He’s right about how the loosening of sexual mores has greatly changed how sexual selection works and how the act of sex has taken on a new purpose in modern, post-industrial & post-internet society. This is a massive change that will have massive downstream effects, mostly in the form of very large amounts of people (in comparison to the past) not having any children at all.

Most of the sex people have nowadays doesn’t result in pregnancy & childbirth and many women have sex with many partners and won’t have nearly as many children as their predecessors. Much like how our understanding of gender, which used to be considered something that was directly influenced by and controlled by our sex, was greatly changed due to industrialization and the internet our notions of sex and child-bearing have also changed.

Now, the only ppl in modern societies who are having kids are people who really want them. There are exceptions, but men and women now no longer live under the social and economic pressures to have children that they did before. Only people who put those pressures upon themselves (mainly talking about ppl who are bent towards social conservatism which is pro-natalist) to have kids are the ones doing it. This trend will absolutely persist and continue into the future. Birth rates have collapsed in nearly all countries and this decline tracks with how developed these countries become. Women no longer need to marry and have kids in order to be settled economically and the social pressure to marry has been consistently whittled down. Men are becoming increasingly sexless with less than half of the men 18-24 regularly having sex. While, having sex ≠ having kids anymore sex is a necessary condition to having children and if less than half of young men are having sex, how few of them are going to have kids?

For the first time in human history, or the history of any species, survival is no longer tied to one’s biological traits but is actually tied to memetics. Memes! Memes being their cultural values, norms, and ideas of what a good life entails. It stands to reason that only pro-natalist Westerners and modern women (who can safely be assumed to be at least slightly more socially conservative than their non-child bearing counterparts) will have kids for the most part (there will always be gold-digging women who breed in order to secure resources from their baby daddy).

We’re looking at a new stage in human evolution which is being driven not my environmental change or biology but by social change and ideology. Arguably, you could say that this is still at its root a biological matter (perhaps our push towards infertility and anti-natalism is a psychological action designed to reduce population so as to reduce resource consumption) but on its face it is clear that the vast majority of ppl who do not have children today do it out of a non-biological desire to simply not have kids.