Galdikas B M, Wood J W
Orangutan Research and Conservation Project, Department of Archaeology, Simon Fraser University.
Am J Phys Anthropol. 1990 Oct;83(2):185-91. doi: 10.1002/ajpa.1330830207.
Comparative studies of birth interval dynamics in wild primates suffer from several problems of analysis and interpretation: (1) the data are always right-censored, (2) sample sizes are usually small, (3) the distribution of birth intervals is expected to be non-normal, (4) early offspring mortality is a confounding variable, and (5) differences in life history (e.g., presence or absence of menopause) can complicate interpretation of the results. A survival analysis designed to minimize these problems is applied to published data on wild chimpanzees and gorillas from Gombe and Virunga Parks, respectively, and to new data on wild orangutans from Tanjung Puting National Park and on a human population, the Gainj of highland Papua New Guinea. According to this analysis, the estimated median birth interval (when the offspring whose birth opens the interval does not die within the interval) is 43.3 +/- 1.0 months for the Gainj, 45.5 +/- 1.2 months for gorillas, 66.6 +/- 1.3 months for chimpanzees, and 92.6 +/- 2.4 months for orangutans.
（1）数据总是右删失的；（2）样本量通常较小；（3）出生间隔的分布预计是非正态的；（4）早期子代死亡率是一个混杂变量；（5）生活史的差异（例如是否存在更年期）会使结果的解释变得复杂。一种旨在尽量减少这些问题的生存分析方法，分别应用于来自贡贝国家公园和维龙加国家公园的野生黑猩猩和大猩猩的已发表数据，以及来自丹戎普丁国家公园的野生猩猩和巴布亚新几内亚高地加因吉族人群的新数据。根据这一分析，加因吉族的估计中位出生间隔（当开启该间隔的子代在间隔期内未死亡时）为43.3±1.0个月，大猩猩为45.5±1.2个月，黑猩猩为66.6±1.3个月，猩猩为92.6±2.4个月。
