Is "dysgenic pressure" a real problem?

In the SF classic “The Marching Morons,” by Cyril Kornbluth (published in 1951, when clinical use of the terms “idiot” and “moron” for persons falling within certain low IQ ranges was not considered offensive), a sleeper wakes in a future where the prudent, childbirth-delaying habits of the more intelligent people, combined with the rampant reproduction of everybody else (made possibly by industrialization and technological progress), has produced a world of, well, morons. Everyone is congenitally stupid, except for a secret society of selectively-bred geniuses, who work slavishly hard behind the scenes (as personal assistants, etc., to the apparent decisonmakers) to keep things working. One time the geniuses experimented with simply going on vacation, retreating to their secret base in Antarctica, and things started falling apart right away.

This kind of thinking was not unusual at the time the story was written. Eugenics had been an intermittenly fashionable cause from the late 19th Century, attracting a lot of truly great minds to its banner – though it was based, then, on imperfect and sometimes pseudoscientific understandings of genetics; and it was always tinged with racism, in some forms inseparable from it. To some, “eugenics” simply meant encouraging negroes to use contraception. And then to the Nazis it meant a great deal more . . . (Kornbluth, at least, gave no hint that differential reproduction of different “races” played any part in Moron World, which seemed to have roughly the same racial makeup of the world of 1951.)

In this ongoing thread on overpopulation, soulmurk posted:

Based on later posts, it appears soulmurk is talking not just about stupidity but about people with congenital physical defects – who, in earlier generations, would have been quickly culled from the gene pool because nobody had the power to save them.

But . . . is any of this a real problem, or is it superstition? I mean, is there any hard evidence that any form of “dysgenic pressure” has been causing the general genetic quality of humanity, or of any particular society, to degenerate by any standard or in any respect, physical or intellectual?

Perhaps not directly related to what the OP is asking, since he’s referring to physical and mental fitness; but a while ago I started a thread Is birth control ultimately self-defeating?, in which I asked if the family-limiting segment of the population was in danger of being outbred. Short answer=no was the consensus.

IMHO, it’s not much of a problem, for several reasons.

First, because we’re already more or less at the bottom where we are degenerating, and not degenerating where we aren’t at the bottom. Despite what Kornbluth and others say, there’s plenty on evolutionary pressure for higher intelligence; for example, a smart guy is more likely to be able to talk a woman into bed ( and possible pregnancy ). A smart person is more likely to avoid killing themselves stupidly before breeding, or stay out of prison, and so forth. Our immune systems are also under constant pressure from disease, even with modern medicine.

The genes that can degenerate already have, far back in prehistory. We are weak and slow and flimsy, because our brains make up for it. Even in the Stone Age, a guy who was strong as an ape but barely smarter would just end up as somebody’s expendable enforcer. You see the same thing in domestic animals; in many ways they have degenerated compared to theit wild counterparts, but they also tend to lose brain mass because it’s our intelligence they depend on.

Second, the “overly compassionate” society these people complain about hasn’t existed that long, given long human generation times; there hasn’t been time for significant degeneration. And in a generation or two, it won’t matter; we’ll just be able to genetically engineer such problems away. As an aside, this is why I consider genetic engineering the worst nightmare of the racist, because it means that even if they are right we can just upgrade the “inferior races”.

Third, these theories are based on the idea that the poor are stupid, not unlucky or oppressed. It’s based on the old idea that social success is a sign of genetic fitness, which is untrue. Poor people have more children partly because that’s how we and other animals are wired ( plus see below ); the more resources you have, the fewer offspring you have and the more effort you put into each; the opposite for those with fewer resources.

Finally, the poor also tend to be poorly educated ( inlcuding sex ed ), and a hotbed of “traditional” beliefs, meaning misogyny. Feminism and condoms stops the overbreeding quite effectively.

Dogs are dumber than wolves? I’d say that depends on the breed. I doubt any wolf could match wits with a German shepherd (provided the two had been raised in and were competing in the same environment).

I’m not sure that they are; that’s why I said “tend to”. You’ll note that dogs are often expected to perform more complex tasks that other domestic animals, and are sometimes bred for intelligence. That’s rare in domestic animals; you don’t see many smart cows running around. Cats do have smaller brains than their ancestors, according to comparisons of their skulls.

Dogs are certainly weaker than wolves; IIRC dog-wolf hybrids are several times as strong as normal dogs.

One reason why it would be dangerous to keep a wolf (or even half-wolf) as a pet. Another reason is, wolves have not been selectively bred for tractable, nonaggressive personalities. Put those together, and . . .

And, unlike wolves, half wolves have no fear of humans.

It is always worth remembering that we have yet to locate a single gene which determines a person’s mental ability. We have known the structure of DNA for over fifty years, we’ve sequenced the human genome, we’ve identified the genes for thousands of physical traits, but we have yet to find the “genius gene”. It’s still a purely theoretical concept. For sure, many leading scientists agree with the conjecture, but there’s no proof.

I recall the issue of the ether, which trouble physicists for many generations. At the end of the 19th century, a pair of experiments measuring the supposed speed of the “drift” in the ether contradicted each other. A number of fanciful theories were devised to explain the experimental results, but in the end the physicists were reduced to the simplest explanation: the ether did not exist. I think something similar must soon happen to genius genes. Researchers don’t hold out much hope for finding a single gene that guarantees high intelligence, so instead they’re moving to more complicated theories. Perhaps intelligence is determined by many groups of linked genes, or it’s a case where the significant gene is only active part of the time, etc… In the end, the simplest explanation may be that we’re not finding genius genes because they don’t exist.

We’d do well to go back and reread these results from the mid 90’s concerning brain development in infancy. We’ve observed that babies start out with an enormous tangle of neural connections. During the first three years of life, most of those connections are eliminated, until only the useful connections remain. The relevant fact is that the pruning occurs not by genetic destiny, but rather it’s caused by stimuli from the outside world. Lots of visual stimulus means that the brain will keep pathways relating to sight; less visual stimulus, and it will remove those pathways.

For another thing we’re not entirely certain how to define mental ability, or whether level of “intelligence” is one thing or several. IQ tests are based on the assumption that an individual has a single characteristic of general intelligence, “g,” but Howard Gardner theorizes intelligence varies along seven independent axes (verbal intelligence, musical intelligence, etc.). Certainly IQ tests reliably measure some stable personal characteristic, in the sense that you can have your IQ tested several times, several years apart, and get roughly the same score; but it’s much less clear what that score means. (All these points discussed earlier in this thread.)

BTW, what ever happened to that ol’ “IQ cap”? (Someday I’ll get around to writing Tom Wolfe a letter . . . :wink: )

I may be misinterpreting this, but doesn’t this suggest that there is little link between genetics and intelligence; it’s not that “the poor are stupid” (to grossly oversimplfy), but that being born on the bottom rung exposes someone to an enviroment more likely to result in low intelligence (not to mention relative access to education)? Therefore, we are in little danger of having “morons outbreed the intelligent elite”: rather, the elite will always be more intelligent, at least relatively speaking, while the underclass will always be less likely to develop intelligence and succeed in society?

AFAIK the evidence still says there’s a strong gentic component to intelligence; it’s just that environment controls how much of that potential can be achieved. In other words, someone who’s badly educated and malnourished won’t develop to his potential, while someone raised in an ideal environment will become as intelligent as he is capable of.

Interestingly enough, one consequence of this is that increasing economic/social equality increases genetic inequality by eliminating the factors that mask that inequality. In other words, instead of the dumber rich guy being able to stay neck and neck with the smarter poor guy due to his superior education and early environment, they’ll both start out at the same level and the poor smart guy will pull ahead.

In the Law & Order: SVU episode "Design, there is a geneticist who specializes in inseminating would-be mothers with sperm from “superior” men. He explains to Stabler:

SCIENTIST: I’m doing this for the human race! Our gene pool is deteriorating! More and more underintelligent people are having larger families, while intelligent people put off marriage and childbearing until late in life!

STABLER: Wait a minute, I’ve got four kids!

BURN! :smiley:

It’s an incorrect argument that “bad” genes aren’t being selected against anymore, and therefore in a few generations we’ll all be crippled by genetic disease.

Thing is, the genes for these rare genetic diseases are much more common than people realize. Let’s say there’s a rare genetic disease that occurs in 1 out of a million people, 300 cases in the US. Assuming random assortment, how common is the allele that causes the disease? You need two copies of the allele to express the trait. In this case, one person in a thousand is a carrier for the trait. So for every person that expresses the trait, you have 1000 people who carry the trait. Allowing that one person who expresses the trait to live is going to increase the incidence of the trait by only a tiny fraction. And eugenically eliminating those who express the trait does almost nothing to “clean up” the gene pool.

To really clean up the gene pool you’d have to eliminate the carriers. But the trouble is that almost everybody is a carrier for one or more really nasty genetic diseases, it’s just that the odds of mating with another carrier is very low except in cases of inbreeding. To eugenically eliminate genetic disease you’d have to prevent the vast majority of the population from breeding…and mutation is constantly adding new deleterious alleles to the mix. For really bad traits the mutation rate is very close to the selection rate…so in my example of a trait where one person in a million expresses the trait and therefore doesn’t reproduce, the gene mutates to the bad allele about one time in a million, which is why the trait persists even though it is strongly selected against.

The rarer a genetic disease is, the weaker the selective pressure against it, which is why the really bad genetic diseases are very rare. And this is why various eugenic schemes will fail, because they just look and the expressed phenotype and don’t take into account genetic load.

Something else has occurred to me – is it possible that, even if we’re not degenerating genetically, our technology has caused us to stop evolving?

Not that that’s necessarily a bad thing.

But what would it mean to “stop evolving”? It would mean that the next generation has exactly the same frequency of alleles as the past generation, and the next, and the next, and the next.

But that can’t happen, simple genetic drift will change allele frequencies.

And we know that different people have different numbers of children. Some have zero, some have 1, some have 2, some have 8. What are the odds that the population of people who have zero kids have exactly the same distribution of alleles as the population of people with 8 kids?

People vary. Part of that variation is genetic. Different people have different numbers of offspring. And therefore, that generation of offspring is going to vary from the parent generation. And we have evolution.

Unlikely. First, there are still plenty of lethal diseases our technology can’t handle. Plenty of people die young for a number of reasons, all of which produce evolutionary pressures. Finally, until all children are conceived deliberately and tested for paternity, persuasiveness will still be selected for.

Huh? All children “conceived deliberately” just changes the details of how persuasiveness is selected for (i.e. it selects for persuading someone to have kids, not just persuading someone to have sex). Testing for paternity doesn’t even change things that much.

It would mean our descendants 200,000 years from now (our species is now 200,000 years old) would be exactly the same species as we are – not something as different from us as we are from Homo erectus (lived 18 million years ago to 70,000 years ago).

Not necessarily a bad thing. For one thing, the time scales involved seem to make this something less than a pressing issue. Evolution is slow. For another, we’ve learned to think of evolution as “progress” from “lower” life-forms to “higher,” but science as such makes no value judgments, and even if we agree on some single measure of “improvement” – e.g., IQ – there is no guarantee that natural selection will produce improved intelligence with each step in speciation. The environment might make other characteristics of greater survival value even at the cost of lower intelligence. If we decide that (or any other hereditary characteristic) is desirable, we almost certainly will have the genetic-engineering technology to upgrade our children to the Next Level (what would be Latin for “Designed man”?) long, long before natural selection would be able to produce another species.

Sorry, Magneto! :slight_smile:

I’m sure you meant 1.8M years ago, not 18M years…

I suprised someone as active on this board as you are, BG, are seemingly unaware of the many, many times this topic has been debated (both here in GD and in GQ). Do a little searching and you’ll turn up at least a dozen threads. I’m not going to rehash all the posts I’ve made in those various threads.

But don’t put too much imort on how biologists slice and dice our hominid ancestors into different species. There was a lot of evolvoing going on in different areas of the world, and while H. erectus seemed to be pretty stable in Asia, other populations (in Europe and Africa) were changing. And don’t be too sure that evolution is a slow process. It can be slow or fast, depending on the selective pressure in the envirnoment.

Correct, flubbed the decimal.

Any “any date” GD search on the keyword “dysgenic” turns up the following:

“Humans are Becoming Genetically Less Intelligent”


No matches at all in GQ. Have there been any other threads on this subject? Should I be using different search terms?

So, how does that relate to our present situation (natural-selection pressures reduced or altered by technology and a human-shaped environment) and what it means for our future?