translation.en: So we've argued that human sexuality has essentially evolved, until agriculture, as a way of establishing and maintaining the complex, flexible social systems, networks, that our ancestors were very good at, and that's why our species has survived so well.
translation.zh: 我们的论点是，人类的性行为 直到农业社会前逐渐形成了 一种建立和维持复杂而灵活的 社会系统、人际关系网的方式。 这种方式我们的祖先很在行， 这也是为什么我们的种族生存得很好。