Bryan Caplan  

Why Have Kids? More on Last's What To Expect When No One's Expecting

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My Selfish Reasons to Have More Kids tries to persuade people to increase their fertility.  Jonathan Last's What To Expect When No One's Expecting explicitly disavows this aim:
Finally, this book is not an attempt to convince you to have babies.  Children are wonderful, in their way.  But you'll find no sentimentalizing about them here.  To raise a child is to submit to a staggering amount of work, much of which is deeply unpleasant.  It would be crazy to have children if they weren't so damned important.
If this is true, though, why did fertility stay high until the modern era?  Last points an accusing finger at government retirement programs.  Before the 1930s...
...[h]aving children made good financial sense.  You invested your resources in raising them so that they would be able to provide for you when you could no longer work.  Beginning with the New Deal, the logistics of this social compact began to change.


In a world in which childbearing had no practical benefit - the government will care for you if you don't have children to do so - then parenthood becomes a simple act of consumption.  People have babies because they want to, seeing it as either an act of self-fulfillment or as some kind of moral imperative.
There's one big problem with this story: Contrary to popular opinion, children have never been a remunerative retirement plan.  In pre-modern times, people rarely lived long enough to collect their "pension."  This has been verified by anthropologists and economic historians alike; see Ted Bergstrom's excellent review in the JEL.  Long before the birth of the welfare state, buying land and money-lending (and even hiding money under your mattress!) made far more financial sense than having kids.

Indeed, as I argue in Selfish Reasons to Have More Kids, kids are a better deal in modern societies than in traditional societies.  In purely financial terms, they're still a money pit.  But at least nowadays you'll probably live long enough to collect two or three decades of non-financial assistance and companionship.

The deeper problem with Last's story, though, is that he doesn't appreciate the weirdness of declining fertility.  In his eyes, what we've seen all makes sense:
A man born into a capitalist system... has to fend for himself and create himself... The man with a family has more obligations, which means less freedom to move and take risks.  In this way, having a family is in a very real sense never in someone's self-interest... In time, as women began to work in serious numbers in the twentieth century, they, too, became individuals who had to keep moving - so today we have two self-interested individuals, and they both know it's not to their advantage to start a family.  It might not even be to their advantage to commit to marriage at all.

I'd say "so what do they do?" but we already know what they do.  They stop having children and they stop getting married.
If you're familiar with evolutionary psychology, the preceding story should baffle you.  Evolution doesn't select for creatures that maximize their individual interest; it selects for creatures that maximize their genetic interest.  We should expect our demand for procreation to be as resilient as our demand for food.  Indeed, given a basic grasp of evolutionary psychology, you'd expect humans to respond to prosperity by breeding like rabbits.

You could object, admittedly, that evolution made us desire sex, not children - and point to contraception as the key innovation.  But non-reproductive sex became available as soon as cavemen figured out where babies come from.  Contraceptive technology has expanded our options, but the effect on fertility is far less clear than people think.  Yes, fertility fell after the introduction of the Pill.  But fertility went way up soon after the U.S. government issued condoms to a whole generation of men during World War II.   Returning G.I.'s had the technology to make a Birth Dearth, but they and their wives chose a Baby Boom instead.

My point, of course, is not "the facts of fertility clash with the theory of evolution, so the facts have to go."  My point, rather, is that Last's story has major plot holes.  Instead of saying, "Of course fertility is declining," he should be asking, "Why on earth is fertility declining?!"  The answer is anything but obvious.

COMMENTS (27 to date)
Joe Cushing writes:

I think you should check out Stephan Molyneux's video "Parenting Suuuucks"

I can say that in my lifetime, I have not earned enough money for me to have kids. I'm 36. I know some have had kids on my income or less but it certainly is not enough money for me. I can't imagine how it would have been if I had kids.

DougT writes:


Last's explanations appear to be a set of just-so stories, unverifiable hypothesis that are entertaining, but do little to really explain the data. In most cases, alternative stories could be constructed.

For example, he notes that when TV is introduced into villages in remote ares of Brazil, the birth rate drops. He attributes this to the "culture" on TV, which glamorizes single, childless women. But it could be simply that TV provided an alternative form of recreation in the evenings, resulting in fewer births.

In any case, just-so stories pop up all over. Whenever I hear one, I'm tempted to call out that "You must not forget the red suspenders!" (How the Whale Got His Throat.

Robinson writes:
But non-reproductive sex became available as soon as cavemen figured out where babies come from.

I agree with the rest of your post but have no idea what this means. Is it saying that cavemen were able to invent contraceptives?

anonymous writes:

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Jason Collins writes:

My latest working paper directly addresses this point - that genetic interest will show through. It is only a matter of time (and a question of timing). In the discussion following Last's book, most people also seem to be ignoring that fertility has ticked up in the majority of advanced economies over the last decade. From the abstract:

We propose that the recent rise in the fertility rate in developed countries is the beginning of a broad-based increase in fertility towards above-replacement levels. Environmental shocks that reduced fertility over the past 200 years changed the composition of fertility-related traits in the population and temporarily raised fertility heritability. As those with higher fertility are selected for, the “high-fertility” genotypes are expected to come to dominate the population, causing the fertility rate to return to its pre-shock level.

I've also penned a blog post on the background to the paper.

Curt writes:

Lots of possible factors, I'm sure, but a few thoughts:

- child mortality was much higher - you knew you'd likely lose some children before they got very old. Now it's pretty rare.

- farming culture could always use more hands - lots of kids meant eventually more folks to help, and usually starting at a fairly young age. Now it seems like children are not usually so able to 'contribute' in a practical way, and financially appear to be more of a cost. (I'd be interested in a comparison of average family size in farming communities versus in cities as of 1900).

- female opportunity in the West has grown a lot - along with reproductive control, means much more thought about when & how many kids to have. My sense is that this is a post 1960s phenomenon.

Peter writes:

Maybe, the reason fertility was higher in the past was that life was harder. In the past there was a much greater chance that your offspring would not make it to adulthood, so people had more children to ensure that at least one of their children grew up. Also, maybe, in the past you had more children so that you could have more laborers to work on the farm, and help generate income.
Today, however, it is much more likely that your child will reach adulthood, so you don't have to have as many children to ensure one of them survives. Also, we are much richer today, so you don't need a child to help you work your land, or generate income.

Joe Cushing writes:

I saw Robinson's response to this and I feel like I should say something too.

But non-reproductive sex became available as soon as cavemen figured out where babies come from.

Non-technological methods for reducing fertility do have an effect on fertility however; humans have developed an unusual sexual appetite in the animal kingdom. Most mammals have a specific annual time window within which reproduction is possible but this is not so with people. All of this constant mating a 100 times a year can easily foil non-technological birth control methods as they are not nearly as effective. I would bet that there were 100s of millions of unplanned births before the 20th century.

I predict that in generations to come, a group of people who have a strong urge to reproduce will evolve. These people will be the one's who baby craving genes get passed down to the next generation. It will be a desire for children that drives reproduction rather than a desire for sex. This is already the case to a large part but I mean it will be much more intense. It could cause a human population explosion that might concern even someone skeptical of Malthusian theories.

It seems that right now another trait that is being selected for is irresponsibility. The more irresponsible people have the most children and pass on their genes. An indifference to having children, coupled with a strong desire for sex, leads to more children so maybe a strong desire isn't even needed. These are the people who are having most of the kids today.

Ken B writes:

Some commenters are oddly puzzled by this:

But non-reproductive sex became available as soon as cavemen figured out where babies come from.

I guess I just have a dirtier mind than most.

Bryan is right here. There is some debate about cultures that allegedly never figure out the connection, but I am skeptical of most of those claims. All the written cultures I know of are aware of the link. And marriage is sacralized largely because of the importance of kids; that suggests an understanding of the process.

Josh writes:

I don't think there's an argument to be made from evolution here.

1. The fact that we have survived to-date does not mean we aren't undergoing natural selection now. If some attribute of affluents or intellectuals makes them less likely to reproduce, they (or at least the affected subset of them) will be selected against.

2. Our species as a whole does not appear to be suffering from difficulty reproducing. If there is a problem, it's limited to a subset of the species.

Reduced reproductive rates for that subset might be bad for the species as a whole if reduced IQ or reduced generational wealth-passing results and is bad for the species. But DNA wouldn't necessarily be observant enough to protect us from it.

Nathan Smith writes:

My theory is that it's Darwinism's fault. We used to have an intuition that having kids was good. Now that's been exposed as an artifact of our selfish genes. We don't want to be their pawns.

Rea writes:

I think the two reasons fertility is declining is because kids are consumption and investment goods.
Today we can easily choose to consume something other than kids--with 99% accuracy. Since kids can be a pain in the ass, it's much easier to decide you'd rather have an iPad, foreign vacations and so on instead of kids.
Secondly, kids are an investment, literally, in the future. But people these days aren't saving (investing) for the future as much as they used to. Saving rates are higher than they were in 2006, but they're still very low. Would I be entirely off base if I suggested that when savings rates were higher fertility rates were higher?
Basically, we're consuming more today, but we want to consume things that are immediately fun to consume. Higher time preference, too, perhaps?

MingoV writes:

Yet another misuse of the word 'fertility'. This blog post is about birth rates, not fertility. Fertility is a couple's ability to produce a baby. Highly fertile couples can have birth rates of zero. Voluntary use of birth control methods does not decrease fertility; it decreases the likelihood of pregnancy.

Joe Cushing writes:


Fertility has two meanings.

Fertility: 2. The birthrate of a population.

Paul writes:

I think Curt's last point comes closest to the truth. As soon as opportunities for women to have careers increased, the opportunity costs for women having children skyrocketed.

Steve Sailer writes:

Alternatively, modern American fertility, which has been fairly stable for going on 40 years, is a default, and what needs explaining is the Baby Boom, which I would attribute to a 15 year Birth Dearth, cheap gasoline, universal car ownership, vast amounts of developable land near jobs, near universal employment of men at high wages, and the cultural self-confidence that comes from Winning the Big One.

Brian writes:

"Evolution doesn't select for creatures that maximize their individual interest; it selects for creatures that maximize their genetic interest. We should expect our demand for procreation to be as resilient as our demand for food."


No, I think you're missing a key point of what evolution does. We are programmed to do things in our genetic interest through a series of proxy signals. We avoid things that are dangerous for our survival by trying to avoid the pain and fear they elicit (what evolution has programmed), and pursue the things that aid survival and procreation through the pleasure and saisfaction they give. Once the proxy signals are divorced from procreation or survival, such as with birth control, there is no motivation for procreative activities. In other words, we have no genetic desire for procreation per se, only a desire to activate the proxies.

Since the environment of civilization causes the proxies to be activated in new ways that never existed in an evolutionary context, we now pursue those new activities. This is "acting in our own self-interest," and we are indeed genetically programmed to do so. Last's story, in other words, makes perfect sense from an evolutionary perspective.

Of course, as you point out, there are more reasons than just sexual pleasure to procreate, and those reasons, though weaker, are still in force. But as the personal and emotional (not financial) cost of childrearing increases (what?, make sure they can read, do lots of activities, get into a good college..., and what about my own career?), the long-term advantages begin to pale in comparison.

It is possible that procreation will pick up again, but that would require either a pro-procreation culture to outprocreate everyone (conservative Christians? Muslims?), or the action of genetic evolution in the modern environment. The latter option would be too slow to have a noticeable effect over any reasonable timeframe.

lemmy caution writes:

Graph of Total U.S. fertility rates with and without adjustment for survival to age 10:

The baby boom was special because of the low infant mortality rate. Having lots of kids was the pre-1920 norm.

Steve Sailer writes:

"In pre-modern times, people rarely lived long enough to collect their "pension.""

That sounds implausible. It's common for people to mistake average life expectancy (e.g., 35) for how long adults could expect to live. Most places in most times, somebody who lives long enough to have kids has a good chance of making to, say, 60.

Ghost of Christmas Past writes:

I think that mainly the preferences of women control the birth rate* and the chief reason the birth rate among middle and upper-class women has fallen so dramatically is women working outside the home. Women engaged in market labor find the opportunity (and direct, for "child care," etc.) costs of children high. Consequently they bear fewer children, then constantly complain to those children, especially the girls, about the difficulty of caring for children and show by word and deed that they prefer attending to their outside jobs over spending time with their children. From one generation to the next this imbues women of the middle or upper classes with antipathy toward child-bearing and raising.

Childbearing imposes little or even (due to welfare schemes) negative opportunity cost on lower-class women with menial or no jobs, so they have more children (it helps that lower-class women are often too dim to use contraception effectively, and generally unworried about paying for "a home in a good school district"). With no jobs to go to, lower-class women spend a lot of time with their children and that teaches the children to favor that life pattern. Additionally, many young women with unstable romantic attachments have children "because I want someone to love (me)."

Once the cultural pattern is established-- that affluent women have few children and lower-class women have many-- all the "aspirational" women seek to minimize childbearing in order to emulate their upper-class role models. Pretty soon a cultural feedback loop drives upper- and lower-class behaviour patterns further and further apart.

No-fault divorce has also driven down childbearing, because children of divorce are frequently traumatized into reluctance to have children of their own, and American men at least have come to understand that they are very likely to get stuck with all the cost of children and none of the joy. Fathering a child on a middle- or upper-class American woman is like playing Russian roulette with three of the six cylinders loaded, since half of such women will eventually sue for divorce and if there are any children of the marriage, American courts will transfer approximately all of the ex-husband/father's discretionary income to his ex-wife for the next twenty years, roughly.** Of course lower-class men without steady jobs anyway have nothing to lose, so they are not similarly deterred from fatherhood.

*In modern Westernized societies, not back in the middle ages or in Yemen. "Womens liberation" is bad for the birth rate, but I think mainly because it enables the mechanisms I describe here to operate.

**The American "child support" system is peculiarly dysgenic-- it rewards a disloyal woman with an ex-spouse's resources while relieving her of his company, encouraging her to find another mate while diminishing his chances of doing so. This practice creates selection pressure for deceitful women, and probably men too, since the only way to avoid supporting someone-else's kids is to be unable to support your own! (I.e., not worth a woman's trouble to marry and divorce.) Society ends up with "blended families" of two kids fathered by a breadwinner and two by a gigolo, instead of four all fathered by a breadwinner.

IVV writes:

Are we sure that lower birth rates aren't due to lower fertility in select populations?

Fertility medicine would seem to be enough of a booming industry to indicate that the total number of desired children is greater than the total number of actual children. So perhaps the society in aggregate isn't actually choosing to have fewer children after all, but is stuck with it for some other reason?

Floccina writes:

IMO this is a great post because it shows that what is commonly believed is wrong.

Funny thing is that I can only think of one good reason to avoid having children and that is the risk of having a very sick or severely handicapped or violent child but that reason is never given.

I loved having children because it gave me an excuse to do fun things (it still does to a certain extent, I just went skiing with my children recently). It is surprising to me that some people see their children as annoying. BTW people (mostly my parents) had scared me about having children but my wife really wanted them so we took the plunge.

MingoV writes:

@Joe Cushing

Fertility has one correct meaning and one common misuse. When epidemiologists and medical professionals refer to the fertility of populations, they aren't referring to birth rate. Sociologists and economists have been misusing the word for enough time that some dictionaries list the misused version.

Sociologists and economists claim to be scientists, so they should distinguish between birth rate and fertility. Otherwise, you get stupid sentences such as poor nutrition reduced fertility which reduced fertility.

JayMan writes:

Modernization has introduced a permanent reduction in fertility, but fertility responds to external conditions. Most importantly, it is dependent on the costs of raising a family. The more affordable this is, the higher the fertility rate.

Evolution might drive us more to have sex than to have children for their own sake, but, as Jason notes, evolution will also fix that.

Lemmy caution's map notwithstanding, fertility rates are high when the wages-to-expenses ratio is high. When they are low, as they are comparatively today, and as they were during the Great Depression, fertility is low. Winning WWII might not be that important for causing the baby boom, because other countries, including the losers, experienced a boom.

Decreasing the income inequality in today's society and increasing the wealth of the average man would boost fertility across the board.

Someone from the other side writes:
Contraceptive technology has expanded our options, but the effect on fertility is far less clear than people think. Yes, fertility fell after the introduction of the Pill. But fertility went way up soon after the U.S. government issued condoms to a whole generation of men during World War II. Returning G.I.'s had the technology to make a Birth Dearth, but they and their wives chose a Baby Boom instead.

Because people always use condoms as much as they should, HIV did never spread much, either. Probably more related to the fact that people thought the trade off between condoms and the risk of having more kids was a pretty darn bad one for condoms. Many still do.

Brian writes:


I doubt that income inequality or wealth has much to do with it. Why do the poor tend to have higher fertility rates?

It's the effort involved, personal and emotional costs, that matters a lot more. As people become better educated and more inclined to pursue "careers," childrearing becomes increasingly burdensome in the short term.

Blurtman writes:

"Reduced reproductive rates for that subset might be bad for the species as a whole if reduced IQ ..... results and is bad for the species."

It would be interesting to examine the assumption that increased IQ is good for society. Any studies that demonstrate this?

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