PING ZHU FOR THE BOSTON GLOBE

Welcome back, mountain lion: Is the Northeast ready for predators?

Tracks in Winchester may have been a false alarm, but experts say big animals are coming. By Keith O’Brien

Brainiac

The ‘future-proof’ city: a proposal

And other recent highlights from the Ideas blog.

uncommon Knowledge

Facebook, the site for disappointment

And more surprising insights from the social sciences.