In a surprise move, Google's chief of search and artificial intelligence John Giannandrea stepped down on Monday. Yesterday, it was reported that he's been hired by Apple. Giannandrea had been with Google since its acquisition of startup Metaweb in 2010.

Metaweb was working on a "database of the world's knowledge," according to the New York Times; after its acquisition, the startup's technology was eventually folded into Google search, helping the engine answer certain questions without the user ever having to navigate to any external sites.

Giannandrea has been with Google during the company's rapidly-increasing interest in artificial intelligence over the past few years. CEO Sundar Pichai declared (perhaps hyperbolically) in January that AI is "more profound" than previous human achievements like electricity and fire.

Google's advanced AI is integral to a number of its products, like Google Assistant. Apple's assistant, Siri, is widely regarded as being behind competing AI assistants in smarts, and consequently, being less useful. It's safe to assume Apple's hiring of Giannandrea is part of a plan to ameliorate that, especially considering that, according to the New York Times, Apple has also hired other prominent figures in the field recently.

Apple has said it places a premium on user privacy when it comes to machine learning. It remains to be seen how that philosophy will jibe with Giannandrea's background at Google, which trains its models largely with data culled from user activity.