This week on SHIFT: German police often use Twitter to update the public about emergency situations. Postings on social media have become an indispensable function for many government agencies. They provide a direct line to citizens.

Computer addiction is a serious problem. It can lead to social isolation, and affect mental- and physical health. Excessive users can suffer anxiety attacks and withdrawal symptoms when they're away from computers.

British artist Emma Allen draws the evolution of the human face for the camera: from the single cell to the Neanderthal to digital man.