The looming crisis in human genetics

http://www.economist.com/displaystory.cfm?story_id=14742737

by rms • 17 years ago

63 62 17 years ago

rms• 17 years ago

The comments on Reddit tear this apart but I don't think it's that bad. http://www.reddit.com/r/worldnews/comments/abjrm/human_genet...

The two main points: genomic data is not as medically useful as family history. What will be discovered is going to do very weird things to political correctness.

Steve Murphy has loudly been expounding about the family history meme for years now. http://thegenesherpa.blogspot.com/

cwan• 17 years ago

I found the article to be unnecessarily patronizing. The idea that the general public can't handle the truth on any number of subjects is simple arrogance. Wasn't it revealed that McCain and Obama shared common ancestry way back? How is it possibly even shocking that yes, there is "mis-attributed paternity and covert mating between classes, castes, regions and ethnicities"?

Take this, one of the final and most bizarre statements: "If the shift from GWAS to sequencing studies finds evidence of such politically awkward and morally perplexing facts, we can expect the usual range of ideological reactions, including nationalistic retro-racism from conservatives and outraged denial from blank-slate liberals."

I agree with you - it'll be a blow to political correctness, but I'm guessing there won't be the "nationalistic retro-racism" the author seems to hype - at least no more so than exists now. But even for political correctness, there will always be those who will deny that differences exist in the face of evidence (just as in the case of "nationalistic retro-racism") as the recent gender studies skirmishes show.

mlinsey• 17 years ago

It was Obama and Dick Cheney.

araneae2• 17 years ago

The central problem is that people don't understand what "heritable" or "genetic" really means. Every trait you can possibly think of has a genetic basis. I.e. having green hair is heritable, because people who dye their hair funny colors are more likely to be risk takers, and those personality traits are more likely in people with a higher fraction with such-and-such neurotransmitter receptors, and the number of those receptors is influenced by some gene by a few percentage points.

Just because it's genetic doesn't mean it's meaningful, anymore than it's really meaningful to say that this mutation which means you have 1% more of x receptor makes you go out and dye your hair green. It's ridiculous, and that's the kind of relationship that all these genes have with pretty much all phenotypes. The reason the effects are so small is because what the gene does is so far removed and from whatever phenotype you're studying. (usually)

goodside2• 17 years ago

'The central problem is that people don't understand what "heritable" or "genetic" really means.'

Apparently so. Heritability does not mean genetic causation. Language is extremely heritable (that is, children almost always speak the same language as their parents), and not because there's a long just-so chain of genetic and hormone events that ends in an innate facility for Cantonese.

cabalamat2• 17 years ago

That's true, but having said that, there are alleles that affect the nature of the language people speak. So there are alleles that give onre better facility at speaking tonal languages, and those alleles are (surprise, surprise) more common among populations that speak tonal languages (such as Chinese).

gort• 17 years ago

"Heritability" means something like "how much of the variation in a population is due to genetic differences". This leads to some odd results, e.g. number of arms has low heritability (almost all variation is due to environment).

Anyway, language is not heritable. The variation in the languages people speak in a population is not due to genes but rather to environmental effects.

carbocation3• 17 years ago

"The reason the effects are so small is because what the gene does is so far removed and from whatever phenotype you're studying."

... unless you study a medically relevant phenotype, in which case the genes are often just a few steps away (namely, transcription and translation, with processing thrown in for good measure).

I would agree that heritability is not all that meaningful (though technically valid) when talking about behavioral traits, though.

araneae2• 17 years ago

There's no reason that medically relevant phenotypes would be that much less complicated (and lets remember that mental health, is, in fact, medically relevant.)

Yes, there are a select few, rare, single nucleotide polymorphisms that are responsible for congenital genetic defects. But plenty of disease involves the interactions of thousands of genes, like cancer, and for those it's really just as meaningless.

lunchbox• 17 years ago

The author's thesis statement is the following:

"The new genetics will reveal much less than hoped about how to cure disease, and much more than feared about human evolution and inequality, including genetic differences between classes, ethnicities and races."

This thesis is revisited in the section on whole genome sequencing:

"The trouble is, the resequencing data will reveal much more about human evolutionary history and ethnic differences than they will about disease genes."

However, it's never explained why next-generation whole genome sequencing will lead to success for one endeavor but not for the other. He only says that today's DNA chips (which don't reveal the whole genome) have failed to uncover the genetic basis for disease.

lionhearted• 17 years ago

Edit: Wow, this turned out to be long. Also, this is fairly politically and potentially "identity hot" and I didn't add in a lot of caveats and disclaimers. If I may humbly request, could you read at least halfway through the comment before voting, and please write in and let me know if it offends, or with any concerns or suggestions? Also, my email is in my profile if I seem off and you're lurking without an account or don't want to comment publicly. I imagine people could read a lot into what I'm saying that I'm not saying, so please feel very welcome to make yourself heard by me if you disagree or dislike anything I've put down. Also, I didn't mention any of the downward spiral thinking that knuckleheads could potentially get into - and yeah, I agree that stuff is ugly and we need to be careful, and no, I'm not a knucklehead. Anyway:

I can tell a lot about someone by asking them in private, when it's just me and them, "So... what do you think of genetic differences between races?" Almost everyone, in private, will agree that there's some - but some people are really, really uncomfortable saying it. Some people, especially very diplomatic people, hedge and qualify first. When I make it known that I'm not particularly judgmental, that I've had friends and lovers of all colors and from all over the place, but that I also have a healthy respect for science and reality - well, the diplomatic people tend to open up a lot more.

Basically I'll put it like this - people of difference descendencies have been observed to have different average heights, weights, body fat percentages, average musculatures, bone densities. Different kinds of blood cells even - if you look at sickle cell anemia, blood cells shaped a little differently than normal make a person more resistant to malaria, but more prone to anemia. Malaria of course, being orders of magnitude more deadly and dangerous than anemia, which is a more long term unhealthiness thing. And sure enough, sickle cells are more present as an adaptation in people descending from formerly high malaria areas - http://en.wikipedia.org/wiki/Sickle-cell_disease#Genetics

Moving on - there's clearly slight variances and differences between people of different descendants. The idea that there's no cognitive differences just seems incredibly unlikely. Now, I think "IQ" or "intelligence" is drastically oversimplified and bunk. But things like abstract recall - how fast can you remember something? Pattern recognition. Dexterity and coordination. And so on - why wouldn't these things be adaptable and heritable? Wouldn't some parts of the world being able to remember a skill after not using it for a long period of time be more valuable than others? (places with harsh winters, for instance?) The ability to think quickly and adapt be better in different places? And if they were, wouldn't you expect natural and sexual selection to make the local population more like that?

This is almost all moot in many practical ways - the only thing that bothers me is that since people don't want to acknowledge that these differences exist, there's been very little work to learn teaching styles that would apply to different people, how different medicine and diet regimes would work better, and so on.

Different groups of people tend towards different lactose intolerance and alcohol intolerance levels - this is only recently being considered in nutrition and diet because the implications of it - different food good better for different races - is not a good political position these days. It would have been easy to test for lactose sensitivity among different groups of people and make recommendations 20-50 years ago, but no one wanted to touch it. Instead, "milk for everyone!" was the official position, which is nonsense. Dairy is terrible for the people it's bad for.

Finally - I'm very curious about what the effects of mixing blood in children would be, and there's been very little research that I know of. From my understanding of genetics, mixed blood children should be particularly strong. My background is mixed Western/Eastern European, and I'd prefer a wife of different bloodlines than my own, as I think it's a very positive thing to do for my children. Obviously you can't control who you fall in love and connect with completely, but if I choose to live in Ankara or Osaka instead of London, that greatly increases the chance my kids are half-Turkish or half-Japanese. I think that'd make them stronger, healthier, and less prone to some of the negative things in my bloodlines. But how much so? When parents have different cognitive backgrounds, which are dominant? For instance, if one parent has much higher natural testosterone levels, is that dominant? That means the children would have higher energy, be more resistant to some diseases, be more willing to act independently and defy consensus, but also have more proneness to violence, anger, and aggression. I generally have high testosterone throughout my family - we've made good soldiers but some of us have had pretty bad tempers. What happens if I marry a woman with a lower natural predisposition towards testosterone? How about different cognitive abilities? We've generally got bad eyesight and bad spatial relations in my family. You'd expect good eyesight should be a dominant characteristic, no? But how much so?

I'd love to see research on this, and I think we will, because you can only hold back science and knowledge through moral fashion for so long before it breaks through.

CamperBob• 17 years ago

The idea that there's no cognitive differences just seems incredibly unlikely.

As long as the difference between individuals in a single population is greater than the mean difference between populations themselves, I don't see much relevance.

Sure, Negroid races as a group don't have the IQ of Caucasians. But Caucasians who attach any importance to that had better look over their shoulder at the Asians, who in turn beat them on the same tests. The Asians don't want to get too smug in a room full of Ashkenazi Jews. Meanwhile, there are plenty of individual Negroids and whitey-birds who outperform plenty of individual Asians and Ashkenazis.

If any lessons have emerged so far from the study of human genetics, it's that your genes are not your destiny. In any just society, an individual's success will always consist of 90% perspiration, 8% inspiration, and 2% DNA.

radu_floricica2• 17 years ago

I'd say even more difference comes from culture. Asians are a huge population, but those who have the greatest success are those with a strong culture for education (Japan, China, South Korea). The same, there are black people on several continents, and the ones who are the easiest to criticize are those who either have a lack of modern culture (countries which didn't completely recover from colonialism) of made a counter-culture which pointedly rejects everything white, including the good parts (education, work ethics etc).

Given these huge differences, a few points of IQ really don't seem to mean anything.

w00pla10• 17 years ago

> As long as the difference between individuals in a single population is greater than the mean difference between populations themselves, I don't see much relevance.

This part is the Lewontin's fallacy (http://en.wikipedia.org/wiki/Lewontin%27s_Fallacy)

tokenadult6• 17 years ago

If any lessons have emerged so far from the study of human genetics, it's that your genes are not your destiny.

Yes, this is something that the leading researchers on human behavioral genetics increasingly acknowledge.

http://news.ycombinator.com/item?id=838534

(The pay-wall workaround mentioned in that submission is no longer active, but the citation to the very current article is still correct.)

Dilpil• 17 years ago

Would mixing two very different gene pools necessarily take the maximum of positive traits from each parent? Couldn't it possibly take the average or even minimum?

Natural selection operates only by influencing who mates- it does not impact the way in which genes are spliced. That is left to the molecular structure of the genes themselves I believe.

bmunro• 17 years ago

A lot of heritable diseases are recessive traits - dominant genes are easier to select against.

Two people from the same background/race etc. are far more likely to carry the same recessive genes for a disease than two from different backgrounds.

This is why inbreeding produces unhealthy individuals. Two individuals that share a parent/grandparent etc will be very likely to inherit identical recessive disease genes from the parent.

Two people of different backgrounds will have offspring that are somewhat more likely to be healthy and have fewer problems.

maxklein6• 17 years ago

It's easy to have this opinion when you are from the group perceived as superior. When you are from the group that is going to receive the "scientifically validated" stamp of inferiority, I think you would be very much against such statements as advocated in the article.

randallsquared2• 17 years ago

So, in your opinion, it's "okay" to have this view if you're not east asian or jewish, but not if you are?

JulianMorrison• 17 years ago

Drawing lines around big groups of people and making sweeping generalizations is exactly what will be made obsolete by proper sequence-the-whole-DNA genetics. You really don't have to give a damn if one parent's ancestry is this and another's is that, if you can look at the actual genes. As information, it's "screened off" - knowing it tells you nothing extra.

frig• 17 years ago

For all the thought you've put into your comment you clearly have a lot of your ego -- probably too much -- invested in being the guy who's not afraid to publicly point out it might be worth making scientific inquiry into racial differences.

Let me point out exactly how you're being stupid here.

The article is about future ramifications of genetic sequencing technology finally becoming economical enough that it's possible to cheaply sequence a person's complete DNA.

You're right that this will allow research to be done of the form: grab a DB with 100k different peoples' sequences; discover strong statistical associations between such-and-such genes and such-and-such amount of alcohol intolerance, and notice that those genes are particularly prevalent amongst people of asian descent.

Where you go awry is your conceptualization of how this information will likely be used; it's a failure to take a premise you've accepted in one part of your scenario -- the premise that DNA sequencing will be cheap-and-thorough enough to allow for research like just sketched -- and failing to apply it to another part of your scenario -- the doctor-patient interaction, and so on.

Given a world in which DNA sequencing is super-cheap and super-affordable, which doctor-patient interaction is likelier:

- doctor says to patient: "you clearly are asian just by looking at you. asians have been shown to have lower alcohol tolerance on average. be careful with how much alcohol you imbibe."

- doctor says to patient: "your DNA sequence contains 7 of the 10 major genes associated with higher levels of alcohol intolerance. this isn't surprising given your family history, but it's nice to know concretely what you've got. be careful with how much alcohol you imbibe."

...which is why you're being stupid: race is a proxy measure for ancestry that's "field-performable" (just look!) and cost-effective and is not an entirely useless proxy measure for ancestry; it is indeed the case that were political bugaboos different than they are that some useful research could be done to characterize racial differences that could be put to general use.

It's also a terribly inaccurate proxy and given the ability to do direct DNA sequencing would be dropped like hotcakes; why use the inaccurate proxy when you can make a direct measurement?

So even in your hypothetical example of looking for a wife: when this research is available, would you not be better served testing for specific genes in a particular individual rather than cutting it off at the level of race? You might still want to move to Ankara if you discovered that "Turks" are likelier than Brits to carry the genes you want your kids to have, but would you really not take it further and check the specific woman's DNA directly (the way that some jews test for tay-sachs at some point in the courtship process)? If you take the research seriously enough to move to Ankara to stack the deck why stop there?

You're essentially making the same kind of mental error you saw in the early dot-com days where people understood that "in the future, you'll buy stuff at home over the internet" -- so were semi-prescient -- but couldn't discard what they already knew about "shopping"; the consequence being that they'd write articles about how you'd sign into some 3d virtual world and then visit an online bookstore and browse the shelves in virtual reality (transporting outdated ideas into a world of new possibilities).

tokenadult6• 17 years ago

I'm very curious about what the effects of mixing blood in children would be, and there's been very little research that I know of.

Actually, there is plenty of research, and most of the research reaches a conclusion consistent with the main point of the submitted article, that people being "mixed" as to "race" doesn't really matter much at the individual level. That's to be expected from Motoo Kimura's now well established theory of neutral molecular evolution,

http://en.wikipedia.org/wiki/Neutral_theory_of_molecular_evo...

which fits human populations quite as well as it fits other organisms.

I write this as a western man (American by citizenship, with ancestry from various temperate and Arctic zone European countries) who married and has four children by a woman from Taiwan (whose traceable ancestry is south Chinese, tropical rather than temperate zone). My four children are healthy, smart (by IQ test), and arguably good-looking, and very ambiguous to untrained eyes as to their "racial" heritage. (My oldest son has variously been described as Asian in America, western in Taiwan, "black" in America, and "Hispanic" in America, and could pass as "Native American" in America.) Before I met my wife, I met many people in Taiwan, where I was then living, who earnestly urged me to marry a Taiwanese woman because then my children would be "smarter and better-looking," which seems to be a common cultural belief about half-Asian, half-western people over there. But I really don't have the slightest evidence that my children have been advantaged in any way by their rather divergent "racial" heritage, and actually my marriage was quite assortative,

http://en.wikipedia.org/wiki/Assortative_mating

http://www.britannica.com/EBchecked/topic/39494/assortative-...

as most marriages are. My wife and I are similar in height, build, presence of allergies, myopia,

http://en.wikipedia.org/wiki/Myopia#Epidemiology

skin color, personal recreational habits, IQ, etc., etc., etc.

Any man can gain a lot of perspective on life from his wife, and it's important to cherish the differences that will still show up even though most people marry assortatively. A cross-cultural marriage will include plenty of differences of cultural assumptions that make for thought-provoking conversation and a richer family life for both spouses and all the children. We have enjoyed our twenty-six years together.

jhancock• 17 years ago

Congratulations on your 26 years together. Cross-cultural marriages can be challenging but rewarding. I've been with my Chinese wife for only 8 years and we have only one son thus far. Whether in Shanghai or small town Georgia, he usually gets attention as being the most beautiful child in the room ;). I account for any noticed positive traits mostly to my being a proud father (I probably only notice the compliments).

berntb• 17 years ago

>>Now, I think "IQ" or "intelligence" is drastically oversimplified and bunk.

Interesting, that goes against what I've seen intelligence researchers claim (g, etc). Do you have good references?

I'm not arguing, I'm asking because I'm curious. I'm aware that some idealists breath fire over this question, but I don't have a horse in that race (as I think the expression is?).

nazgulnarsil2• 17 years ago

the points are moot in a meritocracy. the only reason this is an issue is because entitlements are at stake.

cabalamat2• 17 years ago

No, the reason its an issue is that people's emotions are tied up in their opinions of their own species. They want to believe cetain things about humans, and when science shows them that reality is different from their beliefs, some people take it very badly and refuse to accept reality.

A good example of this is the "controversy" over evolution v. creationism; there's no real controversy, of course, but some people just refuse to accept the reality of evolution so they've created a whole ideology of evolution denial to boost their flagging self esteem. (I suspect that at some deep hidden level, evolution deniers do accept it).

nazgulnarsil2• 17 years ago

good point. I harp about ideology being an inappropriate ego boundary extension all the time but failed to apply it in this case.

dahv• 17 years ago

This article completely side stepped issues of how important everything else is to our lives. We won't solve disease by genetic knowledge. What food we eat, the happiness in our lives, our exercise...these are so important. Genetic knowledge won't teach us how to be healthy, just and peaceful.

As for the differences between the races, as much as they might exist, I can't believe how people can be blind to how culture is extremely influencial.

Take your so-called smarter race (e.g. asian), take them to a "dumber" place like America, and in a few generations they'll be just as dumb.

And the asians aren't smarter. I live in China now, teaching English. Their education system, and the Asian education system in general (i.e. China/Japan/Korea) strongly develops certain skills. Mostly, these involve analysis, logic, and memorization.

However, while this form of education is outstanding for producing people that can do very well at coursework and following directions (as well as become excellent engineers/doctors/research assistants/accountants), it is very poor at producing people who can think for themselves and be creative thinkers. It certainly does not develop critical thinking.

As for the African stereotype...have you looked at what's going on over there? Damn if I could study or learn shit if I'm a starving refugee.

Oh, and I can't believe nobody's seen the film "Gattaca."

tokenadult6• 17 years ago

while this form of education is outstanding for producing people that can do very well at coursework and following directions (as well as become excellent engineers/doctors/research assistants/accountants), it is very poor at producing people who can think for themselves and be creative thinkers. It certainly does not develop critical thinking.

If you are living in China, you are living under a political system in which the current regime dare not encourage critical thinking. As Taiwan democratized, the scope of common people to express critical thinking (about their government and about all other issues of public concern) increased greatly. In other words, the educational system in China is holding back critical thinking only insofar as it needs to be in line with the one-party political system. Sometimes dictatorships have mostly good education in all respects that don't threaten the dictatorship. See

http://news.ycombinator.com/item?id=977549

for my submission of a long, interesting article by a Russian author who now lives outside Russia on mathematics education in Russia and the United States, and how each relates to the governance of each country.

w00pla10• 17 years ago

> Damn if I could study or learn shit if I'm a starving refugee.

You know that most (90%+) Africans are not starving? Africa isn't filled by starving refugees as CNN would like you to believe.

I think the most common comparison with Africans is in the USA.

> Oh, and I can't believe nobody's seen the film "Gattaca."

This is an excellent (and was my favorite) movie and I identify strongly with the main character.

While the movie sends a powerful image, now matter how hard you try, you will not change a person's general intelligence (which is innate).

tokenadult6• 17 years ago

While the movie sends a powerful image, now matter how hard you try, you will not change a person's general intelligence (which is innate).

What is the evidence for this? Most human behavorial genetics researchers talk about a "reaction surface" set for each individual by that individual's genes, but I'm not aware of any researcher who claims to have a proof for an upper limit in how much "general intelligence" (that would be IQ) can change in the case of individuals or in the case of populations. In fact, the existing OBSERVED degree of IQ increases all around the world

http://en.wikipedia.org/wiki/Flynn_effect

has been described by N. J. Mackintosh in these terms: "the data are surprising, demolish some long-cherished beliefs, and raise a number of other interesting issues along the way." (Mackintosh 1998, p. 104). You write, "no matter how hard you try," but it's not clear anyone is trying very hard or very systematically to raise anyone's general intellilgence, but it is happening anyway.

I meet weekly with human behavioral genetics researchers

http://www.psych.umn.edu/courses/fall09/mcguem/psy8935/defau...

and have learned from them that the whole field of human behavorial genetics is becoming much more conservative and cautious in its claims about genetic limits on human potential than it was ten years ago. That's what is said explicitly by Tom Bouchard, one of the most cited researchers in the field.

REFERENCE

Mackintosh, N. J. (1998). IQ and Human Intelligence. Oxford: Oxford University Press.

P.S. Other good, recent reading on this subject is

Neisser, Ulric (Ed.) (1998). The Rising Curve: Long-Term Gains in IQ and Related Measures. Washington, DC: American Psychological Association.

Flynn, James R. (2009). What Is Intelligence: Beyond the Flynn Effect. Cambridge: Cambridge University Press.

Estragon• 17 years ago

I work in this field. The reasons for these problems are probably relatively simple.

1) Current GWASs focus on common variants, but the population explosion over the last few thousand years means it's likely that most human genetic diversity is rare.

2) Current GWASs focus on the marginal effects of variation at single-nucleotide sites, but it's likely that there are complex interactions between different variations.

These misplaced foci of current GWASs have more to do with what we could do with current technology than with what we ought to do, given these biological realities: sequencing was so expensive that it was hard to determine the rare variants; sample sizes were so small that we had to use simplifying statistical assumptions like independent phenotypic effects from each nucleotide variation. Those technological limitations are changing, now.

The "thoughtful geneticists" the article refers to aren't just wringing their hands about this. They are working on both of these issues. (I'm one of them.)

randallsquared2• 17 years ago

Interestingly, the article mentions both of your listed problems as possible escapes from the conclusion.

bioweek• 17 years ago

That sounds fascinating. Are you hiring ...

carbocation3• 17 years ago

I also work in this field. This article is interesting and gets some things right (although is overly alarmist, in my opinion). There are opinions in this article that I disagree with, however.

For example, I disagree with the statement that "... classical Mendelian genetics based on family studies has identified far more disease-risk genes with larger effects than GWAS research has so far."

First, under selection, one would not expect common variants to have tremendous, deleterious effects in general. Second, it is not true that Mendelian studies are superior to GWAS in, say, lipoprotein genetics. There, virtually all of the genes known from studies of Mendelian disorders have been re-discovered through GWAS, with many new findings that were previously unknown. Furthermore, a substantial portion of lipid heritability (~20%) could be explained by GWAS-identified loci as of January 2009. There there is little reason to believe that common variants (>=5% minor allele frequency) should explain all of heritability; so far, so good. The upcoming 100,000 individual lipids GWAS should do a pretty good job of sucking at the marrow for the remaining common variants.

We work with the tools that we have. SNP-chips enabled GWAS. Now that "next-gen" sequencing (worst buzzword ever) has brought down costs, the thousand genomes project will provide us with a list of nearly all variants with MAF>1%. Well-funded groups can afford to deep sequence their population of choice. These provide information that is complementary to the information obtained by GWAS.

In conclusion, GWAS is good for finding common variants. Imputation from thousand genomes should be good for finding low-frequency (>1% MAF) variants. And sequencing is good for finding rare variants. There is no crisis.

narag2• 17 years ago

I'm very confused by the article. Not sure if it's because the language or because it's not very clear. On the one hand it says that there are too little evidence of "hereditability" to be useful to cure diseases. On the other hand it says that there is a lot of evidence, to the point of being "disturbing", of racial traits. What am I reading wrong?

carbocation3• 17 years ago

Regarding the missing heritability, they are claiming that this is a deficiency of GWAS. It then goes on to talk about sequencing, which it says will find lots of evidence for miscegenation, etc. (To which I say, sure, but what of it?)

In case you are not familiar with the methods, the difference between GWAS/SNP analysis and sequencing is this: GWAS relies on surveying ~500,000 (up to 6 million now, but it doesn't really matter) known single nucleotide polymorphisms. So you might ask, "which nucleotides of this subset of the human genome differ in a systematic way between cases and controls."

With sequencing, you are surveying all nucleotides, not just a subset of 500,000. So you instead ask "which nucleotides out of the 3 billion (haploid) differ between cases and controls?"

gfodor• 17 years ago

Shooting down the notion that genetics are tied to race and thusly tied to positive or negative traits brings really brings out the anecdotal evidence logical fallacy in full force.

Just remember, anecdotal evidence is largely the same "logic" used by racists to justify broad stereotypes of people.

kingkongreveng_• 17 years ago

> the genes typically do not replicate across studies. Even when they do replicate, they never explain more than a tiny fraction of any interesting trait.

Epigenetics. Diet and lifestyle have large effects on how a genome is expressed. And even on how the genome is expressed in future generations.

I thought this was well understood? Why no mention of it in the article?

Chi019• 17 years ago

No, Lewontin's fallacy is the belief that if this is true for every trait, the populations are indistinguishable.

Physics Prof Steve Hsu explains the Lewtontin fallacy here:

Further technical comment: you may have read the misleading statistic, spread by the intellectually dishonest Lewontin, that 85% percent of all human genetic variation occurs within groups and only 15% between groups. The statistic is true, but what is often falsely claimed is that this breakup of variances (larger within group than between group) prevents any meaningful genetic classification of populations. This false conclusion neglects the correlations in the genetic data that are revealed in a cluster analysis. See here for a simple example which shows that there can be dramatic group differences in phenotypes even if every version of every gene is found in two groups -- as long as the frequency or probability distributions are distinct. Sadly, understanding this point requires just enough mathematical ability that it has eluded all but a small number of experts.) Update: see here for an explanation in pictures of Lewontin's fallacy. I also edited the paragraph above for clarity.

On the other hand, for most phenotypes (examples: height or IQ, which are both fairly heritable, except in cases of extreme environmental deprivation), there is significant overlap between different population distributions. That is, Swedes might be taller than Vietnamese on average, but the range of heights within each group is larger than the difference in the averages. Nevertheless, at the tails of the distribution one would find very large discrepancies: for example the percentage of the Swedish population that is over 2 meters tall (6"7) might be 5 or 10 times as large as the percentage of the Vietnamese population. If two groups differed by, say, 10 points in average IQ (2/3 of a standard deviation), the respective distributions would overlap quite a bit (more in-group than between-group variation), but the fraction of people with IQ above some threshold (e.g., >140) would be radically different. It has been claimed that 20% of all Americans with IQ > 140 are Jewish, even though Jews comprise only 3% of the total population.

    ...The imbalance continues to increase for still higher IQ’s. New York City’s public-school system used to administer a pencil-and-paper IQ test to its entire school population. In 1954, a psychologist used those test results to identify all 28 children in the New York public-school system with measured IQ’s of 170 or higher. Of those 28, 24 were Jews.

There is no strong evidence yet for specific gene variants (alleles) that lead to group differences (differences between clusters) in behavior or intelligence, but progress on the genomic side of this question will be rapid in coming years, as the price to sequence a genome is dropping at an exponential rate.

What seems to be true (from preliminary studies) is that the gene variants that were under strong selection (reached fixation) over the last 10k years are different in different clusters. That is, the way that modern people in each cluster differ, due to natural selection, from their own ancestors 10k years ago is not the same in each cluster -- we have been, at least at the genetic level, experiencing divergent evolution.

In fact, recent research suggests that 7% or more of all our genes are mutant versions that replaced earlier variants through natural selection over the last tens of thousands of years. There was little gene flow between continental clusters ("races") during that period, so there is circumstantial evidence for group differences beyond the already established ones (superficial appearance, disease resistance).

http://infoproc.blogspot.com/2008/01/no-scientific-basis-for...

cryofan• 17 years ago

oh, no, if genetics reveal differences in humans, then that will make it harder for the rich people to combine many races into each workplace, each neighborhood, each city and each nation. Diversity is how the rich people divide the population, and if the population cannot be divided, then the population will unite against the rich.

Remember, Kids--Diversity is strength....(for the rich)

The looming crisis in human genetics

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