Institute of Biology, Faculty of Bioscience, Pharmacy and Psychology, University of Leipzig, Talstrasse 33, 04103 Leipzig, Germany
Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany.
Proc Biol Sci. 2018 Oct 24;285(1889):20181527. doi: 10.1098/rspb.2018.1527.
Primates were traditionally thought to have a reduced sense of smell. Although there is now evidence that olfaction plays a greater role in primate social life than previously assumed, research on the sense of smell in non-human apes is scarce. Chimpanzees sniff the ground and vegetation on boundary patrols, but the function of this behaviour is unclear. Since chimpanzees are highly territorial and can kill individuals that do not belong to their own community, sniffing might function to gather information about conspecifics, particularly concerning group membership and kinship. To investigate whether chimpanzees recognize group members and kin via olfactory cues, we conducted behavioural bioassays on two groups of chimpanzees at Leipzig Zoo. In a pilot study, we found that chimpanzees responded more strongly to urine than to faeces or body odour. We then presented urine from group members, outgroup individuals and an unscented control in aerated boxes using a simultaneous discrimination task. The first behaviour after a chimpanzee first approached a box was related to olfaction (sniffing, nose within 20 cm, licking) in 83% of cases, highlighting the importance of olfaction as a general investigation mechanism in this species. Chimpanzees sniffed significantly longer at urine stimuli than the control and significantly longer at odours from outgroup individuals than those from group members. Furthermore, the duration of sniffing was positively correlated with relatedness. Our results suggest that chimpanzees use olfactory cues to obtain information about social relationships and fill a gap in our understanding of primate chemical communication.
灵长类动物传统上被认为嗅觉较弱。尽管现在有证据表明嗅觉在灵长类动物的社会生活中发挥的作用比之前认为的要大，但对非人类猿类嗅觉的研究却很少。黑猩猩在边界巡逻时会嗅地面和植被，但这种行为的功能尚不清楚。由于黑猩猩具有高度的领地意识，并且会杀死不属于自己社区的个体，因此嗅探可能是为了收集关于同种个体的信息，特别是关于群体归属和亲属关系的信息。为了研究黑猩猩是否通过嗅觉线索识别群体成员和亲属，我们在莱比锡动物园的两个黑猩猩群体中进行了行为生物测定。在一项初步研究中，我们发现黑猩猩对尿液的反应比对粪便或体臭更强烈。然后，我们在充气盒中使用同时辨别任务呈现来自群体成员、外群体个体和无气味对照的尿液。在黑猩猩第一次接近盒子后，它的第一个行为与嗅觉（嗅探、鼻子距离 20 厘米以内、舔舐）有关，在 83%的情况下有关，突出了嗅觉在该物种作为一般调查机制的重要性。与对照组相比，黑猩猩在尿液刺激下嗅探的时间明显更长，在外群体个体的气味中嗅探的时间明显长于群体成员的气味。此外，嗅探的持续时间与亲缘关系呈正相关。我们的研究结果表明，黑猩猩使用嗅觉线索来获取有关社会关系的信息，并填补了我们对灵长类动物化学通讯理解的空白。
