NEW YORK — “Sesame Street” recently announced it was dismissing three original cast members: Bob McGrath (Bob), Emilio Delgado (Luis) and Roscoe Orman (Gordon). After an outcry from longtime fans, the show reversed course and will meet with the actors in September to continue their relationship.

Welcoming these characters back onto the “Street” is an excellent decision. The program has been undergoing many changes, adapting to the needs of today’s children. New episodes are shorter, include more animation and are targeted to younger audiences than before. But Bob, Luis and Gordon provide one lesson that is as important today as when the program began in 1969: racial integration.

Bob (white), Luis (Latino) and Gordon (African-American) model for children how neighbors interact in a racially integrated neighborhood. They are friends with each other, and kindly father figures for everyone – be they orange or blue, child or monster, giant bird or grouch.

The “Sesame Street” model of showcasing diverse characters has been exported around the world. Over 30 versions of the program exist, and they are broadcast in over 150 countries.

I spent nine months in Nigeria studying its version of “Sesame Street,” called “Sesame Square,” and how it represents diversity. “Sesame Square” shows Muslim and Christian children at school together – a radical statement in a nation where the extremist group Boko Haram has bombed schools, killed teachers and kidnapped thousands of students.

Having an integrated cast was also radical when “Sesame Street” first aired in 1969. So radical, in fact, that the Mississippi State Commission for Educational Television banned the program because it did not believe viewers were ready for episodes showing black, Latino and white children playing together.

Our nation still struggles with race relations – albeit in new forms. Many neighborhoods are still alarmingly segregated, and the widening income gap post-recession means that poverty (often connected to race) becomes concentrated in neighborhoods, reinstating racial segregation. Media images of blacks and Latinos – especially men – continue to reproduce negative, violent stereotypes.

Meanwhile, children’s TV has become somewhat more diverse, but still does not reflect the nation’s racial composition. “Sesame Street” has been a trendsetter in celebrating racial integration, and its multicolored Muppets have always represented the rainbow of diversity here.

But research by Sesame Workshop shows that while the purple, orange and green characters may provide helpful metaphors for human diversity, young children need more explicit messages. For a young child’s literal brain, the lesson that an orange and a green monster can be friends means that an orange and a green monster can be friends – and nothing more. Children are unlikely to apply this message to other situations of diversity.

Sesame Workshop then tested segments wherein a white child visited her African-American friend’s house, and vice versa. The positive effects were higher: In post-tests, most children who had seen the segments expressed wanting to have a friend who was “different” from them. For this reason, it is essential to continue showing diverse human characters on “Sesame Street.”

I am not suggesting that “Sesame Street” decided to release Bob, Gordon and Luis for reasons related to cast diversity. Their reasons have been unclear, apart from a statement saying that “we are constantly evolving our content and our curriculum, and hence, our characters.”

And “Sesame Street” must evolve to survive. Children are different – and watch TV differently – than they did 50 years ago. Fans cried that the program “sold out” when it moved to HBO, but the new arrangement means “Sesame Street” can produce hundreds of more episodes, which will be available nine months later on PBS.

The characters have evolved, too. Research suggests that “green vegetable shows” – TV that is good for you, and teaches about healthy food, academic skills and diversity – doesn’t sell. What sells? Princesses! So the pink and frilly Muppet Abby Cadabby arrived on “Sesame Street,” and brings viewers along with her to Flying Fairy School.

But as the program evolves, it must hang on to its core value of highlighting interaction between diverse human characters. Bob, Luis and Gordon can continue to model intergroup interaction, along with the Catholic and Protestant characters on the Northern Ireland version (“Sesame Tree”), the Israeli and Palestinian characters in Israel and Palestine (“Rechov Sumsum”/“Shara’a Simsim”), and the Moroccan and Spanish characters in Spain (“Barrio Sesamo”). Kids need these diverse role models as much as ever.