Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
Proc Natl Acad Sci U S A. 2013 Aug 20;110(34):13886-91. doi: 10.1073/pnas.1301817110. Epub 2013 Aug 5.
Individuals with insufficient nutrition during development often experience poorer later-life health and evolutionary fitness. The Predictive Adaptive Response (PAR) hypothesis proposes that poor early-life nutrition induces physiological changes that maximize fitness in similar environments in adulthood and that metabolic diseases result when individuals experiencing poor nutrition during development subsequently encounter good nutrition in adulthood. However, although cohort studies have shown that famine exposure in utero reduces health in favorable later-life conditions, no study on humans has demonstrated the predicted fitness benefit under low later-life nutrition, leaving the evolutionary origins of such plasticity unexplored. Taking advantage of a well-documented famine and unique datasets of individual life histories and crop yields from two preindustrial Finnish populations, we provide a test of key predictions of the PAR hypothesis. Known individuals from fifty cohorts were followed from birth until the famine, where we analyzed their survival and reproductive success in relation to the crop yields around birth. We were also able to test whether the long-term effects of early-life nutrition differed between individuals of varying socioeconomic status. We found that, contrary to predictions of the PAR hypothesis, individuals experiencing low early-life crop yields showed lower survival and fertility during the famine than individuals experiencing high early-life crop yields. These effects were more pronounced among young individuals and those of low socioeconomic status. Our results do not support the hypothesis that PARs should have been favored by natural selection and suggest that alternative models may need to be invoked to explain the epidemiology of metabolic diseases.
在发育过程中营养不足的个体通常在晚年健康和进化适应度方面表现较差。预测适应性反应（PAR）假说提出，早期营养不良会诱导生理变化，使个体在成年后相似的环境中最大限度地适应环境，并且当个体在发育过程中经历营养不良，随后在成年期遇到良好的营养时，就会导致代谢疾病。然而，尽管队列研究表明胎儿期暴露于饥荒会降低在有利的晚年条件下的健康状况，但没有研究表明在低晚年营养条件下预测的适应性益处，从而使这种可塑性的进化起源未得到探索。利用一份有充分记录的饥荒和两个前工业化时期芬兰人口的个体生活史和作物产量的独特数据集，我们对 PAR 假说的关键预测进行了检验。从出生到饥荒，我们对五十个队列中的已知个体进行了跟踪，并分析了他们的生存和生殖成功率与出生前后的作物产量之间的关系。我们还能够测试早期营养对不同社会经济地位个体的长期影响是否存在差异。我们发现，与 PAR 假说的预测相反，经历低早期作物产量的个体在饥荒期间的存活率和生育率低于经历高早期作物产量的个体。这些影响在年轻个体和社会经济地位较低的个体中更为明显。我们的结果不支持 PAR 应该受到自然选择青睐的假说，并表明可能需要引入替代模型来解释代谢疾病的流行病学。
