R. B. J. Casey is a professor of psychology at Weill Cornell Medical College. Her focus on adolescent brains includes those of humans and mice. “There is evidence,” she says, “that even adolescent rodents tend to hang out with same-aged peers and tend to have more fights with their parents.” Sound familiar? These behaviors—sensitivity to influence from peers, taking risks, and pulling away from parents—are hallmarks of human adolescence. They have their roots in the hunter-gatherer world of our early ancestors, where success meant surviving and reproducing. What cause-effect relationship does the author identify in the section?

Excerpt from an enemy of the people henrik ibsen mrs. stockmann. (turns to the hall door, listening.) i expect that is mr. hovstad coming. billing. very likely. (peter stockmann comes in. he wears an overcoat and his official hat, and carries a stick.) peter stockmann. good evening, katherine. mrs. stockmann (coming forward into the sitting-room). ah, good evening--is it you? how good of you to come up and see us! peter stockmann. i happened to be passing, and into the dining-room). but you have company with you, i see. mrs. stockmann (a little embarrassed). oh, no--it was quite by chance he came in. (hurriedly.) won't you come in and have something, too? peter stockmann. i! no, you. good gracious--hot meat at night! not with my digestion, when peter stockmann enters, what does his physical appearance to reveal about his character?