Doctoral Dissertation Improvement: Group Decision-Making in Gregarious Primates

从独居生活到群居生活的转变被认为是进化过程中的重大转变之一，群居生活也是灵长类辐射的一个标志。在灵长类等群居动物中，需要协调活动的决定不是由个人单独执行的，而是与其他群体成员协商做出的。然而，如果个别群体成员之间存在利益冲突，要求群体协商一致的决定必然意味着至少对群体中的某些个人做出妥协。博弈论和计算机模拟的最新发展表明，相对于群体生活利益的利益冲突程度，应该预测一个群体所表现出的决策机制；即，一个物种是表现出更民主的还是更专制的达成共识的模式。然而，仍然缺乏实证研究来反驳或支持当前群体决策进化的理论模型。这项由纽约大学博士生Anand Dacier(纽约大学)在特里·哈里森博士的指导下进行的项目的目的是通过解决关于群体达成共识的机制(专制与民主)的假设来研究群居灵长类动物的群体决策；群体成员之间的利益冲突是否可以预测群体决策；领导力如何在整个群体中分配；以及决策对个体群体成员繁殖成功的影响。这项研究采用了一种新的方法，通过操纵喂食平台上资源的空间分布和时间可用性来人为地制造个体之间的利益冲突。通过遵循这一新的实验设置，该研究经验性地评估了最近发展的群体决策进化的理论模型，以及这些模型是否足以解释在灵长类动物中看到的群体决策的差异。通过探索动物群体如何做出集体决策，这项研究有助于更广泛地讨论社会性的演变以及帮助维持社会性的机制。

The change from a solitary life to living in groups is considered one of the major transitions in evolution, and group-living is also a hallmark of the primate radiation. In group-living animals such as primates, decisions that require coordination of activities are not carried out by individuals alone, but are rather negotiated with fellow group members. If there are conflicts of interest among individual group members, however, decisions that require group consensus necessarily implicate a compromise for at least certain individuals in the group. Recent developments in game theory and computer simulation suggest that the level of conflict of interest relative to the benefits of group-living should predict the decision-making mechanism a group displays; i.e. whether a species displays a more democratic or a more despotic mode of reaching a consensus. Empirical studies are still lacking, however, which could refute or provide support for the current theoretical models for the evolution of group decision-making.The aim of this project by doctoral student Anand Dacier (New York University), under the supervision of Dr. Terry Harrison, is to examine group decision-making in gregarious primates by addressing hypotheses concerning the mechanisms by which groups come to a consensus (despotic vs. democratic); whether conflict of interest among group members can predict group decision-making; how leadership is distributed across the group; and the consequences of decision-making in terms of reproductive success for individual group members. This study employs a novel methodological approach, in which conflict of interest among individuals will be artificially created via manipulating the spatial distribution and temporal availability of resources in feeding platforms. By following this novel experimental setup, the study empirically evaluates the recently developed theoretical models for the evolution of group decision-making, and whether such models are adequate to explain the variation in group decision-making seen across the primate order. By exploring how animal groups come to collective decisions, this study contributes to the broader discussion on the evolution of sociality and the mechanisms that help maintain it.