MainThe development of LLMs is very involved and requires large quantities of training data. Yet, although current LLMs2,4,5,6, including GPT-3, were trained on predominantly human-generated text, this may change. If the training data of most future models are also scraped from the web, then they will inevitably train on data produced by their predecessors. In this paper, we investigate what happens when text produced by, for example, a version of GPT forms most of the training dataset of follow...