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Scarring and selection in the Great Irish Famine

Journal: Economic History Review

Date: 2025

Author: Matthias Blum, Christopher L. Colvin, Eoin McLaughlin

Abstract:
How do famines shape the health of survivors? We examine the long-term impact of the Great Irish Famine (1845–1852) on human stature, distinguishing between adverse scarring effects and the apparent resilience of survivors due to selection. Using anthropometric data from over 14,500 individuals born before, during, and after this famine, we find that selection effects were most pronounced in areas with the highest mortality rates. Individuals born in severely affected regions exhibited no evidence of stunted growth, indicating that the Famine disproportionately eliminated the most vulnerable. In contrast, stunting is observed only in areas with lower excess mortality, where selective pressures were weaker. These findings contribute to debates on the biological consequences of extreme catastrophic risks, demonstrating how selection effects can obscure long-term health deterioration. More broadly, our study provides a methodological framework for assessing selection in historical anthropometric research.

Link: Google Scholar

Background and Context

The Great Irish Famine (1845-52)

One of history's most severe famines killed approximately 1 million people (12% of Ireland's population) and forced another million to emigrate, permanently altering the country's demographic and economic structure.

Research Question

This study examines whether survivors of the famine experienced permanent stunted growth (scarring) or whether the most vulnerable perished, leaving only more resilient survivors (selection).

Methodology

The researchers analyzed height data from over 14,500 individuals born before, during, and after the famine using prison records from Dublin (urban) and Tipperary (rural) to measure long-term health impacts.

Video Abstract

Opposite Effects: Scarring in Urban Dublin vs. Selection in Rural Tipperary

DUBLIN Urban Areas SCARRING Heights decreased TIPPERARY Rural Areas SELECTION Heights increased
  • Dublin residents who survived the Famine were shorter, showing evidence of nutritional stunting (scarring effect).
  • Rural Tipperary survivors showed no height reduction, suggesting only the strongest survived (selection effect).
  • This contradicts expectations that famine would universally stunt growth in all affected populations.

Urban Scarring vs Rural Selection: Different Famine Effects by Location

  • Dublin-born individuals showed decreased height (-0.67cm) during the famine, suggesting nutritional scarring persisted into adulthood.
  • Tipperary-born individuals showed increased height (+0.47cm), indicating only the healthiest survived the severe famine conditions.
  • The contrasting patterns demonstrate how selection effects can obscure health deterioration in severely affected areas.

Selection Effects More Pronounced Among Lower Height Percentiles

  • Height percentiles were affected differently by the famine, revealing nuanced selection and scarring effects.
  • In Dublin, the 75th percentile showed greater height reduction (-1.27cm) than the 10th percentile (0cm).
  • In Tipperary, the 25th percentile showed the greatest positive selection effect (+0.94cm).

Devastating Demographic Impact of the Great Irish Famine

  • Ireland lost nearly 20% of its population during 1841-1851, with stark regional differences.
  • Dublin's population increased by 8.7% as rural migrants fled to cities seeking food and shelter.
  • Tipperary lost nearly 24% of its population, illustrating the rural devastation caused by the famine.

Famine Severity Determines Whether Selection or Scarring Dominates

Urban Dublin Lower Mortality Scarring Dominates Height Decreased Rural Tipperary Higher Mortality Selection Dominates Height Maintained Famine Severity Spectrum
  • The study reveals a fundamental pattern: famine severity determines which effect (scarring or selection) predominates.
  • In urban areas with lower mortality, more people survived with permanent stunting (scarring effect).
  • In rural areas with higher mortality, only the healthiest survived, masking any scarring effect.

Contribution and Implications

  • The study resolves a paradoxical finding in famine research: severe famines seemingly produce healthier survivors.
  • The apparent health of populations most exposed to famine reflects extreme selection, not lesser impact.
  • Researchers studying catastrophic events must account for both scarring and selection effects to avoid misinterpretation.
  • The methodology provides a framework for distinguishing between selection and scarring in historical anthropometric research.
  • These insights help explain contemporary famines and could inform disaster response and humanitarian aid policies.

Data Sources

  • Visualization 1 is based on conceptual findings from Figure 1 showing the relationship between famine mortality and height change.
  • Visualization 2 uses data from Table 6 showing height changes in different birth cohorts from Dublin and Tipperary.
  • Visualization 3 uses data from Table 7 showing quantile regression results across height percentiles for Dublin and Tipperary.
  • Visualization 4 uses demographic indicators from Table 1 showing population changes, mortality, and birth rates.
  • Visualization 5 is based on the paper's conceptual framework contrasting selection and scarring effects between urban and rural areas.