We may never listen to NPR Morning Edition again. In a recent installment of “Brain Candy,” we learned that crows can not only recognize human facial characteristics, they can hold a serious grudge. University of Washington researcher John Marzluff ran an experiment asking various people — bald, hairy, young, old, attractive — to take a stroll while wearing the same caveman mask he had previously worn to bother the cranky birds. Even when participants wore the mask upside down, crows screamed, squawked, and scolded en masse at the wearers. Surprisingly, a Dick Cheney mask attracted little attention, except from the students on campus.