Demis Hassabis, the neuroscientist tasked with keeping Google at the vanguard of artificial intelligence, was on a hot streak. Then the AI went haywire. Google’s AI chatbot began angering users with biased and ahistoric responses. Hassabis wanted to make something clear: It wasn’t the intended behavior of the system his team built. “There’s more nuances there than I think the product folks fine-tuning these things further down the line had realized," Hassabis said in a February interview with The Wall Street Journal hours after Google stopped letting its Gemini chatbot generate images of people. Hassabis, 47 years old, was the...