Ringside: The women of boxing

Heather Hardy and Amanda Serrano, two of the biggest names in women's boxing, have known each other for years. But recently, when they climbed into the ring at the Theater at Madison Square Garden in New York City, they weren't thinking about their friendship; they were thinking about combat. Correspondent Kelefa Sanneh talked with exemplars of a sport that still receives much less recognition than men's boxing, and where prizefighting comes without much of a prize.