Keith Hudson wrote:
> Intelligence looms high on the 'desirable traits' list and, as it is
> now acknowledged to be about 70-80% heritable, it has to be an attribute
> which will show clear step-wise gains from one generation to the next.
> Apparently, Prof Robert Lynn ("Eugenics: a reassessment", Praeger Press,
> 2000) thinks that successive gains of 10-15 IQ points will be possible for
> at least two or three successive generations, genius levels for all
> descendants being attainable in a couple of centuries.
> The problem is that the genes for intelligence are still largely
> unknown and probably numerous -- at least 12 -- but Prof Plomin,
> Deputy Director of King's College, London, thinks that it will not
> be long before they are identifiable. ("Behavioral Genetics",
> W.H.Freeman, 2000).FYI: ------------------------------------------------------------------ ------------------------------------------------------------------ Date: Thu, 04 Apr 2002 10:55:46 -0800 From: [EMAIL PROTECTED] To: [EMAIL PROTECTED], [EMAIL PROTECTED] Subject: [**] Nutrition, Cognition, "IQ" clipped from: http://groups.yahoo.com/group/selfish_genes > Date: Wed, 03 Apr 2002 16:10:31 -0600 > From: [EMAIL PROTECTED] > Subject: RE: IQ, EQ and S-G's > You are proposing a hypothesis that malnourishment is the > precurser to intellectual deficits. Once again I wish to refer you > to Arthur Jensen, "Bias in Mental Testing" where this as well as > numerous other hypotheses are addressed with empirical studies. As > for this hypothesis, when one is malnourished to the point that > the central nervous system is stunted resulting in cognitive > deficits, the problems are not limited to the nervous system. The > stunting is seen in muscular and skeletal as well as other > systems. On IQ tests the lowest scoring group in the US is the > African American population which is also the biggest physically. > Just because you can think of a possible pathway to explain the > difference: "When people are malnourished it is only logical to > assume that their resultant IQ would be less," this does not mean > that you have generated any research that actually supports this > hypothesis or that you have examined the literature to find how > the research goes. Please do your homework. There's plenty of research, if you care to look. For starters, try these: vitamins and cognition http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query_old?form=4&db=m&term=vitamins+%26+cognition%5Bmh%5D&dispmax=50&relpubdate=No+Limit&field=All+Fields nutrition and cognition http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query_old?form=4&db=m&term=nutrition+%26+cognition%5Bmh%5D&dispmax=50&relpubdate=No+Limit&field=All+Fields docosahexaenoic acid and cognition http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query_old?form=4&db=m&term=docosahexaenoic+%26+cognition%5Bmh%5D&dispmax=50&relpubdate=No+Limit&field=All+Fields general pubmed (medline) searching: http://www.provide.net/~aelewis/aels/pubmed.htm Note the very interesting work with docosahexaenoic acid (DHA) -- the fish-oil fatty acid (abstract below, URL above) -- suggesting cognitive enhancement when infants are well-supplied with it. Breast milk is much higher in DHA than formula. Could widespread use of commercial infant formulae have caused a small but cumulatively significant decline in mean population IQ? I dunno. But I am tempted to think so, searching as I am for some halfway-rational explanation for the creeping incompetence and witlessness that seems to have become pandemic even in my short (48 yrs) life. :-( By the way, there is an interesting short discussion on the possible utility of improved nutrition for IQ enhancement on pages 391-3 of Herrnstein and Murray's book The Bell Curve. It only cites literature up to 1991; a lot has happened in this area since then, and some of the more significant findings even before then are not mentioned (i.e. it is not a great or exhaustive or current discussion). I bring it up only to point out that that book -- which has been so derided and maliciously mischaracterized (e.g. as a book which thesis is that "blacks are inferior to whites") -- focussed not only on description and statistical analysis, but also on possible remedies. The discussion of remedies was never mentioned in the reams of deprecation and invective aimed at the work. Alan ------------------ http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query_old?uid=10755457&form=6&db=m&Dopt=b Dev Med Child Neurol 2000 Mar;42(3):174-81 A randomized controlled trial of early dietary supply of long-chain polyunsaturated fatty acids and mental development in term infants. Birch EE, Garfield S, Hoffman DR, Uauy R, Birch DG Retina Foundation of the Southwest, Dallas, TX 75231, USA. [EMAIL PROTECTED] The effects of dietary docosahexaenoic acid (DHA) supply during infancy on later cognitive development of healthy term infants were evaluated in a randomized clinical trial of infant formula milk supplemented with 0.35% DHA or with 0.36% DHA and 0.72% arachidonic acid (AA), or control formula which provided no DHA or AA. Fifty-six 18-month-old children (26 male, 30 female) who were enrolled in the trial within the first 5 days of life and fed the assigned diet to 17 weeks of age were tested using the Bayley Scales of Infant Development, 2nd edition (BSID-II) (Bayley 1993) at the Retina Foundation of the Southwest, Dallas, TX. These children had also been assessed at 4 months and 12 months of age for blood fatty-acid composition, sweep visual evoked potential (VEP) acuity, and forced-choice preferential looking (FPL) acuity (Birch et al. 1998). Supplementation of infant formula with DHA+AA was associated with a mean increase of 7 points on the Mental Development Index (MDI) of the BSID-II. Both the cognitive and motor subscales of the MDI showed a significant developmental age advantage for DHA- and DHA+AA-supplemented groups over the control group. While a similar trend was found for the language subscale, it did not reach statistical significance. Neither the Psychomotor Development Index nor the Behavior Rating Scale of the BSID-II showed significant differences among diet groups, consistent with a specific advantage of DHA supplementation on mental development. Significant correlations between plasma and RBC-DHA at 4 months of age but not at 12 months of age and MDI at 18 months of age suggest that early dietary supply of DHA was a major dietary determinant of improved performance on the MDI. Publication Types: Clinical trial Randomized controlled trial PMID: 10755457, UI: 20216233 ------------------------------------------------------------------ ------------------------------------------------------------------ Date: Sun, 07 Apr 2002 12:24:31 -0700 From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] CC: [EMAIL PROTECTED] Subject: [*] Re: Subject: 77% Heredity, 23% Environmen > Date: Sat, 06 Apr 2002 18:21:47 -0600 > From: [EMAIL PROTECTED] > Subject: 77% Heredity, 23% Environment > The point I wish to emphasize is that the majority of the variance > in adult IQ is from genetically based sources. Indeed, that is how it may look right now, given the fact that no one has ever mounted a decent-scale, sufficient-length prospective study of the effects of plausibly-effective nutritional interventions on mean IQ of a population. One does not know until one tries -- and no one has tried. > When measuring the intelligence of large groups of people with > known kinship, the portion of the variance that is accounted by > the kinship variable can be estimated. When the studies are done > with children, lower estimates are found because there are many > environmental variables that come into play from the family. When > the familial, educational, nutritional, and other environmental > variables are held constant, the heredity estimate emerges. In > adults the estimate approaches 80%. Did the researchers control for (e.g.) intake of specific fatty acids (DHA) that were not even known to have a relation to cognitive abilities until, say, 5-10 years ago? Our knowledge of this stuff is still in its infancy. (And unfortunately may remain in infancy, if civilization collapses.) The idea of making a final pronouncement as to the relative contributions of genetics and environment seems silly to me, at this point. We don't yet know what the critical variables might be. > I doubt that my comments will change the mind of any die-hard IQ > environmentalist. I just wanted to clarify the issue for those > that still evaluate the data. Where are the "die-hard IQ environmentalists"? For myself, I watch, read, think... and am open to whatever the data reveals, as well as to new ideas about where the data might lead (if someone bothered to pursue), and am allergic to conclusions rendered before anyone even knows which are the right questions. And if it turns out that IQ is 100% genetic, well, SO BE IT. I, for one, want the truth, not a PC lie. Alan ------------------------------------------------------------------ ------------------------------------------------------------------ Date: Wed, 03 Jul 2002 22:18:35 -0400 From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Re: IQ, environment, and all that > Date: Wed, 03 Jul 2002 10:14:29 -0000 > From: "wolfgang_mozart2" <[EMAIL PROTECTED]> > Subject: Re: IQ, environment, and all that > It seems improbable that that the 4 cubic inch difference in brain > size between East Asians and Blacks is due to environment. Or The issue I raised in my post was IQ, behavior (criminal or not), etc., not anatomy. > consider the huge magnitude of difference between the Jewish median > IQ of 117 and the Sub-Saharan Black median IQ of 70 (borderline > retardation). There is just too much evidence that the differences > in general intelligence is mostly genetic, 80% is genetic, 20% is > environment. There is a lot of research at http://www.eugenics.net/ The 80:20 "fact" was based on evidence now rapidly being dated and superceded by exciting new work such as what I cited, and more; see below. You understand, I trust, that all scientific "facts", and especially ones in biology and medicine, and *especially* especially ones having to do with extremely complex, high-order stuff like behavior and cognitive function, are highly-tentative by their very nature, and subject to repeated revision as new and better information becomes available. In a generation or two, after science has had a chance to really account for the relevant factors, we may be able to make good, solid general statements about the extent to which IQ is genetic or environmental. But for now we are still in the infancy of scientific study of the matter. If you choose, you could start actually reading the research currently being published; see search URLs below. -------------------- Date: Thu, 04 Apr 2002 10:55:46 -0800 From: [EMAIL PROTECTED] To: [EMAIL PROTECTED], [EMAIL PROTECTED] Subject: [**] Nutrition, Cognition, "IQ" clipped from: http://groups.yahoo.com/group/selfish_genes > Date: Wed, 03 Apr 2002 16:10:31 -0600 > From: [EMAIL PROTECTED] > Subject: RE: IQ, EQ and S-G's ..... ..... ------------------------------------------------------------------ ------------------------------------------------------------------ Date: Tue, 09 Jul 2002 15:27:46 -0400 From: [EMAIL PROTECTED] To: [EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED] Subject: [***] IQ, environment, and all that: FOLLOWUP > > Date: Wed, 03 Jul 2002 10:14:29 -0000 > > From: "wolfgang_mozart2" <[EMAIL PROTECTED]> > > Subject: Re: IQ, environment, and all that > > It seems improbable that that the 4 cubic inch difference in brain > > size between East Asians and Blacks is due to environment. [EMAIL PROTECTED] wrote: > The issue I raised in my post was IQ, behavior (criminal or not), > etc., not anatomy. But maybe I *should* have raised anatomy! It may indeed be the case that brain size differentials are due to environment -- *over evolutionary time* (and not even that long an evolutionary time, as you will see). In fact it looks likely. Animal foods in general and long-chain polyunsaturates (such as DHA) in particular appear to have had a role in brain size increase over evolutionary time; see article excerpt below. That is apart from the matter of my earlier post suggesting momentary (spanning, say, years or decades) improvements of cognitive function with DHA and other nutrients. Speaking of brain size, this article asserts that there is "evidence of [an] 8% decrease in human brain size during the last 10,000 years, despite massive increases in starch consumption since the Neolithic revolution which began at about that time." This is quite a remarkable change in such a short time. And, to the extent that brain size correlates with intelligence (limited, but there does seem to be some relationship [1]), this would help explain the amazing prevalence of idiocy and incompetence in the modern world -- the creeping Dilbertization of everyday life. This also raises the startling possibility that neolithic/ agricultural foods (grains, dairy, sugar) may have *caused* the decrease in brain size -- either by virtue of a direct effect (the relative hyperinsulinemia and hypercortisolemia of starch, sugar and dairy?), or simply by displacing the DHA-rich animal products. The neural atrophy that results from cortisol exposure would be consistent with this idea. Could agriculture have had a massive anatomically-evident dysgenic effect in just a few thousand years? Could dietary control (reduction or elimination of agricultural foods) and super-enrichment with the appropriate elements stall or reverse this dysgenesis, if it exists? Could such control and enrichment enhance functional or momentary cognitive capacity (with all that that implies, society-wide) *while at the same time* stalling or reversing this evolutionary-scale dysgenesis, if it exists? Further: the advice to eat less-dense vegetable foods, and perhaps less fat in particular, appears to be dysgenic, given the model suggested below. Following this course would, over generations, cause an increase in gut size at the expense of brain size. This may have been what happened over the last several thousand years. Further: if brain size and associated (?) intelligence really are down so markedly since the advent of the neolithic, and on account of neolithic practices, then this would have impacted everyone; i.e. we would all be, and indeed perhaps ARE, relatively speaking, dumb degenerates. The argument about racial differences in IQ may have some importance, but it pales in relation to this Big Picture -- like bickering over the precise portions of a small pie. By far the most urgent need, then, would be not to establish who is slightly less dumb than the others, and by how much, but to take action to reverse dysgenesis and reduce dumbness, across the board (perhaps best starting with oneself). The paradox would be that the relatively-intelligent would likely be the ones most responsive to information and exhortations along these lines. Alan reference: 1. J. PHILIPPE RUSHTON and C. DAVISON ANKNEY. Brain size and cognitive ability: Correlations with age, sex, social class, and race. Psychonomic Bulletin & Review, 1996, 3 (l) 21-36 http://millennium.fortunecity.com/redwood/547/rushton.htm ------------------------------------------------------------------ EXCERPT FROM: http://www.beyondveg.com/nicholson-w/hb/hb-interview1f.shtml (Humanity's Evolutionary Prehistoric Diet and Ape Diets--continued, Part F) POSTSCRIPT: SIGNIFICANT RESEARCH UPDATES TO Setting the Scientific Record Straight on Humanity's Evolutionary Prehistoric Diet and Ape Diets ..... ..... ..... CO-EVOLUTION OF INCREASED HUMAN BRAIN SIZE WITH DECREASED SIZE OF DIGESTIVE SYSTEM Data points to increasing dependence on denser foods, processed by a less energy-intensive gut to free up energy for the evolving brain. Also, left completely out of Part 1 of the interview above due to my initial passing familiarity with further evidence are recent findings pointing to a correlation between increasing levels of animal flesh in the diet over the eons at the same time the human brain was in the process of near-tripling in size--from 375-550cc at the time of Australopithecus, to 500-800cc in Homo habilis, 775-1225cc in Homo erectus, and 1350cc in modern humans (Homo sapiens). Sufficient amounts of long-chain fatty acids essential to support brain growth While the specific evolutionary factor(s) that drove the increase in human brain size are still being speculated about, one recent paper suggests that--whatever the causes--the evolutionary increase in brain size would not have been able to be supported physiologically without an increased intake of preformed long-chain fatty acids, which are an essential component in the formation of brain tissue. [Crawford 1992] Animal prey likeliest source for required amounts of long-chain fatty acids during human brain evolution Lack of sufficient intake of long-chain fatty acids in the diet would therefore be a limiting factor on brain growth, and these are much richer in animal foods than plant. (Relative brain size development in herbivorous mammals was apparently limited by the amount of these fatty acids in plant food that was available to them.) Given the foods available in humanity's habitat during evolution, the necessary level of long-chain fatty acids to support the increasing size of the human brain would therefore presumably only have been available through increased intake of flesh. Human brain size since the late Paleolithic has decreased in tandem with decreasing contribution of animal food to diet In addition, a recent analysis updating the picture of encephalization (relative brain size) changes in humans during our evolutionary history has revealed that human cranial capacity has decreased by 11% in the last 35,000 years, the bulk of it (8%) in the last 10,000 [Ruff, Trinkaus, and Holliday 1997]. Eaton [1998] notes that this correlates well with decreasing amounts of animal food in the human diet during this timeframe. (Of particular relevance here is that most of this decrease in animal foods correlates with the dawn of agriculture 10,000 years ago.) The central role of DHA in brain growth Eaton [1988] also notes the obvious hypothesis here would be that shortfalls in the preformed long-chain fatty acids important to brain development are logical candidates as the potentially responsible factors, most particularly docosahexaenoic acid (DHA), which is the long-chain fatty acid in most abundance in brain tissue, as well as docosatetraenoic acid (DTA), and arachidonic acid (AA). (The human body can synthesize these from their 18-carbon precursors linoleic acid (LA) and a-linolenic acid (ALA)--obtainable from plant foods--but the rate of synthesis does not match the amounts that can be gotten directly from animal foods. Additionally, an excessive amount of LA compared to ALA, which is likely when plant foods predominate in the diet, inhibits the body's ability to synthesize DHA endogenously, compounding the problem.) This evidence of decreasing brain size in the last 35,000 years, and particularly the last 10,000, represents important potentially corroborative evidence for the continuing role of animal foods in human brain development, since dietary changes in this most recent period of human prehistory can be estimated with more precision than dietary composition earlier in human evolution. While it should be clearly noted here that correlation alone is not causation, at the same time it should be acknowledged that there seem to be no other worthy hypotheses as yet to explain the dietary basis that could have supported the dramatic increase in brain size during human evolution. Recent tuber-based hypothesis for evolutionary brain expansion fails to address key issues such as DHA and the recent fossil record As a case in point, there has been one tentative alternative hypothesis put forward recently by primatologist Richard Wrangham et al. [1999] suggesting that perhaps cooked tubers (primarily a starch-based food) provided additional calories/energy that might have supported brain expansion during human evolution. However, this idea suffers from some serious, apparently fatal flaws, in that the paper failed to mention or address critical pieces of key evidence regarding brain expansion that contradict the thesis. For instance, it overlooks the crucial DHA and/or DHA-substrate adequacy issue just discussed above, which is central to brain development and perhaps the most gaping of the holes. It's further contradicted by the evidence of 8% decrease in human brain size during the last 10,000 years, despite massive increases in starch consumption since the Neolithic revolution which began at about that time. (Whether the starch is from grain or tubers does not essentially matter in this context.) Meat and therefore presumed DHA consumption levels, both positive *and* negative-trending over human evolution, track relatively well not simply with the observed brain size increases during human evolution, but with the Neolithic-era decrease as well, on the other hand. [Eaton 1998] These holes, among others in the hypothesis, will undoubtedly be drawing comment from paleo researchers in future papers, and hopefully there will be a writeup on Beyond Veg as more is published in the peer-review journals in response to the idea. At this point, however, it does not appear to be a serious contender in plausibly accounting for all the known evidence. Co-evolution of increased brain size with concurrent reduction in size of the human gut Recent work is showing that the brain (20-25% of the human metabolic budget) and the intestinal system are both so metabolically energy-expensive that in mammals generally (and this holds particularly in primates), an increase in the size of one comes at the expense of the size of the other in order not to exceed the organism's limited "energy budget" that is dictated by its basal metabolic rate. The suggestion here is not that the shrinkage in gut size caused the increase in brain size, but rather that it was a necessary accompaniment. In other words, gut size is a constraining factor on potential brain size, and vice versa. [Aiello and Wheeler 1995] Human gut has evolved to be more dependent on nutrient- and energy-dense foods than other primates The relationship of all this to animal flesh intake is that compared to the other primates, the design of the more compact human gut is less efficient at extracting sufficient energy and nutrition from fibrous foods and considerably more dependent on higher- density, higher-bioavailable foods, which require less energy for their digestion per unit of energy/nutrition released. Again, while it is not clear that the increasing levels of animal flesh in the human diet were a directly causative factor in the growth of the evolving human brain, their absence would have been a limiting factor regardless, without which the change likely could not have occurred. Other supporting data suggest that in other animals there is a pattern whereby those with larger brain-to-body- size ratios are carnivores and omnivores, with smaller, less complex guts, and dependent on diets of denser nutrients of higher bioavailability. Vegetarian philosophy has traditionally relied on observing that the ratio of intestinal length to body trunk length parallels that of the other primates as an indication the human diet should also parallel their more frugivorous/vegetarian diet. However, this observation is based on the oversimplification that gut length is the relevant factor, when in fact both cell types and intestinal surface area are the more important operative factors, the latter of which can vary greatly depending on the density of villi lining the intestinal walls. In these respects, the human gut shares characteristics common to both omnivores and carnivores. [McArdle 1996, p. 174] Also, intestinal length does not necessarily accurately predict total gut mass (i.e., weight), which is the operative criterion where brain size/gut size relationships are at issue. The human pattern of an overall smaller gut with a proportionately longer small intestine dedicated more to absorptive functions, combined with a simple stomach, fits the same pattern seen in carnivores. [Aiello and Wheeler 1995, p. 206] GO TO NEXT SECTION OF PART 1 _____________________________________________________________________
