Jeff Bezos says more than 1,000 people are working on Amazon Echo and Alexa

Amazon CEO Jeff Bezos is very bullish on his company's artificial intelligence push. So bullish, in fact, that Amazon has invested four years of research into its key project in AI -- and stacked that project with a sizable staff. Bezos said at the Code Conference that the team on Alexa, Amazon's smart voice-assistant software, and Echo, its flagship device, is now more than 1,000 employees. "We've been working behind the scenes for the last four years," he said about Echo and Alexa. Other tech giants are moving into the space.