The Imitation of Intelligence

 

To the Science Museum last night, to see the London premier of The Imitation Game, a film about Alan Turing. Museum staff took ages to manage the audience, and were at cross-purposes as to how to check that customers had bought their tickets. Collectively, they gave the Museum a bad name, and their procedures were no advertisement for science. It gave me time to look at steam engines, and to wonder if I have been too harsh to researchers who claim we are in the grip of dysgenics. The director was interviewed before the film, which was the wrong way round. It meant that many of his answers were of the form “as you will see in the film, but I won’t spoil it for you”. Placed at the end, we could have asked specific questions. Perhaps the Science Museum staff have too high an opinion of themselves.

The film faced a difficult task: it had to show highly complex crypto-analytic techniques in a way which would engage a general audience. Discussing the actual techniques was out of the question, so artistic licence was used in industrial quantities, and in the end the story was that the Germans had built a fiendishly complicated machine and Turing, deeply misunderstood and hindered by colleagues who were fools, eventually built his own machine which solved the puzzle. If you are interested, read Wikipedia or the score of books on the subject. Hugh Sebag-Montefiore’s “Enigma”(2000) is good, but there are many others: Hinsley and Stripp “Codebreakers” (1993) is a good example which comes to hand.

http://drjamesthompson.blogspot.co.uk/2013/07/computable-numbers-computable-humans.html

Better still, spend a day at Bletchley Park. The code breakers used “cribs” much of the time: they knew that enemy weather stations would have to report the weather, submarines the positions of shipping, and that the very most important orders might include the sequence of letters “Hitler”. (I have encoded this sequence on an Enigma machine myself, wearing white gloves, not out of deference to afore-named assassin, but as a courtesy to the curator of the Bletchley Park museum, to protect the machine I was using). Insights into human behaviour (not provided by psychologists) made an important contribution: some German operators did not bother to carry out proper randomisation of initial setting letters and rotors, so it was worthwhile checking whether an operator had been lazy first, and then going through the longer standard checking procedure which assumed full randomisation.

Apart from attending lectures given by Hugh Alexander (sadly before he could talk very much about his code-breaking work) and Captain Jerry Roberts, I have also spoken to others who worked there at the time. A great pity that secrecy was maintained for too long, and much of the machinery destroyed. Probably Churchill’s greatest error, and that is saying something.

Of more interest is how the film depicts intelligence. Heartless, socially awkward, inept, boastful and untidy seemed to have been Turing’s main characteristics in the eyes of the film makers. Also, able to do big sums easily. Finally, to put the nail in the coffin: no sense of humour. Compared to that, his homosexuality was a redeeming sin. The top team of code-breakers were made to look like fools by comparison, which was a crude way of showing his genius. With just a few additional minutes the director could have shown a sliver of the problems and solutions attempted by the team. He did not even deal with the concept of contradiction which was central to Turing’s technique, and useful to the story the film was telling. Hugh Alexander, Gordon Welchman (not depicted), Jack Good, Tommy Flowers (not depicted) were brilliant minds, and better scripts could have been provided for the code breaking team than the bully boy banalities and fisticuffs of the film. The mathematician Peter Hilton was portrayed, but as a mere cypher, and without a mention of his masterly palindrome, the product of a sleepless night:

DOC NOTE. I DISSENT. A FAST NEVER PREVENTS A FATNESS. I DIET ON COD.

When reading a palindrome from left-to-right, it is impossible to locate the "middle" until the entire word has been read completely. Please time how long it takes you to check that it is right, and to identify the keystone letter.

The animations of the bombing of London were very good, probably the best scene in the film. The fearsomeness of the Blitz was well shown. The crossword puzzling Londoners in their shelters was a brilliant idea. Keira Knightly played very well, a star performance. Cumberbatch did the very best with his character. He was believable and moving. The young Turing was also very well played. Charles Dance was a bit over the top as Commander Denniston, but was enjoying himself, and enjoyable to watch. Mark Stewart as the MI6 leader Stewart Menzies was the most convincing. Good supporting parts thoughout, and the spirit of the age well conveyed. A well made film.

What a pity that Turing’s mind was shown as part machine, and mostly autistic demon. The director said in his interview that he had got closer to understanding Turing, but I can only say he still had far to go. He used the device of casting Turing as struggling to pass the Turing test. That’s fine, but some of his concepts could have been animated and explained, without mathematics. The film did not even show that every key press caused one or more rotors to step by one twenty-sixth of a full rotation, before the electrical connections were made, which is what made it so hard to break.

In fact, a contemporary of his whose lecture I listened to shortly before he died, Captain Jerry Roberts (UCL German 1941) said that Turing mostly sat quietly at his desk thinking, such that Roberts “doubted he was earning his corn”, though he revised his opinion later. I cannot think of a way of showing thinking, other than an animation of concepts interacting in a design, cascade or lines of force. The team that made the first TV version of Douglas Adam’s “The Hitchhikers Guide to the Universe” years ago did pretty well, by showing some of the ideas in a news headline type panel on the margins of the screen.

It is silly to expect too much of films, but the audience must have been left feeling that high intelligence was useful in times of need, but otherwise a curse. Tortured genius is just too good a parody for a film maker to turn down.

Advice to men caught unawares

Men are often startled when, without any warning, their dearly beloved suddenly asks “What are you thinking about right now?”

Naturally, the last thing a man should give is a truthful answer. Endless trouble will ensue if the man innocently replies: “Having sex with your best friend”. Therefore, in the unaccustomed role of agony uncle, I would suggest that men prepare a response in advance, and trot it out when required.

The best reply is one which is essentially male, but which avoids revealing any tendency towards mindless impersonal sex with random women chosen only for their physical characteristics. Are there any cognitive tasks in which men have a clear advantage over women? I will leave aside, for another time, the argument that men have a clear advantage over women on all mental tasks, amounting to about 4 IQ points. Also, I will not repeat here the well-established finding that women’s variance in intelligence is less than that of men, so that as tasks get harder proportionately more men can be found at higher levels of intellect (and the same is true at very low levels of intellect as well). The two links shown below cover that ground.

http://drjamesthompson.blogspot.com/2013/09/are-girls-too-normal-sex-differences-in.html

http://drjamesthompson.blogspot.co.uk/2013/09/maths-is-man-thing.html

However, what we need is a supremely male task, with which to blunt the force of the unsettling female enquiry about male mental processes. The text books generally agree that mental rotation (ability to imagine what a complex figure would look like in another orientation) is one in which males excel. For example, Halpern, Beninger and Straight (Sex differences in intelligence, Chapter 13, The Cambridge Handbook of Intelligence, Eds Sternberg and Kaufman, 2011) say: A male advantage in mental rotation is found as early as 3 to 5 months of age (Moore and Johnson 2008; Quinn and Liben 2008). Male performance on mental rotation exceeds that of females across all age ranges, effect sizes ranging from d=0.52 to d=1.49, and increase slightly across the life span. These are very big differences.

The Moore and Johnson paper can be accessed here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2651884/

They say: To demonstrate mental rotation in human infants, we habituated 5-month-old infants to an object revolving through a 240° angle. In successive test trials, infants saw the habituation object or its mirror image revolving through a previously unseen 120° angle. Only the male infants appeared to recognize the familiar object from the new perspective, a feat requiring mental rotation. These data provide evidence for a sex difference in mental rotation of an object through three-dimensional space, consistently seen in adult populations.

Results are on a mere 2o boys and 20 girls, but seem clear cut.

 

The authors are circumspect as to what is causing the sex difference, and they cover all the options.

By 3 months after birth, male and female brains differ structurally (de Lacoste, Horvath, & Woodward, 1991) and functionally (Shucard, Shucard, Cummins, & Campos, 1981), and male and female infants have already experienced a social world that treats them differently (Donovan, Taylor, & Leavitt, 2007; Stern & Karraker, 1989).

I think that the fact that this male skill is evident by 6 months of age is significant. In my view that is long before it could have been shaped up by the usual suspects: a culture which imposes sex differences, families which encourage sex-appropriate forms of play, etc. It has all the appearance of a real sex difference in mental abilities.

So, I can now suggest a reply to sudden enquiries about male thoughts:

“I was mentally rotating three-dimensional arrays”.

If she expresses surprise, reply that her response reveals her incomprehension of the workings of the male mind.

Best of luck.

Global IQ and health

Until relatively recently, intelligence and health were seen as two unrelated matters. This is not surprising, because it is usual to think in compartments, and often very sensible. By compartmentalising thoughts one avoids them spilling over, and making a total mess of disorganised observations. A compartment makes things manageable, keeps things clean and tidy, and brings them within the scope of our limited minds. The downside of such cognitive cleanliness is well known: a link can be overlooked because it lies across a conceptual boundary. Like good generals, reality attacks best when it finds the boundary between two opposing armies: that particular point in the enemy line is weak because each army sees it as of peripheral interest, and any intrusion can probably be blamed on the neighbouring army group. We need liaison officers to bridge the gaps between disciplines if we are to go forward in good order.

For most of my academic life I taught about intelligence in terms of scholastic attainment, and the individual assessment of brain damage, but linked it to little else. Health behaviours were a totally different matter, dealt with by a completely different set of researchers. So, to my shame, I taught about patient compliance with doctor’s instructions and reported the findings of the compliance literature that it did not seem to be related to intelligence. I taught about Flesch readability formulas without considering their g loadings. This was wrong, but it took intelligence researchers to show the omission years later. Gottfredson’s work showed how measures of this sort were distributed about a bell curve, and could be plotted against other intellectual measures. The breakthrough in health linkage came with the Lothian Birth Cohort work, showing that intelligence tested at age 11 was a good predictor of health and lifespan measured 60 years later.

Does this link apply globally?

First, a few preliminary observations. If we can show a link within a particular population, measured by variables (lifespan, problem-solving ability) which can be applied to all populations,  then it is likely (but not proven) that it will be found in all populations. If so, we can look within each population to see if the lifespan/intelligence link holds true. It is worth testing.

Second, one way to do this is to plot each nation in intelligence/lifespan space and see if there is a relationship. Tatu Vanhanen has done this in his book “Global Inequality as a consequence of human diversity” Ulster Institute for Social Research, London, 2014. ISBN 978-0-9573913-7-6

Here is a snapshot of Fig 4.4 on page 104.

 

 

Vanhanen is interested in testing the explanations for wealth given by those who favour external forces (geography, climate, colonialism, governance) rather than the internal force of human differences, which he sees as a more probable cause. He reviews the very broad canvas of environmental explanations for national differences, and also looks at their many criticisms of the causal nature of differences in ability and character. Most economic theorists dispute the effects of intelligence on society, and would not agree that intelligence may be involved in health differences. They argue that the wealth of a society, and how it is organised and governed, are the key drivers of health. They usually leave unexamined the view that intelligence may be a big part of the reason why a society is wealthy and well-organised. Indeed, their approach is one of universal silence on this possibility: differences in ability are never mentioned.

Back to Fig 4.4. The life expectancy measure is given as years above 40 years of age, so as to show fine detail. Across 178 countries the correlations with IQ are as follows: Global Inequality .86; Life expectancy .82; Under 5 mortality .80; Tertiary education .79; Sanitation .73; Income .65; Democratization .56.

So, intelligence (at a national level) correlates with life expectancy (also at a national level) at .82 which is 67% of the variance. Correlation is not causation, but the correlation of intelligence with global inequality makes sense: there is a bell curve of ability and a bell curve of wealth. Correlation, as we have discussed before, is necessary to show a causal link, but not sufficient. The causal chain from intelligence to health is easy to argue, link by link, vaccine by vaccine, public water supply by public water supply.

The correlation between intelligence and lifespan has a simple explanation: clever societies manage threats more expeditiously. They become safer. However, that simple explanation may need to be qualified. Perhaps societies with brighter people live longer because they have environmental and also genetic advantages. This finding has been shown within the Lothian cohort. Early intelligence is a great predictor. Simple reaction time measured in later life is a good predictor, and attenuates the intelligence effect. Perhaps the common factor is “system integrity”, a factor which give the lucky recipients a good brain and a good body.  More of that later.

300,000

 

Snapshot of total of 300,000 all time readers on 6 November 2014. Send a colleague the link.

 

The puzzle comes before the solution

 

I incline to the view that the puzzle comes before the solution, and that the solution is often a long time coming. Each puzzle, once solved, can be passed on as a cultural benefit: here be tigers, don’t shit in the drinking water, planets orbit the sun in elliptical orbits. The great library in Alexandria was the old world’s papyrus internet, and for about three centuries before Christ an agreeable stroll through the stacks was the beginning of many an education. A culture which builds a library gives its citizens an advantage, but the primary cause was the wit that caused the scrolls to be written in the first place.

After completing his studies in Athens, in 245 BC Eratosthenes was called to Alexandria to become the third-ever Chief Librarian. Some years later, hearing that there was a well in Aswam where on the summer solstice the sun shone down to the very bottom (such that a person peering down it could see that their shadow blocked the sun from reflecting up from the water) he realised he could calculate the circumference of the earth without leaving Alexandria.  Using the gnomon, the part of a sundial which casts a shadow (some say by observing the shadow cast from an obelisk near his lodgings) he measured the Sun's angle of elevation in Alexandria at noon on the summer solstice, and found it to be 1/50th of a circle south of the zenith. He assumed the well was due south, that the earth was a sphere, and that the camel drivers were right in their estimates of the distance they had to travel to get to Aswam. On that basis he calculated that the circumference of the earth was 5o times that distance, which turned out to be a fair approximation, in that some of the errors in his assumptions cancelled themselves out.

So, what do we make of his achievement? Eratosthenes had benefitted from a good education, and he had an entire library to guide his thoughts. By the standards of the time he was very probably well fed, well housed and of high socio-economic status. One school of cultural thought would argue that it was only a matter of time before any idle reader, no greater than the next, would burst out of the great library into the Alexandrian sunshine, ready to carry out the necessary calculations. Incidentally, in partial support of that cultural perspective, Eratosthenes was nicknamed “Beta” by his contemporaries, because he was great at many things, but always second and never first. The sort of guy who might never have achieved tenure.

However, as far as we know from the fallible written record, he was the first to calculate the circumference of the earth, and did so by using his brain. There were others just as well educated and as well fed who didn’t work it out. He also is credited with being the father of geography; estimated celestial distances, the diameter of the sun, year length and leap year, doubling the cube, and an algorithm for finding prime numbers. Not a bad haul for a librarian.

I think that the cultural explanation for intellectual achievement is partial and limited, and that the puzzle comes before the solution. Some one has to solve the puzzle, and that the more puzzle solvers you have, the more society flourishes, usually becoming healthier and wealthier.

It might be churlish to mention it, but if we resurrected the puzzle now: “There is a well to the south of you where, one day a year, the sun shines right down to the bottom of the well. What do you conclude from that?” I wonder how many modern citizens, given the accumulated wisdom of another two thousand years, would be capable of realising they could determine the circumference of the earth, and calculate it to a fair approximation.

Fractionating smoke and mirrors

 

In December 2012 I came across a silly study published in Neuron (Hampshire, Highfield, Parkin, & Owen, 2012) which had received credulous expressions of support in the media:

IQ tests have been used for decades to assess intelligence but they are fundamentally flawed because they do not take into account the complex nature of the human intellect and its different components, the study found.

The results question the validity of controversial studies of intelligence based on IQ tests which have drawn links between intellectual ability race, gender and social class and led to highly contentious claims that some groups of people are inherently less intelligent that other groups.

Instead of a general measure of intelligence epitomised by the intelligence quotient (IQ), intellectual ability consists of short-term memory, reasoning and verbal agility. Although these interact with one another they are handled by three distinct nerve “circuits” in the brain, the scientists found.

In a post entitled “What makes a good IQ story” I made a few comments showing why this paper’s conclusions could not be relied upon. As you will detect, I did not think much of their work:

It would seem that there are persons walking about this earth, entirely unsupervised and with access to resources, but with any luck not to heavy machinery, who think that you can make statements about human cognition on the basis of 16 subjects. The level of insolent innumeracy makes one’s jaw drop. 16 persons do not humanity make.

How did this paper get such adulatory press coverage? It told a story that people wanted to believe. It ticked all the boxes required by wishful thinking. Cold fusion, anybody?

Please check that I am giving a fair summary of my opinions at that time by clicking on the link below:

http://drjamesthompson.blogspot.co.uk/2013/01/what-makes-good-iq-story.html

Now, almost 2 years later, the back story can be revealed. Unknown to me, it turns out that, prior to publication, a group of distinguished researchers (Haier, Karama, Colom, Jung, and Johnson) had been asked by the editors of Neuron to comment on the paper. These researchers expressed substantial reservations about the methods and the conclusions of that paper. Nonetheless, it was published. They have corresponded with the lead author subsequently, but have now decided to publish their concerns in the hope that the authors will reply fully to their points, in the usual fashion of academic debate. In the sedate world of academia, this is a challenge, and Hampshire et al. will be expected to reply, point by point.

I can proudly say I thought the Hampshire paper was nonsense from the start, but it is instructive to hear knowledgeable researchers point out the problems in a detailed manner. The reason I was particularly critical is that a few weeks earlier I had listened to a talk by the lead referee Richard Haier at the ISIR conference in December 2012 and he had struck me as a careful and diligent researcher. He is the guy to go for if you want to distinguish between proper results and neuro-bollocks. He and his team had no difficulty answering my pointed questions about the need for reliability in conducting brain scans and the requirement to have large and properly representative subject samples. They did more than answer my questions: they showed that they were very aware of these difficulties which plague the field and lead to the “scan a brain, print a pretty picture, publish a paper” production line of nonsense, and were taking steps to ensure proper procedures and large representative samples. Personally, I can also vouch for Colom and Johnson as sharp reviewers who can spot and correct errors in papers).

The key to the paper was that Hampshire et al had conducted a particular sort of factor analysis which suggested that their large sample of online testees did not show a general intelligence factor, but that a 3 factor solution was the best fit with the data.

Haier et al. reply:

One of the most robust findings in all of psychology is the observation that virtually all tests of mental abilities, irrespective of content and task demands, are positively correlated with each other, leading to the concept of a general factor, designated as “g”.

They then give an excellent explanation of factor analysis and its link with brain imaging research, and their paper is a great teaching resource. Like me, they find 16 un-described persons too slim a basis for coming to any conclusions about brain function. Unlike me, they have gone into every problem with care and patience, explaining normal practice and the caution required in interpreting results. There is great advantage in reading the whole thing, but if you just want to see their review, skip to Appendix A, which contains their unpublished preview of the paper.

https://drive.google.com/file/d/0B3c4TxciNeJZTy1XRi0xcGRhZ0U/view?usp=sharing

In summary, the Hampshire et al paper was never in the running for the Thompson Prize for Plain Statistics. If authors cannot even give me basic statistics on the demographics of their subjects, I will conclude they are not treating the reader with respect.

On a broader front, in reviewing papers for this blog I will stick to my usual rule of thumb: if I can’t understand the statistics, that means they are either extremely good or very bad. If extremely good, I seek further readings on statistics from the bright young sparks of the research world. If they are very bad, I simply say that I would not rely upon them. And make some gentle comments giving the reasons for my reservations.

Cold fusion: a technique for getting headlines out of a badly controlled test tube.

The grand sweep of history

 

Historians differ between those who study specific instances and those who detect general patterns. The former immerse themselves in a defined period, the latter take a broader sweep. Arnold Joseph Toynbee was a good example of that latter, grander genre of comparative history, his best known work being “A study of History” in 12 volumes. Immediately, you can see why few people read him nowadays. 12 volumes is a lot to read, particularly if the punch line comes at the very end, 26 years later. In his day he was extremely popular, and very influential. Not now.

He studied the rise and fall of 26 civilizations and concluded (in the words of the Encyclopaedia Britannica)  that they rose by responding successfully to challenges under the leadership of creative minorities composed of elite leaders. I suppose that coming to a conclusion like that was a major reason why he fell out of favour. That was history in the style of Thomas Carlyle, who believed that history showed that dynamic individuals like Frederick the Great could master events and make a difference. Toynbee believed something similar, in that he believed that the growth and decline of civilizations was a spiritual process, writing that "Man achieves civilization, not as a result of superior biological endowment or geographical environment, but as a response to a challenge in a situation of special difficulty which rouses him to make a hitherto unprecedented effort."

The counter reaction to Toynbee was pretty severe. Some argued, on the basis of attacks levelled against his particular historical examples, that the whole edifice was doomed. Seriously, they asserted that getting one period wrong in some particulars invalidated the idea of general forces in human affairs. No room for approximations or even moderately strong correlations. As Joachim Fest said later in his 1973 biography of Hitler, the first substantial account of the dictator by a German scholar, that although Marxist historians saw biography as little more than courtly flattery compared to the inevitable forces of class struggle, the one thing you could certainly say about Hitler is that here was a man who had made a difference, a terrible difference. History would have been different without him. People can make a difference, for good or ill.

These matters link to a related debate, about the wealth and poverty of nations, and the extent to which the general wealth and health of a nation depends on the intelligence of the people, or in a refinement, on an intellectual minority. From an empirical point of view, this becomes a matter of predictive power. In calculating the wealth and health of a nation, is the best prediction to be obtained by knowing the average intelligence of the people, or the intelligence of the brightest 5%? Come to that, is intelligence required for national success, or is it better to have a good climate and plenty of valuable natural resources?

Toynbee imagined that neither biological endowment or geographical environment caused the rise and fall of civilisations, but he was very probably wrong on that count. Certainly, the current argument is between those (probably a minority) who stress biological endowment against those (probably a majority) who believe that geographical environment is the key factor. “Guns, Germs and Steel” was widely read, even though it was obviously wrong from page 19 onwards. It was written by a scholar willing to say things he did not really believe, but which suited the times. If the citizens of Papua New Guinea are really the most intelligent persons on earth as Jared Diamond asserted, then we would hanging on every word they say, and employing them to sort out the world’s problems. As per usual, the polemic was widely read and commonly believed. Far fewer people have read any publications on group differences in intelligence. A minority interest, to be sure.

I take the view that the most plausible hypothesis is that, over many generations, people adapted to the geographies in which they lived, and took on characteristics which included some differences in intelligence and personality. They created societies which initially arose out of those geographies and which were also increasingly moulded by those inherited genetic adaptations. The adaptations are never perfect, but are a work in progress, always delayed and somewhat out of step with new circumstances, particularly when those circumstances change fast, as in sudden changes in climate, disease, and invasion. So, the state of any current society will be a snapshot of accumulated genetic differences and more recent cultural adaptations. I see intelligence as the cause of differences in wealth and health, though those differences are mediated by institutions and habits (arising out of earlier clever or not so clever solutions to problems). I also accept that it may turn out that a common factor of system integrity is the cause of both intelligence and health. That is the nuisance about the empirical ideal: every conclusion always requires updating.

Some of these views are shown below:

http://drjamesthompson.blogspot.co.uk/2013/01/the-wealth-of-nations.html

http://drjamesthompson.blogspot.co.uk/2013/09/david-landes-economic-historian.html

http://drjamesthompson.blogspot.co.uk/2014/01/ses-and-heritability-of-intelligence.html

http://drjamesthompson.blogspot.co.uk/2014/05/is-smart-fraction-as-valuable-as.html

Now, in the grand historical tradition, Gerhard Meisenberg has launched a thought provoking chapter which makes striking, if gloomy, predictions.

G. Meisenberg, 2014: Cognitive human capital and economic growth in the 21st century. In: T. Abrahams (ed): Economic Growth in the 21st Century: New Research, pp. 49-106. New York: Nova Publishers.

https://drive.google.com/file/d/0B3c4TxciNeJZLXpuNnVLU094YTQ/view?usp=sharing

His chapter explores the interdependency between economic growth and cognitive human capital, which is also described as cognitive skills or intelligence and is measured either as performance in scholastic achievement tests or IQ. It shows that unlike the mere amount of schooling, intelligence has been a robust predictor of economic growth in the recent past. Plausible mediators of the intelligence effect include greater labour productivity, better institutions, more competent management, lower fertility, and wider time horizons.

Gerhard believes that the Flynn Effect will boost emerging countries but peak soon, and thereafter the main trend will be demographic and downwards, a clear dystopian perspective. Ever cheerful, I bring you the main arguments:

The starting point for this chapter is the obvious fact that economic change is the result of human agency. Therefore we need to seek its sources in the physical, mental and moral qualities of the economically active population. In other words, we have to seek explanations for large-scale economic developments in the human capital of the population: how it is formed, and how it is translated into economic outcomes.

My claim is that intelligence is the most general driving force and a major limiting factor for economic growth. It has played this role in the past, and is predicted to continue doing so in the foreseeable future. The face validity of this approach is evident when we realize that sophisticated minds are required to create and maintain complex business enterprises and government bureaucracies, make inventions, and use these inventions in the service of greater efficiency. Fairly high intelligence is needed not only for innovation, but also for the maintenance of industrial and administrative structures once these have achieved high levels of complexity and efficiency.

Intelligence is distributed unequally across countries. Average IQs in Sub-Saharan Africa, although difficult to measure with confidence (Rindermann, 2013), are around 70 while IQs in East Asia average 105. With 15 IQ points defined as one standard deviation, this difference is more than 2 (within-country) standard deviations on the “global bell curve” (Lynn, 2008). One likely reason for the great magnitude of cognitive differences between countries is that Flynn effects have been small or absent in today‟s less developed countries at a time (roughly between the 18th century Enlightenment and today) when mental horizons and psychometric intelligence were rising in the West. The “great divergence” (Pomeranz, 2000) between the West and the rest in economic history was, to the extent that we are able to reconstruct it, accompanied by an equally great cognitive divergence.

If Adam Smith was right with his claim that the pursuit of personal gain translates into benefits for the entire economy, and if intelligence promotes personal economic success, it follows that everything else being equal, macroeconomic outcomes will be more favorable in a society with higher rather than lower average intelligence. This argument has been presented by Lynn and Vanhanen (2002, 2006, 2012) in their argument for a causal effect of intelligence on national wealth.

 

Intelligence is predicted to favour economic growth because it improves job performance, management practices, institutional quality, technological and administrative innovation, ethical conduct, demographic behaviour and/or investment decisions―in other words, most of the factors that economists have ever proposed as determinants of economic growth. Anything that is affected by intelligence net of other causes, and that itself affects economic growth, is a bona fide mediator of the intelligence effect.

Intelligence promotes economic growth through multiple channels. Reduced fertility is a major mechanism, and it appears to mediate the effect of education as well (see Figure 4). “Good government” is another important mediator of the intelligence effect although “small government” is not. Good business management, or “managerial capital” (Bloom et al, 2010; Bruhn, Karlan & Schoar, 2010), may be important as well, but no good indicators of managerial capital are available at the country level. It is reasonable to expect that the quality of business management tends to be high in countries with effective government institutions, because both depend on the competence of managerial personnel. Therefore the governance indicators may, in part, be proxies for good business practices as well.
Another possible mediator of intelligence effects that is difficult to measure at the country level is the willingness and ability to cooperate. A review by Jones (2008) shows that cooperativeness, measured in the Prisoner‟s dilemma game, is positively related to intelligence. This correlate of intelligence may explain some of the relationship of intelligence with governance. Other likely mediators of the intelligence effect include less red tape and restrictions on economic activities (“economic freedom”), higher savings and/or investment, and technology adoption in developing countries.

Meisenberg believes that the environmentally driven increase in intelligence will continue for a while and then plateau. Eventually, as the demographics change, intelligence levels will start dropping again.

I hope I have said enough to prompt you to have a read.

Intellect and infectiousness

In terms of title deeds to the planet, bugs are the freeholders, and we humans hold a short lease. Bugs got started long before us. We humans arose very recently, as a combination of micro-organisms: a bolted together job, cannibalising tiny biological gadgets useful for survival into one large-headed, improbable, bipedal ape.

The basic reproductive rate of a communicable disease is the number of new cases over the course of infection, in otherwise uninfected person who have not been vaccinated.  When R₀ is above 1 the infectious disease spreads, below 1 it dies out. The rate is affected by the duration of infectivity of patients, the infectiousness of the organism, and the number of susceptible people in the population that the affected patients are in contact with.

There is an another factor, not directly mentioned but subsumed into the “susceptible people” calculation, which is whether you can tell whether infected persons are carrying an infection, which then allows you to avoid them. Avoidance may be costly in other ways, but it is usually effective.

The usual R₀ calculations show how easily the various bugs can reproduce in human hosts. This is good science, and also makes sense, in that the methods of transmission are comprehensible. No miasmas here. Airborne bugs move from human to human easily,  bugs are conveyed fairly easily in droplets, and in fluids they are transmitted least easily of all.

So, when people say that Ebola is hard to catch, and that measles is more of a problem, they are probably quoting these figures, tabulated by WHO and CDC from various sources. Bugs can be rated for their dangerousness (forgive me for lumping together bacteria, viruses, prions, and all the rest) to the prototypical average human.

That last concept is somewhat fluid. Some humans move around a lot, like truck drivers; interact a lot, like prostitutes and salespeople; or stay at home a lot, like the elderly, the fearful, and bloggers. In other words, the basic reproductive rate is a useful rule of thumb, but not sacrosanct, and subject to revision. For the sexually promiscuous, HIV is dangerous; for the faithful or uninterested, HIV is largely irrelevant. For that reason, the above estimate of 2-5 new HIV cases per infected person reflect behavioural differences between persons and groups, in which intelligence and conscientiousness play a part. For fearful people who act upon their worries about germs, the rate of infection may be lower. For those who never wash their hands the rate may be higher. For parents who do not ask other parents in the class whether their children have been vaccinated, the rates of infection for their own children are probably higher. You cannot have herd immunity unless the herd is willing to cooperate. Cooperative varies from one society to another, depending largely on trust.

Hence, although the bugs themselves vary in virulence, humans vary in their capacity to defend themselves. Not knowing about germ theory (ignorance); not working things out by observation and deduction (lack of intelligence); and not bothering to change habits or protect others (lack of conscientiousness) all affect the infection rate. So, the “pure” reproductive rate needs to be corrected for impure, messy humans, and the main variance seems to lie in conscientiousness and intelligence. The more a society implements the health advice of their brightest researchers, the better their chances of survival. In an evolutionary sense, if people do not quickly change their habits they are at risk of dying. So, the cultural habit of touching and kissing dead bodies, intended to convey respect and love, needs to change fast. Also, people who do not understand contagion, from ignorance, lack of intelligence or lack of conscientiousness, or a combination of all three, will probably die more frequently than those who do.  Denying a disease exists is not clever. So, at the very end, the factors of conscientiousness and intelligence are tested every time an infection gains access to one person. Will it gain access to another, or die out?

Of course, knowledge and good organisation can be imported from outside any community, so good peripatetic teachers can change local behaviours, given time. Some men who would not otherwise have used condoms in Africa will do so if Bill Gates provides them. Some countries organise well, others badly. Knowledge and skills are either home-grown or bought in, and in an open society the best brains, from wherever they can be found, will be applied to the hardest problems, wherever those are found.

The medieval age did not know what caused the great pestilence. One third of the world died as a consequence, or so Froissart thought. Some at that time worked out the bare bones of how it was transmitted from person to person. They imposed quarantine (40 days isolation) and in those cases many lives were saved. The Pope took advice, and sat between two large fires at Avignon, and survived. Some just trusted to luck, dancing, and booze. Not much use, but one way to face likely death. The poor died more than the rich, because they were closer to the disease vectors, rats and fleas; and probably because they had lower defences physiologically.

In some ways the reproductive rate is a typical statistic: it conveys useful information, and leaves out important caveats. Notice I had highlighted that the rates are calculated for unvaccinated persons. Of course, vaccination is the prime example of the application of intelligence to disease control. From a planetary perspective, intelligence aliens will look for civilizations that know how to control diseases. Perhaps, rather than the little green men saying: “Take me to your leader” when they land, they will demand from behind a biohazard barrier “What bugs do you humans carry on this planet?”

The current concern about Ebola is understandable. Ebola is at the stage when it can be almost stamped out, reduced to small recurrent outbreaks over the years which can also be stamped out. If we fail the test and get it wrong then it will spread and be a permanent hazard, rather like AIDS which claims 2.5 million new cases every year. Measles had plenty of time to spread before we could do much about it. That is why it currently infects more people and kills more people in absolute numbers than does Ebola, at present. However, when comparing diseases we need to understand compounding, which changes the statistics rapidly. In military terms we have to stop the invasion before the virus has established a beach head.   We are being tested for our collective intelligence and diligence right now, when a disease known for 40 years (nothing in biological time, but a reasonable period for solving a problem in cultural time) has surged into a larger urbanised population, further from the forests and closer to the airports.

But, apart from intelligent things like vaccination, sterilization, disinfection, epidemiology, and the organisation of public health measures, what does intelligence have to do with disease control? Do diseases really test our intelligence and personality? Questions of that size require a number of answers, so I think we need to step back from the specific issue of infectious disease, and first of all look at the link between intelligence and health more generally.

Modern epidemiology has always understood the impact of class. Social class is easy and cheap to measure, and can even be estimated from afar by looking at people’s occupations, clothing, manners and wealth indicators. Intelligence is harder and more expensive to measure, and casual estimates are likely to be biased towards verbal ability. For all those reasons, IQ as an explanatory cause of variance has taken a back seat. Lastly, genomic analysis has become available only very recently, and is still very expensive, but it is very likely that it will scoop up some of the variance previously ascribed to environmental factors.

How good is the link between intelligence, health and lifespan? Intelligence is associated with better health and longer lifespans, but it is not entirely clear why. The early explanation was that more intelligent people learned quickly how to avoid health hazards. They gave up smoking sooner in life, bothered to read the medicine labels, and followed health advice generally. All this makes sense, and leads to some simple prescriptions: take care, take advice, read the labels, wash your hands and avoid riding motorcycles and putting your fingers in mincing machines.

http://www.udel.edu/educ/gottfredson/reprints/2004currentdirections.pdfdon’t

Currently, it seems possible that both intelligence and health reflect a general underlying bodily system integrity, a fundamental mens sana in corpore sana which, if you are lucky enough to have it, gives you health, intelligence and long life without much exertion on your part. This insight arises from the fact that simple reaction time measures taken in later life (but not the more complex choice reaction time tasks one would have predicted) also show predictive power when it comes to longevity, and partly moderate the effects of childhood IQ. I will come back to that another time.

Always wanting to be on the right side of the very best research, I turned to Stuart Ritchie to suggest the key reference:

Catherine M Calvin, Ian J Deary, Candida Fenton, Beverly A Roberts, Geoff Der, Nicola Leckenby, and G David Batty. Intelligence in youth and all-cause-mortality: systematic review with meta-analysis. Int J Epidemiol. Jun 2011; 40(3): 626–644.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3147066/

The authors did a systematic review and found 16 independent studies with a combined total of 1,107,022 participants. They checked for publication bias, and were able to exclude it. The bare results are as follows: A 1-standard deviation (SD) advantage in cognitive test scores was associated with a 24% (95% confidence interval 23–25) lower risk of death, during a 17- to 69-year follow-up. There was little evidence of publication bias (Egger’s intercept=0.10, P=0.81), and the intelligence–mortality association was similar for men and women. Adjustment for childhood socio-economic status (SES) in the nine studies containing these data had almost no impact on this relationship, suggesting that this is not a confounder of the intelligence–mortality association. Controlling for adult SES in five studies and for education in six studies attenuated the intelligence–mortality hazard ratios by 34 and 54%, respectively.

Before going into any details, it is worth underlining how poorly social class of origin performs in studies which include measures of childhood intelligence. The idea that class, in the sense of family environment and culture, acts as a canon which shoots us out a variable distance into society (small, poor, feeble guns sending their canon balls short distances; large, rich, powerful guns propelling their progeny long distances) appears to be in error. As to adult SES, I think that is more likely to be a creation of prior intelligence than a confounder. Equally, education in societies where it is free is more a measure of intelligence than a fully independent cause of advancement.

Individual differences in intelligence (cognitive ability, mental ability) test scores, as measured by standardized IQ-type tests in childhood, show an inverse association with risk of death from all causes throughout adulthood. That is, higher intelligence appears to confer protection. This finding is replicated in prospective cohorts from several Westernized countries,1 across different ranges of intelligence,2 and in follow-up periods from early through to late adulthood.2–4

Mental ability scores from early life are associated with later adulthood morbidities, and before any somatic symptoms or risk factors of disease are manifest, provide evidence that cognitive abilities may be predictive of later health outcomes.

A second issue yet to be evaluated systematically is the extent to which intelligence as a predictor of mortality is confounded by early-life environmental influences including socio-economic factors. Socio-economic status (SES) is established as an important determinant of public health inequalities,15–18 including risk of mortality, and it can carry influence in childhood, via factors such as family income and parental education, to predict individual differences in childhood intelligence.19^,20 In this context, therefore, intelligence may be considered a mediating variable on the pathway between early-life influences and adult health outcomes. If early social factors substantially confound the link between intelligence and longevity, then adjusting for childhood SES would sizeably attenuate the effect size of the association between intelligence and mortality. In their systematic review, Batty et al.1 identified three out of nine studies that adjusted for childhood SES: one of these showed no change from an unadjusted model, and two had modest attenuating effects, suggesting that intelligence has independent effects on .

In a fixed effects model, a 1-SD advantage in intelligence was associated with the lower risk of all-cause mortality (HR 0.76, 95% CI 0.75–0.77) (Figure 3)risk of mortality from those of early socio-economic influences.

Nine studies that included 18,733 deaths, reported effect-size models adjusted for childhood SES, measured either by father’s occupation or income, 2^,36^,50^,51^,56^,59^,61 the highest socio-economic index recorded for either parent,3 or father’s education.53 Heterogeneity was very low in unadjusted (Q=8.56, I²=6.6%, P=0.38) and adjusted models (Q=7.49, I²=0.0%, P=0.48). In a fixed effects basic model the HR for this subgroup of papers did not deviate from the HR for the 16 studies (HR 0.76, 95% CI 0.75–0.77). However, even after adjustment for childhood SES there was a very small attenuation (by 4%) of the effect size (HR 0.77, 95% CI 0.75–0.79) (Figure 5). Excluding the large study of over one million Swedish men had no effect on the aggregate effect size of the childhood SES-adjusted model, except to slightly widen the 95% CI parameters (HR 0.77, 95% CI 0.74–0.80). Compared with the unadjusted model of this smaller group of studies in which there were 4608 deaths (HR 0.77, 95% CI 0.74–0.80), controlling for childhood SES had no effect on the intelligence–mortality gradient when the influence of this largest weighted study was removed.

This is a very important finding, given that some psychologists, when presented with intelligence test results that predict later outcomes, are absolutely sure that intelligence is caused by social class, and thus dismiss the findings out of hand.

The authors go on to “adjust” for later educational attainment, as if it were an externally imposed factor. I think this is incorrect, because in any society which offers free education, attainments will have a very large component of prior intellectual ability. So, to “adjust” in this way is to remove part of the effect of intelligence. However, they may have been indulging in bending over backwards to show exactly how the results would look if this (questionable) procedure were applied, even if they may doubt the fairness of the “correction” themselves. In fact, they reveal the latter point in the discussion: the results to date cannot tell us for certain whether education and adult SES are simply partial mediators of the association between intelligence and mortality, or whether the results reflect over-adjustments if both factors are partial surrogates for intelligence, or if these variables confound intelligence–mortality associations.

Among the six studies that adjusted for educational attainment, there were 16,023 deaths out of 1,026,742 participants.3^,51^,53^,56^,63^,65 Again, the aggregate effect size for this subgroup of studies in an unadjusted model (HR 0.76, 95% CI 0.74–0.77) was no different from that for all 16 studies. After adjustment for education (HR 0.89, 95% CI 0.86–0.91), the effect of intelligence on mortality was reduced by 54.2% (Figure 5). Exclusion of the large Swedish cohort3 from the model, as expected, widened the CI parameters (HR 0.87, 95% CI 0.81–0.93), but still reduced the intelligence–mortality gradient by 45.8% from the unadjusted model.

In summary, intelligence is a good predictor of later health and lifespan, and is far better than social class of origin. That general pattern has been confirmed in many studies of individual disorders. For example, patients in the UK believe that cardio-vascular problems can be controlled by statins, and they have been led into these beliefs by their doctors. The Deary gang know better.

http://www.ncbi.nlm.nih.gov/pubmed/20101181

Does IQ predict cardiovascular disease mortality as strongly as established risk factors? Comparison of effect estimates using the West of Scotland Twenty-07 cohort study are revealing.

When CVD mortality was the outcome of interest, the relative index of inequality (sex-adjusted hazard ratio, 95% confidence interval) for the most disadvantaged relative to the advantaged persons was (in descending order of magnitude for the top five risk factors): 5.58 (2.89, 10.8) for cigarette smoking; 3.76 (2.14, 6.61) for IQ; 3.20 (1.85, 5.54) for income; 2.61 (1.49, 4.57) for systolic blood pressure and 2.06 (1.07, 3.99) for physical activity.

So, after smoking, low IQ is the biggest risk factor in cardiovascular disease, and by prescribing statins doctors are playing about with a pill which may reduce what is only a minor factor.

As we have seen, brighter people tend to live longer, but only partly because they take clever precautions, and partly because of a possible common factor which creates a good brain in a good body.

We can show that childhood IQ predicts later health. We can show that the IQ effect is more powerful than the different environments provided by different social classes in Western countries. Clearly, this raises the obvious corollary, if we can show an IQ effect in UK, USA, Sweden, Australia and Denmark, can we show that the IQ/health relationship holds in other countries across the world?

More of that later.

Inbreeding: Two Tribes?

 

Mohd Fareed has provided the sample sizes for each degree of relatedness, and an explanation for the larger number of first cousin marriages, which is the cultural norm in those communities. I have added in, from his paper with Mohammad Afzal, the degree of relatedness for each group and the mean IQ and standard deviations. The results are intriguing.

                                                           n         Relatedness  IQ       sd

Non-inbred                          225         .0000         96.51 (16.25)

Second cousin                       31          .0156          88.57 (13.99)
First cousin once removed   21          .03125        79.70  (6.51)
First cousin                         105          .0625          68.72   (7.15)
Double first cousin               26          .125             59.52 (14.99)

Mohd says: Now a question may arise in the mind of the public, why aren’t the sample sizes uniform? The answer is: among Muslims,  first cousin marriages constitute about 70% or even more of marriages, as compared to the other inbred categories.

Anyway, let me get stuck into these results, which are the sort of statistics I can understand. First cousins, the most numerous in the sample by far, have half the normal standard deviation, as do first cousins once removed. Why? The first cousin result cannot be a small sample size problem. Why this massive restriction in variation? Second cousins and double first cousins have the normal variation. Why? Variance reduces with degree of inbreeding and then bounces back again for the most inbred. Why? I can think of a possible psychometric hypothesis, suggested to me by an esteemed person of my acquaintance, but I haven’t got round to reading all the textbooks on population genetics kindly recommended to me by distinguished scholars (extremely expensive books, by the way) so could population geneticists please help?

That perplexing problem aside, the IQ for the entire inbred category comes out at IQ 72. The “marry your cousin” meme reduces the average IQ by almost 2 standard deviations. Cruelly, these believers will have been cast into such a state of mental weakness that convincing them of the downside of cousin marriage may take a long time, Bollywood notwithstanding.

If we put together the 225 outbred with the 183 inbred we get an overall IQ of 85.5. Given that Lynn’s mean value for India is about 82, Pakistan about 84 these results are within measurement error, and closer to the Pakistan figures. Lynn’s lists are not complete, and need updating,(he does the job himself, without any funds of the sort that PISA commands)  but they are given below for comparison anyway.

In summary, this sample seems very much like the other samples from India and Pakistan in terms of mental ability. What seems clear is that to get an understanding of the potential underlying ability we need to make a massive allowance for inbreeding. Scores of about IQ 96 should be possible in outbred groups.

To understand the regional social and political behaviours as they are at the moment, we need to understand that there are two tribes in contention: higher status outbreeds of average IQ 96, with considerable freedom from their cousins; and lower status inbreeds of average IQ 72, condemned by chains of obligation to perpetual, uncomprehending cousinhood.

Now, as Mohd Fareed says, Muslim India is not the only part of the world that encourages cousin marriage, but I hope that altruists not yet bound for West Africa could give Fareed and Azfal a call, to see if they can give them a hand with genetic counselling materials, training genetic councillors, and working with local researchers and activists to change the cultural meme of arranged cousin marriages. Better still, if you are a Hollywood actor or director, why not Tweet them now, or if that is too much effort, get your people to send their people a cheque?

 

Summary data from Lynn.

India     1,339       CPM      88             Gupta & Gupta, 1966

India    1,359        SPM       87             Chopra, 1966

India    5,607       CPM       81              Sinha, 1968

India    1,050       CPM       82             Rao & Reddy, 1968

India  3,536         SPM       84             Majumdar & Nundi, 1971

India      180         SPM       79              Mohanty & Babu, 1983

India      100         SPM       78              Agrawal et al., 1984

India      748         WISCR  79             Afzal, 1988

India      500         CPM       86            Bhogle & Prakash, 1992

India         29         CPM       82           Jyothi et al., 1993

India       569        SPM        82           Raven et al., 1996

India      828        CPM        80           Barnabus et al., 1995

India    8,040       SPM       88            Raven et al., 2000

India        569        SPM      81             Raven et al., 2000

India: median                   82

 

Pakistan    349     GEFT    84            Alvi et al., 1986

Pakistan    140      SPM     84            Rahman et al., 2002

Pakistan  1,662   SPM      82            Ahmad et al., 2009

Pakistan  2,016   SPM      86            Ahmad et al., 2009

Pakistan: median            84

More sex, cousin?

 

Regular readers will remember this topic, but here is the link to a previous post:

http://drjamesthompson.blogspot.co.uk/2013/04/fancy-some-sex-cousin.html

Interesting work on the link between cousin marriage and intelligence has been published by Farid and Afzal who have collected Wechsler test scores on inbred children in Muslim areas of India. They chart a very substantial effect of genetically driven cognitive decline, with consequentially higher rates of mental retardation in the inbred families. The differences are enormous: 25 IQ points of retardation on average, and a massive, mind-bending 37 IQ points for the most inbred. Can it really be as bad as that? Has inbreeding caused different groups to diverge so much that they are an average 1.67 standard deviations apart? Think of the heated debates and the social and political ramifications of a 1 standard deviation difference between African Americans and European Americans in the USA. Intellectual differences of close to 2 standard deviations will be of greater consequence in the Muslim world and beyond.

Mohd Fareed and Mohammad Afzal. Estimating the Inbreeding Depression on Cognitive Behavior: A Population Based Study of Child Cohort. Published: October 14, 2014. DOI: 10.1371/journal.pone.0109585

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109585

They say: A cohort of 408 children (6 to 15 years of age) was selected from inbred and non-inbred families of five Muslim populations of Jammu region. The Wechsler Intelligence Scales for Children (WISC) was used to measure the verbal IQ (VIQ), performance IQ (PIQ) and full scale IQ (FSIQ). Family pedigrees were drawn to access the family history and children’s inbred status in terms of coefficient of inbreeding (F).

They summarise their results: We found significant decline in child cognitive abilities due to inbreeding and high frequency of mental retardation among offspring from inbred families. The mean differences (95% C.I.) were reported for the VIQ, being −22.00 (−24.82, −19.17), PIQ −26.92 (−29.96, −23.87) and FSIQ −24.47 (−27.35, −21.59) for inbred as compared to non-inbred children (p>0.001). The higher risk of being mentally retarded was found to be more obvious among inbred categories corresponding to the degree of inbreeding and the same accounts least for non-inbred children (p<0.0001). We observed an increase in the difference in mean values for VIQ, PIQ and FSIQ with the increase of inbreeding coefficient and these were found to be statistically significant (p<0.05). The regression analysis showed a fitness decline (depression) for VIQ (R² = 0.436), PIQ (R² = 0.468) and FSIQ (R² = 0.464) with increasing inbreeding coefficients (p<0.01).

Inbreeding (consanguineous marriages among humans) produces homozygous offspring, since the mating of pairs occurs between genetically closely related individuals. The phenomenon of inbreeding or endogamy, increases the level of homozygotes for autosomal recessive genetic disorders and generally leads to decreased fitness of a population known as inbreeding depression which provides a major focus in clinical studies [21].

Parental consanguinity has been associated with increased risk of adverse prenatal outcomes including stillbirths, low birth weight, preterm delivery, abortion, infant and child mortality, congenital birth defects, cognitive impairments, malformations and many other complex disorders [12]–[32].

A study has revealed that the overall incidence of congenital malformations was 2.5 times higher amongst the children of inbred families when compared to that of non-inbred families [33]. Consanguinity has been associated with significant decline in mean values for height, weight and body mass index (BMI) and the subsequent depression on children growth, much influenced in proportion to their inbreeding coefficients with least variation for non-genetic factors [21].

Genealogical information (family pedigrees) up to five generations back (volunteered by the parents) helped in ascertaining the consanguinity persuasion of their marriage and thus, child’s inbreeding status was determined. The information provided by the parents was cross checked by seeking help from the elder members of the family. In case of ambiguity such data were omitted.

Wright’s path relationship method for calculating the coefficient of inbreeding (F) was used for all mating types following the order: double first cousin (F = 0.125) > first cousin (F = 0.0625) > first cousin once removed (F = 0.03125) > second cousin (F = 0.0156). In non-consanguineous families or for the distant marriages, the coefficient of inbreeding was effectively zero (F = 0.000) [21].

The authors did full Wechsler tests, so this is a gold-standard assessment, and somewhat unusual in standard publications on intelligence with large sample sizes. In another unusual move in contemporary publications, they have plotted out their data so as to show the distributions. Respect. I am almost reaching out to give them the, as yet mythical, Thompson Prize for Plain Statistics. The intelligence scores are massively shifted to the left (lower intelligence) in the inbred group.

The mean difference in VIQ, PIQ and FSIQ showed a significant inflation with the increase of the degree of inbreeding (p<0.05, using post-hoc tests) and followed the order: double first cousin > first cousin > first cousin once removed > second cousin > non-inbred. This indicates the risk for cognitive impairments or ID was more common among the subjects having greater value of inbreeding coefficients.

The Table below shows the massive drop in Verbal, Performance and Full Scale intelligence associated with consanguinity measured by the F inbreeding coefficient. For the guidance of those about to marry, the worst effects are when two double cousins marry (see list above for verbal descriptions) and check the figures below for the F coefficient categories.

 

The Full Scale results are drawn out here.

Actually, I may have to hold back the Thompson prize, because they have now reversed the direction of IQ scores, so that high scores are on the left, against usual convention. Pity the poor reader. Nonetheless, the wind blowing through these intellects is clear: the Double First Cousins peak in severe mental handicap, the Non-inbred are at virtually normal scores.

This is all pretty dramatic stuff. The authors have done well. Good sized sample, excellent quality intelligence testing, plainly described results. 

However, I am not one to let any researcher get away lightly. The authors do not give the final group IQ, nor do the answer the obvious question: if 45% of this Muslim sample are inbred, what would their IQs look like if they stopped inbreeding?

For general guidance, the overall group IQ would be interesting to compare with other measures of Middle East Muslim intelligence, and with Indian intelligence estimates. Lynn’s mean value for India is about 82, Pakistan 84. Specifically, in this sample it would appear that Muslims who avoid cousin marriage have IQs of 96.5 which is relatively close to Greenwich Mean IQs. Seen in this light, one bad cultural habit has damaged the intellects of normally able people.

I would like to see the sample sizes for each level of inbreeding, so that I can do a few more back-of-the-envelope calculations on what might happen over a few generations if we let loose that great Western invention: Romantic Love. This provides the perfect excuse to ditch your responsibilities to your pushy parents, up sticks and strike out into the blue yonder looking for True Love, far away from your cousins. Time for Bollywood to triumph over tradition.