Life-history theory, chronic childhood illness and the timing of first reproduction in a British birth cohort

Proc Biol Sci. 2012 Aug 7;279(1740):2998-3002. doi: 10.1098/rspb.2012.0220. Epub 2012 Mar 28.


Life-history theoretical models show that a typical evolutionarily optimal response of a juvenile organism to high mortality risk is to reach reproductive maturity earlier. Experimental studies in a range of species suggest the existence of adaptive flexibility in reproductive scheduling to maximize fitness just as life-history theory predicts. In humans, supportive evidence has come from studies comparing neighbourhoods with different mortality rates, historical and cross-cultural data. Here, the prediction is tested in a novel way in a large (n = 9099), longitudinal sample using data comparing age at first reproduction in individuals with and without life-expectancy-reducing chronic disease diagnosed during childhood. Diseases selected for inclusion as chronic illnesses were those unlikely to be significantly affected by shifting allocation of effort away from reproduction towards survival; those which have comparatively large effects on mortality and life expectancy; and those which are not profoundly disabling. The results confirmed the prediction that chronic disease would associate with early age at first reproduction: individuals growing up with a serious chronic disease were 1.6 times more likely to have had a first child by age 30. Analysis of control variables also confirmed past research findings on links between being raised father-absent and early pubertal development and reproduction.

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Child, Preschool
  • Chronic Disease
  • Cohort Studies
  • Father-Child Relations
  • Female
  • Humans
  • Life Expectancy*
  • Longitudinal Studies
  • Male
  • Maternal Age*
  • Models, Biological
  • Mortality*
  • Reproduction / physiology*
  • United Kingdom
  • Young Adult