  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.
