Hacker News Reader

Comment by btilly | Hacker News Reader

These demographic trends are, unfortunately, only temporary.

From the point of view of evolution, birth control is a disaster. I have done exactly the activity evolution has programmed me to do to continue the species, regularly, for over 20 years. Only twice did it result in children, and both times were conscious choices on my part.

However evolution knows how to face these disasters. There is a small minority of people who have the option of birth control, who have all of the same economic incentives that I do, yet choose to have lots of children. Their children are less likely to want to use birth control than mine. Thanks to exponential growth, that minority that chooses to have children regardless will become a majority. And after that point, voluntary birth control and economic incentives will not suffice to keep the population from growing.

This is literally evolution in action.

View on HN

You said it, brother (sister?). In each country there are subcultures (religious fundamentalists, usually) that have birth rates well above replacement. Secular culture has managed to peel away many of their kids in recent decades but, with the kind of uninspiring, plasticky productions currently streaming out of Hollywood / big label music, that process is about to change. Let's just say, your radio is likely to play a lot more Christian rock in your old age.

I'd say it's a lot more likely to be playing Mariachi than Christian rock...

You forget that Hispanics are also quite religious.

But do they listen to 'Christian Rock'?

It isn't just religious fundamentalists - it's also people with low conscientiousness. They have no moral aversion to birth control, they just don't think too hard about the consequences of unprotected sex (it feels nicer, and condoms are at the drugstore three blocks away).

And while Mormon's rapid breeding might prevent demographic malaise, the rapid breeding of low conscientiousness people won't - the very trait that causes them to breed rapidly also causes them to be generally unproductive.

I have to call bullshit on this one. Most of us here, supposedly "conscientious" people, can trace our being here (in the existential sense of "being") to some ancestor with "low consciousness".

Birthrates are falling rapidly around the world, yes, including in places you may think are populated with "low conscious" people. The reason is very prosaic: urbanization. As people get crammed into smaller areas, they naturally start to reproduce less.

It goes back to the fundamental human urge to take care of our offspring: an overcrowded city is also a highly competitive city (Tokyo, Hong Kong, New York etc illustrate this best) so people who live in that environment that don't want to bring more offspring into the world.

Even in a country like India, the population growth is almost all rural. The birth rate of city-natives in big cities has dropped well below replacement level, and cities are gaining population because of immigration and within one generation those rural-turned-city-dwellers have low birth rate.

Both zeteo and myself are discussing differential birthrates between populations.

If population A (e.g. mormons, people of low conscientiousness) has a birthrate of X, and B (everyone else) has a birthrate of Y, with X > Y, then population A will eventually become the entire population. The eventual birthrate will be X.

Even if both birthrates are reduced by some exogenous factor K (e.g. urbanization, reducing from X -> K x X, Y -> K x Y), this fact doesn't change.

Both of you are missing something important. A population with a high birthrate will only achieve that dominance if the children remain in that population. A variety of religious communities have been able to maintain high birth rates, but do not retain all of their children, and their children therefore do not maintain birth rate.

One way to think of this is that, instead of the physical birth rate of people with the trait, what is the rate with which the trait manages to reproduce itself? A trait of "being Mormon" with an average of 6 kids, of whom 2 become Mormon, leads to a Mormon population of stable size, forever having 6 kids per couple.

If the Mormons manage an average of 2.5 Mormon kids per couple, then their population will grow without bound, though they may never be an actual majority of the population. However history shows that culture is malleable. They may grow that fast now, but a rapid social change can destroy the dynamic. (Witness Italy and Ireland, both strongly Catholic, with declining populations.)

Now contrast this with, say, a genetic trait that manifests as a strong desire to actually have children. Eventually you get a population of people who really want children, most of whose children really want children. This type of fundamental desire is more stable than a social construct.

I believe that there are such traits out there in the population. They are much more strongly favored today than in the past. Eventually those traits, whatever they are, will become more widespread, and evolution will have happened.

>Both of you are missing something important. A population with a high birthrate will only achieve that dominance if the children remain in that population.

Great-great-grandparent:

> Secular culture has managed to peel away many of their kids in recent decades but [...] that process is about to change

Point.

However I, personally, see no sign of that process changing. Popular culture does not have to be good to pull away the children of religious people. It merely has to be attractive. And popular culture is constantly, relentlessly, optimizing for shallow attractiveness.

It doesn't even have to be attractive. It just has to be less oppressive than the religious culture.

I agree with your major point, but Ireland has a growing population in terms of birth rate. The only reason the overall population isn't growing is because of emigration between the ages of 18-25. The birth rate did go down during the boom, but its gone right back up to late 1970's levels during this current recession.

For some bizarre reason, Irish people love having babies.

Full disclosure: I am a childless Irish male in my older 30's, I know many people I grew up who have had kids since the economy went into the crapper.

Thank you for correcting me on that data point.

I personally suspect that the long oppression of the Catholic Church under English rule lead to a cementing of how important it is to the Irish people. I further suspect that, in time, Ireland will become as secular as other countries. But that time is not yet here.

It's not really evolution, strictly speaking, unless you believe that the choice to avoid using birth control is somehow determined by a person's genes.

Cultural evolution? Cultures certainly behave like organisms. A culture of birth control could easily get out of hand and exterminate the group the espoused it. E.g. Shakers.

Weaker than that. Not determined, but just affected.

As a random example it is known that genes play a big role in causing ADHD, which is associated with a variety of risky behaviors, which might conceivably be correlated with increased reproduction rates.

If ADHD people has kids 10% faster than the rest of the population, then in something 30 generations, we'd expect over half the population to have ADHD. That's about 750 years. (I do not know if this is the case with ADHD. I'm throwing it out as a random example. For all I know there is no real difference. Or, in the presence of birth control, a 20% difference.)

It isn't just ADHD, though. Every possible genetically determined characteristic that limits how effectively birth control prevents you from having children is now being aggressively selected for. All else remaining equal, in a few hundred years we are likely to see significant behavior shifts in our species.

Reply on news.ycombinator.com