Popul Stud (Camb). 1976 Jul;30(2):243-7. doi: 10.1080/00324728.1976.10412732.
Summary Standard one-sex linear models of Lotka or Bernardelli always approach asymptotically an exponential growth mode with stable age distribution. Realistic non-linear models need not possess this property. The present analysis uncovers a possibly realistic ease where an existent mode of balanced growth is 'unstable', giving way when slightly perturbed to an asymptotic every-other generation limit cycle of determinable amplitude, and which is stable. The nonlinear model utilizes the hypothesis of R. A. Easterlin that age-specific fertility will tend to be lower for age classes that are relatively swollen in total number. By virtue of the law of diminishing returns, wages and feeling of security will tend to be low for such swollen groups. A possible rebound in fertility in the 1980s is implicit in the Easterlin hypothesis.
洛特卡或贝尔纳德利的单性别线性模型通常以稳定年龄分布的指数增长模式渐近。现实的非线性模型不一定具有此属性。本分析揭示了一种可能的现实情况，即现有平衡增长模式是“不稳定的”，当受到轻微干扰时，它会向可确定幅度的每两代限环渐近，并且是稳定的。非线性模型利用了 R.A.伊斯特林的假设，即年龄特定的生育率往往会随着总数量相对膨胀的年龄组而降低。由于收益递减规律，对于这种膨胀的群体，工资和安全感往往会较低。伊斯特林假设中隐含了 20 世纪 80 年代生育率可能出现反弹。
