What is the fine-grained topic of the following text: I went down the route of exploring the differences between the American-English and British-English and viewed it as an evolution of the language, then focusing my attention to the work of Charles Darwin and came to realise that the relationship with his work and the evolving language was vey similar as I was the environment thatcaused the change. Only return the topic.
The comparison between the evolution of language (American-English and British-English) and Charles Darwin's theory of evolution.