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.

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gblargg 35 minutes ago | parent | next [-]

> any genetic trait that causes people today to think "You know, I think I'm going to remain childfree" is specifically selected against

More specifically, the genetic trait of being susceptible to the childfree brainwashing. People aren't born not wanting to have kids, since all their ancestors did.

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chmod775 28 minutes ago | parent | next [-]

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.

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derektank 19 minutes ago | parent | prev [-]

>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.

	▲	chmod775 10 minutes ago \| parent \| next [-]
		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. [1] https://en.wikipedia.org/wiki/History_of_birth_control
	▲	margalabargala 6 minutes ago \| parent \| prev [-]
		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.

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dachris 25 minutes ago | parent | prev [-]

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.