November 07, 2006
Selective Pressure Grows For Belief In God

In the comments section of my previous post Eternal Youth, Overpopulation, And Instincts To Reproduce some readers objected to my argument that natural selection will reverse the continuing decline in fertility seen in many (though not all) countries. My response is simple: I'm not going out on some speculative limb. This is basic Darwinian Evolution 101. Given new selective pressures (in this case industrial society) increasing frequencies of alleles that raise fertility will eventually reverse the decline in baby making. The signs of this selective pressure are not hard to find. Eric Kaufmann has an essay in the November 2006 issue of Prospect Magazine entitled Breeding for God where he argues the fertility advantage of religious believers over non-believers is selecting for more religious populations.

The Mormons, for example, like Stark's early Christians, have maintained a 40 per cent per decade population growth rate for 100 years. They remain 70 per cent of Utah's population in the teeth of substantial non-Mormon immigration, and have even expanded into neighbouring states. In the 1980s, the Mormon fertility rate was around three times that of American Jews. Today the Mormons, once a fringe sect, outnumber Jews among Americans under the age of 45.

Natural selection is selecting for genetic variations that favor religious belief because religious believers are more inclined to put having children above having higher living standards. In the process of selecting for more fertile humans natural selection is also selecting for more religious humans.

The rise of the conservative religious Right in America is due to natural selection. Liberals have fewer babies than conservatives. Some of the difference is genetic. Some is due to values passed along to children.

An important recent article in the American Journal of Sociology by Michael Hout, Andrew Greeley and Melissa Wilde examines trends in American religious denominational growth in the 20th century. The authors find that conservative Protestant denominations increased their share of all white Protestants from one third among those born in 1900 to two thirds for those born in 1975. Three quarters of the growth of white conservative Protestant denominations is demographic, since they have maintained a fertility advantage over more liberal denominations for many decades.

We can not count on a continued decline in fertility in industrialized societies.

The world march toward secularism and lower fertility shows signs of reversing. The proportion of the world's population that is religious is now growing. Fertility will likely follow.

The share of the world's population that is religious is growing, after nearly a century of modest decline. This effect has been produced by the younger generations in the developing world rejecting secularisation, combined with higher religious fertility levels. Throughout the world, the religious tend to have more children, irrespective of age, education or wealth. "Secular" Europe is no exception. In an analysis of European data from ten west European countries in the period 1981-2004 I found that next to age and marital status, a woman's religiosity was the strongest predictor of her number of offspring.

Genetic variations that increase both conservatism and religiosity are being selected for in America.

As Arthur Brooks of Syracuse University recently wrote in the Wall Street Journal, "if you picked 100 unrelated politically liberal adults at random, you would find that they had, between them, 147 children. If you picked 100 conservatives, you would find 208 kids. That's a 'fertility gap' of 41 per cent. Given that about 80 per cent of people with an identifiable party preference grow up to vote the same way as their parents, this gap translates into lots more little Republicans than little Democrats to vote in future elections."

Secularization of Muslims in Europe is not going to bring Musliim fertility down to white European fertility. Why? The Muslims aren't secularizing. So much for the inevitability of secularization.

Muslim secularisation would certainly alter this picture and forms a cornerstone of the Norris-Inglehart thesis. But a glance at the surveys of ethnic minorities in Europe reveals little evidence of this. In Britain, second-generation Afro-Caribbeans and eastern European Christians tend to be less religious than their parents but more so than the wider population. Yet there is virtually no change at all in the religiosity of Bangladeshi and Pakistani Muslims between the first and second generations. A recent study of Dutch ethnic minorities paints a similar picture of religious retention among Muslim groups.

Supposedly inevitable never-ending trends like secularization and declining fertilty are not forever.

Conservatism might be getting selected for independent of religiosity.The full Arthur Brooks essay points out that even adjusted for religious belief conservatives are more fertile than liberals.

The fertility gap doesn't budge when we correct for factors like age, income, education, sex, race--or even religion. Indeed, if a conservative and a liberal are identical in all these ways, the liberal will still be 19 percentage points more likely to be childless than the conservative.

Breaking fertility rates down by race and state brings out big differences between fertility rates.

The single most useful and understandable birthrate measure is the “total fertility rate.” This estimates, based on recent births, how many children the average woman currently in her childbearing years will have. The National Center for Health Statistics reported that in 2002 the average white woman was giving birth at a pace consistent with having 1.83 babies during her lifetime, or 13 percent below the replacement rate of 2.1 children per woman. This below-replacement level has not changed dramatically in three decades.

States, however, differ significantly in white fertility. The most fecund whites are in heavily Mormon Utah, which, not coincidentally, was the only state where Bush received over 70 percent. White women average 2.45 babies in Utah compared to merely 1.11 babies in Washington, D.C., where Bush earned but 9 percent. The three New England states where Bush won less than 40 percent—Massachusetts, Vermont, and Rhode Island—are three of the four states with the lowest white birthrates, with little Rhode Island dipping below 1.5 babies per woman.

Average fertility rates of large groups are less important than large differences between fertility rates of smaller groups. Those large differences are a sign that there are factors at work that are cancelling out the trend toward lower fertility. Those groups with higher fertility are going to be much larger portions of future generations. So will their higher rates of fertility. Just as they do their kids will have more kids.

Before anyone argues that religiosity's effect on fertility is due to social environment rather than genetics check out my post Twins Study Finds Adult Religiosity Heritable. Also see my previous post Sydney Brenner: Biological Evolution Is An Obsolete Technology

Offspring genetic engineering to raise IQ could in theory work against religiosity and fertility. IQ and religiosity are highly negatively correlated. On the other hand, religious folks could probably choose genetic variations that increase religiosity to balance the genetic variations they give their offspring to increase intelligence. Also, people could give their offspring genetic variations that boost the odds that the parents will become grandparents. See my post Will Offspring Genetic Engineering Cause Population Explosion?.

I expect natural selection will win and drive human populations up by orders of magnitude unless instincts are reprogrammed with genetic engineering.

Share |      Randall Parker, 2006 November 07 04:38 PM  Trends Demographic

bee said at November 7, 2006 6:28 PM:

Randall- I am surprised that you engage in such foolish reasoning as exhibited by your last two posts. There is not any material evidence to suggest that religious belief is genetic. You must check your wild faith in reasoning without facts or bounds lest you be labeled a religious zelot and people move to restrict your reproduction.

Randall Parker said at November 7, 2006 8:23 PM:


Regarding the reaction to my last two posts I am surprised by how many people think the mind has somehow magically escaped the genes that code for it. I figured a general appreciation was developing for how much the mind comes from genes.

I'm going to have to do a lot more posts that demonstrate the biological basis for instincts and genetic influences on cognitive processes. It is clear that the Blank Slate myth is still alive and well.

Vincent said at November 7, 2006 9:43 PM:

I think that the number of people that can really get the idea that their minds are heavily influenced by outside factors like genetics and mimetics is very, very small indeed. The cognitive bias towards the idea of free will may well be entirely too difficult to overcome in this type of environment. Articles like this will always be received in this manner, I think.

Randall Parker said at November 7, 2006 10:04 PM:


I'm reminded of split brain studies done on people whose corpus callosums were cut to control severe epilepsy. It has been many years since I learned about this but it is my recollection that in these patients the half of the mind that generates speech creates impromptu rationalizations to explain what the other half does because the speaking half does not have direct access to the motivations for why the other half does things.

Mats-Erik Pistol said at November 7, 2006 10:06 PM:

Very good post Randall. However religion and fertility will decouple genetically in the future. There is per se no advantage for religious genes in our society and more importantly religious and fertility genes are NOT the same. Presently they seem to be coupled since most (but certainly not all) religious groups have high fertility. Even more, the most fundamental ones have the highest fertility within any given group as well. For example hasidic jews have a tremendous birthrate and they are more numerous than the fundamentalist polygamist mormons with equally high birth-rate. Thus jews will outnumber mormons in a few hundred years time. Even Amish and Hutterites will outnumber mormons in that time-range. My point is that fertility genes will prosper but religious genes will only "hang on" accidentally and since there is no selection pressure for the religious genes they will disappear (on a time-scale of hundreds of thousands of years though). In the old times, when we were hunting, apparently religion conferred a selective advantage genetically. I do not see why though and I have never seen an explanation, neither has anybody seen the problem either.
You will have many posts against you since people in general do not understand evolution. It is in my experience too difficult for most people to understand. The fact that genes compete and not individuals seems impossible to explain to the general public who even think groups are the competing elements.

Mats-Erik Pistol said at November 7, 2006 11:35 PM:

Since I am at it. It is also interesting to note how IQ is selected for these days. There is no selection for IQ at all and thus IQ will decrease in the future, since traits not selected for disappear. Also, in our society the most educated women are the ones that have the fewest children. Granted - IQ and education are only weakly correlated but still some correlation exist. This state of affairs will prevail until overpopulation (or rather resource scarceness) starts to kill people. Then selection pressure reappear, this time in a very different society than the hunting-gatherer society. Money will present a strong pressure for example.
Note though that in fundamentalist mormon society the most successful men are selected for, since they practice polygamy. This might change my conclusions if funcamentalist mormons become the predominant human species on earth.

James Bowery said at November 8, 2006 12:49 AM:

Group hypocrisy seems to be the trait being selected for. By that I don't mean merely behaving contrary to your beliefs but rather preaching to non-kin groups contrary to the behavior of your kin group. This means your kin-group's preachers-to-others may behave quite selflessly and non-hypocritically. The key is their ability to spread biologically toxic memes to non-kin groups to which the kin group is relatively immune.

The blank slate theory of human nature is an example of such a biologically toxic meme.

The Superfluous Man said at November 8, 2006 12:48 PM:

"For example hasidic jews have a tremendous birthrate"
Poland Poverty Syndrome might kick in, in which hassidic Jews are too numerous to live off other productive Jews. It may take, say, the downfall of the welfare state in Israel first. At which point most chassidim will have productive jobs, just as during the peak of Lithuanian (Hassidic) Jewry, only the very bright went to yeshiva to study.

"My point is that fertility genes will prosper but religious genes will only "hang on" accidentally and since there is no selection pressure for the religious genes they will disappear"
The religions of which we speak encourage high fertility. Sure, there may be a decoupling of sorts among the religious, but only amongst some fraction thereof, which would inevitably be outbred. The fertile but not religious would have their genes averaged over all the non-religious, diluting their effect. Fertility without a supposedly cultural motive seems rather odd and unlikely to me, however.

"This state of affairs will prevail until overpopulation (or rather resource scarceness) starts to kill people."
It seems that technology is increasing at a faster rate than population, at least in the West. So until that changes, your scenario is unlikely.

"Note though that in fundamentalist mormon society the most successful men are selected for, since they practice polygamy."
Wasn't it more the church leaders family who gets the womyn? Regression to the Mean + Cousin Marriage --> little to no positive impact on population IQ. By the way, the IQ of a selected population can be calculated by (New Pop) = (narrow heritability)x(difference between the population selected and population at large). Heritability of IQ is about .75. If you picked a bunch of white couples with an average IQ of 140, and the average IQ of the offspring would be 100 + 30 ((140-100)x.75), that is, 130 IQ. Cochran's paper about Ashkenazi intelligence has it.

Mr. Bowery, I am quite certain that your first paragraph made no sense.

Randall Parker said at November 8, 2006 6:14 PM:


Since the religious have more kids than the non-religious how can genetic variations that make people more prone to religiosity not be fertility boosting?

To put it another way: What is it about religious belief that boosts fertility? Partly this depends on the particular religion. Mormonism glorifies creation of families for example. Religions that are more supportive of family creation will grow more rapidly and so those religions will grow versus other religions.

Unless secular ideologies come along that encourage family formation and the having of many offspring I do not see how we can expect the non-religious to have as many kids as the religious.

rsilvetz said at November 8, 2006 7:50 PM:

It is clear that the Blank Slate myth is still alive and well.

Show me where the genes that code for calculus, English and every other damnable epistemological construct are and we'll have that conversation. The fact is you are a blank slate knowledge-wise when you are born. And the limits of what is written by nurture and bounded by genes is very much open to debate.

What I think gets swept under the carpet, and I agree with you there, is that there are influences and they are genetic in origin. We disagree on whether or not a particular influence is major or minor and whether it's overridable.

Conversely, one cannot escape consciousness existing either. It's not a genes/environment dichotomy when dealing with humans. This doesn't mean we aren't influenced by genes but it does mean we are not totally at their mercy either. No other animal on the planet can fold the long-term awareness of the consequences of decisions back into his/hers daily life.

Vincent said at November 8, 2006 8:51 PM:

rsilvetz, it is of course unlikely that genes coding for specific aspects of knowledge are coded into our genetics. But, it stands to reason to believe that genes can code for the internal architecture of our thinking processes, thereby making some pursuits far more accessible than others. Someone who finds math and music easy and English and writing hard will, can you guess it, choose to pursue math and music.

As far as us being at the mercy of our genes, I think we are far more at mercy to our cognitive processes. It may well be *possible* to overcome our genetic limitations, but the right idea of how to do it may never come to us. The genetics might limit our cognitive processes, and keep us from ever contemplating real change. And even if we did, we may well consider it "too hard" or "too much work", and thereby "choosing" to be limited by our genetics.

One can hold onto the idea of free will all one likes, only to be let down much later in life when they realize that they never really made any progress on that thing in yourself they always wanted to overcome. Or one could accept one's cognitive limitations, try to gain a functional appreciation for them, and seek out others to help make up for those limitations.

James Bowery said at November 9, 2006 8:20 AM:

The closest thing to legitimate academic support the blank slaters have had is behaviorism and the high priest of behaviorism, B. F. Skinner, did say that although there are schedules of reinforcement (reward/punishment) and other developmental flexibility that can change that which we find reinforcing to some extent, the starting conditions that determine what we find reinforcing are largely genetic.

Now, this doesn't mean that just because some kid enjoys calculus that he has "a gene for calculus" per se. What it may mean however is that the kid may have a correlation structure of genes/memes. Say:

1) some genes code for finding social status rewarding
2) some genes may code for the 'g' factor (which may give him an aptitude at solving hard calculus problems)
3) lack genes that code for other means of finding social status
4) be in a social milieu -- a meme pool -- that accords social status for solving calculus problems as well as being captain of the football team or lead singer in a rock band.

It should be no mystery how genes and memes are both involved in his finding calculus reinforcing.

crush41 said at November 9, 2006 11:30 PM:

But at what point(s) did fecundity lose its evolutionary advantage? The Great Generation had lots of kids. The baby boomers didn't. This was largely cultural, economic, and technological, not so much Darwinian.

In any case, I'm less confident that the Occident will swing back into baby-making mode, especially as the individual costs of doing so become ever greater (as educational tracts extend ever-longer into people's mid- and late-twenties, a larger dependent population squeezes the fertile working population economically, etc).

Bob Badour said at November 10, 2006 6:28 AM:


What makes you think the costs of having children increase? I suggest living standards have increased much faster than costs.

Bob Badour said at November 10, 2006 7:10 AM:

Sorry for posting again so soon, but I just ran across something relevant.


The largely cultural, economic and technological changes affected the evolutionary landscape. Traits that previously raised reproductive fitness ceased to do so. Where status seeking and responsibility previously increased reproductive fitness, those traits now reduce reproductive fitness.

The Darwinian part comes in what happens next. Now that the evolutionary landscape has changed, natural selection will change the frequency of different alleles so that new traits become more frequent than before and will eventually drive up the total fertility rate again.

I suggest your lack of confidence in natural selection derives from assuming future generations will be just like you and like the people you know well. They won't. Natural selection will drive an increase among the population you find alien.

For example, check out this Steve Sailer article from VDARE about an illegal immigrant couple who had quadruplets; even though, they already had six kids. Note that to have the quads, the mother reversed a tubal ligation and took fertility drugs. Why? Because her husband has an additional four kids by three other women!

She reversed the tubal ligation and took fertility drugs in spite of the fact that the state already pays large sums of money on a disabled son born before the quads and in spite of the fact that she and her husband lacked the resources to properly raise her existing six children (and God only who knows how many of his kids.) Cost? Who cares about the cost of raising children? Certainly not this couple.

Randall Parker said at November 10, 2006 5:13 PM:

Robert Silvetz,

The big difference in interest in babies between men and women seems obvious enough. I doubt that is taught. Little girls prefer to play with dolls. Little boys want to play war. Some teen girls want desperately to have children and get themselves knocked up so they can.


The fact that cultural, economic, and technological changes caused people to have fewer kids is itself Darwinian. Why should it? Why didn't these forces work equally in all people? Why are some people getting heavily educated and still having 3 or 5 or 6 kids?

To put it another way: Why do people want possessions? Why do they want status? Are these innate drives? If so, do people vary in the extent to which they have these drives? If so, do people who have fewer drives for possessions then become willing to spend more on having more kids?

My point is that if you look at all the drives that people have surely some of them are innate. Also, some vary between people for genetic reasons. Some can indirectly but still substantially affect the desire and willingness to have kids. People who are less annoyed by babies crying in the middle of the night, who are more able to fall back asleep after being wakened, who are less fatigued by kids will have more kids. So of course there are alleles that natural selection can act on in the current environment to increase fertility.

Randall Parker said at November 10, 2006 5:23 PM:


Basic question: Do allelic variations exist that influence fecundity in the modern world? If the answer is yes then of course they will be selected for. I see some obvious qualities of humans that are at least partially genetically controlled (e.g. religiosity and IQ) that influence fecundity. So natural selection has at least those to work on. But it seems extremely likely to me that other qualities that have genetic influences also contribute to fecundity. So it seems to me that natural selection has plenty to work on.

bee said at November 12, 2006 12:51 PM:

Randall- the correlation you assert likely non-existant or at best trivial. The population growth you observe is do to forces much larger than religion. Islamic society is not simply a religious order. Much of what defines it is social in nature. Let's quit using reasoning with what ifs that are a mile long. It is science fiction but not science.

Randall Parker said at November 12, 2006 2:53 PM:


You just assert that I'm wrong. I point you to studies showing a genetic basis of a tendency to believe in God. I point you to results of different religious groups reproducing at different rates. Muslims were not the only religious group I used for example. I also used Christians within the US. Secular people have fewer babies than believers. Particular faiths exert even stronger pressure to reproduce.

But the tendency to believe is itself partially genetically based and I provided a link for that from a twins study.

Rob said at November 13, 2006 1:55 PM:

It has been several years, but I believe Edward O Wilson (esteemed evolutionary biologist) has a chapter (or maybe just a few pages) detailing the reasons that he believes that a propensity towards religion is genetic in his book Consilience. I found his reasoning compelling at the time, but I don't remember the details today and don't have the book handy.

I don't see why this irritates people so much. Large parts of our lives, mental and physical, are dictated by our genes. Get used to it. It's not like you're exactly helpless either.

On the other hand, I'm not convinced that religion is necessarily going to be selected for, as there are pressures in the other direction as well. If, for example, a sect finds itself the target of genocide due to its beliefs, it might see its numbers decline rapidly...

Personally, and without much in the way of scientific evidence, I think that a tendency towards religion was a survival trait in early humans. A group that could bind together and work effectively as a unit had a great advantage over groups that could not. This - and other factors - could reasonably have selected for religion. But there is no evidence - that I know of, anyway - that this effect scales upwards. What is good at the tribal level may not be good at the level of a 100-million-person state. In fact, at the national level religion just may be harmful, if viewed purely from a survival standpoint and not a moral standpoint.

But, hey, it makes for fun discussions either way.

Joan Philips said at November 20, 2006 2:02 PM:

Most people have offspring because they are able to. Liberals enable conservatives to have large families by offering them generous tax breaks for dependents, subsidised daycare, paid maternitiy leave, etc, etc. As one who does not reproduce for moral reasons, I am offended by the generosity to breeders, even though I am very liberal and favor welfare in general. Why in the world should a comfortably middle class family be given a tax break just because they made the lifestyle choice to reproduce? I know that money makes a difference. All but the most zealot religious families won't have large families if they cannot afford them.

Stop rewarding conservatives for breeding, and they will stop breeding.

Matt said at December 31, 2006 1:34 PM:

Hey guys, religious belief is not under natural selection- either positive or negative.. There is not a heritable component, which is necessary for selection to operate.

Randall Parker said at December 31, 2006 3:11 PM:


How do you know there is not a heritable component. Really, how do you know?

I link back to a twins study that suggests there is such a component.

Just because ideas are taught does not mean there can't be cognitive tendencies to believe that vary due to genetic causes. Moods aer partly heritable. One can be predisposed to depression, anxiety, happiness and other states of mind. Why not a predisposition to believe the unproven? Why not different feelings when praying?

For example, do calm minds get different levels of enjoyment or satisfaction from praying than hyperactive minds? I'd expect so. Would the resulting different reactions to attempts to pray cause differences in tendencies to believe? I would expect so.

Josh said at February 11, 2009 5:07 PM:

Randall, I agree with you. I've been noticing this for years. The religious right may win through numbers by 2100.

However, given the fact that people with a strong drive to reproduce are more strongly selected for in low-fertility populations (as you said in that other post), perhaps the nonreligious and their descendants will have the last laugh in the long run. :)

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