Wildlife Research Center, Kyoto University, Japan; Kumamoto Sanctuary, Kyoto University, Japan.
Wildlife Research Center, Kyoto University, Japan; Kumamoto Sanctuary, Kyoto University, Japan.
Psychoneuroendocrinology. 2021 Mar;125:105119. doi: 10.1016/j.psyneuen.2020.105119. Epub 2020 Dec 21.
Oxytocin has drawn significant research attention for its role in modulating mammalian social behavior. Despite generally conserved roles, oxytocin can function differently even in closely related species. Previous studies have shown that bonobos and chimpanzees, humans' two closest relatives, demonstrate considerable behavioral differences, including that bonobos look more at others' eyes than chimpanzees. Oxytocin is known to increase attention to another's eyes in many mammalian species (e.g. dogs, monkeys, and humans), yet this effect has not been tested in any nonhuman great ape species. This study examined how intranasally-administered oxytocin affects eye contact in bonobos and chimpanzees using eye tracking. Following administration of either oxytocin or saline control with a nebulizer, chimpanzees (n = 6) and bonobos (n = 5) were shown images of conspecific faces while their eye movement was recorded. Oxytocin changed the eye-looking behavior of bonobos and chimpanzees differently. We found that oxytocin increased eye contact in bonobos but not chimpanzees; while one chimpanzee showed an increase, interestingly, 5 out of 6 chimpanzees showed decreased looking to the eyes compared to the mouth, suggesting moderate eye avoidance. Given the importance of eye contact in their social interactions, our results suggest that oxytocin may play modulatory roles in bonobos' and chimpanzees' species-specific social behavior and underscore the importance of oxytocin in hominid social evolution.
催产素在调节哺乳动物社会行为方面引起了广泛的研究关注。尽管作用普遍保守，但催产素在密切相关的物种中甚至可能发挥不同的作用。以前的研究表明，黑猩猩和人类的两个最亲近的亲属，表现出相当大的行为差异，包括倭黑猩猩比黑猩猩更关注他人的眼睛。已知催产素在许多哺乳动物物种（如狗、猴子和人类）中增加了对另一个人眼睛的关注，但在任何非人类大型猿类物种中都没有测试过这种效果。本研究使用眼动追踪技术，检查了鼻内给予催产素如何影响倭黑猩猩和黑猩猩的眼神接触。在使用喷雾器给予催产素或生理盐水对照后，展示了黑猩猩（n=6）和倭黑猩猩（n=5）的同种面孔图像，同时记录了它们的眼球运动。催产素改变了黑猩猩和倭黑猩猩的眼神行为方式不同。我们发现，催产素增加了倭黑猩猩的眼神接触，但没有增加黑猩猩的眼神接触；虽然一只黑猩猩表现出增加，但有趣的是，6 只黑猩猩中有 5 只与嘴巴相比，眼睛看向的次数减少，这表明中等程度的眼睛回避。鉴于眼神接触在它们的社交互动中的重要性，我们的研究结果表明，催产素可能在倭黑猩猩和黑猩猩的特定物种的社会行为中发挥调节作用，并强调了催产素在人类社会进化中的重要性。
