灵长类动物是人类的近亲，在进化的过程中它们与人类发生了分歧，它们的一些行为有时令人难以捉摸。近日，科学家找到了雄性卷尾猴(capuchin monkey)为何将尿液涂裹在身上原因。
研究发现雄性卷尾猴将尿液涂抹在身上的行为是为了吸引单身的雌性卷尾猴
据国外媒体报道，研究发现雄性卷尾猴将尿液涂抹在身上的行为是为了吸引单身的雌性卷尾猴。据研究人员介绍，雄性成年卷尾猴身上的尿液会散发出男性气息，能够引发雌性卷尾猴的一系列脑部活动。
早前也有关于这类的研究，当时科学家想通过对尿液的检测而得出结论，结果并非得偿所愿。早前科学家还猜测这种行为能帮助卷尾猴保持体温或者是能便于猴子间的区分。
美国德克萨斯州三一大学(Trinity University)的心理学博士金伯利(Kimberley Phillips)教授一直在从事有关灵长类动物生物学与神经学基础行为的研究。他发现当附近有雌性卷尾猴时，雄性成年卷尾猴会增加身上涂抹的尿液比例。
于是他进行了更深入的研究，金伯利博士使用了磁共振成像技术来扫描雌性卷尾猴的大脑。当雄性卷尾猴的尿液气味被雌性"捕捉"到时，雌性卷尾猴的脑部活动会变得活跃起来。这证实了雄性成年卷尾猴将尿液涂裹身上是为了吸引雌性卷尾猴。该项研究刊登在了最新的美国灵长类动物学杂志(Journal of Primatology)上。
雄性成年卷尾猴的尿液中会掺杂着较高浓度的睾丸激素，以便让雌性卷尾猴能检测到它的气味。卷尾猴生活在南美洲中部，猴群内的雄性个体多于雌性，一般以雄猴为群体的首领。另外，睾丸激素浓度影响着雄性成年卷尾猴在猴群的地位，往往浓度越高的雄性地位也就越高。
金伯利教授表示，雌性卷尾猴能用大脑区分出成年雄性卷尾猴和小卷尾猴的尿液，这也许是猴群中异性沟通的一种方式。（生物谷Bioon.com）
生物谷推荐原文出处：
Am. J. Primatol. 73:1-7, 2011. DOI: 10.1002/ajp.20931
Why do capuchin monkeys urine wash? An experimental test of the sexual communication hypothesis using fMRI
Kimberley A. Phillips1,*, Courtney A. Buzzell2, Nicholas Holder1, Chet C. Sherwood3
Keywords:urine washing;olfactory communication;Cebus
Abstract
Urine washing (UW) consists of depositing urine on the hands and vigorously rubbing the body. As urine contains chemical and pheromonal cues, UW may convey socially relevant information. Although ritualized UW is observed in many New World primates, including capuchin monkeys, the functional significance of UW remains unclear. In this experiment, we investigated the social signaling hypothesis of UW. Specifically, we hypothesized that UW by males conveys socially relevant signals that females can detect. We used functional magnetic resonance imaging (fMRI) to test whether adult female capuchins show differential brain activation in response to adult male and juvenile male capuchin urine. We expected to see changes in activation of structures involved in olfactory processing, including the piriform cortex, medial preoptic and anterior hypothesis, orbitofrontal cortex, hippocampus, and cerebellum. Data were acquired from four adult female capuchin monkeys. Presentations of odor stimuli (obtained from unfamiliar males) were made during fMRI acquisition using a standard ON-OFF design. All fMRI data were spatially normalized to a template and analyzed using the FMRI Expert Analysis Tool Version 5.98, part of the FMRIB's Software Library (www.fmrib.ox.ac.uk/fsl). Whole brain analyses revealed significant activations in the inferior temporal cortex, parahippocampal gyrus, precuneus, hippocampus, pulvinar, and cerebellum when females were presented with the adult male urine. Notably, significantly greater signal activation was observed in several regions associated with olfactory processing, when subjects were presented with adult male urine as compared with urine from juvenile males. Our results indicate that UW serves a social communicative function in capuchins, providing support for the sexual signaling hypothesis.
