For the last 100,000 years, big critters have been hunting (and haunting) our human ancestors. Think saber-tooth cats, giant kangaroos and big snakes.

This evolutionary legacy of predation has stuck with us into modern times in the form of anxiety and the fight-or-flight response.

Halloween may have come and gone, yet the fear lingers on. Rob shares his thoughts about why we’re scared:

WBEZ 91.5 Afternoon Shift (October 31, 2012):

Slate: What Are You So Scared Of? (October 15, 2012)