Department of Population Health and Primary Care, The Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7TJ, UK.
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.
生活史理论模型表明，幼年生物体对高死亡率的典型进化最优反应是更早达到生殖成熟。一系列物种的实验研究表明，存在生殖计划的适应性灵活性，可以最大限度地提高适应性，正如生活史理论所预测的那样。在人类中，来自比较死亡率不同的社区、历史和跨文化数据的研究提供了支持性证据。在这里，通过比较在儿童期被诊断出患有降低预期寿命的慢性疾病的个体和没有患有慢性疾病的个体的首次生殖年龄，在一个大型（n=9099）纵向样本中以新颖的方式检验了这一预测。选择纳入慢性疾病的疾病是那些不太可能因将生殖的努力转移到生存上而受到显著影响的疾病；那些对死亡率和预期寿命有较大影响的疾病；以及那些没有严重致残的疾病。结果证实了慢性疾病与初次生殖年龄较早有关的预测：患有严重慢性疾病的个体在 30 岁之前生育第一胎的可能性是其他人的 1.6 倍。对控制变量的分析也证实了过去关于父亲缺失和青春期早期发育与生殖之间联系的研究发现。
