Genes, phenotypes and populations

[Monique]

There seems to be a lot of confusion about the influence of genes on phenotypes. I happen to have worked in the field, so I will just give my view on the matter.

Geneticists are studying populations and try to find genes that cause the population to be at risk for certain phenotypes. Examples of populations: a family, a country, a race. Examples of phenotypes: severe combined immune deficiency (SCID), alzheimer, atherosclerosis, alcoholism.

The best population for a geneticist to use for their studies are isolated populations. There are different kinds of isolated population:
* geographic (Pacific island chains, Arabia, Inuits)
* cultural (Indian castes, Amish)
* historic (Quebec - Sanguenay Lac-Saint-Jean, S. Africans, native Americans)

The reason you want to use isolates is that the following are likely: rare alleles are enriched, the population is homogeneous, environmental factors are homogenous and more detailed things I won't go into. It makes it easier to find a correlation.

Even with such special population it is important to choose special sampling designs (unrelated case/control, parent/child, relative pairs, nuclear families, extended pedigrees). In isolated populations you have the most power to detect genetic effects when you sample from huge pedigrees, that is why they started the deCODE project in Iceland.

The search of these scientists have been succesfull: look for instance at the Finnish disease heritage. There are 35 monogenetic disease that are more prevalent in Finland than in any other population. For more information, this is an excellent website http://www.findis.org/main.php?action=disease

Does that mean the finns have a sick population? No, diseases that are frequent in other populations are rare in the finns (like cystic fibrosis), it's like a balance. Can you define the finns by those 35 diseases? No, the diseases are distributed regionally.

Scientists are most succesfull in finding monogenetic diseases, since their inheritance pattern is easy to detect. Diseases that inherit in a dominant fasion, have a high penetrance and low age at onset are easiest to find. Most importantly they need a very good definition of the phenotype they are looking for.

The case is, most genes that cause disease don't follow those rules. Disorders like alcoholism or psychiatric disorders are difficult to define and are heavily influenced by the environment someone grows up in. Only with good matched controls will a study succeed to find a correlation.

That is an important point: matched controls, you cannot compare apples with pears. In recent threads I feel that has been the main obstacle.

Another important point: the populations. In the discussion before, the populations were very carefully choosen and defined. Finding genes on a mixed genetic background is very difficult.

I certainly do believe that certain populations can harbor different genes. The thing that pops to mind most clearly is milk intolerance. Milk tolerance is a mutation, Dr. Leena Peltonen discovered the genetic basis. The following is a nice article http://www.newscientist.com/news/news.jsp?id=ns99991787 but again, this is a very well defined disease and is not influenced by outside factors.

I'd be very careful with extrapolating data on poorly defined phenotypes to poorly defined populations.

 

[donnie]

There seems to be a lot of confusion about the influence of genes on phenotypes. I happen to have worked in the field, so I will just give my view on the matter.

With reference the motivation for starting this thread:
"Let freedom reign. The sun never set on so glorious a human achievement."
- Nelson Mandela

 

[marcus]

There seems to be a lot of confusion about the influence of genes on phenotypes. I happen to have worked in the field, so I will just give my view on the matter.

Geneticists are studying populations and try to find genes that cause the population to be at risk for certain phenotypes. Examples of populations: a family, a country, a race. Examples of phenotypes: severe combined immune deficiency (SCID), alzheimer, atherosclerosis, alcoholism.

The best population for a geneticist to use for their studies are isolated populations. There are different kinds of isolated population:
* geographic (Pacific island chains, Arabia, Inuits)
* cultural (Indian castes, Amish)
* historic (Quebec - Sanguenay Lac-Saint-Jean, S. Africans, native Americans)

The reason you want to use isolates is that the following are likely: rare alleles are enriched, the population is homogeneous, environmental factors are homogenous and more detailed things I won't go into. It makes it easier to find a correlation.
...
...
I'd be very careful with extrapolating data on poorly defined phenotypes to poorly defined populations.

Hello Monique, in the historic category when you say S.Africans do you mean the Bantu majority of the Union of South Africa, or the Boers, or does S. stand for Subsaharan? It wasn't clear what historically isolated population you meant.

I commend you for openly and straightforwardly confronting the issue of
:surprise: RACE :surprise:
that we so often have difficulty coming to grips with in PF and elsewhere.

there is a fearsome lot of baloney and mythologizing about race.
I wish as Mentor you would zap people who just talk silly about it.
But you probably won't so i will use the Ignore feature to tune them out if they show up.

I see that you connect race with the technical idea of ISOLATE.
That is, a group of people who only date within the group.
(Indian castes are an example because social rules prevent marriage between caste.)
An isolate, as you use the word (a noun not a verb) is a group of people that doesn't mix reproductively very much with the other people for whatever reason.
If you wanted to destroy all races in the USA you could force people to marry randomly.

Within an isolate, there can be genetic features or DNA aspects that are distinctive----I think you are telling us----and indeed, as you suggest, that is why geneticists like to study isolates. (an Indian caste, some people on a pacific island, Subsaharan Africans).

I live near a large university campus and I notice the Han Chinese students keep pretty much to themselves. Han date Han, it looks to me.
Maybe Asian students in general tend to mostly date other Asians. Maybe that is an Isolate too.

OK, so Monique I recognize you are an expert, obviously, and I am trying to learn about Race from you.
The first thing I think you are telling me is that it has to do with mating behavior (a group of people can choose to make themselves into an isolate, like the Amish, or in past times the Jews, simply by consistently mating within their group----or they can be made into an isolate by other people's treatment, and then if there is enough visible phenotypic difference then it gets to look like a race)

The second thing I think you are saying is that once you have an isolate, then a geneticist can look for statistical differences in the DNA or in the phenotypic expression of the DNA or whatever----genetic differences between isolates.

Have I got it right so far? (there is some monster question hiding in the wings and maybe BlackVision will show it to us----there must be some real scary issue or people wouldn't be walking around with their hot-buttons showing----but what is it? so far this seems pretty harmless)

 

[marcus]

just for reference I want a link to a thread Nereid started called
Is their a scientific basis for race?
https://www.physicsforums.com/showthread.php?t=25340

I haven't read this thread beyond the first couple of posts but I want to
quote the first thing I saw there from selfAdjoint because it shows that we have a fair amount of agreement already
https://www.physicsforums.com/showthread.php?p=208729#post208729

----quote from sA---
I am on record as saying the concept of human races is prescientific. And the way most people use it, it is. But it has been brought to my attention that biologists commonly use the term race for subpopulations of species other than human, and that this term seems to have a more or less well defined basis. So I suggest that we look into this concept of race in nonhuman species and see whether or not it can be meanignfully extended to human populations, and what populations it would than apply to.

I would also suggest that the "box checking" type of self identification that has been so much discussed in connection with statistics may be meaningful in sociology but is much less so in biology. So we may have legitimate schools of interpretation.
----end quote---

I think that what Monique is telling us is that the term "race" which biologists use does, in fact, apply to humans as to other species of animal. Race has a clear scientific basis and is a scientifically useful concept, as applied to humans---if I understand Monique correctly.

 

[selfAdjoint]

Boy am I glad you noticed that, Marcus. I had the feeling I had dropped that post into a black hole.

 

[marcus]

that was a crazy discussion back there at Feedback!

but nereid linked me to "Scientific Basis" and
your post was one of the clearest things I got out of what little
of that I read.

 

[marcus]

It seems to me that we humans may be "on the cusp" of
getting for the first time a rational and constructive understanding
of our races

maybe this is overly optimistic.

BTW I am interested by Black Vision----he may be an utterly reprehensible malefactor. but I don't know anything about that. The main thing is I didnt see (in the limited sample) anything un-objective-----which is already very singular as i am subjective all the time. And he always seems to get a whole lot of people mad at him. Quite enviable in a way.

Another strange thing about Black Vision is his name. As if he was, like Korean, and didnt want anyone to know. So he puts Black on his name to suggest that he's black.

The way NoahAfrican puts African on his name. Its a custom in internet handles. But in NoahAfrican case it is authentic for sure.

However in Black Vision case it might be "flying false colors" on the handle.
He says to me "I won't tell you my race because I don't want to be profiled---I want you to consider my words on their own merit." But here he is with a loud Black Vision handle. that does not compute. Either he wants the identification or not.

Also english not first language, so could be Asian, e.g. korean. Anyway the guy is brilliant and i hope he sticks around. never a dull moment

 

[Monique]

Hello Monique, in the historic category when you say S.Africans do you mean the Bantu majority of the Union of South Africa, or the Boers, or does S. stand for Subsaharan? It wasn't clear what historically isolated population you meant.

I meant the Boers in South Africa, I should've been more precise..

there is a fearsome lot of baloney and mythologizing about race.
I wish as Mentor you would zap people who just talk silly about it.
But you probably won't so i will use the Ignore feature to tune them out if they show up.

Well, I wish I could zap people who are out to stigmatize..

I don't necessarily connect race to an isolate, actually I don't like to think in races: I like to think in populations.

Within an isolate, there can be genetic features or DNA aspects that are distinctive----I think you are telling us----and indeed, as you suggest, that is why geneticists like to study isolates. (an Indian caste, some people on a pacific island, Subsaharan Africans).

It depends on the history of the isolate. Certain historical events like the plague or famine shrinks down a population to a small size, followed by expansion of the population (a bottleneck). Finland went through several bottlenecks. Another historical event that impact on a population is the founder effect: this means that the population was settled by few individuals, an example are the Mormons. Some social influence would be consanguious marriages: in some countries it is normal to marry cousins.

There are a number of things that can happen to the DNA.. the explanation would be rather technical.. I'll try to keep it simple.
* genetic drift causes rare alleles to become frequent (or frequent to become rare)
* inbreeding causes recessive diseases to be more prevalent
* markers on DNA are shared between families
* fewer alleles are present of a gene

I live near a large university campus and I notice the Han Chinese students keep pretty much to themselves. Han date Han, it looks to me.
Maybe Asian students in general tend to mostly date other Asians. Maybe that is an Isolate too.

O sure, they might be a mini-isolate. Remember: a family can be an isolate too, right now the main focus of researchers is to connect people in a population to one common ancestor. Analysis of data from such a micro-isolate could give extra power to detect effects. Unfortunately, we need biostaticians that can write us programs to handle large families like that. I've seen such a pedigree, it would span the four walls of a conference room.

OK, so Monique I recognize you are an expert, obviously, and I am trying to learn about Race from you.
The first thing I think you are telling me is that it has to do with mating behavior (a group of people can choose to make themselves into an isolate, like the Amish, or in past times the Jews, simply by consistently mating within their group----or they can be made into an isolate by other people's treatment, and then if there is enough visible phenotypic difference then it gets to look like a race)

I don't necessarily think I am an expert. I did attend a conference on the genetics of isolated populations so I do have insights, it was the first conference of its kind.

Again you mention race, I don't like that word since I don't know what it means. Are the Amish a separate race? I guess a tree could be draw, where the Amish are a small branch off their ancestors. But truely, I don't know how to quantify race.

The second thing I think you are saying is that once you have an isolate, then a geneticist can look for statistical differences in the DNA or in the phenotypic expression of the DNA or whatever----genetic differences between isolates.

I don't think anyone has ever analyzed the statistical difference in DNA of isolates compared to phenotypes. The major hype at the moment is to give as many people in an isolate medical evaluations and do whole genome scans of those individuals. The idea is that the isolate has some characteristic that makes it easier to find a gene.

 

[selfAdjoint]

However in Black Vision case it might be "flying false colors" on the handle.
He says to me "I won't tell you my race because I don't want to be profiled---I want you to consider my words on their own merit." But here he is with a loud Black Vision handle. that does not compute. Either he wants the identification or not.[/quick]

Or it might not be a racial reference at all. "Black vision" does after all have a meaning of its own in English.

 

[iansmith]

Again you mention race, I don't like that word since I don't know what it means.

In biology, some use race to mean a division within a species. Thus, in certain fields it is used as a synonym for subspecies or, in botany, variety. In the case of honeybees, for instance, it stands as a synonym for subspecies. In this usage, race serves to group members of a species that have, for a period of time, become geographically or genetically isolated from other members of that species, and as a result have diverged genetically and developed certain shared characteristics that differentiate them from the others. Although these characteristics rarely appear in all members of the group, they are more marked in or appear more frequently than in the others.

http://www.wordiq.com/definition/Race

This article I quoted does good job a discussing race in different aspects.

 

[Dagenais]

Another strange thing about Black Vision is his name. As if he was, like Korean, and didnt want anyone to know. So he puts Black on his name to suggest that he's black.

Does knowing his race matter on an internet forum?

 

[Mazuz]

Again you mention race, I don't like that word since I don't know what it means. Are the Amish a separate race? I guess a tree could be draw, where the Amish are a small branch off their ancestors. But truely, I don't know how to quantify race.

Can't we just define race as the genes and culture of a population?

 

[Monique]

http://www.wordiq.com/definition/Race

This article I quoted does good job a discussing race in different aspects.

Right, but how isolated are the human populations? How divergent are they? How different is one population from the other?

With genes you can do homology mapping. If you have a single gene that over evolution duplicated into a number of other genes and those mutated, you can map the genes into a tree and see which one gave rise to another. It will give you a branched output.

With humans you might be able to do the same thing, but we have ~30,000 genes. All these genes have a number of alleles. You might be able to come up with a gene that is characteristic for a certain branch: think for instance about lactose tolerance or aldehyde dehydrogenase deficiency.

But the term Caucasian is very outdated, although it is still used in peer-reviewed biology papers.

Can't we just define race as the genes and culture of a population?

So the Japanese would be a race, the Saumi would be a race, the Inuits would be a race? I prefer to say these groups are all populations: you acknowledge they have different characteristics.

Some families have a gene that cause them to be very small. That certainly does not make them a different race, although they do look very different. If these people would only mate among other small people, I think you may call them a sub-population.

 

[plus]

How different is one population from the other?

You would have to define a norm to measure this.

So the Japanese would be a race, the Saumi would be a race, the Inuits would be a race? I prefer to say these groups are all populations: you acknowledge they have different characteristics.

How much difference is there between a jap and a korean genetically?

Some families have a gene that cause them to be very small.

Are you sure that it is only 1 gene? I always thought that it would be several genes controlling height.

 

[plus]

Some families have a gene that cause them to be very small.

Do you finally admit that some families might have some combination of genes causing them to commit more crime, or to have lower IQ?
If there were many of these families and they became isolated from the rest of humanity, would they still have genetic prevelence of high crime and low IQ? What if there were millions and millions of such people? And if they were like this due to evolution and not chance?

 

[Nereid]

How much difference is there between a jap and a korean genetically?

Between any two individuals, far more than between the two groups. "Evidence from the analysis of genetics (e.g., DNA) indicates that most physical variation, about 94%, lies within so-called racial groups. Conventional geographic "racial" groupings differ from one another only in about 6% of their genes." Source: American Anthropological Association

 

[Monique]

Do you finally admit that some families might have some combination of genes causing them to commit more crime, or to have lower IQ?

Did I ever refute that? No.

 

[Adrian]

"Originally Posted by plus
Do you finally admit that some families might have some combination of genes causing them to commit more crime, or to have lower IQ?"

It's noteworthy that phenotypes like "high IQ" and, even more so, "predisposition to crime" are poorly defined. That plus the limited knowledge of the genome and proteome we have at this point make it hard to decide if they're actually genetically determined and if yes, what genotype corresponds to them.

For now, we basically have to stick to crisply and clearly defined phenotypes that can be traced back to one or a very limited number of genes in the interpretation of genomic data. More complex questions are better left unanswered until we have the means to tackle them rather than being "answered" with unscientific speculation.

 

[Neo]

"Originally Posted by plus

It's noteworthy that phenotypes like "high IQ" and, even more so, "predisposition to crime" are poorly defined. That plus the limited knowledge of the genome and proteome we have at this point make it hard to decide if they're actually genetically determined and if yes, what genotype corresponds to them.

Have you heard of Robert Plomin? I recently read about "high IQ" genes possibly on chromosome 6.

Here is an article about it:
http://www.wellesley.edu/Chemistry/chem227/nucleicfunction/transcription/sci-gene-intelligence.html

 

[Evo]

That is an excellent article Neo, I had read that some time ago, but I haven't seen anything about any progress. Are there any updates? He seemed to be on the right track.

Also, I agree with his concerns about the potential for misuse, but there is so much potential for helping people with learning disabilities and diseases like Alzheimer's.

 

[Evo]

I found the answer to my own question. Here is the update, Plomin never published his continued studies.

Here is the gist of the article -

Now a groundbreaking study of the interaction among genes, environment and IQ finds that the influence of genes on intelligence is dependent on class. Genes do explain the vast majority of IQ differences among children in wealthier families, the new work shows. But environmental factors -- not genetic deficits -- explain IQ differences among poor minorities.

The work, to be published in the November issue of the journal Psychological Science, is part of a new wave of research that embraces a more dynamic view of the relationship between genes and environment. Although older research treated nature and nurture as largely independent and additive factors, and saw people as the sum of their genetic endowments and environmental experiences, the emerging view allows that genes can influence the impact of experiences and experiences can influence the "expression," or activity levels, of genes.

In Turkheimer's study, the impact of genes on IQ varied depending on a child's socioeconomic status (SES), a sociological measure that includes household income and other elements of class and social status.

Until recently, Turkheimer and others said, research had indicated that the "heritability" of IQ -- that is, the degree to which genes can explain the differences in IQ scores -- completely dominated environmental influences. That led some to call into question the value of programs such as Head Start, which are based on the assumption that by improving the childhood environment through extra attention, nutrition and care, a child's intellectual future could be improved.

But it turned out that virtually all those studies on the heritability of IQ had been done on middle-class and wealthy families. Only when Turkheimer tested that assumption in a population of poor and mostly black children did it become clear that, in fact, the influence of genes on IQ was significantly lower in conditions of poverty, where environmental deficits overwhelm genetic potential.

"This paper shows how relevant social class is" to children's ability to reach their genetic potential, said Sandra Scarr, a professor emerita of psychology now living in Hawaii, who did seminal work in behavioral genetics at the University of Virginia.

Specifically, the heritability of IQ at the low end of the wealth spectrum was just 0.10 on a scale of zero to one, while it was 0.72 for families of high socioeconomic status. Conversely, the importance of environmental influences on IQ was four times stronger in the poorest families than in the higher status families.

"This says that above a certain level, where you have a wide array of opportunities, it doesn't get much better" by adding environmental enhancements, Scarr said. "But below a certain level, additional opportunities can have big impacts."

Here is the entire article.

http://www.washingtonpost.com/ac2/wp-dyn/A12059-2003Sep1

 

[Neo]

That is an excellent article Neo, I had read that some time ago, but I haven't seen anything about any progress. Are there any updates? He seemed to be on the right track.

I agree: the article is old but the research is new. As far as being on the right track, I'd say his data is interesting but the "genes" he suggests are introns -- they don't code for protein since the intronic nucleic acids are spliced out from the final mRNA by spliceosomes, which implies that what he has found isn't significant in itself -- merely that there's possibly a weak promotor in the coding region that could marginally affect intelligence level.

Are you involved in the online high IQ community at all? The bigger HIQ societies feature interviews with prominent scientists in the field, including Jensen.

Anyway, many similar studies are being done here at Harvard, where I conduct cancer research. Also, Plomin's other articles, that indirectly suggest that genetics is the square root of intelligence, are worth taking a look at.

Try pubmed.com and type Plomin R in the search discriminator.

 

[marcus]

Have you heard of Robert Plomin? I recently read about "high IQ" genes possibly on chromosome 6.

Here is an article about it:
http://www.wellesley.edu/Chemistry/chem227/nucleicfunction/transcription/sci-gene-intelligence.html

Neo this is really exciting news.
Thanks so much for bringing it!
All this stuff is fairly new to me. I agree with Evo about the need to prevent abuse-----in the article the kind of abuse that was mentioned was setting up testing centers where prospective parents would pay to find out if they had this gene or not----a kind of profiteering off of people's natural vulnerability when they are thinking about having children.

but I hope we can look at the scientific advance this represents.
The particular gene only has a 2 percent effect, or about 4 IQ points.

Indeed the figure I saw was intelligence is only around 58 percent heritable (the rest being environmental) and one expects that literally scores of genes are involved.

I hope a lot of people read this Nicholas Wade article you link to.
He gives the authors as...well, let me quote that part:
"...current issue of the journal Psychological Science, was conducted by Dr. Robert Plomin, a leading American behavioral geneticist who works at the Institute of Psychiatry in London. His co-authors include Dr. David Lubinski and Dr. Camilla Benbow. Their talent search program, known as the Study of Mathematically Precocious Youth, supplied the test subjects..."

So we should be on the lookout for online stuff by Plomin, Lubinski, Benbow! maybe we can get some primary source material, not just journalist accounts!

 

[Monique]

Also, I agree with his concerns about the potential for misuse, but there is so much potential for helping people with learning disabilities and diseases like Alzheimer's.

But Alzheimer doesn't have anything to do with IQ in the conventional sense: plaques in the brain cause the deterioration of brain function. I co-published a paper (in Neurogenetics) that shows evidence for a gene on chromosome 20, but there are so many other chromosomal regions that might also be involved. It's not easy finding genes.

I completely agree with Adrian: we have to stick to crisply and clearly defined phenotypes. Alzheimer is much more clearly defined than a learning disability.

 

[Evo]

Here is where you can get a copy of the study. The abstract is below.

Socioeconomic status modifies heritability of iq in young children
Eric Turkheimer, Andreana Haley, Mary Waldron, Brian D'Onofrio, and Irving I. Gottesman

Scores on the Wechsler Intelligence Scale for Children were analyzed in a sample of 7-year-old twins from the National Collaborative Perinatal Project. A substantial proportion of the twins were raised in families living near or below the poverty level. Biometric analyses were conducted using models allowing for components attributable to the additive effects of genotype, shared environment, and nonshared environment to interact with socioeconomic status (SES) measured as a continuous variable. Results demonstrate that the proportions of IQ variance attributable to genes and environment vary nonlinearly with SES. The models suggest that in impoverished families, 60% of the variance in IQ is accounted for by the shared environment, and the contribution of genes is close to zero; in affluent families, the result is almost exactly the reverse.

http://www.blackwell-synergy.com/links/doi/10.1046/j.0956-7976.2003.psci_1475.x/abs/;jsessionid=k5H6HY-OcjI8

 

[Neo]

Here is the update, Plomin never published his continued studies.

He actually did publish quite many studies after the 1998 pub. He's probably best classifed as a developmental psychologist with a diversity of research interests.

Here are just a dozen:

1: Walker SO, Petrill SA, Spinath FM, Plomin R. Related Articles, Links
Nature, nurture and academic achievement: A twin study of teacher assessments of 7-year-olds.
Br J Educ Psychol. 2004 Sep;74(Pt 3):323-42.
PMID: 15296543 [PubMed - in process]

2: Eley TC, Sugden K, Corsico A, Gregory AM, Sham P, McGuffin P, Plomin R, Craig IW. Related Articles, Links
Gene-environment interaction analysis of serotonin system markers with adolescent depression.
Mol Psychiatry. 2004 Jul 6 [Epub ahead of print]
PMID: 15241435 [PubMed - as supplied by publisher]

3: Price TS, Dale PS, Plomin R. Related Articles, Links
A longitudinal genetic analysis of low verbal and nonverbal cognitive abilities in early childhood.
Twin Res. 2004 Apr;7(2):139-48.
PMID: 15169599 [PubMed - indexed for MEDLINE]

4: Gregory AM, Eley TC, O'Connor TG, Plomin R. Related Articles, Links
Etiologies of associations between childhood sleep and behavioral problems in a large twin sample.
J Am Acad Child Adolesc Psychiatry. 2004 Jun;43(6):744-51.
PMID: 15167091 [PubMed - indexed for MEDLINE]

5: Gregory AM, Eley TC, Plomin R. Related Articles, Links
Exploring the association between anxiety and conduct problems in a large sample of twins aged 2-4.
J Abnorm Child Psychol. 2004 Apr;32(2):111-22.
PMID: 15164855 [PubMed - in process]

6: Fernandes C, Paya-Cano JL, Sluyter F, D'Souza U, Plomin R, Schalkwyk LC. Related Articles, Links
Hippocampal gene expression profiling across eight mouse inbred strains: towards understanding the molecular basis for behaviour.
Eur J Neurosci. 2004 May;19(9):2576-82.
PMID: 15128411 [PubMed - indexed for MEDLINE]

7: Eley TC, Liang H, Plomin R, Sham P, Sterne A, Williamson R, Purcell S. Related Articles, Links
Parental familial vulnerability, family environment, and their interactions as predictors of depressive symptoms in adolescents.
J Am Acad Child Adolesc Psychiatry. 2004 Mar;43(3):298-306.
PMID: 15076263 [PubMed - indexed for MEDLINE]

8: Spinath FM, Price TS, Dale PS, Plomin R. Related Articles, Links
The genetic and environmental origins of language disability and ability.
Child Dev. 2004 Mar-Apr;75(2):445-54.
PMID: 15056198 [PubMed - indexed for MEDLINE]

9: Becker-Blease KA, Deater-Deckard K, Eley T, Freyd JJ, Stevenson J, Plomin R. Related Articles, Links
A genetic analysis of individual differences in dissociative behaviors in childhood and adolescence.
J Child Psychol Psychiatry. 2004 Mar;45(3):522-32.
PMID: 15055371 [PubMed - indexed for MEDLINE]
10: Loat CS, Asbury K, Galsworthy MJ, Plomin R, Craig IW. Related Articles, Links
X inactivation as a source of behavioural differences in monozygotic female twins.
Twin Res. 2004 Feb;7(1):54-61.
PMID: 15053854 [PubMed - in process]

11: Viding E, Spinath FM, Price TS, Bishop DV, Dale PS, Plomin R. Related Articles, Links
Genetic and environmental influence on language impairment in 4-year-old same-sex and opposite-sex twins.
J Child Psychol Psychiatry. 2004 Feb;45(2):315-25.
PMID: 14982245 [PubMed - indexed for MEDLINE]

12: Plomin R, Turic DM, Hill L, Turic DE, Stephens M, Williams J, Owen MJ, O'Donovan MC. Related Articles, Links
A functional polymorphism in the succinate-semialdehyde dehydrogenase (aldehyde dehydrogenase 5 family, member A1) gene is associated with cognitive ability.
Mol Psychiatry. 2004 Jun;9(6):582-6.
PMID: 14981524 [PubMed - in process]


This is rewiew is also informative:
Plomin R, Spinath FM. Related Articles, Links
Intelligence: genetics, genes, and genomics.
J Pers Soc Psychol. 2004 Jan;86(1):112-29.
PMID: 14717631 [PubMed - indexed for MEDLINE]

 

[marcus]

I agree: the article is old but the research is new. As far as being on the right track, I'd say his data is interesting but the "genes" he suggests are introns -- they don't code for protein since the intronic nucleic acids are spliced out from the final mRNA by spliceosomes, which implies that what he has found isn't significant in itself -- merely that there's possibly a weak promotor in the coding region that could marginally affect intelligence level.

I don't know as much about this as Evo. very new to me. could you explain a little more

Are you involved in the online high IQ community at all? The bigger HIQ societies feature interviews with prominent scientists in the field, including Jensen.

never heard of the HIQ community, sounds a bit awful or at least off-putting

Anyway, many similar studies are being done here at Harvard, where I conduct cancer research. Also, Plomin's other articles, that indirectly suggest that genetics is the square root of intelligence, are worth taking a look at.

what do you mean square root? It sounds nice and I would presume you mean that intelligence is the result of multiplying two factors together namely nature and nurture---genetics and environment---but this is something of a Old Saw is it not?

Try pubmed.com and type Plomin R in the search discriminator.

I am used to finding math and physics eprints in arXiv.org. Is pubmed connected to a source of eprints? I will try what you suggest...

 

[Evo]

So we should be on the lookout for online stuff by Plomin, Lubinski, Benbow! maybe we can get some primary source material, not just journalist accounts!

No, Plomin doesn't seem to be aggressively pursuing this anymore. Here is Plomin's website.

http://www.robertplomin.com

Originally Posted by Monique
But Alzheimer doesn't have anything to do with IQ in the conventional sense:

Alzheimers was Plomin's reason to continue the research.

 

[marcus]

I think you already answered the questions I was having while i was still typing. It sounds like Plomin's initial results sounded promising but didnt pan out---and he's not a real geneticist just a devel.psych dabbling in it.
Shucks.

 

[Neo]

I don't know as much about this as Evo. very new to me. could you explain a little more

Basically he didn't find genes that code for intelligence, unfortunate as the reality is. He found a "place to look," a perspective. The variant region with a 0.5 correlation with high intel isn't part of the coding region of DNA. You see, there are segments (that are not converted into protein) called introns, which are present in pre-mRNA. And these introns are cut out by spliceosomes and therefore don't code for amino acids (monomers of proteins). The variant genes he found lie in this region -- the non-coding part of DNA. So he didn't actually find "intelligence genes." He found what might be a protein promotor or something near one that might be involved with an intelligence gene.

 

[marcus]

Basically he didn't find genes that code for intelligence, unfortunate as the reality is. He found a "place to look,"...

thanks for the additional clarification and also for pointing to Nicholas Wade's article about this in the first place.

dont we worry a lot about intelligence though? Maybe what those geneticists should be pursuing is straighter teeth and less acne.
As a teenager I believe I would have appreciated knowing that someone
was making an effort about what really matters.

But Neo, if you come up with some more leads like this please post them. It is fascinating.

 

[Evo]

Are you involved in the online high IQ community at all?

No, I would be eaten alive.

Anyway, many similar studies are being done here at Harvard, where I conduct cancer research.

That's fascinating. Sounds like you will be a great resource here. I see you've been around a long time, but rarely post.

Also, Plomin's other articles, that indirectly suggest that genetics is the square root of intelligence, are worth taking a look at.

I am sure that others are still pursuing his earlier work. I may continue digging.

 

[plus]

Did I ever refute that? No.

You still have not answered my question. And this question also goes to Evo.

 

[plus]

Here is where you can get a copy of the study. The abstract is below.

Socioeconomic status modifies heritability of iq in young children
Eric Turkheimer, Andreana Haley, Mary Waldron, Brian D'Onofrio, and Irving I. Gottesman

Scores on the Wechsler Intelligence Scale for Children were analyzed in a sample of 7-year-old twins from the National Collaborative Perinatal Project. A substantial proportion of the twins were raised in families living near or below the poverty level. Biometric analyses were conducted using models allowing for components attributable to the additive effects of genotype, shared environment, and nonshared environment to interact with socioeconomic status (SES) measured as a continuous variable. Results demonstrate that the proportions of IQ variance attributable to genes and environment vary nonlinearly with SES. The models suggest that in impoverished families, 60% of the variance in IQ is accounted for by the shared environment, and the contribution of genes is close to zero; in affluent families, the result is almost exactly the reverse.

http://www.blackwell-synergy.com/links/doi/10.1046/j.0956-7976.2003.psci_1475.x/abs/;jsessionid=k5H6HY-OcjI8

This is only 1 study, which contradicts with many other studies.
At age 7, it is a well known fact that people's IQ is more affected by environment than genetics, while at maturity this situation reverses. A more useful study would be to see how things are at age 30.

 

[Evo]

This is only 1 study, which contradicts with many other studies.
At age 7, it is a well known fact that people's IQ is more affected by environment than genetics, while at maturity this situation reverses. A more useful study would be to see how things are at age 30.

This study took a newer approach. Unfortunately some of the "popular" earlier studies had questionable financial backing and the results may have been biased.

From the article "The work, to be published in the November issue of the journal Psychological Science, is part of a new wave of research that embraces a more dynamic view of the relationship between genes and environment. Although older research treated nature and nurture as largely independent and additive factors, and saw people as the sum of their genetic endowments and environmental experiences, the emerging view allows that genes can influence the impact of experiences and experiences can influence the "expression," or activity levels, of genes.

But it turned out that virtually all those studies on the heritability of IQ had been done on middle-class and wealthy families. Only when Turkheimer tested that assumption in a population of poor and mostly black children did it become clear that, in fact, the influence of genes on IQ was significantly lower in conditions of poverty, where environmental deficits overwhelm genetic potential"

This study also appears to be a bit different. Of course other studies are being done so only time will tell if similar studies provide similar results.

I find this study very interesting. I haven't had a chance to read the entire study yet, but it appears to be solid. It's refreshing to see something new, isn't it?