Given that fertility rates are currently plummeting worldwide, the principles of natural selection would dictate that humans are currently undergoing very high selection pressure for specific traits.
Basically, any genetic trait that causes people today to think "You know, I think I'm going to remain childfree" is specifically selected against, and any trait that causes people to want more children will be selected for. I'd argue that the invention of reliable birth control was that biggest change in human selective pressures in history. Evolution made sex highly pleasurable and desirable because it often resulted in passing on your genes. That's no longer true with reliable birth control, and with such a huge environmental shift natural selection will act on other avenues that cause people to have children.
Evolution is surprising and complicated enough that that might not be the full picture.
People have relatives and relatives have many genes in common.
If there are genetic traits that predispose people to remaining childless, it could wind up that populations with those genes end up with larger branches on their family tree.
It's been a while since I read the Selfish Gene, but its central point is that natural selection is about genes, not individuals.
Why did you just assume there are genes that predict "not wanting children"? It's happening uniformly all around the world, and is much better predicted by things like wealth and freedom than anything else: cultural reasons, not heredity.
It is safe to assume pretty much any proclivity has some, however minor, genetic basis. Separated twin studies have shown enough similarities in basically every aspect of personality that it's a plausible bet.
All over the world, some groups are deciding not to have kids and some are. Globally declining fertility rate says nothing about genetic proclivity to want children unless fertility rate goes to zero.
I think you've misunderstood my point. To clarify, there was strong selection pressure in the past to "make sex desirable" (and obviously I'm oversimplifying a lot here, but the premise still holds) because that was enough to ensure that passing on your genes was the result a large percentage of the time.
Now, though, birth control has broken that connection between "having sex" and "making babies", so now "making sex desirable" no longer is enough of a trigger that results in passing on your genes. So, in that sense, the environment in which humans reproduce has changed drastically, in a short period of time. So now there should be strong selection pressure for people to have children beyond just making sex enjoyable. Whether that shows up in a stronger innate desire for children themselves or whatever I won't speculate on - I'm just making the point that widespread birth control is a huge change to humans' environment to which natural selection should act on, by definition. What I am not saying is that "not wanting children" currently is the result of some fundamental genetic difference between sub-populations.
I think my point still stands? For selective pressure to select anything, there has to be preexisting genes that predict how much someone wants kids. And again, cultural and material factors are so much more important than genetic ones on the matter, that I don't believe the latter has any quantifiable effect.
True, and here's an interesting twist: as you wrote, this is mainly happening due to "I think", so it's primarily on a memetic level. Humans also pass on lots of thought/behavioral aspects to their children (memes). Therefore I'd expect that selection on the behavioral level is happening much faster than on a genetic level.
Idiocracy's "stupid genes win" likely won't happen, my theory is that selection will remove memes (behavioral/thought/cultural patterns) that cause childlessness from the meme pool much faster.
Could also well be that natural selection will rear it's ugly head again first. I previously thought that people rejecting the evolutionary theory (creationists etc) were just backwards and anti-science. But I've realized since that this is a too simple judgement. The ethical implications of evolution are dark. Humans have had a word for selection since the dawn of language - "death".
A bit sad that paraphrasing Paul Watzlawick in this context fits very well: one cannot not participate in evolution.
> my theory is that selection will remove memes (behavioral/thought/cultural patterns) that cause childlessness from the meme pool much faster.
The sociologist Eric Kaufmann wrote a book Shall the Religious Inherit the Earth?, arguing that traditionalist religious groups (such as ultra-Orthodox Jews and the Amish) will become demographically dominant in the long-term (decades and centuries) due to their greater fertility and high retention rates (>80% of their children stay in the group as adults)
I think the possiblities that a minority can leave the group is an important escape valve for them. Now assume that in the future they are going to be not such a minority anymore like today, then what happens? Maybe some oscillation like for Lotka-Volterra situation, perhaps a bit different?
The possibility of defection to mainstream society actually increases the selective pressure against defection-promoting alleles/memes, compared to if that possibility didn’t exist; the mainstream acts as a genetic/memetic sink to absorb those alleles/memes, reducing their prevalence in the next generation.
I think the fact that in e.g. the United States there are multiple such high fertility traditionalist religious minority groups coexisting makes it unlikely any one of them will end up completely dominant in coming centuries. More likely, I think, conservative religious groups will ally together across confessional boundaries to attain shared policy objectives (e.g. government funding of private religious schools). As such, I don’t think the possibility of defection to secular society will disappear; secular people will still exist, just numerically and politically weakened compared to today.
One reason our ancestors had plenty of children is that children were a large net-benefit to them.
Many modern societies are structured in a way that makes children an economic negative to their parents. From an individuals' POV, the "smart" play is not having children and hope others do.
Individuals believe that they do not need children because they have saved up for retirement, not accounting for the fact that if everyone did this and there was nobody left to do any work once they reach retirement age, that money will be worthless and they'll be unable to retire. The alternative is mass-scale immigration, and that's becoming unpopular. For an example of what happens if a society has neither enough children, nor immigration, see South Korea. Poverty among the elderly is rampant and they are increasingly being forced back into the labor market.
Many western societies needed to start applying a large multiplier to parental benefits decades ago.
>People aren't born not wanting to have kids, since all their ancestors did.
What evidence do you have that all their ancestors wanted to have kids? I can think of a lot of reasons why people may have had kids without necessarily wanting them. They wanted to have sex in an era before birth control. They were pressured into it by the social norms of their local community. They were raped. Etc.
I have a lot of criticism of the childfree movement but I think it’s pretty disrespectful to assume they’re not being honest when they say they don’t want to have kids and that they’ve always felt that way.
Birth control is older than the Bible[1], it just wasn't as effective. Humanity as a whole was very aware how babies come to be.
Ways to have fun without coitus aren't a recent invention either.
Human reproduction and raising children is an unusually taxing, time-, and resource-intensive process, which is why we've applied our considerable intellect to plan for that since forever.
I've read that wikipedia article, and I got the impression that to say that birth control just wasn't as effective is an understatement. One more my finding: the idea of planning your family is relatively modern: Malthusians promoted it widely. It doesn't mean people were not thinking along these lines before, but our widespread understanding of how important it is is mostly a modern phenomena. Like the idea to postpone a marriage and reproduction was not very popular before modernity. We've applied our considerable intellect to invent these things and to make not so smart people to be aware of our findings, but these are very recent ideas. In agrarian world you need a lot of people to feed your armies, so any attempts at birth control would be deemed illegal, amoral or whatever. Kings and popes would do anything to stop people from slowing down their reproduction. Which they did, witch hunt clearly stated that witches are guilty of killing yet unborn babies, ie abortions.
Weren't these more about "human population planning"?
> the idea of planning your family is relatively modern
The term "family planning" is. The general concept is not, which is why we have two thousand year old papyrus talking about birth control.
Note that at no point I used the word "family" - because just our modern understanding of a family will muddy any attempt to compare to historical fact.
Involuntary reproduction has been a tiny tiny minority of births for the past few millenia at least. It happens and is awful but it should not be construed to constitute a large part of any person's ancestry.
They may be honest when they express themselves initially, but their revealed preference later ends up being very tragic. I know several women, and others who are friends of my wife, that did the "I don't want kids" routine only to realize that this was a huge mistake and enter the dating market at 37 to find nothing but a wasteland. People can pretend that their own reason can override their biological reality, but only to a point. "I don't want to have kids" means you die alone. Eventually people realize this.
I'm almost 40 and never wanted kids. As a kid, everyone would say things in the context of "when you have kids of your own..." and I always knew that I didn't want them.
If I lived in a world without reliable birth control, I may have ended up with kids I didn't want, but I'm lucky that I have other options.
Kids shouldn't be raised by people who don't want them, and not everyone is born with the biological drive to reproduce.
Your view that [most] people are born wanting kids may be biased from societal pressure and a historical lack of options.
> Stop sharing your opinions. You will literally be extinct soon. Your existence doesn't matter.
What an insane take. You have no idea what that person's contributions are to this world, or how long those contributions will be relevant after they pass.
Basically, any genetic trait that causes people today to think "You know, I think I'm going to remain childfree" is specifically selected against, and any trait that causes people to want more children will be selected for. I'd argue that the invention of reliable birth control was that biggest change in human selective pressures in history. Evolution made sex highly pleasurable and desirable because it often resulted in passing on your genes. That's no longer true with reliable birth control, and with such a huge environmental shift natural selection will act on other avenues that cause people to have children.