Yes, sex scenes in cinema can be steamy, scandalous things. However, more than almost any other trend, you can map out how progressive, inclusive, and sexually liberated Hollywood has become based on what they will (and won’t) allow on our screens over the decades.  And boy, do they allow a lot.

Most intimate scenes meet the bare minimum of being sexy, but a good sex scene can go a long way into changing the entire dynamics of a movie, from its central relationships to its themes. To celebrate the evolution of onscreen sex, we’ve compiled a brief guide to some of the most noteworthy steamy scenes around. This is certainly not a complete guide to Hollywood’s most intimate scenes, but it’s a good start if you’re wondering how we got to such an threesome-happy cinematic climate.

1 ‘Ecstasy’ (1933)

Ecstasy (1933): This Czech-Austrian romance was the first non-pornographic movie to feature a sex scene. Photo: Elektafilm

There’s a good chance you’ve never seen this Czech-Austrian romance, but it justifiably made history books. The black-and-white film was already controversial for featuring Hedy Lamarr swimming and streaking naked, but Ecstasy may also be the first non-pornographic movie to show onscreen sex. Not only that but the movie also showed a female orgasm, though the scene in question never showed the actors’ faces.

2 ‘North by Northwest’ (1959)

North by Northwest (1959): The classic Hitchcock thriller may not have featured a sex scene, but it contained some of the most suggestive imagery for its time. Photo: MGM

This may be the most unabashedly sexual non-sex scenes in all of film history. At the end of the thriller, Alfred Hitchcock certainly couldn’t show his romantic leads Cary Grant and Eva Marie Saint consummate their love. However, he could heavily suggest the act, which is exactly what he did. At the end of the film, Grant’s character suggestively invites his new wife to the upper berth of the train. The train then immediately enters a tunnel. The director addressed the scene, saying it was “probably one of the most impudent shots I ever made.”

3 ‘Personal Best’ (1982)

Personal Best (1982): Though it was a box office flop, this movie about women's athletics was one of the first mainstream films to seriously depict a romantic lesbian relationship. Photo: Warner Bros.

Though it was a box office flop, this movie about a group of women trying to qualify for the 1980s Olympics paved the way for more nuanced film in several ways. For one, the movie focused on female protagonists and offered a realistic look into the world of women’s athletics. However, it’s the movie’s central relationship between an older lesbian played by Patrice Donnelly and a bisexual woman played by Mariel Hemingway is the reason why it’s on our list. This was one of the first mainstream films to depict a loving, genuine romantic relationship between two female leads.

4 ‘The Terminator’ (1984)

The Terminator (1984): It's the franchise that helped redefine action movies and sci-fi, and it could have never happened without one pivotal hookup. Photo: Orion Pictures

Hear me out on this one. Even if you hate everything about The Terminator, the James Cameron-directed movie helped revolutionize the mainstream action flick and bring big budget sci-fi to mainstream theaters. However, do you remember what’s at the center of this Arnold Schwarzenegger-led super franchise? Future resistance leader John Connor. Without one seemingly-pointless sex scene in the middle of the first Terminator, none of this cyborg awesomeness could have ever existed. The Terminator would not have been back. He would just have a horrible future where he dies. Vulture once argued this was one of the most important sex scenes in film, and it’s hard to argue with that.

5 ‘Henry & June’ (1990)

Henry & June (1990): Starring Uma Thurman, this Oscar-nominated film was the first movie to receive an NC-17 rating. Photo: Universal Pictures

Directed by Philip Kaufman and starring Fred Ward, Maria de Medeiros, and Uma Thurman, this fictionalized drama about Anaïs Nin’s relationship with Henry and June Miller holds a high honor. It was the first film to ever be assigned a NC-17 rating. Prior to the rating, the MPAA would assign adult films an X rating. However, because an X rating wasn’t trademarked, distributors of pornography started to use the rating on the movies they produced, causing the MPAA to switch to the trademarked rating system it still uses today.

Henry & June is also one of three Oscar-nominated films to have a NC-17 rating. The others are Wild at Heart and Requiem for a Dream.

6 ‘Showgirls’ (1995)

Showgirls (1995): Starring Elizabeth Berkley and Kyle MacLachlan, this movie received the widest release of any NC-17 film in history. Photo: United Artists

Of course the Elizabeth Berkley and Kyle MacLachlan-led erotic drama about one stripper’s rise to showgirl status was going to be controversial. However, it’s surprising that this sex and nudity-filmed film is still scandalous to this day. The NC-17-rated Showgirls was the first film to get a wide release in mainstream theaters, and it still has the widest release for a film of its rating in cinematic history.

7 ‘Crash’ (1996)

Crash (1996): David Cronenberg's divisive movie was remarkable for how it combined sex, violence, and a bizarre fetish.Photo: Alliance Communications, Recorded Picture Company

It’s not too surprising that a film from David Cronenberg would make this list. The psychological thriller about a group of people who take sexual pleasure from car crashes received mixed reviews from critics and flopped at the box office. It was released with NC-17 and R-rated versions. However, it was one of the first mainstream films to depict graphic sexual acts alongside intense violence.

8 ‘The Brown Bunny’ (2003)

The Brown Bunny (2003): Chloë Sevigny notoriously performed an unsimulated sex act in this arthouse drama. Photo: Wild Bunch, Vincent Gallo Productions

It all comes down to one blowjob scene in the final moments of this arthouse drama. The Brown Bunny received a fair amount of critical attention and led to a feud between legendary critic Roger Ebert and director Vincent Gallo, but the spotlight of the film will always be on Chloë Sevigny. Sevigny was one of the first big-name actresses to perform an unsimulated sex scene, a decision for which she was heavily criticized for. In their announcement that they were dropping her, the Williams Morris Agency called the scene “one step above pornography.” Sevigny has since defended the arthouse movie and the scene.

9 ‘Brokeback Mountain’ (2005)

Brokeback Mountain (2005): Starring Heath Ledger and Jake Gyllenhaal, this was one of the first and biggest mainstream movies to depict a gay relationship between its two leads. Photo: Focus Features

This Western romance is far from the first movie to feature a romantic relationship between two male leads. However, it was one of the most controversial and biggest movies to do so. Instead of hinting at an erotic relationship, Brokeback Mountain was unapologetically a love story between its two big-name leading men — Heath Ledger and Jake Gyllenhaal. The movie was widely criticized from largely conservative organizations and critics. However, it went on to make over $83 million against its $14 million budget.

10 ‘Blue Valentine’ (2010)

Blue Valentine (2010): This romance received an NC-17 rating because Ryan Gosling had the audacity to go down on Michelle Williams. Gosling later called out the MPAA for sexism. Photo: The Weinstein Company

Here’s a sex scene to get mad about. After countless movies featuring men receiving oral sex from women, this Ryan Gosling and Michelle Williams romance received an NC-17 rating for portraying the opposite. The scene in question is beautifully intimate and loving between the movie’s married couple. Gosling was outraged and accused the MPAA of sexism. “There’s plenty of oral sex scenes in a lot of movies, where it’s a man receiving it from a woman – and they’re R-rated. Ours is reversed and somehow it’s perceived as pornographic,” he said.

(This article originally appeared on decider.com and was written by Kayla Cobb)