Abstract People often value an item more when they own it than when it is available for purchase, and consequently are relatively reluctant to trade. This is the “endowment effect”, which has been widely documented in human populations and also in some non-human species. This paper develops a simple model in which it is adaptive to have a bias against trade, potentially explaining the basis of the endowment effect. The bias against trade arises from the strategic nature of trade in a moderately competitive environment: the interest of a potential trading partner in making the exchange is evidence that the decision maker already has the more valuable object. The model predicts that an endowment effect is promoted by large uncertainty about the fitness value of items, and also by conditions in which there are on average small gains to be had from trade. Because the model employs a simple bounded rationality heuristic for trade, it explains how the endowment effect could arise in species that lack theory of mind and related strategic reasoning abilities. The model also suggests an explanation for why endowment effects are so rarely observed in biological markets that exist between species. Because the trading classes have very different fitness functions, there is negligible competition across those classes. Consequently, there are substantial mutual gains to trade, so our model predicts there is unlikely to be adaptive pressure for an endowment effect.

中文翻译：

---

禀赋效应的演变

摘要 人们通常在拥有物品时比在可购买时更看重它，因此相对不愿意交易。这就是“禀赋效应”，它在人类群体和一些非人类物种中得到了广泛的记载。本文开发了一个简单的模型，在该模型中它可以适应对贸易的偏见，这可能解释了禀赋效应的基础。对贸易的偏见源于适度竞争环境中贸易的战略性质：潜在贸易伙伴在进行交换时的利益证明决策者已经拥有更有价值的对象。该模型预测，物品的适应度值的巨大不确定性会促进禀赋效应，以及从贸易中平均获得小额收益的条件。因为该模型对贸易采用了简单的有限理性启发式，它解释了禀赋效应如何在缺乏心理理论和相关战略推理能力的物种中出现。该模型还解释了为什么在物种之间存在的生物市场中很少观察到禀赋效应。由于交易类具有非常不同的适应度函数，因此这些类之间的竞争可以忽略不计。因此，交易会产生大量的相互收益，因此我们的模型预测，禀赋效应不太可能存在适应性压力。它解释了如何在缺乏心理理论和相关战略推理能力的物种中产生禀赋效应。该模型还解释了为什么在物种之间存在的生物市场中很少观察到禀赋效应。由于交易类具有非常不同的适应度函数，因此这些类之间的竞争可以忽略不计。因此，交易会产生大量的相互收益，因此我们的模型预测，禀赋效应不太可能存在适应性压力。它解释了如何在缺乏心理理论和相关战略推理能力的物种中产生禀赋效应。该模型还解释了为什么在物种之间存在的生物市场中很少观察到禀赋效应。由于交易类具有非常不同的适应度函数，因此这些类之间的竞争可以忽略不计。因此，交易会产生大量的相互收益，因此我们的模型预测，禀赋效应不太可能存在适应性压力。