Gunther Stent was one of the leading figures in the 'phage group, a group of molecular biologists who transformed the science of biology back in the 1940's, '50's, and 60's. He died on June 12th [Gunther Stent, an Early Researcher in Molecular Biology, Is Dead at 84].Today's Citation Classic from John Dennehy is the book The Molecular Biology of Bacterial Viruses by Gunther Stent. In keeping with his main theme, John often uses the citation classic to highlight the influence of past scientists and not necessarily the significance of a single paper. Stent's name is not associated with any one experiment, or even a series of experiments. His influence extended well beyond his ability to do important experiments.
I first encountered Gunther Stent at the annual 'phage meeting held at Cold Spring Harbor every summer. I learned pretty quickly that he thought on a different plane than the rest of us. I also observed first hand the respect he earned from other famous biologists. At the time I was just a graduate student, I'm certain that Gunther Stent was unaware of my existence.
Later on I began to read Stent's articles on the history and philosophy of biology and I was greatly influenced by his writing.1 Stent had an amazing ability to sift through the garbage and get to the heart of an argument; especially if that meant going against the perceived wisdom of his intellectual peers. Here are two examples from THE DILEMMA OF SCIENCE AND MORALS published in Zygon in March 1975. Stent is discussing contradictions between modern science and Western moral traditions.
The first example we might consider concerns the teaching of evolution in the public schools, which evidently has come a long way from the days of the Scopes Monkey Trial in Tennessee half a century ago. In 1972 the Curriculum Commission of the California State Board of Education held hearings in response to the demand of some Christian fundamentalist groups that in the officially approved biology textbooks the biblical account of Creation ought to be presented on an equal footing with the Darwinian view as an explanation of the origin of’ life and of the species. Although much of the argument before the Commission pertained to the question of whether the theory of evolution is merely an unproven speculation, as alleged by the fundamentalists, or a solidly documented scientific proposition, as claimed by the biologists, the deeper point at issue was religious freedom.
For the fundamentalists held that a Christian child in a tax supported school has as much right to be protected from the dogmas of atheism as an atheist child has to be protected from prayer. Hence, it would follow that the classroom teaching of Darwinism as the only explanation of biocosmogony is an infringement of the religious freedom of Christian parents to raise their children in the faith of their choice. This argument seems completely justified, whether or not it is true as claimed in pro-Darwinian testimony at the hearings by liberal, apologist clergymen that one can be a good Christian without taking the biblical account of Genesis all that literally. After all, the fundamentalist faith is to take the Bible literally. But the inference that follows from admitting the justice of the fundamentalist claim is not that biology texts should give Genesis equal time with evolution. Rather, it is to be concluded that no public school system can operate effectively in a heterogeneous social setting without having its curriculum prejudice the minds of the pupils against the cherished beliefs of some of the citizens. In other words, in this case the ultimate Christian ethical aim of freedom and individual rights has to give way to the pagan aim of mounting a pedagogically effective society.
The second example is much more controversial, yet the logic is impeccable. This is not the sort of thing that modern liberals (I am one) want to hear, but the very fact that they cover their ears and chant nonsense verses at the top of their lungs is the problem that Stent addresses. Most of us don't realize that the conflict between science and culture is much deeper than the fight between scientist and Biblical literalists would suggest. If you are going to adopt the positions of science and rationalism then there are some implications that may be hard to confront. Sweeping them under the rug, as many try to do, is hypocritical.
We may now consider the ethical conflicts surrounding two applications of human genetics. One of these is the very troublesome matter, at least for present-day American society, of the heritability of intelligence and in particular of the problem whether there exist significant racial differences in intelligence genotype. On the one hand, it seems reasonable to think that if there is a significant variation in the genetic contribution to intelligence between individuals, or between racial groups, then this factor ought to be taken into account in the organization of society. But, on the other hand, the mere acknowledgment of the existence of this factor, let alone taking it into account in social action, seems morally inadmissible, a scientistic underpinning of racist ideology. An excellent exposition of this problem was recently provided by W. Bodmer and L. L. Cavalli-Sforza, who show that the heritability of intelligence, unlike extrasensory perception and telepathy, is a genuine scientific proposition.
First, it is possible to obtain a meaningful measure of intelligence through IQ tests, at least insofar as the concept of intelligence applies to the capacity to succeed in the society in whose contextual setting the tests are given. Second, there do exist significant differences in IQ between individuals and between social and racial subgroups. Third, it is possible, at least in principle, to perform studies that can ascertain the relative contribution of genetic and environmental factors to the observed differences in IQ. Bodmer and Cavalli-Sforza find that there is sufficient evidence at present to make it very likely that within a socioeconomically homogeneous group heredity does make a significant contribution to extant differences in IQ. When it comes to the considerably lower mean IQ of American blacks, however, they conclude not only that the currently available data are inadequate to ascertain whether this fact is attributable mainly to hereditary or mainly to environmental differences, but “that the question of a possible genetic basis for the race IQ differences will be almost impossible to answer satisfactorily before the environmental differences between U.S. blacks and whites have been substantially reduced. . . .” Finally, “[since] for the present at least, no good case can be made for [studies on racial IQ differences], either on scientific or practical grounds, we do not see any point in particularly encouraging the use of public funds for their support. There are many more useful biological problems for the scientist to attack.”
In my opinion, this recommendation, which trivializes the problem scientifically, amounts to taking the easy way out from a serious dilemma. What if, as Bodmer and Cavalli-Sforza admit could be true, there does exist a significant genetic contribution to the mean IQ differences found between blacks and whites? They think that this “should not, in a genuinely democratic society free of race prejudice, make any differene.”’~ But if the races really differed hereditarily in intelligence, then racism would not be a “prejudice” but a true perception ofthe world and one of which a rational society ought to take account. For instance, in this case, the black-white disparities in socioeconomic levels would not reflect discrimination at all but merely an underlying biological reality. And hence the aim of an egalitarian, multiracial society would be just another unattainable, utopian dream. We thus encounter another Machiavellian contradiction between the two incompatible ethical systems of our heritage. The pagan ethics of communal purpose, which science serves, would demand that every effort be made to ascertain whether the member races of a multiracial society do in fact differ hereditarily in their intelligence. But the Christian ethics of ultimate values, which inspire science, holds racism to be an absolute evil in that it is subversive of the fundamental concept of the freedom and responsibility of the human soul. Hence, these ethics demand an uncompromisingly hard line against research on race intelligence. Since there must not be any hereditarily determined racial differences in intelligence, research that entertains the possibility of such differences is a priori evil.
In today's world we need more Gunther Stent's, not fewer.
1. Incidentally, I'm currently reading Richard Dawkin's anthology of Modern Science Writing. Stent is not in that book but, then again, neither are many other scientists who should be there. It's probably no coincidence that most of those scientists express opinions that differ from those of Richard Dawkins.
[Photo Credit: Left-to-right: Esther Lederberg, Gunther Stent, Sydney Brenner and Joshua Lederberg. From Wikipedia : "The original photo is owned by the Esther M. Zimmer Lederberg Estate. With the permission of that Estate's Trustee, Matthew Simon, I have adapted the photo for free use."
I, too, met Gunther Stent on a couple of occasions, during his "end of science" phase.
ReplyDeleteStent's writings contributed to the disillusion and abandonment of science that we see so often, even this many years later. IMHO, he discouraged young scientists, and one could make a case that he enabled the creationists.
What unmitigated horsehocky, and a smirch on an otherwise distinguished career.
Frank
This is the stupidest thing ever...Stent credits christianism with antiracism, when christianism has proven repeatedly to be compatible with racism.
ReplyDeleteHe wants us to become racists out of anti-religious paranoia? Please. There is stupid: and then there is Stent stupid.
If silly arguments like these are all the "evidence" for racial differences in IQ that you have, Larry... Again, if you studied the environmental factors that affect intelligence, you would not say something as blatantly false and stupid as "genes are the reason why smart people tend to have smart chidren"
You're looking like a mere Ben Stein to me on this topic, Larry. Nobody is stoppping research inopt racism. The simple fact is that the evidence is not there.
Stent just follows in the tradition of jackasses ilke Watson who think ideas taht are merely politically incorrect are also truths that cannot be investigated. And that's it!! They completely ignore the fact that racism was before considered true until curcial, "classic" studies were shamefully debunked by Gould and Lewontin. Do neoracists have scientific data for their racism? None whatsoever. Only this conspiracy argument, which is retarded, and false.
ReplyDeleteI prefer holocaust deniers and 9/11 conspiracists...they are much less harmful than Noble prizes talking out of their ass, to begin with (Neither Watson or Stent are experts on the topic, just mere "opinologists")
At first the description of Stent's reasoning sounded like our Torbjörn Tännsjö, a professor in philosophy who holds a chair in 'Practical Philosophy' at Stockholm University. He also draws out arguments to a logical conclusion, despite its controversial nature.
ReplyDeleteBut when I noted that Tännsjö is what I think philosophers would say a consequentialist (actually, a utilitarian). For example, Tännsjö doesn't claim that terrorism is bad in itself, but due to its consequences. (A position which got him criticism from likewise rational Ingemar Hedenius, the philosopher that shamed the Swedish church from arguing apologetics in the national arena.)
Tännsjö would probably claim that research on racial differences isn't bad in itself, nor is the society that would take such differences into account bad in itself, but the later has bad consequences.
So what about racial differences in size? Small organisms would be much more efficient than large, consuming less food, clothes or in general area (and minerals). Seems to me a rational society ought to take that into account, and accept that bacteria has priority over others for socioeconomic reasons.
I think what Stent does is admirable; but I do think his methods lack a certain je ne sais guoi.
This comment has been removed by the author.
ReplyDelete"Intelligence genes" do not carry in themselves a fix, additive contribution to intelligence.
ReplyDeleteEpistatic interactions are sufficient reason to refute Larry's silly "folk wisdom" that "genes are the reason why smart parents tend to have smart children"
You see, a combination or cocktail of genes that may contribute to a person's intelligence can be lost in sexual combination at the next generation!. If you care to read any Lewontin, this idea of "blood lines" of intelligence (an idea older than science, by the way) is nothing but baloney (That's good news for your children, Larry: They are NOT condemend to repeat your sillines!!).
Note I am not saying anything like there is no genetic component of intelligence. I am only demanding the minimal dose of sophistication the topic demands, on purely biological terms. This is a complex trait. It's not wrinkly peas and a single loci that we are talking about here.
Intelligence is spread out among many, many genes. Their interactions, and their interactions with the environment contribute to this trait.
The mere presence of a gene does not ensure it's contribution to intelligence. For instance, it is never the case that people will consistently do better in IQ tests if they have a given gene. Rather, their effect is argued using statistical tools: "propensity", rather than determination, of a slight increase in IQ tests.
This is because,a s stated above, whether the gene has an effect or not will depend on the other genes as well as on the environment; such is the nature of this complex trait. (Indeed, the best "intelligence gene" ever argued depends completely on breast-feeding for its effect)
Do I even need to mention the environment at this point? Epistasis is enough!
All I'll say is that environment, demonstrably, has a HUGE effect on intelligence, quite capable of doing away with any small genetically determined differences (Indeed, even mutations that produce mental retardation can be rescued with an appropiate nutrition).
I recommend everyone to read Harvard population geneticist Richard Lewontin on this topic,and specially how non-additivity relates to reaction norms that have different, non-overlapping curves.
Larry, you are just not being a good scientists. You come alogn with these whiney politcla arguments rather than data, and romaticize the politically incorrect only becuase of a wrong headed, vacuous "rationalism". You think you are showing yourself "oh so rational", challenging the emotions with non-PC statements.
Rational truths are so completely regardless of our emotions, be they bad OR good. Bad emotions do not indicate rational truths, Larry. Sorry if you were trying to make a great demonstration of "reason over emotions"...for "forcing" the point, you just end up showing how easily are mislead by vacuous "rationalist" demagoguery.
This topic is actually quite biological, Larry.
Sanders: "Intelligence genes" do not carry in themselves a fix, additive contribution to intelligence.”
ReplyDeleteAnd the person who says they do is ...?
Sanders: "Intelligence is spread out among many, many genes. Their interactions, and their interactions with the environment contribute to this trait.”
And the person who disputes this is ...?
Sanders: “For instance, it is never the case that people will consistently do better in IQ tests if they have a given gene.”
And the person who asserts that this is so is ...?
Sanders: “This is because, as stated above, whether the gene has an effect or not will depend on the other genes as well as on the environment; such is the nature of this complex trait.”
And the person who disputes this is ...?
Sanders: “Epistasis is enough!”
That is a very bold assertion. Citation please.
Instead of attacking strawman opponents with sophomoric arguments, how about taking on, say, the findings of the “twin” studies? The evidence that intelligence has a strong and significant genetic component is compelling and not easily dismissed with denialist tactics. Further, outside of abusive or nutritionally or psychologically impoverished situations, no one really knows what “environment” is (although it's been studied hard). About the best one can do to define “environment” in this context is that it is “not genetic.”
No one disputes that the difference in intelligence between members of two species is genetic. To assert, in the face of the evidence to the contrary, that the difference in intelligence between two members of a given species has no genetic basis at all ranks right up there with the denialists of evolution: in both cases it appears to be people motivated by ideology.
Sanders: “I prefer holocaust deniers and 9/11 conspiracists...”
Naturally.
To Sanders:
ReplyDeleteNice hat.
Divalent,
ReplyDeleteIs it OK to say that the genetic determination of intelligence is "the reason why smart people tend to have smart children"?
See Larry's comments in:
http://sandwalk.blogspot.com/2008/06/blacks-have-rhythm-asians-arent.html
That phrase is nothing but poor science. Different things, beyond genes, enable to replicate the intelligence of parents...such as a wealthy, highly educated socio-economical context, vs. an undernourished, uneducated context of poverty. These things have undeniable effects, quite more readily demonstrable and well-documented than any proposal of "intelligence genes".
"how about taking on, say, the findings of the “twin” studies?"
Lewontin takes them on, specially regarding the uncontrolled aspects of the lives of twins. Also, check this out:
Nature. 1997 388(6641):417-8.
The heritability of IQ.
Devlin B, Daniels M, Roeder K.
IQ heritability, the portion of a population's IQ variability attributable to the effects of genes, has been investigated for nearly a century, yet it remains controversial. Covariance between relatives may be due not only to genes, but also to shared environments, and most previous models have assumed different degrees of similarity induced by environments specific to twins, to non-twin siblings (henceforth siblings), and to parents and offspring. We now evaluate an alternative model that replaces these three environments by two maternal womb environments, one for twins and another for siblings, along with a common home environment. Meta-analysis of 212 previous studies shows that our 'maternal-effects' model fits the data better than the 'family-environments' model. Maternal effects, often assumed to be negligible, account for 20% of covariance between twins and 5% between siblings, and the effects of genes are correspondingly reduced, with two measures of heritability being less than 50%. The shared maternal environment may explain the striking correlation between the IQs of twins, especially those of adult twins that were reared apart. IQ heritability increases during early childhood, but whether it stabilizes thereafter remains unclear. A recent study of octogenarians, for instance, suggests that IQ heritability either remains constant through adolescence and adulthood, or continues to increase with age. Although the latter hypothesis has recently been endorsed, it gathers only modest statistical support in our analysis when compared to the maternal-effects hypothesis. Our analysis suggests that it will be important to understand the basis for these maternal effects if ways in which IQ might be increased are to be identified.
"No one disputes that the difference in intelligence between members of two species is genetic"
I dispute it is "merely" genetic. Despite limitations of genetic differences, you can get a Gorilla or chimpanzee to know sign language and participate in a human context quite beyond anything it would use in nature. Likewise, a human isolated from the context of language is unlikely to learn to talk (as suggested by hundreds of cases of children brought up under strange or depriving conditions)
As to how much the behavior of a certain species can resemble that of another, depending on its developmental environment, was tested by Kuo, in the 30's and 40's, who raised different species together, using surrogate mothers...with very interesting results.
"To assert, in the face of the evidence to the contrary, that the difference in intelligence between two members of a given species has no genetic basis at all ranks right up there with the denialists of evolution: in both cases it appears to be people motivated by ideology"
Every single biological process has some genetic "basis", be it the toenail of my foot or polka-dancing.
The question is whether it is genetically DETERMINED. Do you know what determined is in developmental biology?
The fact that, as in anything, genes are required, does not mean the trait cannot be affected by environment (specially the nutritional and cultural environment for intelligence) nor does it mean that environmental conditions did not have an important role in the evolution of species differences.
I prefer holocaust deniers and 9/11 conspiracists becuase they are obviously nuts... but when academics, supposed "rationalists", notable (or not-so notable) biochemistry professors, decide to reach outside the realm of their expertise, to proclaim that genetic determination of intelligence is "airtight", that smart people have smart babies because of their genes... and further romanticize racism as the unfair taboo of science...
I'm sorry. That's just too much stupidity rolled up together.
It's Arthur Jensen and "The Bell Curve" all over again. Stephen Jay Gould must be turning in his grave. And to think I believed IQ had been sufficiently debunked by psychologists and biologists years ago.
ReplyDeleteChristophe Thill says,
ReplyDeleteIt's Arthur Jensen and "The Bell Curve" all over again. Stephen Jay Gould must be turning in his grave. And to think I believed IQ had been sufficiently debunked by psychologists and biologists years ago.
I side with Gould (and Lewontin) in the fight against biological determinism. I'm also on their side when it comes to combating the misuse of science. Like them, I believe that the best society will be a socialist one.
Stent wasn't talking about any of those things and neither was I in past postings. The complaint in these cases is against all those who side with the "good guys" but who go too far. Those people (see comments above) would have you believe that there cannot be a genetic component to intelligence.
Why do they make such a silly claim? Because to admit that intelligence might be hereditary opens up the possibility that different groups might have statistically different numbers of alleles for intelligence.
Since that possibility is too difficult to deal with, they prefer to stick their head in the sand and pretend that genes (alleles) cannot affect intelligence.
Gould knew the difference between real science and his fight against biological determinism and the misuse of science. That's why he writes in The Mismeasure of Man (p. 155) ...
The hereditariona fallacy is not the simple claim that IQ is to some degree "heritable." I have no doubt that it is, though the degree has clearly been exaggerated by the most avid hereditarians. It is hard to find any broad aspect of human performance or anatomy that has no heritable component at all. The hereditarian fallacy resides in two false implications drawn frm this basic fact:
1. The equation of "heritable" with "inevitable." ....
2. The confusion of within- and between-group heredity....
Gould has never claimed that genes (alleles) play no role in intelligence. His arguments are always against false exaggerated claims and against social policies based on those false claims.
He has made this point many times, not only in The Mismeasure of Man but elsewhere as well. Here's a quotation from his essay "Racist Arguments and IQ" reprinted in Ever Since Darwin (p. 243).
I do not claim that intelligence, however defined, has no genetic basis—I regard it as trivially true, uninteresting, and unimportant that it does. The expression of any trait represents a complex interaction of heredity and environment. Our job is simply to provide the best environmental situationfor the realization of valued potential in all individuals.
I agree with Gould. Let's provide the best environment possible for everyone in our society. You don't do that by pretending that individuals don't have genetic differences.
"I agree with Gould. Let's provide the best environment possible for everyone in our society"
ReplyDeleteI'm pretty sure this is NOT what your other dirty little heroes
Stent and Watson are thinking. Environmental supplementation may be useless, a waste, if there is no genetic potential there.
Didin't you say "we need more Stents"? This is how Stent thinks:
"But if the races really differed hereditarily in intelligence (...) the black-white disparities in socioeconomic levels would not reflect discrimination at all but merely an underlying biological reality. And hence the aim of an egalitarian, multiracial society would be just another unattainable, utopian dream"
Let's clear up a little more the story about "intelligence genes", where Larry fails to make some important and inescapable biological distinctions.
There is a big difference between alleles that ruin intelligence, which have pretty obvious and large effects (no statistics needed), and genes that supposedly ADD intelligence (whose effects are, surprise, always difficult to detect). Larry flunks here (once again), failing to make the distinction between "necessary" and "sufficient". Genes are necessary building blocks for a normal intelligence, but they do not "contain" intelligence. I have already pointed out that nutrition and cultural environment are EQUALLY necessary to attain simply NORMAL levels of intelligence.
"Because to admit that intelligence might be hereditary opens up the possibility that different groups might have statistically different numbers of alleles for intelligence Since that possibility is too difficult to deal with, they prefer to stick their head in the sand and pretend that genes (alleles) cannot affect intelligence."
Again: your Ben stein syndrome of persecution is false. Different groups with statistically different numbers of "intelligence alleles" have already been documented. If I remember correctly, Ashkenazi jews have greater frequencies of alleles that produce severe mental disorders.
Do you think some PC complot is trying to hide these facts? No, because it is obvious that the greater frequency of these diseases does not imply that this group in any way of inferior genetic intelligence. The substantial majority has functional genes.
Their higher frequency may reflect bottleneck events of the population history (much like with many other crippling genetic diseases also differently represented in different groups).
Now, a different thing is whether you think POSITIVE SELECTION has been tweaking (improving) the general "genetic intelligence" of any specific group: that is, not by eliminating the mentally deficient, but by the greater success and accumulation of genes that tend to "add" to intelligence.
Unfortunately, when a gene has only mild effects, and further, when it often has no effect at all depending on context (either of genetic or environmental background).... selection is going to be veeeery inefficient. And such is the case with every gene that has ever been suggested to "add" to intelligence.
"Unfortunately, when a gene has only mild effects, and further, when it often has no effect at all depending on context (either of genetic or environmental background).... selection is going to be veeeery inefficient. And such is the case with every gene that has ever been suggested to "add" to intelligence."
ReplyDeleteAnd yet, however you measure it, in any genetic deme there is a variation in "intelligence" (dull people and bright people, and lots of ordinary people)- so something is causing a trait to vary. Twin and sibling studies suggest that this is not down solely to environment.
If intelligence is causal or correlated with evolutionary fitness, then in a population of the right size and environment it will be selected for.
Now that may be true of populations, but it is not necessarily true of individuals. So if dark green people were brighter on average than light green people, that would be a scientific finding. To assume in advance that a particular light green person was stupid would be predjudice.
Now I don't know whether the claims that different genetic demes (I'm avoiding the unscientific judgement of 'race by colour') on average are true, but I would be very suprised if there wasn't at least some variation between demes, if only because I suspect there are too many different environments for natural selection *not* to work.
But once we get past the scientific data, we have to decide what to do about it... is is not ought, after all.
LM:
ReplyDeleteThose people (see comments above) would have you believe that there cannot be a genetic component to intelligence.
Hmm. You lost me here, which are "those people" in which comments?
I believe that the best society will be a socialist one.
In an ironic twist, economists debate how much of free market and interventionism that characterizes societies mixed economies.
Let's provide the best environment possible for everyone in our society. You don't do that by pretending that individuals don't have genetic differences.
Reasonable agenda. Dunno what basis from which to conclude that ethically (except utilitarian, so it is "good" for something - which is kind of ironic) - not Stent's obviously.
DJ:
ReplyDeleteIf intelligence is causal or correlated with evolutionary fitness, then in a population of the right size and environment it will be selected for.
Layman here, but let me walk this through from my ignorant perspective to see if I understand some of this.
If John Hawks et al are correct and specifically natural selection rate has increased two orders of magnitude in humans because of environmental change (need for selection) and population increase (response to selection), wouldn't one be on the lookout for such effects as above?
Besides, AFAIU they claim massive selective sweeps from this, a cause for near neutral changes as well I assume, so that wouldn't be much of a loophole.
This would tend to agree and support your argument I believe.
So what would happen if selection or sweep is at work here? Say selection; would the variance in your genetic demes decrease, and all demes be pushed in the same direction, but at different responsive speed and final fixated magnitude? If so, wouldn't it be hard to predict if the overall (over all demes) variance would go up or down?
In other words, is it possible to say beforehand that if intelligence has a genetic component and happens to be selectable (or sweepable), that the final outcome will in principle be any different for a global society (as an effect) than if it is purely environmental? It doesn't even have to be a multimodal outcome over the global society, does it?
Maybe one has to separate further; population effect, individual outcome (as you note), societal effect (i.e. how individuals would respond to presented facts, regardless of the actual population effects), and societal "ought".
Torbjörn Larsson:
ReplyDeleteMy suspicion is that intelligence is a selectable trait, although I also expect that extremely dull or extremely bright people may be less fit from an evolutionary point of view.
However intelligence is just one trait amongst many and there will be trade-offs. Take lactase retention for instance. This genetic change (which varies from deme to deme) enables older children and adults to digest milk successfully. Does this trait reduce selection effectiveness for intelligence (because people with retention have a better diet and don't have to hunt or gather so much) - or does it increase the selectability for intelligence (because a better diet enables more growth of brain cells during development, increasing variation for selection)? I've no idea.
And as for sexual selection, that is another argument entirely.
There is not a single case of an intelligence gene that has been positively selected in a given group, and it's not because they haven't being looking for it (as "Ben Stein" Moran thinks).
ReplyDeleteMicrocephalin, required for normal brain growth, is an excellent example. It has been argued to have been selected outside of africa, using tests that are based on the frequency of alleles (These require making some assumptions about population history & equilibrium). But when you test whether the allegedly selected alleles improve IQ, there is absolutely no difference. I consider the greater frequencies of certain microcephalin alleles outside of africa to be the probable result of a founding effect.
Usually, genes that can be selected have a consistent, readily observable phenotype (even if subtle) and a known mechanism of selection, for instance, sickle cell and immunity to malaria.
The fact that despite years of research no such thing has ever been documented for an "intelligence gene" is consistent with the complexity of the trait at hand, since context-dependency of the effects of genes involved makes them difficult to select (this is not a trait resulting from merely additive effects of genes, as assumed in Fisher's models)
And no, this does not mean that intelligence cannot evolve, or that it could not have evolved. Negative selection is always there, but it's not what produced greater intelligence in humans. Behavioral plasticity is the forefront runner, mutation and negative selection follow behind.
I can give you some empiricla examples of animals about how behavioral plasticity directs evolution. This fact was acknowledged by Mayr himslef.
At the end of the day, the bigger problem is the narrow, reductionist view of evolution, centered only on genes and selection.
Also: the experiment of selection of intelligence in humans has been attempted in may ways, some more drastic than others, and was formalized in the practice of eugenics. It would not surprise me that some actually more extensive or serious attempts were tried out in history. The nazis selected their own "wonder" children (none of which became the new Einstein)
ReplyDeleteI do not expect any process of selection to be capable of producing a lineage increased in intelligence, since the genes do not have simply additive or even consistent effects.
In other words, my prediction for any regime thinking about selecting intelligence in humans: colossal failure!
It just doesn't work like that. If you want smarter people, the good old-fashioned library is the better approach.