increased program effectiveness and larger impacts at scale.

Sections include:

  • One Size Does Not Fit All
  • Individual Variation Is the Norm, Not the Exception
    • ACEs and Individual Variation
    • Influences on Variation in Health Outcomes: The Example of Childhood Asthma
  • Between-Group Differences Are Rooted in Social and Economic Inequities
  • Implications for a Mindset Shift in Policy and Practice

Suggested citation: National Scientific Council on the Developing Child. (2024). A World of Differences: The Science of Human Variation Can Drive Early Childhood Policies and Programs to Bigger Impacts: Working Paper No. 17. Retrieved from www.developingchild.harvard.edu

Content in This Guide

A World of Differences: The Science of Human Variation Can Drive Early Childhood Policies and Programs to Bigger Impacts

Working Paper 17

It is widely accepted that investing in early childhood development helps build the foundations of a healthy, productive, and equitable society. Guided by that knowledge, a range of broad-based programs and targeted services clearly make a significant difference for millions of young children, yet a closer look at program evaluation research shows that some children benefit greatly, some benefit less, and some not at all. Within this variation lies opportunity. Increasing the effects for all children—especially those who currently benefit the least—may be the key that unlocks greater impacts for society.

Related Resources

InBrief | A World of Differences: The Science of Human Variation

Working Paper 17 InBrief

It is now widely accepted that investing in early childhood development helps build the foundations of a healthy, productive, and equitable society. Guided by that knowledge, a range of broad-based programs and targeted services make a significant difference for millions of young children, yet a closer look shows that some children benefit greatly, some benefit less, and some not at all. Within this variation lies opportunity. Increasing effects for all children— especially those who benefit the least—may be the key that unlocks greater impacts for society.

Place Matters: The Environment We Create Shapes the Foundations of Healthy Development

The environment we create shapes the foundations of healthy development. The built environment, including the physical and social aspects of our surroundings, plays a critical role in shaping our experiences and opportunities. Children who grow up in safe, supportive, and stimulating environments are more likely to thrive.

Place Matters: What Surrounds Us Shapes Us

Every environment is infused with a combination of influences, which can have positive and negative impacts on health and development. The infographic illustrates how the influences from a child’s social, built, and natural environments—as well as the systemic factors that shape those environments—interact with each other to shape early childhood development and lifelong health.

Connecting the Brain to the Rest of the Body: Early Childhood Development and Lifelong Health Are Deeply Intertwined

Cover image of working paper 15,

The rapidly advancing frontiers of 21st-century biological sciences now provide compelling evidence that the foundations of lifelong health are built early, with increasing evidence of the importance of the prenatal period and first few years after birth.

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