Languages have diverse characteristics that have emerged through evolution. In modern English grammar, the perfect is formed with \textit{have}+PP (past participle), but in earlier English the \textit{be}+PP form also existed. It is widely recognised that the auxiliary verb BE was replaced by HAVE throughout evolution, except for some special cases. However, whether this evolution was caused by natural selection or random drift is still unclear. Here we examined directional forces in the evolution of the English perfect with intransitives by combining three large-scale data sources: EEBO (Early English Books Online), COHA (Corpus of Historical American English), and Google Books. We found that most intransitive verbs exhibited an apparent transition from \textit{be}+PP to \textit{have}+PP, most of which were classified as `selection' by a deep neural network-based model. These results suggest that the English perfect could have evolved through natural selection rather than random drift, and provide insights into the cultural evolution of grammar.

翻译：语言的特征多样性源于演化过程。现代英语语法中，完成体以have+过去分词形式构成，但早期英语中亦存在be+过去分词形式。学界普遍认为，除特殊案例外，助动词BE在演化过程中已被HAVE取代。然而，此种演化究竟源于自然选择还是随机漂变，至今尚未明晰。本研究通过整合三大规模语料库——EEBO（早期英语书籍在线）、COHA（美国历史英语语料库）与Google Books，考察英语不及物动词完成体演化中的定向力。研究发现，多数不及物动词呈现出从be+过去分词到have+过去分词的显著转换过程，其中大部分被基于深度神经网络的模型归类为选择作用。这些结果表明，英语完成体的形成更可能经由自然选择而非随机漂变实现，为语法文化演化提供了新的认知视角。