That would only make sense if the issue was biological and not socioeconomic. No one's getting selected out when the issue isn't a biological predisposition to avoiding procreation.
A better way to frame it is: which group is more likely to propagate their genes and have more ancestors 100/1,000/10,000 years in the future? Is it the group that can afford to have more children and successfully raise them, or the group that can't afford large families?
It doesn't matter if the cause is biological or socioeconomic. Just because humans have science, medicine, economics, etc. doesn't mean evolution has "stopped".
Not to mention there is evidence of infanticide in early human societies. Indeed, it's been postulated that post-partum depression evolved to make getting rid of a potentially problematic baby (e.g. during times of famine) easier emotionally.
So 'birth control',in the sense of "ways to have sex but not make more humans" has more or less always existed - even in times of relatively high fertility. Don't agree that current low birth rates can be entirely explained by the pill.
In the ancestral environment, kids "just happened". There were people who specifically tried to have more children, but they would only have a small advantage over the vast majority of accidentally made children.
Fast forward to modernity. Now, children are only being born to people who specifically choose to do so. A small change in socioeconomics accidentally privileges people with a biological quirk.
I met plenty of ppl who talk about the climate or cost of housing as the reason for other ppl but I never knew of anyone making a decision this way. You know someone?
The point is that "I don't want to have children because I'm worried about the impact of climate change" (social) or "I don't want to have children because I think it'll be too expensive" (economic) is not caused by biology and thus there is no selecting such concerns out of the gene pool.
Not even mentioning that evolution doesn't even meaningfully work at these short timescales. Modern humans are essentially identical to ~40,000 years ago, simply not enough time and pressure for evolution to do its thing.
Parents who fail to instill love and desire of family into their kids won’t get to be grandparents. A few decades ago maybe you could take it for granted “everyone ends up having kids” now it obviously is a dead end unless you really help your kids through it. It feels to me like the next generation will have parents who will be intentional about this value. Others won’t bother having kids to begin with.
It'd take regression back to a society where women are considered to have no value outside of being child factories, for parents to be able to indoctrinate their kids into reproducing with no concern for how good of a life they can actually give those kids.
It could also simply be lead poisoning
How do you know that? Are those really the reasons, or is the underlying reason "I don't really feel an urge to want kids, so I'm using this reason to justify it"?
Evolution works slowly, but that's because most traits have fairly minimal benefits. Marginally better eyesight might mean a 2% better chance of procreating. Assuming there's some genetic factor for "emotional desire to have children regardless of the circumstances", the chance of procreation rate for that is rapidly approaching 100%.
It's obviously far more complicated than that - it will be an interesting question for future biologists - if there are any!
I think we should also recognize the the generation in question might have difficulty with relationships. Having kids means finding a partner bought into the idea too and taking the leap. It seems people aren't figuring that out until much later.
The number of infants globally peaked around 2014-2017 and most of the future population growth will be due to larger generations replacing smaller ones.
The decline in population already started, but we're not seeing it thanks to how long we live.
Put another way, someone choosing to have kids isn't necessarily changing the balance between the child-bearing and child-free population in the world. If we could freeze the conditions that cause people to not want kids and keep them constant, we won't see the child-free "die out" and be replaced by people who only or predominantly want to have children. We'll just continue to see roughly the same proportion of people wanting and not wanting to have kids.
You're just looking at those who don't have children at all vs those who do, but that's not the whole story.
People don't decide these things in a vacuum - all over the western world statistics show that people have on average one child less than desired - mostly due to external pressures like availability of real estate and/or stable employment.
The environment simply doesn't support having more children, so those who do have them don't allow themselves to have more - much like animals which don't breed in captivity.
Countries like France largely staved off population decline because they decided to create an environment where people can have children as they naturally would.
This is an outdated view...