Department of Anthropology, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada.
Am J Primatol. 2010 Jun;72(7):600-6. doi: 10.1002/ajp.20813.
High cortisol levels are known to cause low fecundity and increased mortality; thus, the prospect of using cortisol as a measure of population health is an exciting one. However, because so many factors can interact to influence cortisol release, it can be difficult to interpret what exactly is creating changes to cortisol levels. This study investigates variation in fecal cortisol levels in a population of black howlers (Alouatta pigra) from 350 fecal samples collected from 33 individuals in more than 4 years. A general linear mixed model revealed that cortisol varied significantly with fruit availability and contact with tourists. When fruit availability was low, cortisol increased, likely because when fruit availability is low monkeys eat less fruit, thus obtaining less sugar. This result may simply reflect cortisol's metabolic function of mobilizing glucose. It also indicates that these monkeys may be experiencing periods of food stress throughout the year, which was earlier thought to be minimal for a primarily folivorous species. Presence of tourists was the only other factor found to lead to high cortisol; with exposure to tourists increasing stress levels. These results highlight the importance of understanding how physiological factors can influence cortisol, making it easier to interpret results and determine the external social or ecological stressors that may increase cortisol.
高皮质醇水平已知会导致低生育率和死亡率增加；因此，皮质醇作为衡量人口健康的指标是一个令人兴奋的前景。然而，由于许多因素可以相互作用影响皮质醇的释放，因此很难解释到底是什么导致了皮质醇水平的变化。本研究调查了来自 33 只个体的 350 份粪便样本中黑吼猴（Alouatta pigra）粪便皮质醇水平的变化。一个广义线性混合模型表明，皮质醇水平随水果的可获得性和与游客的接触而显著变化。当水果供应不足时，皮质醇水平会升高，这可能是因为当水果供应不足时，猴子会少吃水果，从而摄入较少的糖分。这一结果可能只是反映了皮质醇在调动葡萄糖方面的代谢功能。这也表明，这些猴子可能全年都经历着食物压力期，而此前人们认为这对于主要以树叶为食的物种来说是最小的。只有游客的存在被发现会导致皮质醇升高；接触游客会增加压力水平。这些结果强调了理解生理因素如何影响皮质醇的重要性，这使得更容易解释结果，并确定可能增加皮质醇的外部社会或生态压力源。
