AT the 2014 Winter Olympic Games, the Norwegian cross-country skier Therese Johaug was vying for her first individual gold medal. Fresh off a world championship in the 10-kilometer race, she was now competing in the 30-kilometer. More than a gruelling hour later, Ms. Johaug landed the silver, finishing less than three seconds behind the gold medalist — her training partner, Marit Bjorgen.

The two Norwegians are the top two female cross-country skiers in the world and fierce competitors. Instead of being bitter rivals, they are best friends.

This is an extreme example of something that happens every day: women helping one another, professionally and personally. Yet the popular idea is that women are not supportive of other women. At school, we call them “mean girls” and later, we call them “catty” or “queen bees.” (What’s the derogatory male equivalent? It doesn’t exist.)