Evidence shows that people feel mild positive moods when no strong emotional events are occurring, a phenomenon known as positive mood offset. We offer an evolutionary explanation of this characteristic, showing that it improves fertility, fecundity, and health, and abets other characteristics that were critical to reproductive success. We review research showing that positive mood offset is virtually universal in the nations of the world, even among people who live in extremely difficult circumstances. Positive moods increase the likelihood of the types of adaptive behaviors that likely characterized our Paleolithic ancestors, such as creativity, planning, mating, and sociality. Because of the ubiquity and apparent advantages of positive moods, it is a reasonable hypothesis that humans were selected for positivity offset in our evolutionary past. We outline additional evidence that is needed to help confirm that positive mood offset is an evolutionary adaptation in humans and we explore the research questions that the hypothesis generates.

中文翻译：

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人们为什么心情良好。

有证据表明，当没有发生强烈的情绪事件时，人们会感到轻微的积极情绪，这种现象被称为积极情绪抵消。我们对该特征进行了进化论的解释，表明它可以提高生育能力，繁殖力和健康水平，并教other其他对生殖成功至关重要的特征。我们审查研究表明，积极的情绪抵消在世界上几乎是普遍的，即使是生活在极端困难的人们中也是如此。积极的情绪增加了适应能力的类型，这可能是我们旧石器时代祖先的特征，例如创造力，计划，交配和社交。由于积极情绪的普遍存在和明显优势，这是一个合理的假设，认为人类是在我们进化的过去中被选择为积极抵消的。