title: Life-history theory, chronic childhood illness and the timing of first reproduction in a British birth cohort.
abstract: 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.
authors.affiliation: Department of Population Health and Primary Care, The Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7TJ, UK. d.waynforth@uea.ac.uk
authors.forename: David
authors.initials: D
authors.lastname: Waynforth
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D015331:Cohort Studies; D005219:Father-Child Relations; D005260:Female; D006801:Humans; D008017:Life Expectancy; D008137:Longitudinal Studies; D008297:Male; D008423:Maternal Age; D008954:Models, Biological; D009026:Mortality; D012098:Reproduction / Q000502:physiology*; D006113:United Kingdom; D055815:Young Adult