John Hancock, one of the oldest and largest North American life insurers, will stop underwriting traditional life insurance and instead sell only interactive policies that track fitness and health data through wearable devices and smartphones, the company said on Wednesday. The move by the 156-year-old insurer, owned by Canada's Manulife Financial Corp, marks a major shift for the company, which unveiled its first interactive life insurance policy in 2015. It is now applying the model across all of its life coverage. Interactive life insurance, pioneered by John Hancock's partner the Vitality Group, is already well-established in South Africa and Britain...