Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK.
Proc Biol Sci. 2011 Apr 22;278(1709):1189-94. doi: 10.1098/rspb.2010.1675. Epub 2010 Oct 6.
The evolution and expression of different forms of cooperative behaviour (e.g. feeding, guarding, sentinel duties, etc.) are usually studied independently, with few studies considering them as a single syndrome. However, studies investigating individuals' investment across a suite of different behaviours reveal that they are correlated, suggesting a single mechanism determining the evolution and expression of cooperative behaviours. A hormonal mechanism could achieve this, and one possibility is oxytocin (OT), which affects several prosocial or alloparental behaviours independently. We show, using a double-blind experiment, that peripheral administration of OT to social, free-living meerkats Suricata suricatta elevates a suite of cooperative behaviours. Treated individuals increase their contributions to communal, cooperative activities (digging, guarding, pup-feeding and associating with pups) and decrease initiation of aggressive interactions, compared with a saline control. This suggests that different forms of cooperative behaviour form a single syndrome with a common causal basis. If our peripherally administered OT acts in the same way as the naturally released hormone, then a general tendency to prosociality may be modulated by this hormonal system. Therefore, it may be difficult for an individual to decouple expression of cooperative behaviours that provide the practitioner with benefits from those that provide the recipient with benefits. It may also explain why social species typically exhibit a suite of cooperative behaviours, without having to invoke independent evolution of each.
不同形式的合作行为（例如喂食、警戒、放哨等）的进化和表现通常是独立研究的，很少有研究将它们视为单一综合征。然而，研究个体在一系列不同行为中的投资情况表明，它们是相关的，这表明有一个单一的机制决定了合作行为的进化和表现。激素机制可以实现这一点，一种可能性是催产素（OT），它可以独立影响几种亲社会或利他行为。我们通过一项双盲实验表明，向社交、自由生活的猫鼬（Suricata suricatta）注射外周催产素会提高一系列合作行为。与生理盐水对照组相比，接受治疗的个体增加了对公共、合作活动（挖掘、警戒、幼崽喂养和与幼崽在一起）的贡献，减少了攻击性行为的发起。这表明不同形式的合作行为形成了一个单一的综合征，具有共同的因果基础。如果我们外周给予的 OT 以与自然释放的激素相同的方式起作用，那么这种激素系统可能会调节亲社会的一般倾向。因此，个体可能难以将为施惠者提供好处的合作行为的表现与为受惠者提供好处的合作行为的表现分离开来。这也可能解释了为什么社会物种通常表现出一系列合作行为，而不必独立进化每一种行为。
