As OpenAI’s web chatbot became a global sensation in recent months, artificial intelligence practitioners and investors have wondered how a seven-year-old startup beat Google to the punch. Google runs two of the world’s foremost AI research groups, yet a startup quickly developed a product, ChatGPT, that tens of millions of people have already used and that Google’s leaders view as a potential threat to its search engine.

It turns out OpenAI had a secret weapon: former Google researchers. In the months leading up to ChatGPT’s release, OpenAI quietly hired at least five Google AI employees who were instrumental in tweaking the chatbot so it could be ready to launch in November, according to a person with knowledge of the matter. And OpenAI continues to attract talent from Google. Last month, the startup hired a Google researcher who helped create a type of machine-learning model that Google has used for its search engine and that OpenAI later used for ChatGPT. At least four other researchers from Google Brain, the company’s main AI group, have moved to OpenAI in recent weeks.