It’s the evolution of animation. It can be argued that “The Simpsons” opened the door for Cartoon Network’s Adult Swim, which in turn kicked down the door to let in shows including “Bojack Horseman,” “Archer” and “Rick & Morty.” U.S animators are serving up not only raunchy comedy but also sophisticated storytelling. Outside the U.S., animated features have a long history of telling difficult stories — most recently “The Swallows of Kabul” and “Funan” are two films that tackled horrific events. Animation aimed at adults is on the rise worldwide.

In his recently released white paper, “Adult Animation Finally Breaking Free of Its Comedy Shackles,” John Evershed, head of High Concentrate, which specializes in the packaging, development and sales of animated TV series and movies for adult audiences, notes that adult animated series have been driving ratings on both linear TV and SVODs for the past few years. He also notes that it’s the fastest-growing animation category, with room for more. That success coupled with the need for content that breaks through the clutter has also driven the expansion of animated offerings as there are more buyers than ever, Evershed writes.

“Now that more and more topics are being taken on by animation, the ability to cross over from live action into the animation space is not necessarily writing to animation anymore — you’re writing the same stories but you’re doing them in animation,” says Corey Campodonico, one of the heads and founders of the animation shop ShadowMachine (“Bojack Horseman”). “I think that’s the big breakthrough in adult animation. In general, the sophistication level has gone up significantly and I think audiences are really excited for that.”

Content creators are embracing animation for what it can do for their storytelling.

Showrunner Alexandra Rushfield, whose credits include live-action series “Parks and Recreation” and “Shrill,” embraced stop-motion animation for her upcoming HBO Max show “Santa Inc.” because “it’s a very visually weird world. There’s a whole Christmas world that has a history in animation. The visual adorableness is cut against the R-rated content of it.”

She likes the idea of being able to use any kind of actor as, say, a gingerbread man, or a snowball.

“I was just reading something and it said ‘snowball fight’ and thought, ‘Oh, that would be good — two snowballs fighting like a cockfight or something.’ There’s just so many possibilities.”

Shadowmachine co-founder and co-topper Alex Bulkley echoes that: “It’s an opportunity for writers and creators to take the gloves off and tell the story they want to tell with really no limits. It’s liberating for a lot of writers and creators to start thinking in that space. But there’s always got to be a reason for animation and you want to make sure that you’re using what animation can be.”

The shingle’s behind Quibi’s “The Andy Cohen Diaries,” which will chronicle the life of the Bravo TV producer and personality.

“His storytelling ability is so fun. It’s not really traditionally animated show — it’s more like a surreal kind of visual storytelling,” Campodonico says.

Adds Bulkley: “What we’ll always encourage is for people to embrace what animation can do for the story.”

John Harvatine IV and Tom Root (“Robot Chicken”) are behind “Crossing Swords,” an animated series for Hulu that bows June 12 and puts familiar children’s toys into rather raunchy and hilarious situations.

“One thing we really like is the juxtaposition of these really cute, fun-looking characters in situations that are a little bit naughty or a little bit painful,” Harvatine says. “You know, if a human were hit a certain way it would be really bad, but with these peg people it just looks funny and peculiar; we can push things more and it doesn’t make us seem like monsters.”

Producer-writer-director Laurent Zeitoun’s latest feature is “Fireheart,” which explores the world of firefighters in 1920s New York City and tells the story of a 16-year-old girl who will have to become a hero in order to save her city.

It’s Zeitoun’s second animated feature, after “Ballerina” (aka “Leap!”); he had worked in live action, producing films such as “The Intouchables” and “The Death of Stalin.”

“I arrived by chance in animation, I wasn’t from that world,” he says. “But I was amazed by the power of the story in animation. I am a story addict. I’ve always believed in the power of animation in telling stories.”

As with a growing number of filmmakers, he sees that “animation is a great vehicle to show the challenge of life. It is a perfect medium to talk about death to talk about guilt, revenge, inequality.”

Japanese animators have been grounded in complicated, nuanced stories for decades, such as those created by Studio Ghibli. “Totoro,” “Kiki’s Delivery Service,” “Howl’s Moving Castle” and “The Wind Rises” are some of the titles beloved worldwide. Studio Ghibli founder/film producer Toshio Suzuki says until 1980, “animation [in Japan] was considered more to be for families and kids. However, there was this one epoch-making film called the ‘Space Battleship Yamato,’ and that was very important in a way that it opened up a whole range of audiences to watch and appreciate animation, so there was a big shift there.”

He adds that Studio Ghibli’s first release was 1984’s “Nausicaä” “and this was a film that we didn’t target just kids and families, but we thought that our audience should include grownups and a more mature audience, too. So not just Studio Ghibli, but around that time, a lot of the Japanese studios that were making animation started making animation for the wider range of audiences.”

Distributor GKids can take a lot of credit for opening up American audiences to Studio Ghibli features; it recently helped broker the HBO Max deal for the studio’s library. GKids also has distributed sophisticated international animation such as “The Secret of Kells,” “Mirai” and “The Breadwinner.”

“I think generationally younger filmmakers have grown up with a more diverse exposure of animated stories from around the world,” says GKids president Dave Jesteadt.

“Every few years there’s a new benchmark film that can really showcase the ability of these films to reach a broad adult audience and not just a narrow or niche audience,” he says. “And that has also fueled the financial side of helping producers and investors get comfortable with these kinds of stories that can be pretty resource-intensive to make.”

Jesteadt notes that GKids’ more recent acquisitions have skewed toward adult animation “as part of a broader trend.” He uses “Funan,” “which was a really beautiful film about a family that dealt with Cambodia and the genocide and war there” as an example.

“In that particular film, animation helped the film stay authentic to a time and place but also bring viewers into a tough subject. … I think automatically you feel emotionally unprepared to engage with a story like that. I think there’s something that’s more inviting about the animation format that helps tougher subject matter be discussed and really reach more audiences.”

“Funan” explores life in Cambodia under the genocidal Khmer Rouge regime. Courtesy of GKids

The wildly popular Crunchyroll has been unspooling anime since 2006. “It’s a community that really welcomes diversity,” says Alden Budill, head of global partnerships and content strategy. “That is starting to play out more visibly in the content. We’ve seen some pretty interesting trends in representation.

She notes that Crunchyroll announced a slate of originals earlier this year, and “we are seeing creators emerge that are inspired by anime using the medium to tell their stories and their experiences.”

That includes “Onyx Equinox,” a story created by Latina showrunner Sofia Alexander set in Aztec Mexico. “It is visually inspired by the style of anime but the story immediately immerses you into a different space and time that is distinctly not Japanese and with characters that look unlike others you’ve seen in other anime. That’s really exciting to see that storytelling emerge.”

The style helps inform the content at Trioscope Studios, launched by veteran producers and entrepreneurs L.C. Crowley and Brandon Barr along with animator and VFX artist Greg Jonkajtys to create content using the proprietary Enhanced Hybrid Animation platform.

It’s not motion capture, however. “When comparing us to motion capture we’re using zero ping pong balls to capture performance because we have actors on a stage,” Barr says. “And it’s almost like black box theater — they are in costume, they are performing — they are not wearing blue suits, the things you are used to seeing in VFX. Actors report that it’s a truly liberating experience creatively because they’re creating characters in stories like they would onstage. The other advantage is that because there’s no motion capture it’s faster. You’re taking that native performance and dropping it directly into our CG sets.”

Trioscope is in production on Netflix’s WWII action drama “The Liberator” and recently partnered with Truly*Adventurous to adapt co-founder Greg Nichols’ article “The Havana Job” as a series.

“We set out on a quixotic mission 2½ years ago to develop a new method of telling stories we thought needed to exist and we didn’t see a method that fit our needs so we created one,” says Barr.

“Here in America animation is kids or if it’s adult it’s subversive comedy, and so our thesis was perhaps the way it looks is most important, but what’s missing is that innate human emotion. So we started working on how we could build real human emotion and full actor performances into an animated environment. That way you’re getting all the suspension of disbelief and the world building that animation brings, but you still feel the humanity of the story,” says Barr. “And we thought if we can provide that audiences we’d be creating a whole new sensation or whole new experience for storytelling.”

As the Trioscope team demonstrated its work to filmmakers, excitement grew over its possibilities, and the fact that filmmakers didn’t need previous toon experience.

“We’ve shown people clips — directors, writers, producers, actors — and they all have the same reactions. ‘Oh my gosh that looks amazing! I have a story I want to tell in that realm that I could never get made before because it was too costly too expensive and animation was never an option for me because the [emotional range] was limited but now I see you guys have cracked it,’” says Barr.

“The Liberator” and “The Havana Job” are “two great examples of Trioscope development,” says Chad Crowley, as both were written as a live-action drama “that were in turnaround because they were too expensive or too complicated to shoot.”

“The Liberator” is set on the Italian front and had “many cast and location changes. It just became very challenging. But the idea of being able to imagine that in an animated environment invigorated writer Jeb Stuart,” notes Crowley

With streamers and other content distributors taking more chances, it’s a golden age of animation as creatives discover the freedom of tooning up.

“I think there’s an appetite and I thinking audiences have always been there for more serious and deep topics,” says Campodonica.