Already after the end of the Second World War, a certain degree of pre-marital sex had been normalised for roughly half the Western population. Alfred Kinsey’s two books on male and female sexuality in 1948 and 1953 further normalised the idea of sex for pleasure among the Western intelligentsia, albeit using hugely inflated statistics about average sexual activity and some data derived from the systematic molestation, rape and torture of children between the ages of five months and 15 years.

Aside from academia, sexually liberal attitudes further filtered into popular media. Sexual content became more common in 1950s literature, and 1950s movies and music were bursting with sexual innuendos that their producers could push past the censor. Meanwhile, Elvis Presley’s suggestive hip movements on The Ed Sullivan Show were so shocking his subsequent television appearances filmed him from the waist up – but everybody knew about them anyway. Also, magazines like Playboy increasingly pushed the notion of sex without shame for men. Marilyn Monroe was the cover girl and centrefold for the first issue in 1953. The mainstream circulation of pornographic magazines peaked in the 1970s before declining in favour of film and VHS. In 1965, a shift in the editorial tone of Cosmopolitan magazine similarly pushed the idea of sex without shame to a target audience of working women in their 20s and 30s.

In several Western countries, after a series of lawsuits and legal precedents, censorship on movies and television was drastically loosened from the late 1960s onwards. From then on much more sexually explicit themes and visuals appeared in mainstream movies. Films such as The Graduate (1967), in which a young man is seduced by an older married woman, caused a tremendous stir.

The first outright pornographic films were legalised in Denmark in 1969 and in the United States a few years later, kicking off the “Golden Age of Porn”, where such films were screened in mainstream cinemas to much public acclaim/outrage/arousal – until the availability of VHS porn turned spanking it to a movie into a much more private affair. One of the most notable financial successes of the era, Deep Throat, starred Linda Lovelace, who was physically abused and coerced to perform, encapsulating the dark side of the porn industry which persists to this day.

Meanwhile, 1960s counterculture spurned the more chaste practices of previous decades, popularised the notion of sex for pleasure in the mainstream and combined sexual liberation with movements for social reform. New schools of thought rejected marriage and monogamy as forms of oppression, and in many cases championed promiscuity and/or polyamory. At the extreme end of this trend, numerous sex cults sprang up in North America and Europe and continued to enjoy a heyday throughout the 1970s, until government authorities moved against them in the 1980s and ’90s, sometimes with bloodshed, invariably with traumatised victims of sexual abuse.

While the popular imagination exaggerates the number of young people in the 1960s and ’70s who were “hippies” or “swingers” – roughly 1.5 to 3 per cent of the population compared to the much more straightlaced majority – their prevalence in all kinds of media forever reshaped public attitudes towards sex as a form of entertainment and pleasure.

By the late 1960s, homosexuality had been legalised in most Western countries. Prior to that, such acts could land a person in prison for several years (indeed, prior to 1861 in Britain, such acts could attract the death sentence). During the early 20th century, many legal authorities turned a blind eye to homosexual activities that were not completely blatant. But even where jail sentences were not imposed, social stigma was intense.

With homosexuality classified as a mental illness, many individuals were subjected to unnecessary shock therapy, chemical castration or lobotomy by the medical establishment. In the mid-20th-century West, the public’s growing embrace of the concept of sex for pleasure, separate from reproduction, enabled the justification for consenting adults to do what they pleased. But even after legalisation, homosexuality was largely excluded from the general atmosphere of sexual tolerance and acceptance for decades. Social stigma persisted and “closeted marriages” remained a widespread phenomenon for many years. Homosexuality was still considered a mental illness by most psychiatric organisations until the 1970s or ’80s, and public attitudes towards homosexuality were generally hostile until the 1990s.

In the West today, open hostility towards homosexuality is most common in certain religious sects that have holy texts which prohibit it (with some denominations being more hostile than others). Secular hostility tends to be more sporadic and is often politically motivated, with the risk of public condemnation making much of the day-to-day hostility more covert. Meanwhile, across the wider world, homosexuality is still illegal in 71 countries, and in 11 countries the penalty is death.

Gender affirmation surgery first became medically possible for the gender dysphoric in the 1920s. The first well-known patient was Dora Richter, in Germany, who had her testicles removed in 1922, and her penis surgically reconstructed into a vagina in 1931. She disappeared in the 1930s and is presumed to have been murdered by the Nazis. Danish painter Lili Elbe also had transitioning surgeries in 1930-31, but died from complications during the fourth surgery, which attempted to transplant a uterus and construct a vaginal tract.

In 1952, veteran Christine Jorgensen made national headlines for having a successful affirmation surgery. In the aftermath of the publicity, the practice became increasingly common across the West, with the number of clinics increasing significantly with each decade. However, broad public acceptance of trans people did not occur until extremely recently, in the mid-to-late 2010s. This shift towards acceptance at the present time has come with a significant backlash, objecting to the more malleable use of pronouns, the efficacy of transitioning to treat dysphoria and lower the rates of suicidal ideation, and the medical ethics and legality of transitioning children and teenagers.

Perhaps the most widespread and successful social reform movements in the 1960s and ’70s were the efforts devoted to women’s rights, today classified under the conceptual umbrella of second-wave feminism (the first-wave title being applied to the suffragettes). Numerous individuals and organisations across the developed world worked to secure equal pay legislation and workplace equity, which contributed to the exponential increase in the number of married and unmarried working women. They also advocated for the use of birth control as the key to sexual liberation and independence from male control. They supported female victims of rape and domestic violence, setting up shelters and crisis centres.

More ardent second-wave theorists decried traditional social structures as designed solely for the benefit of men, equated modern marriage with chattel slavery, raised concerns that Western culture facilitated and encouraged sexual violence against women and theorised that heterosexual sex was frequently male-centric, tainted by a misogynistic culture and could sometimes constitute patriarchal exploitation and assault.

Excerpted with permission from The Shortest History of Sex, David Baker, Pan MacMillan.