Robots and artificial intelligence are upending everything we thought we knew about what it means to be human.

The boundaries between person and machine are becoming difficult to define. Human brains power robotic limbs; an artificially intelligent machine serves as the manager for tens of thousands of workers; chatbots act as digital replicas of us. Humanity is, in effect, getting an upgrade.

What were once capabilities thought unique to humans are now powering technologies that could offer the ability to extend and deepen our lives—or supplant our livelihoods.

Quartz explores the stories of humans who are navigating the complex reality of a world where machines have brains.

Reuters/Mike Blake