Microsoft has decided it needs more real brains working on artificial intelligence. The company said Thursday it is combining the team working on bots like Cortana with its longstanding Microsoft Research lab into a single 5,000-person unit. "Microsoft has been working in artificial intelligence since the beginning of Microsoft Research, and yet we've only begun to scratch the surface of what's possible," Shum said in a statement. The move comes amid the departure of Qi Lu for health reasons, as first reported by Recode. Shum will take over the search efforts that Lu had been responsible for, while Rajesh Jha will take over responsibility for all of Office and get a promotion to executive vice president.