In their earliest years, humans worried about wild animals, finding food and safeguarding their belongings. To protect themselves, their bodies went into flight, fight or freeze mode. Muscles became tense. They sweat to cool themselves down. Heart rates went up to circulate blood to large muscles. Stomach discomfort made sure they weren’t feeling hungry. Luckily, the ones who survived are our ancestors and passed those traits on to us. “When there’s a threat, our body responds,” said Regan Gurung, executive director of the Center for Teaching and Learning at Oregon State University and professor of psychological sciences. He spent 20 years at the University of Wisconsin-Green Bay.