Doctoral Dissertation Research: Cooperation and Status Competition in Public Goods Games

本研究探讨了在竞争性社会困境中，对显示性奖励的进化偏好如何调节男性和女性的慷慨行为。在人类社会中，利他合作是不可或缺的，在建立促进亲社会决策的机构方面已经取得了很大进展。经济学家关注的是惩罚和奖励，但他们经常发现，激励会排挤合作的内在动机，对效率产生不利影响。与此同时，进化生物学家早就认识到，即使没有正式的经济激励，以野生食物为生的群体也会有效地组织合作，尤其是食物分享。根据进化心理学，该研究假设这种合作依赖于男性对竞争之外的独特和可展示的奖励（奖杯）的偏好。第一项研究采用控制实验室实验，研究在有奖杯奖励的慷慨竞争中，合作是否会持续，以及在同样有价值但非独特和不可展示的奖励的环境中，合作是否会破裂。此外，本文还探讨了男性对奖杯奖励的竞争是否是造成这种差异的驱动力，而女性的竞争是否受到奖杯的调节。PIs假设，女性搭便车者对合作者的互惠会减轻她们的负面情绪，从而维持合作。第二项研究将研究范围从“赢者入”扩展到“输者出”机制。假设女性在“失败者出局”的环境中会更合作。原因是，在地位竞争中获胜并获得与女性接触的特权的倾向——一种被“优胜者”机制捕获的倾向——在整个人类历史上都有助于男性的健康。然而，女性的适合度受到生殖所需物质资源的限制：只有相对弱势的女性，未能达到阈值资源水平，才无法获得生殖成功。因此，女性避免相对处于不利地位的偏好可能会使女性对“输掉”机制敏感。更广泛的影响：合作遍及人类社会；这是人类不可缺少的活动。该项目为促进人类群体的亲社会活动提供了新的方向，并具有广泛的跨学科应用。特别地，这项研究是在行为经济学、进化生物学和人类学的联系，借鉴和扩展了代价信号理论。这对那些旨在研究导致竞争倾向中观察到的性别差异的潜在因素的文献有直接的影响，这些因素可能部分解释了当代性别工资差距。该项目开辟了在不牺牲效率的情况下促进人类群体合作的新途径。研究结果可能对任何涉及自愿遵守的领域产生重要影响，包括配偶关系、雇主和雇员关系、市场交易以及遵守法律标准。

This research addresses how evolutionarily evolved preferences for displayable rewards modulates male and female generosity in competitive social dilemmas. Altruistic cooperation is indispensible in human societies, and much progress has been made towards developing institutions to promote pro-social decisions. Economists have focused on punishment and rewards, but often find that incentives can crowd out intrinsic motives for cooperation and detrimentally impact efficiency. At the same time, evolutionary biologists have long recognized that cooperation, especially food sharing, is typically efficiently organized in groups living on wild foods even absent formal economic incentives. Drawing on evolutionary psychology, the study hypothesize that such cooperation relies on male preferences for unique and displayable rewards (trophies) out of competition.The first study uses a controlled laboratory experiment to investigate whether cooperation is sustained in a generosity competition with trophy rewards, and whether cooperation breaks down in the same environment with equally valuable but non-unique and non-displayable rewards. Further, it investigates whether males' competition for trophy rewards is the driving force for such differences while female competitiveness is modulated by trophies. The PIs hypothesize that reciprocity from female free-riders towards co-operators mitigates their negative emotion and consequently sustains cooperation.The second study extends the investigation from "winner in" to "loser out" mechanisms. Women are hypothesized to be more cooperative in "loser out" environments. The reason is that the inclination to win status competitions and obtain privileged access to females, an inclination captured by a "winner-in" mechanism, has contributed to male fitness throughout human history. However, female fitness is limited by material resources necessary for reproduction: only relatively disadvantaged females who fail to achieve threshold resource levels fail to achieve reproductive success. Thus, female preference to avoid becoming relatively disadvantaged may leave females sensitive to "loser-out" mechanisms.Broader Impact: Cooperation pervades human societies; it is an indispensible human activity. The project informs new directions in promoting pro-social activity in human groups, and has wide cross-disciplinary applications. In particular, this investigation lies at nexus of behavioral economics, evolutionary biology and anthropology, drawing from and extending the theory of costly signaling. It has immediate implications for literatures aimed at underlying factors responsible for observed gender differences in competitive inclinations that might partially explain contemporary gender wage gaps. The project opens new paths to promoting cooperation in human groups without sacrificing efficiency. The results could have an important impact in any domains where voluntary compliance matters, including relations between spouses, employers and employees, market transactions, and conformity to legal standards.