2023年第58讲总第809讲

题目：The Impact of Longevity on Fertility Decisions（长寿对生育决策的影响）

地点：江南体育官网516

时间：2023年12月22日13:30-16:30

主讲人：Pro. Zhen Zhang, Ph.D in Demography, Director of Institute of Population Studies, Fudan University. His research expertise and interest include survival and longevity, population aging, formal demography, social demography. Zhen's recent research includes how the abnormally high sex ratio at birth accelerates population aging in China and other affected countries. His earlier publications include Population Health Transition in China: Achievements in the Co-evolution of Health Governance and Health Strategies, Population Aging Caused by a Rise in the Sex Ratio at Birth, The Ratio of Expansion to Compression: A New Measure of Lifespan Disparity, Impact of Demographic Uncertainty on Population Projection and Policy-making: The Case of China. Zhen received Ph.D in Demography at Peking University. Before moving to Fudan University in 2013, Zhen held a position as Research Scientist at the Max Planck Institute for Demographic Research in Rostock, Germany.

张震，人口学博士，教授，复旦大学人口研究所所长。他的研究专长和兴趣包括生存和寿命、人口老龄化、形式人口学、社会人口学。张震最近的研究聚焦于异常高的出生性别比如何加速中国和其他受影响国家的人口老龄化。他早期的发表作品包括《中国的人口健康转型：卫生治理和卫生战略共同演变的成就》、《出生性别比上升引起的人口老龄化》、《扩张与压缩的比率：一种寿命差距的新测量》、《人口预测和政策制定中人口不确定性的影响：以中国为例》。张震毕业于北京大学，获人口学博士学位。2013年加入复旦大学之前，张震曾在德国罗斯托克的马克斯•普朗克人口研究所担任研究员。

内容简介：Increased longevity not only gives us more time, it also lengthens the period of return on our investments. Our early investments in education, health care and skills development have the advantage of a longer payback period. As lifespan disparity decrease, the expectation of sustained returns over time becomes more predictable and stable. Strategies with fewer children have a higher resilience and a stronger survival advantage than having more children. Due to the principle of compound interest, investment returns are likely to grow exponentially, which means that gaps due to underinvestment in human capital in earlier years are also likely to grow exponentially. As life expectancy increases, these cumulative lifetime financial setbacks can become considerable. From an evolutionary game theory perspective, the proportion of people adopting the first strategy increases over time across the population, and the fertility rate of the population declines. Thus, increased longevity greatly increases the cumulative cost of the investment in reproductive time, which in turn depresses fertility.

寿命的延长不仅给予我们更多时间，而且延长了我们投资回报的周期，使我们在教育、医疗和技能发展方面的早期投资具有更长期的回报优势。随着寿命差距的减小，对持续回报的期望随着时间的推移变得更加可预测和稳定。相较于生育更多的子女，采取较少子女的策略具有更高的弹性和更强的生存优势。复利的原则的影响下，投资回报很可能呈指数增长，这意味着由于早期对人力资本的不足投资而产生的差距也可能呈指数增长。随着预期寿命的不断延长，这些累积的终身财务挫折可能变得相当可观。从进化博弈理论的角度来看，采取第一种策略的人口比例随时间在整个人口中增加，人口的生育率下降。因此，增加的寿命大大增加了生殖时间投资的累积成本，进而抑制了生育率。