Hacker News Reader

Comment by Ifkaluva | Hacker News Reader

I’m going to try to win the award for the most controversial theory on this thread.

The real reason we are having population shrinkage is because evolution did a crappy job. It didn’t tune us to want to have kids, it tuned us to want to have sex, and it linked to sex to reproduction.

As we got smarter, and eventually develop contraception, we are essentially reward hacking evolution’s crude hack.

What’s going to happen over the next few decades is that a few variants here and there are going to spread throughout the population that actually lead to more kids, not just through desire for sex. It will be a population crash, followed by a recovery.

View on HN

Last month, the US Census Bureau released their 2025 population estimates. In the ~5 years from April 1, 2020 to July 1, 2025, it estimates Kiryas Joel's population grew from 32,956 to 47,147 – a 43.1% increase. [0] That's not spectacular in the figures themselves–you'll see bigger bumps when new suburbs are established–but it is spectacular in being almost all due to natural increase instead of migration.

Evolution is still working, if we understand it as having both biological and cultural components. Give it a few centuries, and secular people will be outnumbered by ultra-Orthodox Jews, and the Amish, and radtrad Catholics, and Mormon polygamists, and so on. That's the thesis of Eric Kaufmann's 2010 book Shall the Religious Inherit the Earth? – and I believe, on the whole, he's right.

[0] https://www.census.gov/quickfacts/fact/table/kiryasjoelvilla...

I’ve heard this theory before. I think in the medium term it will have some effect, but a lot of these ultra religious groups have high attrition.

In the long run, evolution will have to do the job properly and actually genetically make us want more kids.

> but a lot of these ultra religious groups have high attrition.

Many of them actually don’t. How could Kiryas Joel be growing so fast if it did?

80-90% of children stay in the faith, and when 6 kids is considered a small family, and families with >10 kids are common - losing 10-20% in each generation doesn’t prevent exponential growth

The other factor - a constant defection rate combined with exponential growth in the underlying population produces exponential growth in absolute number of defectors - it is easy for outside observers to misread that defector boom (e.g. the “off the derech”/OTD phenomenon) as a sign the sect is in trouble

> In the long run, evolution will have to do the job properly and actually genetically make us want more kids.

Why would biological evolution “have to” if cultural evolution is doing the job for it? Of course, the two work in tandem, but the biological contribution may turn out to be an increase in frequency of alleles that make people happy in high demand sects, rather than direct desire for children

>I’m going to try to win the award for the most controversial theory on this thread.

Extremely easy to beat that.

You can see that global population used to stay at around half a billion until around 1700. The growth is a recent thing.

So let me propose a more controversial theory - lead made people have a lot of children.

You can't beat this.

Lead? Lead was used for millenia. The Romans made copious use of lead.

And the Romans had many children?

Humans had many offspring for millennia, humanity has had fewer offspring since lead has been banned.

I'm not the one proposing the theory, but that's a correlation.

Reply on news.ycombinator.com