“The Playground Gets Even Tougher:” New York Times

Mean-girl behavior, typically referred to by professionals as relational or social aggression and by terrified parents as bullying, has existed for as long as there have been ponytails to pull and notes to pass (today’s insults are texted instead). But while the calculated round of cliquishness and exclusion used to set in over fifth-grade sleepover parties, warfare increasingly permeates the early elementary school years.

“Girls absolutely exclude one another in kindergarten,” said Michelle Anthony, a psychologist and co-author of the new book “Little Girls Can Be Mean.” When her own daughter was manipulated by a “friend” into racing down a slide booby-trapped with mud, making it appear to a group of boys as though she’d soiled her pants, Dr. Anthony was taken aback. “You don’t expect to run into that level of meanness in a 7-year-old.”

Unfortunately, not too surprising. But still— wow.