Early life experiences have profound effects on later life health and on Darwinian fitness in many mammalian species, including humans. However, while it is clear that early life adversity often leads to compromised health, reproduction, and survival in adulthood, it is less clear why these links have evolved. Here, we review hypotheses from the evolutionary biology literature that have been proposed to explain how natural selection could produce early life environmental sensitivity. We evaluate competing hypotheses in light of their empirical support, and also discuss three emerging topics related to these evolutionary discussions. Specifically, we focus on: (i) whether different classes of early life effects evolve in different ways; (ii) how the existence of short, acute sensitive periods during development (e.g. gestation/pregnancy) informs evolutionary thinking about early life effects; and (iii) what to consider when using fitness proxies, including behavioral traits, to test evolutionary hypotheses. We conclude these discussions with suggestions for empirical work that could help resolve current debates about the causes, consequences, and adaptive significance of early life effects.

早期的生活经历对以后的生活健康以及包括人类在内的许多哺乳动物物种的达尔文适应性都有深远的影响。然而，虽然很显然，早期的逆境通常会导致成年后的健康，生殖和生存受到损害，但不清楚这些联系为何会发展。在这里，我们回顾了进化生物学文献中的假说，这些假说已经被提出来解释自然选择如何产生早期生活环境敏感性。我们根据它们的经验支持来评估竞争假设，并讨论与这些进化论讨论相关的三个新兴主题。具体而言，我们关注：（i）不同类别的早期生命影响是否以不同方式演变；（ii）发育过程中短期，急性敏感期的存在（例如 妊娠/妊娠）有助于人们对生命早期影响的进化思考；（iii）使用适应性代理（包括行为特征）来检验进化假设时应考虑的因素。我们以经验工作的建议来结束这些讨论，这些经验工作可以帮助解决当前有关早期生命影响的原因，后果和适应性意义的辩论。