For most of their history, comic books have had a diversity problem. Most superheroes have been white men, with a smattering of white women or black men in there, but rarely in the most important roles.

Things have been changing in recent years, though, and Marvel Comics is leading the way. They’ve been retooling some established heroes as more diverse characters. Spiderman was a black teen for a while, Ms. Marvel is now a Pakistani girl, and they even made Thor a woman (though male Thor is still around–it’s complicated). They’ve introduce more women, like Maria Hill and Jessica Jones, and soon Iron Man will be a black woman.

Tony Stark, who has been Iron Man since the character’s debut in the 1960s, will be stepping down so that Riri Williams, a newly introduced character, can take over.

As always, there are fans who cry and gnash their teeth and threaten to stop reading comics–or even sometimes make threats against artists and writers when these kinds of things happen in comic books that they love. Change can be a difficult thing.

But Marvel knows that when you’ve been working with the same characters for 50 years or more, you need to find ways to keep things fresh. In the past they’ve tried all kinds of gimmicky stunts. In the beginning, maybe diversifying their cast felt the same. But so far, characters like Miles Morales (Spiderman) and Kamala Khan (Ms. Marvel) have been hits, and they’ve been bringing in more new readers (or returning readers) than they’ve been driving away. Diversity is, in short, good for business, which anybody who studies diversity will tell you over and over again.