Misty Copeland, a soloist with American Ballet Theatre, will become its first African-American female principal ballerina. The dance company, which is celebrating its 75th anniversary this year, announced the decision on Tuesday. The 32-year-old Copeland joined American Ballet Theatre in 2001 and has been a soloist with the prestigious dance company since 2007. She was among several dancers given new roles at a meeting the company held on Tuesday.