Poorer people, on average, die younger. This stark pattern holds even in wealthy nations with generous welfare systems, suggesting that money alone does not explain the gap. In Norway, for instance, 40-year-old men in the least affluent groups can expect to live years less than their wealthiest peers, a difference that has proven stubbornly resistant to broad prosperity. The finding points to something deeper than income: the circumstances of a person's early life.

Researchers are increasingly convinced that the conditions in which children grow up — housing, nutrition, education, stress and social stability — leave a biological imprint that shapes health decades later. chronic stress, poor diet and limited opportunity accumulate over time, raising the risk of heart disease, diabetes and other conditions. Because these influences begin so early, policies aimed only at adults may arrive too late. The emerging lesson is that longevity is not simply a matter of personal choice, but of the environment into which a person is born and the support available along the way.