Many animals participate in biological markets, with strong evidence existing for immediate cooperative trades. In particular, grooming is often exchanged for itself or other commodities, such as coalitionary support or access to food and mates. More contentious is the possibility that nonhuman animals can rely on memories of recent events, providing contingent cooperation even when there is a temporal delay between two cooperative acts. Here we provide experimental evidence of delayed cross-commodity grooming exchange in wild dwarf mongooses (Helogale parvula). First, we use natural observations and social-network analyses to demonstrate a positive link between grooming and sentinel behavior (acting as a raised guard). Group members who contributed more to sentinel behavior received more grooming and had a better social-network position. We then used a field-based playback experiment to test a causal link between contributions to sentinel behavior and grooming received later in the day. During 3-h trial sessions, the perceived sentinel contributions of a focal individual were either up-regulated (playback of its surveillance calls, which are given naturally during sentinel bouts) or unmanipulated (playback of its foraging close calls as a control). On returning to the sleeping refuge at the end of the day, focal individuals received more grooming following surveillance-call playback than control-call playback and more grooming than a matched individual whose sentinel contributions were not up-regulated. We believe our study therefore provides experimental evidence of delayed contingent cooperation in a wild nonprimate species.

许多动物参与生物市场，有强有力的证据表明直接合作贸易。特别是，修饰经常被交换为自身或其他商品，例如联盟支持或获得食物和配偶。更有争议的是，非人类动物有可能依靠对最近事件的记忆，即使在两次合作行为之间存在时间延迟时也能提供偶然的合作。在这里，我们提供了野生侏儒猫鼬（ Helogale parvula）延迟跨商品梳理交换的实验证据。）。首先，我们使用自然观察和社交网络分析来证明修饰和哨兵行为（充当举起警卫）之间的积极联系。对哨兵行为做出更多贡献的群体成员得到了更多的修饰，并拥有更好的社交网络地位。然后，我们使用基于现场的回放实验来测试对哨兵行为的贡献与当天晚些时候收到的梳理之间的因果关系。在 3 小时的试验期间，焦点个体的感知哨兵贡献要么被上调（回放其监视呼叫，在哨兵回合期间自然给出）或未经操纵（回放其觅食近距离呼叫作为控制）。在一天结束时回到沉睡的避难所，与控制呼叫回放相比，焦点个体在监视呼叫回放后接受了更多的修饰，并且比哨兵贡献未上调的匹配个体获得更多修饰。因此，我们相信我们的研究提供了野生非灵长类物种延迟特遣队合作的实验证据。