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ggose: generalist genes of small effect
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Plomin Blueprint

Robert Plomin. Blueprint. Allen Lane, London. 2018

Plomin has written the book that summarizes his career, the one that he previously avoided writing because of what he describes as his own cowardice. Harsh judgement, but investigators into the genetics of intelligence are given a rough ride in contemporary academia, where genetics generates a hostility not meted out to sociological explanations. Over his long and highly productive career Plomin thought it prudent to publish in scientific journals, rather than to go public with all his views, which would invite even more criticism than he was already getting from doing his scholarly work. So, this is his “coming out” book.

The analogy of a blueprint, of course, makes more sense to my generation than it probably does to more recent ones. No engineering analogy will fit the intricacies of biology, but the implication is clear: DNA is what makes stuff happen, given only some basic environmental circumstances habitually found on this planet. The genetic code is causal.

A blueprint is a plan. It is obviously not the same as the finished three-dimensional structure – we don’t look like a double helix. DNA isn’t all that matters but it matters more than anything else put together in terms of the stable psychological traits that make us who we are. (Prologue, ix)

I agree with the sentiment. I merely note that people now often say of organizations and products and cultural creations that “they have the DNA of their predecessors”. DNA is now a meme.

So, what does Plomin say, now that no reticence is required?

1 Plomin has written a clear and non-technical account which ought to be accessible to a wide audience. For example, pages 24 and 25 explain variance, covariance and correlation in simple terms, with two illustrative scatter plots, and subsequent pages show how correlations found in identical and fraternal twins are used to estimate heritability. Plain language is hard to write. This book reads well, and ought to reach a wider public. Even for those who have been reading his papers for the last decade, there are new things to learn from seeing the whole story in one place.

One natural casualty of writing for a general audience is that the text is reference-free. Some scholars may be hurt not to see their names in print, but it is the findings that matter. There is no author index, but a full 59 pages of supporting notes. These differ in their nature and intensity: some list relevant publications, others explain ideas and misconceptions in far more detail. Readers will differ in whether they read the notes, and if so, at what stage. I mostly left them to the end of each chapter, so as to let the narrative flow while scribbling in my own questions in the margins.

2 Plomin has given an enlightening account of his research career, culminating in the long-term Twins Early Development Study, which has become a front runner in the DNA revolution. Research is a life-consuming business. Some researchers give up their weekends, most don’t. TEDS has more than 12,000 twins, and has generated 55 million items of data, described in over 300 published papers and 30 PhDs. Respect.

3 Plomin shows that there is strong evidence that, as a rule of thumb, most human characteristics are 50% heritable. He concludes his second chapter saying: “Inherited DNA differences are by far the most important systematic force in making us who we are”.

4 Plomin makes big inroads into that great big squashy thing “the environment” by showing that important aspects of it are heritable. At first this sounds nonsensical, but I think Plomin wins through. For example, at first glance it would appear that because some mothers read to their children and others do not, the former habit is the key to children’s language development. Whole programs have been devoted to this supposition, including well meaning projects giving books to families, because it has been found that number of books in the house predicts children’s scholastic achievements. On the contrary, Plomin shows, “parents who like to read have children who like to read”.

Plomin first found this when studying stressful life events (relationship problems, financial status and illness) which seemed to be truly external to the individuals concerned. Identical twins were twice as similar as fraternal twins on these measures (correlations of .30 and .15 respectively). These apparently completely environmental events were almost a third due to genetics.


Identical twins are more concordant for divorce (55%) than fraternal twins (16%). Divorce does not rain down unbidden from the sky: it happens more frequently to those who are joyful, engaged with life, emotional and impulsive. So there. In 20,000 adopted individuals the likelihood of divorce was higher if their real mother, who played no part in their upbringing, later got divorced, than if their adoptive mothers later got divorced. After controlling for genetics, Plomin says, no environmental causes of divorce have been identified.

Divorce doesn’t just happen by chance. We make or break our relationships. We are not just passive bystanders at the whim of events “out there”. Pg 39.

TV has been associated with many unfavourable outcomes, perhaps unfairly. Interestingly, parents and their children are more similar (.30) than adoptive parents and their adopted children (.15) in the time they devote to this freely chosen activity. In fact, heritable components are found in many traits which had been classified as “external” such as chaotic family environments, being bullied, neighbourhood safety, being exposed to drugs, and quality of marriage. Plomin calls this “the nature of nurture”. Smart, but confusing. I said in 2013 that they were “self-made environments” or “personally created niches”. Our genetics influences us in the way we build our nests.

Plomin explains:

Some children have more accidents than others: the number of children’s scrapes and bruises shows genetic influence. For adults, automobile accidents are not always accidental either, of course. Automobile crashes are often caused by reckless driving – driving too fast, taking chances or driving under the influence of alcohol and other drugs. Pg 48.

Years ago I had hoped that the Home Observation for Measurement of Environment would provide detailed indications of which aspects of the environment were worth manipulating so as to boost children’s intelligence. Families showed the expected .5 correlation with HOME, adopted children half that. All the good parenting is revealed to be half of it due to genetic causes. Brighter parents have brighter children. Although it looks as if encouragement is doing the trick, it is at most half of the cause of the children being bright. Plomin concludes:

Genetic differences in children’s aptitudes and appetites affect the extent to which they take advantage of educational opportunities. [] This is a general model for thinking about how we use the environment to get what our DNA blueprint whispers that it wants. Pg 51

5 Plomin reveals the counter-intuitive finding that DNA matters more as time goes by. Heritability estimates for intelligence rise as we age, possibly because the niches we create help boost our intellectual skills over our lifetimes. Eventually, we become more like our parents.

• Category: Science • Tags: Genetics, Heredity, Robert Plomin 
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Group 5 fists hold closely together

“Scientific Racism” is an oxymoron. The truth cannot be racist, and lies cannot be science. If you say something truthful about a racial difference then that is true, not a lie, and not racism. If you say something about racial groups which is untrue, then that is not science, it is false, and science has to correct mistakes as soon as possible.

Scientific racism is a contradiction in terms.

Nonetheless, the epithet “scientific racism” is often thrown at any study of racial differences as if, whatever the outcome of the research, the mere investigation transgresses some a priori truths. The argument seems to be: “we know that racial differences do not exist, so those who argue against that view are wrong, whatever their investigations may suggest”. In simple terms, if a person can be considered a racist, then the fact that they “do science” is simply another one of their fiendish tricks. The scientific part becomes an additional outrage, a vain attempt to prove true something already known to be wrong.

The blanket condemnation of evidence-seeking is not always applied to differences which have medical connotations. Race-based differences in vulnerability to illnesses is often exempt from hostile criticism. A welcome respite. However, the evolutionary processes which affect the organs of the body are not guaranteed to leave the brain above the audit, somehow exempt from selection. If one genetic group differs in one regard it is worth studying if they differ in other regards.

It may not be obvious at first, but if you want to combat racism and sexism you need the benchmark of open discussion about racial and sexual differences. Otherwise, how do we know which claims about group differences are clearly wrong and which are right? These are empirical matters and you need to establish the truth before you can demonstrate what deviates from it. The most effective way to find the truth is free and open inquiry into all group differences. We should be on the side of those who want to know more, not those who want to know less. We should oppose those who want other people to know less, while they are free to find out as much as they can, and then decide what to hold back.

I know that some researchers will want to hold back findings which they believe will halt their careers. It is a tough choice. I sympathize with their dilemma, and look forward to the day when they can all publish their findings openly.

The study of racial differences has been criticized as pseudo-science. Of course, one should be against pseudo-science, as one should be against pseudo-journalism, and pseudo-outrage and pseudo everything. But why should one branch of science be called pseudo, and another not? All branches of science depend on maintaining scientific standards whatever the topic is. Any errors need to be corrected by better methods. There is as much scope for error when comparing racial groups as when comparing social class groups. Selection criteria are rarely pure, and can be subject to confounding.

We should aim for high standards in everything we investigate. One way to achieve that is to examine the ideas we love with as much ferocity as the ideas we find repellent. That will keep us closer to the truth.

• Category: Science • Tags: Academia, Political Correctness, Racism 
No conferring
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nature nurture

A bit of back history: I started learning about intelligence and intelligence tests when I was an undergraduate in 1964-1968. This included taking group intelligence tests at the beginning of my psychology course, and giving face to face Wechsler tests in my final year. I then started my first research project leading to my PhD: “Cognitive effects of cortical lesions sustained in childhood” which involved about 300 neuro-psychological examinations, and I did about another 300 Wechsler examinations on the psychiatric wards from 1968 till the late 70s. My first publication was in 1970 on “Intellectual abilities of immigrant children” and I had the odd experience of lecturing Arthur Jensen on the subject barely one year after the publication of his famous paper.

Thereafter I concentrated on other psychological topics, but still wrote a summary chapter on intelligence in 1980. Jensen’s “Bias in mental testing” had a big impact on me, making me revise many of my earlier opinions. I also wrote some papers in the early 80s on testing cognitive ability in severely handicapped patients. Basically, I kept in touch with the subject, but didn’t start reading in more detail again till the late 90s, and then making it a focus of attention from about 2002 onwards. I started going to International Society for Intelligence Research meetings in 2007, after which I abandoned a book I had almost completed on intelligence, finding that it was better to keep looking at new findings rather than summarize older work.

It was only after an ISIR conference in 2012 I began blogging, mostly to justify to myself the cost of the journey by spreading the word more widely than the few delegates who had been able to attend. My blog had 4 readers to begin with, though that quickly grew to 20, and later even as high as 116. Number grew further. I rank myself merely as an occasional publisher of research, and an informed commentator.

Around that time I wrote to my university’s lecture room booking department. I wanted to have an open meeting for students. Potential speakers sounded a note of caution: if group differences were to be discussed they feared hostile interruptions and damage to their careers. Opinions varied about the risks, but eventually I reluctantly decided meetings would have to be invitation only, for speakers and a few others. I hoped that participants would change their minds and begin to welcome sympathetic journalists, and a wider audience. Meetings were announced on my blog, but without location details, and papers reported afterwards. Quite a few readers wanted to attend, and I regretted not being able to invite them all. Speakers were very cautious about career-limiting publicity, and feared that some prospective attendees simply wanted to make trouble. Even when intelligence researchers met privately there was concern about any photographs being taken, and different attitudes as to what, if anything, could be reported.

Toby Young, a journalist and free schools advocate gave the 2017 ISIR Constance Holden lecture about the difficulties of conducting intelligence research. He had attended the London conference for about two hours to talk to the speakers and gather material, and in his ISIR lecture described the London conference as “like a meeting of Charter 77 in Václav Havel’s flat in Prague in the 1970s.”

Six months later he was appointed to a Government committee, and this triggered fiercely negative reactions from political opponents to his generally conservative views. Because his ISIR lecture mentioned the invited conferences at UCL they were described in lurid and misleading terms, such that many speakers later had problems with their own universities. Moral: if you want to have a conference on intelligence research and group differences, avoid universities.

Enough background. Here is the reply written by the participants, published in the journal Intelligence.

Gould effect

It may seem other-worldly to answer press misrepresentation with an academic paper six months later, but academic debates are a slow affair, since they require people to read texts and think about arguments. There ought to be long moments of quiet when all you can hear are pages turning.

P.S. “No conferring” is a catch-phrase from University Challenge, said by the quiz master to remind each team of 4 undergraduates that they have to answer the initial question on their own.

• Category: Science • Tags: Censorship, Intelligence, IQ, Political Correctness 
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School of Education Headshots

Disinviting is an awkward word for a disagreeable act: inviting someone, and then once they have accepted, withdrawing the invitation. Naturally, this is more hurtful than not being invited at all. I have not been invited to many things, and ignorance is bliss. To have been invited, and gone through the process of preparing for the event, gathering material and adapting it to the requirements of the occasion, and then being told you are not wanted is a sharp rejection. Hopes have been raised only to be dashed later: the contrast is a cruel, high amplitude rebuff.

I had not previously heard of the International Association of Educational and Vocational Guidance, but I have written to them, asking them for their explanation about their actions. To assist those who don’t know Prof Gottfredson, including possibly some members of the International Association of Educational and Vocational Guidance, I add a link to: her letter to them, a letter of support from Russell Warne, an interview with her in 2007, from which, quite coincidentally, I had been quoting approvingly a few days ago, and another link to her CV. Have a quick glance at it and then see if you can thing of a better person to invite to address a vocational conference.

IAEVG Dis-Invites Keynote by Prof. Gottfredson

The Board of the International Association of Educational and Vocational Guidance (IAEVG) Rescinded Its Invitation to Professor Linda Gottfredson to give a keynote address at its 2018 conference in Gothenburg, Sweden, October 2-4.

Letters to the IAEVG Board protesting its decision
• Prof. Linda Gottfredson, October 1, 2018 (includes 4 letters to IAEVG defaming Dr. Gottfredson and requesting the Board disinvite her)

• Prof. Russell Warne, October 1, 2018

Judge Dr Gottfredson for yourself

• Profiles in Research
• Curriculum Vitae

• Category: Science 
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After the furore, farrago and stramash of Prof Alessandro Strumia talking about sex differences, I went back to the BBC last night to read about other news. Of course, my eye was caught by a story entitled: The Women standing up for Science

There were 3 interviews with women university researchers, apparently selected because they had tweeted criticisms about the lecture.

Dr Jennifer Rohn, cell biologist, University College London

Prof Strumia’s comments: If you took them at face value, they could be quite demoralising – he is a big-shot professional. Most of what he presented has been debunked and there’s been a swift universal rebuttal from the science community of his comments.

Dr Jess Wade, physicist, Imperial College London:

Prof Strumia’s comments: They are really damaging to the community. Most of us realise that having diversity, having people who think differently to you, is so important to research. If you only have people who look and think the same, you will never progress.

Dr Sylvia McLain, biophysicist, University of Oxford

Prof Strumia’s comments: I think he’s weak and feeling threatened. In nature, some oak trees kill off small oak trees so they can grow bigger and stronger.

Of course, all three may have said much more, but it is odd that none of that was reported, when a couple of killer blows on the content of the lecture would have received wide publicity. I looked for other things they might have said elsewhere, and in one case found better particulars:

Dr Jess Wade, reported in the New Scientist, who had attended the conference, said of Strumia’s lecture:

Sadly, the event was overshadowed by a talk given by Alessandro Strumia at the University of Pisa, Italy, a long-standing member of the CERN collaboration. He had told organisers he would present a historical look at women’s representation in academic publishing. Instead, he insulted the professors coordinating the meeting, the audience of young women and, now, women scientists all over the world.

In a nutshell; he claimed that women weren’t as good at physics, were promoted too early and received disproportionate funding given their ability. Unlike my talk, backed by evidence, he cited a bunch of poorly thought out gender science from right-wing thinkers. These included James Damore, who was fired from Google last year for holding similar views.

The is an interesting comment, particularly the notion that declaring researchers to be “right-wing thinkers” is a way of refuting a proposition. Dr Wade is working to get more women into studying science, which is a good thing. On the issue of sex differences, one of her stated sources on sex differences is Angela Saini’s “Inferior”.

Other tweeters again suggested that Strumia’s comments were factually wrong, outdated, irrelevant, discredited and so on, but without providing references, presumably because all those criticisms were so well known that further explanation was unnecessary.

If I can find any more information on the counter-arguments, I will let you know.

• Category: Science 
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The closest I have ever been to Big Physics was the Stanford Linear Accelerator, in the company of Prof Theodore Postol, who felt it would be a good antidote to my jet lag, as we discussed anti-ballistic missile defence strategy. Postol also went down the corridor to see if I could meet Amos Tversky, but he had to give a seminar. Sad loss.

I have never visited CERN, but like most other people have read about its wondrous search for the fundamental units of the universe. What a wondrous thing is man! And, of course, woman. And thereby hangs a tale.

At a conference recently, Prof Alessandro Strumia gave his opinion about excellence in physics, particularly theoretical physics, and you can see his lecture slides here:

The lecture shows the relationship between publication and citation rates, and being hired in Physics jobs for different countries, and explains sex differences in STEM subjects by psychometric results, particularly the greater standard deviation of ability for men.

Typically for a physicist, he has summary graphs will compress a lot of data, and slide 23 is a good example. Brighter people publish more, and the brighter they are the higher the probability they will be men. Neat slide.

Strumia citation by IQ

He also adds in a personal note about not being appointed to a job when he had more publications than the successful candidate. OK, I understand the gripe, but general data are more powerful than any individual case. He understandably objects to female sex being used as a positive reason for overlooking weaker publication and citation achievements. He argues that Physics has been built mostly by men, and he is right, so far. The present century may change that (see Nobel prize today), but his evidence suggests not.

I think this is a good presentation, data rich, and worth debating. Do I need to explain what debating means? Not to readers here, but for the audience elsewhere: it means that different opinions and conjectures are discussed in the light of how well they fit with reality. One cannot debate opinions until one has heard them. Some fools are asking how he was “allowed” to address a conference on women in science. Unless the conference organizers view women as frail souls who need to be protected from unsettling thoughts, then his lecture was well placed.

It would have been good to see the subsequent question and answer session, and to see any other reworkings of his findings which may follow. There is always room for argument about academic metrics, but often the results are so clear (some people publish far more than others, and are cited more than others) that it serves the purpose well enough. In former times it would not need to be explained that one can hear a lecture without agreeing to all or any of it, and one can also see which points need to be checked, and what counter-examples of similar strength can be put forwards. A conference which is based on one hypothesis which cannot be questioned has no place in science.

Strumia is now “under investigation” at both CERN (CERN is a culturally diverse organisation bringing together people from dozens of nationalities. It is a place where everyone is welcome, and all have the same opportunities, regardless of ethnicity, beliefs, gender or sexual orientation) and his University of Pisa (“for reported violations of the University Community fundamental values”). His email at CERN no longer seems to get through to him. Perhaps too many people are sending him messages of support.

By the way, in the middle of this public farrago, I cannot pass up an opportunity to make a methodological point. It has long been argued that when a standard CV is given a male name rather than a female name, the former is more likely to be hired by subjects in an experiment. That is to say, that raters (both men and women are equally prone to this) rate the man more highly, as being more competent.

Powerful stuff, I used to think. However, that is not the real test. The more honest test is to take a selection of male and female application forms, remove names and anything which might reveal their sex, and then get raters to judge their quality.

Naturally, this story has attracted a lot of silly commentary. Some complained that Strumia spoilt a party dedicated to boosting women into science.

My own view is that I am not interested in the sex of theoretical physicists. It is none of my business. I do not expect occupations to be representative of the general public, merely representative of the best talent. I hope Physics job holders will be highly representative of the best thinkers. My primary interest, tempered by an inability to understand their formulations beyond a superficial level, is whether their testable hypotheses eventually get validated. I was pleased when the “goddam” particle was found, though it has yet to influence my life. However, there is always a lag. The Solvay conferences changed the world. Someone, somewhere, perhaps in CERN, will give us the next transformation in our understanding of matter.


• Category: Science 
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Linda Gottfredson

Linda Gottfredson, author of the most supported and cited statement on intelligence,

and the researcher who has done most to explain what intelligence means in everyday life, in terms of specific tasks, training needs, and occupational choices and achievements


has just been dis-invited from an occupational conference in Sweden where she had been invited to give the keynote speech about another one of her many achievements: her theory of circumspection and compromise in occupational choices.

The four critics have dredged up the old insults of three decades ago, which nearly finished her university career, and from which she emerged vindicated after a two year struggle: the usual hostile stuff from the Southern Poverty Slander Center and assorted partisan critics, asserting that her findings, writings and thoughts are riven with racism etc, and the Conference organizers seem to think that her occupational stuff, much utilized in Sweden, represents her angelic side, but the group differences stuff, true or not, means she must be banished into the outer darkness, for fear of contagion with the Evil Eye.

Have a look at what she wrote in reply to them, and particularly the four letters that spooked the supine conference organizers into dumping their star speaker.

In the midst of all this depressing and horrible farrago, humour is never too far away. The very last anonymous letter No.4 is priceless. This terminal fool wants Linda defenestrated because she/he/they will otherwise have to boycott the meeting, but mostly because unless the witch hunters do it pronto, she/he/it will miss out on the early bird reduced conference rates!

You could not make it up, and it seems unlikely anyone can make up Sweden.

You might drop them a very polite line, very polite please, asking the Conference President to explain herself

[email protected]

If you want to e-meet Linda, here she is talking about her lifetime’s work.

• Category: Science • Tags: IQ, Political Correctness 
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I want to explain, once again, my arguments on the question of weight, obesity, diet and dieting. I’d like to make some suggestions as well, if only to counter the impression some readers got that I did not realize how difficult many find it to change their diet, and also the impression that I would not give any advice. I do wonder how much advice is necessary, when the main factor is clear, but here goes anyway.

When food eaten and activity undertaken are in balance, few people are fat, though there is some variation around the major factor causing weight gain, which is food eaten. As far as we know, being lean was the norm until recent times for all but the richest people, who could afford to live off the fat of the land. Previously, food was scarce and work was hard. Now, food is plentiful and most work is sedentary.

If physical labour decreases, perhaps because of automation and increased leisure, and food is cheaply and readily available, people, on average, get fatter. They eat more than their bodies need. There is still variation between one person and another. This increased average weight seems to be the pattern in the world since 1950. Pacific islanders top the list, then some Caribbean ones, Arab countries, then in 17th place the US, for which the weight gain has been startling: by 2014 the average BMI was 28.9 This is very high. Americans have gotten fatter, very fast. The UK is in 40th place at 27.3 and this is high and also a relatively recent phenomenon.

Here is an illustrative list:

Although people vary, they varied in ancient times and they vary now, but the average weight has gone up. This is so recent it cannot be due to generational changes, though some people may be more prone to putting on weight than others, within some narrow limits depending on amount of food eaten. The general increase in weight over the last 5 decades cannot primarily be due to genetics. Eating too much is the strongest hypothesis. We should exclude that before seeking other explanations.

By the way, the general screening indicator of body mass index has to be refined by racial differences: black, Asian and Pacific groups are more at risk, and should probably aim for BMI 22 or lower. The National Institute for Clinical Excellence says: “Limited evidence suggests that a BMI threshold of 23kg/m2 in black and Chinese populations may be approximately equivalent to an overweight cut-off point of 25kg/m2 in white European populations.” That is to say, to reduce their risk of diabetes, these populations probably have to be thinner than the European healthy target.

Either people have to eat less or to exercise very much more. If anyone thinks to the contrary, all they have to do is to show that weight is not linked to calorific intake and energy expenditure in controlled circumstances. Settings in which access to food is carefully controlled reveal the basic relationship: eating too much makes you fatter. Self-report only reveals the capacity for self-deception. Meals are reported, snacks forgotten.

I see this as a practical issue, rather than a moral one. If you are fatter than you want to be, eat less. In most ways this is up to you. You are free to be any weight you like. The broader social impact depends on externalities: taking up more space in public seating and consuming more resources in public health systems. In a community which shares the costs of any excesses, then anything which makes you unwell and unproductive has a negative impact on your neighbours. If you can afford it, it is your business how fat you are. If you can’t, your slimmer neighbours are carrying you. In the UK about 90% of type 2 diabetes is estimated to be due to overeating. This is a heavy burden.

How does one eat less? Really, this should not need any further explanation, but here are some practical suggestions, for those who felt I had none to offer. All diets work, and start working immediately. Inconsistently applied and quickly abandoned diets don’t have a chance to work. Saying that diets don’t work is like saying that computer backups don’t work. If you can discipline yourself to do them, they work very well.

There is no point in going on a diet to lose some weight, if going on a diet is considered to be something which will last a few weeks, to be replaced by the habitual level of eating, because then there will eventually be a return to habitual weight. Diets have to be maintained long term and will consist of a wide variety of good food, so that it can be enjoyed and accepted as normal. It will no longer be seen as a diet once you have trained yourself to eat well. It will not be dieting, but a sustained change in how much is eaten. Not a 12 week diet but a permanent change towards enjoying healthier delicious food.

At this stage you might be seeking a justification for starting to diet. The main function of any diet is to interrupt and restrain eating more than necessary. Diets impose artificial restraints, and if they have any effects they are due to calorie reduction. There is simply no way round the fact that if you eat more fuel than your body needs your weight will increase. The laws of thermodynamics apply to you even if you do not believe in them.

If you want details, see citric acid cycle link:

All food is converted more or less easily to glucose, but fat has more calories per gram. There is little benefit in restricting yourself to one or the other food category, but remember that high fat like butter, cream, and oils produces far more glucose. There are guidelines about the balance of those three, and twice as much carbohydrates as protein seems to be a sustainable plan for weight loss. I leave these blends to you. Nutritionists advise a balanced diet, and can give you their interpretations as to what that means. The percentages of carbohydrates and proteins required tend to be given with rather wide estimates.

You may have a view about the slimming effects of particular mix of fat, protein and carbohydrates. Consider a man eating 2500 calories per day or a woman eating 2000 calories who want to take in an extra calorie of food. Whatever blend of fat, protein and carbohydrate they choose, these will still be digested down to glucose, and they will gain in weight. Better not to have the extra calorie.

How can people motivate themselves to make such a change?

Often a health problem triggers a change, or some event which makes a person note and regret their weight. Without some pressing reason it is unlikely there can be any change in eating habits.

A digression. Some people think that you cannot judge advice about diet unless you know the writer’s personal experience, so here is an irrelevant brief personal history: I have been reasonably thin all my life: skinny as a child, slightly less so in my 20s and 30s. At roughly age 30, though still thin and never above BMI 25, I made some changes to stop gaining further weight: no longer having any sugar in hot drinks and not drinking lots of milk. Things carried on as before. In March 2015 I was at my standard BMI of 24 to 24.5 but found that my blood pressure had been high for six months and decided to drop my weight. University of Cambridge researchers had suggested that the really healthy BMI was 22 or below, but they reluctantly declared 25 as being OK simply because they were advised that the public would not do anything to mitigate their weight if they were set apparently impossible targets.

• Category: Science • Tags: Bmi, Diet 
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Totalitarianism-Crushes-Pollution-in-China (1)

Prof Zhang, Economist, Peking University says, regarding the results in his paper about the effects of pollution:

We are also puzzled by the difference in math and verbal tests as well as the gender difference.

Prof. Chew of National University of Singapore found similar results for college students, greater impact on male than on female students. He gave a talk last year at Peking University. However, in the later public version, his paper mainly emphasizes the impact on decision making. Perhaps he is leaving the findings on the impact on intelligence to another paper.

Because reviewers asked us to do so many robustness checks (in the end the appendix is 59 pages long), we didn’t have space to explore the heterogenous effect between rural and urban areas and across occupations in our paper.

In our paper, we didn’t compare the rural and urban sample. It is possible to run separate regressions to see if there are any systematic differences. Urban pollution has received more media attention although the surrounding areas may be more polluted. For example, most the pollutants for Beijing come from nearby counties in Hebei Provinces, where most polluted industries are located. In fact, air quality in many counties in Hebei province are worse than in Beijing.

In another related paper, we look at the impact of air pollution on happiness between those working indoors or outdoors and find indeed greater impact for those working outdoors. See the attached paper.

I suggested to Prof Zhang suppose that he might look back at those who were in very polluting occupations, and thus find the upper limits of the 3 year effect.

In summary, these are interesting findings which will have to be followed up. At the moment the reported effect of pollution is perplexing, and we may need a better model of how pollutants affect the nervous system.

• Category: Science 
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China AirPollution2

News has come in from China that air pollution has a large and cumulatively damaging effect on intelligence, particularly on older people with less education. Perplexingly, the effect is on Vocabulary, but not Maths. Even more specifically, the verbal decrement hits men harder than women. What is going on? How could bad air have such a specific effect, and all this within a mere 3 years?

In terms of the wider debate about whether intelligence tests mean anything, does this prove that intelligence tests actually test intelligence, or does it mean that they only test intelligence when measuring pollution, but not when they test differences between one person and another, or one group and another? Perplexing stuff. Odd that some critics who doubt that people can be validly tested for intelligence have no doubt about intelligence when the effect of a pollutant is identified.

However, in many eyes this paper about a pollution effect on intelligence proves the case for bicycles and the banning of diesels, or cars generally.

This would not be the first time that researchers have found that pollution damages the mind.

Those researchers found that for each 5ug/dl exposure at age 11 overall IQ dropped by 1.61 points. The effect on perceptual reasoning was a bit higher, the effect on working memory a bit lower, and nothing much on verbal comprehension.

What have the new researchers found?

The impact of exposure to air pollution on cognitive performance
Xin Zhanga, Xi Chenb, and Xiaobo Zhang

The paper is detailed, and carefully argued. Population sampling is very good. They studied sulphur dioxide, nitrogen oxide and particulates (PM10).

chinese pollution figures

A 1 SD increase in average API (exposure to pollution) over 3 years before the interview is associated with 1.132 points (0.108 SD) drop in verbal test scores.

Air pollution has a stronger effect on white matter (required more by verbal tests) than on gray matter (required more by math tests). Since men have a much smaller amount of white matter activated during intelligence tests, their cognitive performance, especially in the verbal domain, tends to be more affected by exposure to air pollution.

I am not sure why the response to overall pollution is so specific. It just seems odd. I am also not sure about the proffered explanation for the sex difference. It is based on a finding from Haier 2005 about white and grey matter activation in doing verbal and mathematical tasks. Anyway, they say it is a future research topic.

The scoring system is not the total number of items correct, but the highest rank of question achieved. This might introduce artefacts if the items are not perfectly ranked. It might also cause problems if the ranking of maths problems is easier to achieve than the rankings of word recognition. The test starts at different points according to the completed school stage of the participants. So, it is targeted at ability levels, and may be a little less reliable than a full test, but this is probably a minor issue. They control for family income and years of education, which will reduce individual variation in scores because such “corrections” assume that neither variables are caused by intelligence. They tested 25,486 respondents from the national sample, so perfectly good for this study. They omitted the 1.3% of subjects who had moved from one part of the country to the other (though with more time it would have been interesting to see if their results were affected by moving to more or less polluted places). They excluded those with very polluted occupations.

The population-weighted annual mean concentration of PM10 over 2014 in China is 112 μ g/m3, much higher than the National Ambient Air Quality Standards (NAAQS) published by the U.S. Environmental Protection Agency (EPA). This is a very important point in the supplementary materials, which in my view would have been better placed in the body of the main text. I could not find tables showing the effects for cities versus the countryside, which would have been informative.

It is good to see intelligence testing being used in this work. The results are interesting and quite alarming. However, it is hard to see how they could be having the particular reported effects on Vocabulary and not Maths, and for men more than women. If the very high level of pollution in China is having a massive impact then I would expect that no person or ability would remain unaffected. If pollution in 3 years is having such a big effect, even on Vocabulary alone, it is a puzzle that intellectual and scholastic achievement tests in China do not appear to reveal this effect, and regularly come well above Western achievements. The effect of pollution on intelligence is worth further investigation.

• Category: Science • Tags: China, Pollution 
James Thompson
About James Thompson

James Thompson has lectured in Psychology at the University of London all his working life. His first publication and conference presentation was a critique of Jensen’s 1969 paper, with Arthur Jensen in the audience. He also taught Arthur how to use an English public telephone. Many topics have taken up his attention since then, but mostly he comments on intelligence research.