> Fewer young adults are engaging in casual sexual intercourse now than in the past, but the reasons for this decline are unknown.
And this recently discussed article
https://www.nytimes.com/2021/02/20/opinion/sunday/endocrine-...
> Scientists are concerned by falling sperm counts and declining egg quality. Endocrine-disrupting chemicals may be the problem.
In heterosexual groups, it's challenging for many men (from my experience) who are interested in casual sex but the effort is simply too high for them to pursue so they largely just check-out (I know quite a few heterosexual males who just feel like it isn't worth their time anymore). In other groups like the LGBTQ+ arena, specifically gay men, it's not nearly as difficult to find the sexual reward many seek and as a result, you'll find casual sex seems quite high. I have quite a few friends here as well and they continue to seek and find causal sexual encounters, dates, etc. or at least they say.
I'd be very interested to see if any empirical data exists that shows casual sex rates over time, normalized, and broken into heterosexual and non-heterosexual groups. If there's a similar decline in both groups then I suspect endocrine disruption may be the real problem. If there's less correlation, I'd tend to think much is culturally driven.
They are outcompeted due to a lack of initiative and willpower; that's evolution doing its job.
Psychology has been weaponized to optimize addictive behavior loops. Instead of going outside and talking to people being the norm, now people have to make a concerted effort to pull themselves away from their psychologically addictive pocket sized happy fun device, convince others to do the same, and then arrange a time to go out.
Socializing is messy, painful, and difficult. But for the majority of human civilization, there weren't very many alternatives for entertainment!
>Luxury may inflame in the fair sex the passion for enjoyment, but it seems always to weaken—and often to destroy—the powers of generation
Adam Smith, The Wealth of Nations
Given that he wrote that when North America was a rebellious colony where no chemicals were in common use and that we essentially all much, much, much richer than the rich people he talks about here it seems more likely to be something fundamentally human.