Muller Martin N, Lipson Susan F
Department of Anthropology, Harvard University, Cambridge, Massachusetts, USA.
Am J Primatol. 2003 Aug;60(4):161-6. doi: 10.1002/ajp.10103.
Urinary testosterone and cortisol concentrations were quantified in a large number of samples (>500) collected from wild male chimpanzees (n=11) over the course of 1 year. For both steroids, urinary concentrations were higher and more variable in the morning than in the afternoon. Urinary creatinine levels showed no such diurnal pattern. These patterns are consistent with studies of steroid excretion in humans and gorillas. This study emphasizes the importance of considering time of day as a confounding variable in field studies of primate endocrine function. It also suggests that if a small number of samples are to be used to characterize an individual's basal steroid levels, afternoon samples may be preferable because they show less intra-individual variability.
对从11只野生雄性黑猩猩身上采集的大量样本（超过500个）中的尿睾酮和皮质醇浓度进行了为期1年的定量分析。对于这两种类固醇，尿浓度在早晨比下午更高且更具变异性。尿肌酐水平没有这种昼夜模式。这些模式与人类和大猩猩的类固醇排泄研究一致。本研究强调了在灵长类动物内分泌功能的野外研究中，将一天中的时间作为一个混杂变量加以考虑的重要性。它还表明，如果要用少量样本表征个体的基础类固醇水平，下午的样本可能更可取，因为它们显示出的个体内变异性较小。
