The looming crisis in human genetics

Great Debates
81

(Apologizing for truncating what may be some of your key points, but they are enumerated just above…)

A spirited defense, indeed, of what I might summarize as the notion that environmental variables can never be perfectly controlled for, and therefore we should only draw the conclusion that genes have some, but permanently unquantifiable, influence in phenotypic expression.

While I disagree with this view, I recognize that it provides significant comfort to those who want us to all humans be the same–who want to believe the Bambuti would secure proportionate representation in the NBA if they simply had the same nurturing…

OK.

82

So Chief Pedant, you say that you are aware that there is an unquantifiable and ;potential overwhelming uncertainty regarding the relative effects of genes and environment. And you acknowledge that there is no possible mechanism to disentangle the two. And you acknowledge that there is no evidence at the moment that genes are important.
Yet every post you have in this thread has stated that the contribution of environment is minor and can be readily controlled for.
Which of these are we to believe?

83

Why? I mean why this belief? There certainly doesn’t seem to be much ( if any ) evidence for this now.

I mean I commend you for keeping an open mind about possibly being wrong. But the impression I get is that you think this is highly doubtful. But being confident, for example, that genetic differences in intelligence will be traced to just a few key genes rather than a model involving hundreds complexly interacting with the environment, seems on the face of it to be not much more sophisticated than simple faith. Or is it your preconceived notions that you are looking to validate, in much the same way you claim others are :)?

84

I don’t understand why people are so hot and bothered by this statement. Of course genetics will be controversial. In the places where it confirms people’s prejudices there will be a lot of I told you so’s, and in places where it shows those prejudices to be bullshit there will be a lot of I told you so’s. But in any case, it’s going to happen.

I just think that people aren’t really very imaginative about this. They think of ‘IQ’ as a genetic trait, but don’t really give much thought to breaking down what IQ might mean. Faster and more solid neuronal connections leading to a stronger memory? A slightly higher conduction speed leading to faster calculation/reflexes? Increases of milliseconds can make a HUGE difference in the speed of a person to act.

Perhaps one group of people is more likely to have quick sympathetic responses, that allows them to act more quickly, while some other people have a stronger parasympathetic response which leads to them being, ‘chill bra’.

The essential point of this is that the make-up of our consciousness is a highly parallel structure, and any slight increase in any of the minor faculties that make up our major cognitive processes will be beneficial to those processes. So genetics will likely to determine certain feature-sets in aggregate, where it still won’t allow us to judge a person by their ethnicity as there are so many factors going in to determining predisposition, that we’ll still have outliers that deviate from the mean within any ethnic grouping.

85

My apologies if I have not stated my own bias clearly: environmental influences can be, and have been, reasonably accounted for in determining the relative influence of nature versus nurture. Genes are critical and all evidence to date supports that contention.

For a given individual, the contribution of nurture might be quite profound in determining their current success, though the lack of success is not typically irreversible. For the most part, it is a testable hypothesis that even a given individual’s specific success or failure at a given pursuit is a result of their nature or nurture since, for the most part, nurturing influences do not do permanent damage.

Example: Tiger and I, and golf. Tiger had optimum nurturing on top of optimum genetic gifts. He’s the best there is. I have marginal genetic gifts for that skillset; my golf handicap is doomed to remain in the single digits, even had I been exposed to Tiger-level nurturing. That maximum potential is determined by my genes. Moreover–and this is the testable part–here’s a thought experiment: limit Tiger’s exposure to golf until he is, say, 20. Give me optimum golf coaching from birth until I am 20. Now give Tiger–with his current gene set access to optimum golf coaching. Within a brief period of time Tiger would overtake me and be better (though not world #1). In the real world, so to speak, this happens all the time, whether the skillset being improved upon is learning calculus, memorizing history or playing basketball. While nurturing has a strong influence on improving anyone, the ceiling it bumps up against is the individual’s genetic heritage.

86

This is what he asserts in every thread on this subject. What is interesting is that he matter-of-factly insists that nurture can readily be controlled for when comparing two different populations, but he never uses the terms that show he understands how scientists actually do this. The results of hypothetical “what if” experiments are his evidence. Not evidence that already exists.

There is no non-insulting way to tell another poster that they don’t know what they are talking about, which is why I don’t even bother anymore.

87

Tiger Woods had the optimum nurturing for golf talent? Really? The best possible environment, ever? What about that time he was sick for three days when he was 12 and didn’t get to practice? That’s suboptimum, ain’t it?

He was trained by his Dad, but was his Dad the best golf coach in the universe? Tiger Woods also didn’t have the virtual reality training that will become available in 2047, nor the direct neural stimulation training available in 2199.

And the thing is, Tiger Woods may be a great golfer, and if you had the same training you’d probably be a shitty golfer. And that’s because of Tiger’s inborn talent. No one is arguing that there is no such thing as talent. But what exactly is that talent? There ain’t no “good golfer” gene. Tiger has some inborn constellation of good reflexes, good eyesight (enhanced by LASIK surgery to 15/20!), steady nerves, intense focus, superior accuracy, and great physical condition that allow him to excel at golf.

But maybe he missed his calling as the best watchmaker in Zurich, if only he had been born in 18th Century Switzerland to a family of watchmakers. More likely, he’d be the best hunter in the village if he had been born at a more typical period in human history. Unless he got clawed by a leopard when he was 12, which damaged his hand and one eye, so instead he limps around the village and makes crappy clay pots, because he can’t hunt anymore.

88

The article does cite twin studies to back up the belief that genetics does play a role in determining intelligence. However, twin studies themselves are in doubt. The idea behind such studies is that if identical twins show more similarities than fraternal twins, the difference can only be explained by genetics. But there’s no sound reasoning behind this; there are any number of factors which could, potentially, drive the behavior of twins closer together.

Can you point to some of those factors? Joseph suggests an ideal experiment:

…a scientifically acceptable study would compare the resemblance of a group consisting of MZAs reared apart from birth and unknown to each other, versus a control group consisting not of reared-together identical twins, but of biologically unrelated pairs of strangers sharing all of the following characteristics: they should be the same age, they should be the same sex, they should be the same ethnicity, the correlation of their rearing environment socioeconomic status should be similar to that of the MZA group, they should be similar in appearance and attractiveness, and the degree of similarity of their cultural backgrounds should be equal to that of the MZA pairs. Moreover, they should have no contact with each other until after they are evaluated and tested.

Well, look at ‘virtual twins’ - pairs of adoptive children, or a biological child and an adoptive child, who are very near in age and have been reared together since infancy.11 Like adoptees, VTs do not share genes but only the environment. Most important, they replicate the twin situation, but without the genetic link. Since they are matched so closely in age and time spent in the home, virtual twins provide a tighter control than usual adoption studies. And they provide a pure estimate of environmental effects.

The correlation in IQ for 90 pairs of VTs was .2612 compared to typical correlations of .86 for MZs, .60 for DZs and .50 for ordinary siblings. (Some of the VT pairs were of different sex; so are some DZ and sibling pairs.) We can also compare the VT correlation against those for MZ twins reared apart (.78) and DZ twins reared together (.60). The fact that MZ twins who do not share environments are more alike than VTs who do is difficult to explain without reference to genetic factors.

*Personally, I would look at it this way. The twin studies do, generally, suggest a genetic link to intelligence and other products of the human mind. But the actual tests of the genome keep coming up blank, and that’s much stronger evidence against a genetic link, strong enough to overrule the twin studies. Bottom line: the 98% of us who aren’t twins should have some say in this matter too. *

Studies don’t just look at twins.

“Data from more than 8000 parent-offspring pairs, 25,000 sibling pairs, 10,000 twin pairs and adoption studies provide evidence that genetic factors play a substantial role in the variation of general intelligence, with heritability estimates ranging from 40 to 80%”

–Burdick et al, Cognitive variation in DTNBP1 influence general cognitive ability. Human Molecular Genetics, 2006, Vol 15, No. 10.

89

Personally, I would look at it this way. The twin studies do, generally, suggest a genetic link to intelligence and other products of the human mind. But the actual tests of the genome keep coming up blank, and that’s much stronger evidence against a genetic link, strong enough to overrule the twin studies.

Nonsense. Human height is a highly heritable, classic polygenic trait. Until recently, there had been limited success in identifying the specific genetic variants that explain normal variation of human height. The advent of large-scale genome-wide association studies, however, has led to dramatic progress. In the past 18 months, the first robust common variant associations were identified and there are now 44 loci known to influence normal variation of height. You will probably see similar progress with intelligence. There are likely to have identified hundreds of genes affecting IQ.

90

On the issue of brains, establishing a link between certain brain structures and personality types doesn’t prove that the personality types are determined by genes. Neuroplasticity–the ability of the brain to “rewire” it’s own neurons, creating new pathways and removing or altering old ones–is an established fact. Some instances of severe epilepsy are treated by removing half of the brain, yet even in that extreme instance the brain can compensate and regain the functionality that was lost; it doesn’t even take a particularly long time. Hence, there’s experimental evidence that the functionality of our brain is not determined by the state we’re in at birth.

Far from confirming that our brains are entirely or mainly shaped by our genes, there is experimental evidence that the shape of our brains are highly dependent on the experiences we undergo. From this article:

and

Once again, it comes down to evidence. Evolutionary psychologists posit the exist of a large number of “modules” governing behavior such as eating, mating, social living, and so forth, there’s just no evidence that these modules exist. Or as the Panskepp duo puts it:

Put in plain English, that means that the evolution of the brain gave as a brain capable of changing to do what’s appropriate in new situations, not one that’s genetically programmed to do certain things all the time.

91

I have never denied the genetic role in shaping two legs, nor in things like height as Chen suggests. What I doubt is the role that genes supposedly play in shaping what everyone would agree to be parts of our personality. For example, in the Pinker article he lists intelligence, religiosity, political orientation, television watching, and so forth. That’s where I don’t see any evidence that our genes are in control.

Obviously I’m aware of the argument that genes provide a propensity in a certain direction. Some people having even gone so far as assigning numbers, such as saying that violent behavior is sixty percent determined by genes and forty percent not. But this is silly. Imagine that I slapped you and then said, “Don’t blame me! That was sixty percent the fault of my caveman ancestors.” Obviously if I perform an action, it was either my choice to perform it or else it wasn’t. I can’t make forty percent of the choice and have sixty percent of the choice made for me.

Nobody would deny that people have certain tendencies in behavior, “grooves” that they fall into. If someone watches four hours of TV every evening, it’s easy to keep up that pattern and difficult to break it. Nonetheless, choice still exists. A person with a propensity either chooses to follow the propensity or chooses to break out of it. At the bottom of every human action, there is choice.

Which leads us to the point that there’s a group of people out there who have even closer genetic ties than identical twins. I speak, of course, of a single individual at different times in his or her life. For example, when I was a teenager, I watched television constantly. Now, I barely ever watch it at all. So what’s up with that. Clearly when I was a teen, I felt a propensity towards watching TV. Now I feel no such propensity. So therefore I cannot have had any propensity encoded into my genes for that particular topic. And since individuals can choose to change their habits, beliefs, and preferences during their lifetimes, the same argument works for any other portion of personality.

92

Then you haven’t met my neighbors :stuck_out_tongue:

What is it that motivates people to try to prove something like this? So let’s say we do discover that some groups of people are “less capable” than others. When the world finally figures out that the people with genes similar to mine are all stupid and violent is the government going to start hunting us down? Just asking so I can prepare. Or is the whole point of the exercise so we can finally say “I told you so, those people are inferior to us!” Seems like a big waste of money if that is all we get, unless the research can reveal a way for the losers to straighten up and fly right.

93

Exactly. Bottom line, Chief Pedant is a racist; as are many others that routinely post in threads such as these. This is their religion. No point in arguing facts and studies with men of faith.

94

*brickbacon wrote
Exactly. Bottom line, Chief Pedant is a racist; as are many others that routinely post in threads such as these. This is their religion. No point in arguing facts and studies with men of faith. *

Exactly, it’s easier & more persuasive to just use the race card on them.

95

We’ve argued against the guy repeatedly and it’s always the same ole stuff: racialist ideology dressed up in evidence-deficient assertions and bullshit that falls apart under slight scrutiny. After a certain point it’s not “playing the race card” to call a duck a duck; it’s simply stating the obvious.

::looking down at my watch::

By my calculations, the NBA is scheduled to appear in this thread very shortly. We will be told that the predominance of blacks in basketball is proof that athletic abilities are influenced by race, therefore intelligence is too. White predominance in hockey, golf, and tennis will be dismissed as counterevidence of this claim. Basketball, we will be told, is equally accessible and socially desirable by all races and ethnic groups, ergo, black overrepresentation has to mean blacks are genetically inclined to be athletic. That American blacks are actually shorter than American whites on average will be disregarded. Why? Don’t ask why, it just will be for unexplained reasons. After pages of discussion, a cite may finally be scrouged up to support these earnest assertions, but a cursory examination of the material will show that the cite doesn’t support the assertion at all. Cue the end of the thread when we realize we are talking with a True Believer masquerading as an open-minded scientist.

There. I just saved this thread from going on for 7 pages. Any questions?

96

This is correct, I think, under the ordinary definition of the word. I am also a sexist. I believe, in short, that there are genetic differences among any two populations, and within certain populations the disparate distributions create average phenotypic differences at the population level which are immutable despite nurturing.

The question of interest should be not so much what term is correct as which concept is correct. Would the Bambuti, if given equal opportunity and nurturing, be proportionately represented in the NBA? Those who would say “no” are, by definition, racists.

Perhaps that last question of mine can be directed toward You With the Face… :slight_smile:

97

(Bolding mine)

All of those things are given their maximum potential for expression by genes. There may not be “a” good golfer gene, but the potential for greatness is established by genes, and the limitation to excellence despite nurturing is genes.

You have confused the issue around nurturing. To whatever extent Tiger did not have perfect nurturing and still ended up the best golfer in the world, that’s evidence for genes and not nurturing. And to whatever extent other individuals have had equivalently superb nurturing and did not end up performing at Tiger’s skill level, that’s evidence for genes. You have, unfortunately, undermined the very point you are trying to make (assuming you are trying to argue against genes).

But you are correct in saying that I would be a poor golfer and Tiger would be a great golfer with identical training. The difference is that his training would be layered upon superior genes.

98

The reason I hold this view (that g will be determined by a handful of genes rather than hundreds) is that it seems to me to be most consistent with Occam’s razor and most likely from an evolutionary perspective.

Consider height as a parallel. We humans have a broad range of heights and various populations (Bambuti and Dinkas, say) have significant average differences within the ranges of their cohort. It’s possible that hundreds of genes govern this (and of course, as with intellect, a substantial percent of one’s phenotypic potential is environmental) but so far we haven’t found hundreds.

Nevertheless, it does not fundamentally change much of anything substantive; the position that there is disparate gene distribution among various cohorts does not require an acceptance that only a handful of genes govern a phenotypic trait. In any case, the time is not so far away when we’ll find out for sure, I think (to the point of the OP).

99

*By my calculations, the NBA is scheduled to appear in this thread very shortly. We will be told that the predominance of blacks in basketball is proof that athletic abilities are influenced by race, therefore intelligence is too. White predominance in hockey, golf, and tennis will be dismissed as counterevidence of this claim. Basketball, we will be told, is equally accessible and socially desirable by all races and ethnic groups, ergo, black overrepresentation has to mean blacks are genetically inclined to be athletic. That American blacks are actually shorter than American whites on average will be disregarded. Why? Don’t ask why, it just will be for unexplained reasons. After pages of discussion, a cite may finally be scrouged up to support these earnest assertions, but a cursory examination of the material will show that the cite doesn’t support the assertion at all. Cue the end of the thread when we realize we are talking with a True Believer masquerading as an open-minded scientist.

There. I just saved this thread from going on for 7 pages. Any questions?
*

The basic point I think is that genes influence many abilities. And genes show different frequency distributions across groups leading to average group differences.

One example is the RR variant of ACTN3, a gene that affects fast generation of muscular force and correlates with excellence at speed and power sports. The opposite variant of the gene is called XX. Tests indicate that the ratio of people with RR to people with XX is 1 to 1 among Asians, 2 to 1 among European whites, and more than 4 to 1 among African-Americans.

In terms of different average performance across sports Jon Entine wrote a book about this about a decade ago. Slate also tackled the subject during the Beijing Olympics. Entine’s piece is a bit out of date, but is interesting in terms of the different groups who tend to do well in different sports.

http://www.jonentine.com/reviews/straw_man_of_race.htm

Physics Prof Steve Hsu has written some posts about this also.

100

His arguments are not persuasive, and he is a racist. He even admits it.

Brilliant!