Saturday, March 9, 2013

Low-hanging fruit?

Labrador retriever running an obstacle course. Can dog intelligence shed light on human intelligence? (source)

My last post described a Chinese project to identify the many genes that contribute to normal variation in human intelligence. If successful, it will simply demonstrate what we already know, i.e., genes are largely responsible for the differences in intelligence we see among normal individuals. 

We know this from intelligence testing, particularly from studies on IQ differences between twins. This evidence, however, has been largely discredited in the eyes of many people, particularly those who act as gatekeepers in the halls of academia. As one scholar told me:

A key problem is funding. Intellectuals on today’s review panels 'came to consciousness' in a climate when intelligence testing was thought to be wrong and invalid. Very few scientists are open to new ideas […] So it often takes a generational turn-over before there is a swing back to a fresh look at intelligence.

I doubt things will change much when the old guard dies off. In some ways, the academic environment was more open-minded two decades ago, when there were still people, often in key positions, who had entered academia before the 1960s. Change will probably come when new evidence manages to bypass the gatekeepers, and this will most likely happen where the marketplace of ideas is less controlled, like in China. Yes, the same country we like to scold for not being sufficiently free and democratic.

What other new evidence could bring change? This question led me to ask the h-bd discussion list: “If you had access to sufficient funding, equipment, and trained personnel, what kind of research project would you like to do or see done?”

A behavioral geneticist suggested the following projects:

1) Investigate individual differences in cognitive abilities in other animal models. a) create a reliable scale. b) establish whether a g factor emerges in other mammals. c) find out the correlates of such a g factor (phenotypic and genetic)- which would be uncontaminated by SES and therefore lay to rest many controversies that arise in humans studies. [Disclaimer, I have started on this with dogs (60 dogs, all one breed, all farm living and am actively seeking funding to continue the project].

2) Investigate the correlates (particularly fitness-relevant correlates of intelligence in populations of hunter-gatherers. Not to examine mean differences between populations - but to test evolutionary hypotheses. Is intelligence associated with offspring number? Social status? Health? Life expectancy? We do not know the fitness optima for intelligence in any human population.

As for myself, I would want to determine whether the Visual Word Form Area is a product of nature or nurture. This could be done by following the same methodology that Zhu et al. (2009) used to prove that our ability to recognize faces is largely hardwired.  If the same is true, or even partly true, for our ability to recognize strings of letters, i.e., words, we would have a compelling argument for gene-culture co-evolution.

I would also want to see whether Tay-Sachs carriers, i.e., heterozygotes, really do have a higher mean intelligence than people without this allele (Frost, 2011). Such a study would be a cinch to do, yet no one has bothered. How come?

Finally, as with hbd* chick, my eyes glaze over when discussion focuses too long on IQ or SAT scores. We need to go beyond intelligence and look at genetic differences that may underlie variation in personality traits, regulation of emotions, time orientation, and so forth. There is more to being human than just intelligence.


Frost, P. (2011) Five years later … still no study, February 4, Evo and Proud.

Zhu, Q., Y. Song, S. Hu, X. Li, M. Tian, Z. Zhen, Q. Dong, N. Kanwisher, and J. Liu. (2009). Heritability of the specific cognitive ability of face perception, Current Biology, 20, 137-142.


Beyond Anon said...

While IQ might be boring we can still glean information from IQ tests about the relative selective advantage of different parts of tests for different populations.

This is from Jensen and was found on Cochran's blog, I think:

Surprisingly, blacks tend to perform relatively better on the more culture-loaded or verbal kinds of tests than on the culture-fair type. For example, on the widely used Wechsler Intelligence Scale, comprised of 11 different subtests, blacks do better on the culture-loaded subtests of vocabulary, general information, and verbal comprehension than on the nonverbal performance tests such as the block designs. Just the opposite is true for such minorities as Orientals, Mexican-Americans, Indians, and Puerto Ricans. It can hardly be claimed that culture-fair tests have a built-in bias in favor of white, Anglo, middle-class Americans when Arctic Eskimos taking the same tests perform on a par with white, middle-class norms. My assistants and I have tested large numbers of Chinese children who score well above white norms on such tests, despite being recent immigrants from Hong Kong and Formosa, knowing little or no English, and having parents who hold low-level socioeconomic occupations. If the tests have a bias toward the white, Anglo, middle-class, one might well wonder why Oriental children should outscore the white Anglos on whom the tests were originally standardized. Our tests of Mexican-Americans produced similar results. They do rather poorly on the culture-loaded types of tests based on verbal skills and knowledge, but they do better on the culture-fair tests. The same holds true for American Indians. All these minorities perform on the two types of tests much as one might expect from the culture-bias hypothesis. Only blacks, among the minorities we have tested, score in just the opposite manner.

Perhaps it is not surprising that all of the outside Africa groups are on one side.

In some sense, though, it is better if there is not too much knowledge out there about the genetics if intelligence, because the elites will just use it for themselves.

Anonymous said...

Heritability of the Specific Cognitive Ability of Face Perception

Anonymous said...

"We need to go beyond intelligence and look at genetic differences that may underlie variation in personality traits, regulation of emotions, time orientation, and so forth. There is more to being human than just intelligence."

Okay, so assume that intelligence and many other personality traits such as delayed gratification versus immediate gratification has no relationship to intelligence (doubtful, I think) but let's assume there's no relationship: the areas you suggest we study will open the same "oh, we can't go there can of worms" the pc crowd abhors.

So, you just have to ignore them. Period. Western society's Orwellian academic-media alliance will be around for the rest of your lifetime, at least. You simply have to ignore them or if they try to shut you up, you have to fight back, not let them bully you. Period.

Anonymous said...

BTW, Peter, at least here in the US we are interested in IQ not just because of scientific curiosity and the value of learning what we can of the brain, but also because the ignoring of innate intelligence differences has led to many social problems. Our schools are a horror because of it. Our pocketbooks are in a mess as well. Of course, the pursuit of knowledge for its own sake as well as for practical use is a victim too.

HBD chick, in saying what she did about the study of IQ was, if I understood her correctly when she said "her eyes glaze over" was pointing out the hbd reality of her female scientific sensibilities going more to the study of human relationships rather than the quantitative study males puruse with their interest in IQ and intelligence.

Anyway, we her in our country have to address the problems that keep us living a lie our they'll destroy us from within. We are broke, you know, and our pc politicians are still dumping money into the blank slate pit.

Sean said...

Correction:- Embarrassed myself there. Kuusamo is in the east and the infantile NCL is in common on the western coastline of course. Still, I'm thinking the disease seems to be common in a remote region where there may have been fewer Swedes and Russians to take managerial roles

Anonymous said...

I just stumbled on this today reading the MMA subreddit...

Bone density by race:

Black females have same bone density as white males when they are younger than 55.

Bone density difference between black males and white males is similar to the difference in bone density between white males and white females.

Anonymous said...

Mine would be:

Does IVF using special forces sperm donors have a greater success rate?

On the basis of the premise that miscarriage is partly a way of shedding genetic load and the assumption that special forces types will have less genetic load on average.

Additionally i've read but don't know if true that there is a preference for Danish sperm. I wonder if that is a customer preference or a success rate preference on the part of the clinics and if the latter then further wonder if the success rate of different nationalities is also related to genetic load.

2nd would be testing the gay germ theory.

Anonymous said...

"While IQ might be boring"

I wouldn't go that far but tempting people to dabble in hbd could use different bait for different types of people.

For example anyone interested in fertility - which is a lot of people - would be interested in things like the apparent fertility sweetspot for people who are 4th cousins.

Anonymous said...

oh yes and 3rd

Do medical side-effects cluster by ancestry?

There must be terabytes of medical research related to various meds going back decades where side-effects were collated. I wonder if those clusters mapped onto regional ancestry.

For example some pill or other had side-effects A, B and C but they clustered e.g.
- one cluster of patients had high A, medium B and low C
- one cluster had high B, low C and very little A
- one cluster just had medium B

and then see if this clustering mapped onto ancestral background e.g. cluster 1 having ancestral links to a region on the Italian side of the Alps and cluster 2 to a region on the Swiss side etc.

(I doubt there'd be enough data to take it all the way but i'd have thought a preliminary look to see if there's distinct clustering could be pretty productive on its own.)

JayMan said...

See here for a bunch of posts on the usefulness of HBD for things other than IQ.

Anonymous said...

Here is a rough breakdown of dog IQ by breed:


M said...

so assume that intelligence and many other personality traits such as delayed gratification versus immediate gratification has no relationship to intelligence (doubtful, I think)

That's a complicated question.

On the one hand, we have evidence that prefrontal damage messes up impulse control and various forms of behaviour necessary for success (intellectual, social, economic) while leaving IQ tests unimpaired.

So IQ and self control might be expected to be uncorrelated (or possibly even a mild negative correlation when you control for whole brain size and energy use).

Whereas, IQ test performance is described as sensitive to parietal and temporal lobe damage, which leaves executive function (the kinds of self monitoring or self awareness or intuitive behaviours which in the general case constitute a successful life strategy) relatively untouched.

Check out the PASS Theory of Intelligence -

(Although of course there are more regions involved in these kinds of processing than these than just those in the cerebrum).

On the other hand, mutations which improve whole brain efficiency or lead to increased whole brain energy use or whole brain size increase would have global effects on success oriented personality traits as well as intelligence. So there is reason to expect a positive correlation.

(Also there may be positive synergies between the real traits in real life - intelligence leads to good decision making which makes self control / executive abilities more valuable, while self control / executive abilities may lead to people being in positions where intelligence has greater functional value and increased returns.)

Even within intelligence, separate functional networks can be found, sensitive to regional damage with relatively isolable effects, but they seem to a large extent to be positively correlated and benefit from the same ontogenic factors.

M said...

Interestingly but as a side point to my mention of with prefrontal-temporoparietal brain regions, Zilles et al 2001* found a shape difference in (procrustes matched) Japanese and European (German) brains, which interestingly enough did not actually appear to reflect the same relative regional size, with a stretching of all regions equally (for the longer, narrower brains of Europeans versus the shorter, wider brains of the Japanese).

That is, it wasn't the case that Europeans had for instance, longer and narrower brains than the Japanese but without any changes in regional volumes, because the regions all were longer and narrower in proportion to the brain

Actually what was reflected was relatively stretched (wider, taller, longer) prefrontal and to a lesser exten occipital region in Europeans relative to a relatively stretched temporal and parietal region in the Japanese brain (wider, taller, longer). (Figs 7-10)

Europeans of course, do not have supremacy on many tests of (prefrontal associated) executive function (e.g. Wisconsin Card Sorting), but may have relatively enhanced abilities on some theory of mind abilities and in terms of constructing a self concept.

This may have historically helped give rise to more fluid societies, where individual strengths could be more usefully pooled to teamwork based projects (strong civil institutions which were not particularly under top down hierarchical control and visionary independent minded scientists).

It's interesting to consider whether this regional size difference has contributed to this.

Beyond intelligence is certainly an interesting matter, although tougher to put on a rigorous quantiative psychometric framework.

* As a tangent to a tangent, Zilles et al also found that the brains for both Japanese and European had different patterns of sexual dimorphism. These patterns were actually rather opposite (!) with European males showing the same kind of expansions relative to European females as Europeans relative to Japanese AND Japanese males showing the same kind of patterns relative to Japanese females as Japanese relative to Europeans.

M said...

The cleverest dogs are working border collies.MANY of the greatest working Collies have been carriers for Collie eye anomaly" Border collies also tend to suffer from another quite different disease; something called Ceroid-Lipofucinosis (AT same link the breeder says one of his best dogs has it).

Humans get something similar, its called Neuronal ceroid lipofuscinosis Up until the 1900s it was thought to be identical to Tay-Sachs.

Pretty interesting Sean!

M said...

Also of interest -

The anthropologist Anne Weaver has associates cognitive modernity with a relative expansion of the cerebellum relative to the cerebrum.

She finds pre-late Pleistocene Homo Sapiens to share with the Neanderthals a relatively smaller cerebellum relative to cerebrum, whereas AFAIK in brain shape pre-late Pleistocene Homo Sap is distinguished from Neanderthal by a vertically led parietal and temporal expansion relative to a relatively smaller occipital region.

In recent humans, the cerebral hemispheres are relatively smaller and the cerebellum relatively larger than in terminal Pleistocene humans. The cerebellum did not reach modern proportions until the very late Pleistocene (some time after 28,000 years BP) postdating by several thousand years the appearance of modern humans in territories occupied by archaic human groups (Weaver, 2001; Weaver, 2005)

Parietal and temporal expansion would fit with enhanced language and symbolic capabilities in pre-Holocene Sap relative to Neanderthal, however the changes in the cerebellum would rather be linked to its functions where "the cerebellum modulates the outputs of other brain systems to make them precise. Removal of the cerebellum does not prevent an animal from doing anything in particular, but it makes actions hesitant and clumsy. This precision is not built-in, but learned by trial and error. Learning how to ride a bicycle is an example of a type of neural plasticity that may take place largely within the cerebellum."

If we think of the rise of imitative learning through complex culture in Holocene Homo Sap there is a kind of intuitive sense here.

Weaver suggests this is or is linked to a peramorphic (opposite of paedomorphic) change in Holocene humans -

Peramorphosis is a form of heterochrony that involves terminal extension of the latest phase of maturation. In the human brain, the period of late maturation involves vigorous synaptic pruning in the cerebral cortex, accompanied by an increase in subcortical volume due to myelination and expansion of subcortical circuitry.
Peramorphosis is a credible mechanism to explain putative cognitive and neurological differences between recent humans and their Terminal Pleistocene and Holocene predecessors. For example, ontogenic shifts in the timing and duration of cortical growth and subsequent pruning can have significant effects on IQ (Shaw, Greenstein et al., 2006).

The protracted phase of brain maturation during adolescence in modern humans is correlated with a shift in cognitive and psychological strategies in which the cerebellum participates. This shift in cognitive strategies appears to reflect more efficient neural organization and sharing of information among cortical and subcortical brain regions (Katz and Steinmetz, 2002).

Behaviorally, the late phase of brain maturation results in the capacity for formal operational thinking, greater voluntary control of behavior, cognitive flexibility, social identity formation, and an enhanced ability to fine-tune cortical activity (Giedd, Snell et al., 1996; Luna, Thulborn et al., 2001; Giedd, 2004; Blakemore and Choudhury, 2006; Shaw, Greenstein et al., 2006).

In tasks that require voluntary control of reflexive/impulsive response tendencies, adults exhibit reduced reliance on the neocortex and greater recruitment of the cerebellum than adolescents do (Luna, Thulborn et al., 2001).

Modern humans may be able to automatically perform certain functions through the cerebellum in ways which free up there cerebral capacity for other tasks.

Weaver links this change to the spread of new variants of ASPM and MCPH, which will be interesting if true.

M said...

Also be interesting to compare a whether there may be a similar pattern of cerebrellar expansion in domesticated animals!

Comparing wolf to dog brains -

Interestingly, in dogs compared to wolves there is a progressive ventral pitching of the brain and an increase in brachycephaly. This is true of humans compared to our ancestors.

However within dog breeds, ventral pitching is associated with dolichocephalic dogs relative to brachcephalic dogs! This is interestingly similar to humans as well, where brachycephalic Mongoloids tend to have (more ancestrally) dorsally pitched brains together an otherwise more derived brachycephalic shape).

Anonymous said...

Why don't you do the Tay-Sachs study? What's an anthropology degree for?

Sean said...

Guy Debord thought revolutionary change was coming too. Ask not what people believe, but whether it would be useful for them to continue acting 'as if' they did believe it. Put it another way: do they want to be driving a taxi for a living? No, I'm not exaggerating; Larry Summers did no more than "casually speculated that one of the possible reasons there were relatively few female mathematics professors might be that men were just a bit better at math than women". He got cut off at the knees.

That study co-authored by journalist Roger Highfield, which he said proved group differences were 'bunkum' ("what most of us [my emphasis] have suspected all along"), made use of an MRI scanner.

Obama is going to give billions to a brain mapping study. See here. So, there are bigwig supporters and big bucks for the right proposal, but it is very naive to think anything that gets funding could change the scientific consensus. Or vice versa.

Anonymous said...

IQ & self control correlate positively, as long as you don't restrict the range. even IQ & basketball shooting accuracy will weakly correlate positively IF you include the severely retarded (old term, sorry) in your sample. see the scatter plot: if the extremely retarded are low on both the X & Y variables (as they would be for self control - or even so called "emotional IQ") you will get a positive correlation. it may be a small correlation - such as with head size & IQ, but you will get it, as long as you don't restrict the range, or lose variability by categorizing a continuous variable. idiots complain about the low correlation between GRE & graduate grade point - but both the X & Y variables are so restricted in range - if you include extremely retarded people, well duh - you will clearly strengthen the correlation!

M said...

However within dog breeds, ventral pitching is associated with dolichocephalic dogs relative to brachcephalic dogs! This is interestingly similar to humans as well, where brachycephalic Mongoloids tend to have (more ancestrally) dorsally pitched brains together an otherwise more derived brachycephalic shape).

NB, with this (I was having another quick readover of the paper) - I think I have actually made a brief assumption which was incorrect.

The paper actually describes a ventral pitching of the posterior brain in brachycephalic dogs and in dogs generally, which is of course causes a dorsal pitching of the anterior brain, and this is what Mongoloids have. - "In Africans the whole cranial base is rotated into a forward-downward position, while in Asians it is rotated in the opposite way. The Europeans occupied an intermediate position."

Sean said...

I think ‘regulation of emotions, time orientation, and so forth’ depend on the ability to:- detach oneself from animal desires; envision alternative plans of action while evaluating the likelihood of them succeeding; imagine the resulting situation for any particular plan of action in a variety of time frames; evaluate the plan with the greatest realistic chance of achieving the aim. Most important of all is the ability to keep in mind what it is you care about the most (the preferred good) while you’re making a decision. And to do that you need a powerful working memory.

I'm not sure that animals can't do much of that, to a certain extent, but what is specific to humans is the ability to preserve and transmit their reasoning, thereby enabling others to use it and act differently. Culture, in other words. A lot of HBD seems to imply that culture doesn't make a difference. Perhaps that is why many see it as lacking in humanity.

To take an extreme example; alcoholics are lacking in regulation of emotions and time orientation, yet Alcoholics Anonymous has enabled alcoholics to quit drinking.

Tyrion Lanister said...

Dr Frost, I wanted to ask some questions:

1- Causality is, in my opinion, the key scientific question in connection with intelligence and IQ. Suppose we had a battery of athletic skill measures: swimming, javelin throwing, long-distance running and so on. Imagine that we then factor-analysed them and came up with a factor, which turned out to be a g factor, involving a basis such as the ratio of slow twitch to fast twitch muscle fibres. The question is, where would that have advanced us if we didn’t know the causal mechanisms of muscle use, and movement and motor patterns? The counterparts of this in cognition are the cognitive mechanisms underlying cognitive capacity. To what extent does the correlation pattern that g seems to exemplify help us understand the real causal mechanisms underlying cognitive capacities? I’m inclined to say that g has provided approximately zero benefit in helping us with cognitive modelling.

2-One has to be awfully careful to make clear what we mean by adaptation. In my view, we must not talk about social success as being an adaptation: that will lead us right up the wrong path. The dependent variables used in some studies are variables that you would expect to show this pattern in an intensely competitive society such as the USA. We should bear in mind that it is at least possible that different sorts of results would be obtained in a collectivist society such as East Asian societies. These variables could be rather culture-specific. This issue impacts on about changing the cultural environment over time, and even the question of social intelligence. Do you agree that many of these data may be very much culture bound? The USA is a very peculiar

3- Ulrich Neisser, in his review of your book “The g factor”, points out that when you compare reaction times in people with higher and lower IQs, the maximum responses are very similar_it tends to be more the variance that separates the two. Is that correct, and if so what do you make of it?

4- I have a very simple methodological question, which derives from the comment about the role of linkage. What about analyses using genetic covariance approaches in which you contrast correlations among monozygotic (MZ) and dizygotic (DZ) twins, with an effort to see whether or not the genes that are contributing to intelligence are co-varying in that way? For example, some studies suggest that assortative mating is not genetically covariant, even though it has a high correlation with your g factor. The correlation between MZ twin spouses in intelligence is no higher than the correlation of DZ twin spouses. This seems to come about solely because of social homogamy effects: people just get tossed together who are somewhat equal in IQ in social settings. The data on head size are ambiguous or undecided with respect to whether or not IQ and head size are genetically covariant. On the other hand, if you found that there are genetically covariant relations underlying these correlates, is that design suffcient to move you a step forward in the way that a comparison of between- and withinfamily correlations may not be?

5-One issue that I am interested in is what accounts for the genetic variation from an evolutionary viewpoint. In life history theory, building both a bigger body and a bigger brain is somatic investment. It is investment in the future because it costs the organism energy to do so now, and only over time may the organism reap the benefits of the investment reproductively. It is possible that there is genetic variation in somatic investment more generally, in a sense variation across individuals in their willingness to bet that there’s enough of a future to make somatic investment worthwhile. It is not clear that the genetic variation has anything to do with building a better brain per se: it could simply be genes that code essentially for somatic investment. What do you think about this?

Tyrion Lanister said...

6-Do you think that the kind of research programme would be enhanced by looking at animals that have been bred for different abilities? Is it possible to breed rats for maze learning ability, for example?Is this finding that breeding tends to have effects that are relatively task specific have implications for the notion of g, which implies that individual skills ought to derive out of g? Surely on the basis of the hypothesis that g is ‘driving’ the individual skills, you would expect that the breeding would actually have a more general effect than it does, wouldn’t you?

7-It seems that there are two distinct ways that the study of individual differences could inform the study of the species-typical cognitive architecture. First, it’s probably impossible to understand even one individual’s mechanisms of social judgement and social inference without having an idea of the
dimensions of variation between people with respect to which any individual has to make judgements. If we want to choose a sexual partner or trading partner, or discriminate in hiring an employee, we need a rich set of cognitive inference procedures which are presumably going to be tuned to the typical
distributions and covariances that exist within our species with respect to mental, physical and social traits. I don’t think we will be able to understand the social judgement mechanisms without studying individual differences in psychology. A second tack is to say that we have the g factor, and we have a bunch of group factors (verbal, spatial, etc.): do those group factors now fall into any aspects of the cognitive architecture?

8- Intercorrelations between tasks are higher for lower g subjects and this is very interesting from the genetic point of view. It seems to suggest that in so far as those phenotypic correlations reflect genetic covariances, g is being caused mostly by harmful mutations that have pleiotropic effects on multiple systems and that g does not necessarily reflect a spread of different strategies. That is, g reflects damage caused by particular mutations with multiple effects. This could account for why correlations between tasks are higher at lower g. Is that a coherent idea? If the optimal phenotype that is the ‘unmutated’ genome, the species-typical genome represents high g, then as you accumulate more and more deleterious mutations that each have pleiotropic effects in multiple systems, they’re going to introduce the correlations between defiicits in multiple systems. This will in turn introduce higher intercorrelations at lower g levels.

9- How fast would the genetic correlations change between traits that may have been valuable in the past? Genetic correlations involving longevity and fecundity may change immediately, but genetic correlations with health and growth and so on may change more slowly. I have a question for you. There’s a lot of talk in evolutionary biology about the importance of coevolutionary processes in maintaining genetic variance, with the primary one being host^parasite/pathogen coevolution. How important do you
think coevolutionary processes are, as opposed to mutation?

10- One question about the apparent infertility of smarter people. The situation is more complex because of the costs of rearing children. Ruth Mace and one or two others have developed models recently that show rather nicely that when the costs of rearing start to bite the cost required to place your offspring in advantageous positions in society, which is the problem we have now in a highly educational-based society really pays you to have fewer children, given that there’s likely to be a correlation then between IQ and social/ economic achievement. This apparent negative correlation may be something similar to David Lack’s findings on optimum clutch size in birds. Offspring number is contingent upon circumstances, and restricting the number of children may be an optimal strategy in terms of lineage survival. Is intelligence related somehow to reproductive patterns?

Tyrion Lanister said...

11- What do you think about the hypothesis put forward Crabtree? Are humans slowly losing their cognitive capabilities as adverse genetic mutations fail to be weeded out by evolutionary pressures?
By the other hand some people were saying that there are IQ gains. So therefore all of our grandparents must have been mentally retarded?. This idea that the IQ gains were spurred by competition and awareness of the larger world of people to be emulated might also explain the relative poor performance of blacks who sociologists claim are generally not so competitive over these issues?

12- Is having a high g functional in terms of fitness? If g is basically an index of fitness and if it is indeed the case that fitness isdetermined by the deleterious mutation load, there is not going to be sexual dimorphism in mutation load, right? After all, the two sexes basically share the same genes except those on the Y chromosome. Andrew Pomiankowski talk about accelerating selection and this idea that selection favours increased phenotypic variance, that this would increase the number of loci and the strength of loci effects on the sexual character. How this would happen? To some non-biologists this might sound a little ‘magical’. Do you have a different view about how this works?

13- Do you think that variation in g itself is higher in men than women?. At least with respect to the behavioural advertisements of intelligence, it is true that from the risk-seeking model that Andrew Pomiankowski advocated one would expect higher variation in males than in females. The more relevant question is whether g is an index of fitness: if so, one would not expect sexual dimorphism in g, because there should be no sexual dimorphism in overall average fitness. This is less true if g is more like a costly indicator (rather than an index) of fitness. The fact that there is a sex difference in brain size even after controlling for body size suggests that brains are costly and they might be functioning more as indicators. I do not know what the relation is between the g factor and brain size in that regard.

14- Are there any heritable variation in mate preferences for intelligence?. Geoffrey Miller say that we all have exactly the same mate preferences and the same rank order of sexually desired cues we pay attention to, and we would still end up assortatively mating for intelligence, valuing intelligence highly and favouring intelligent males. Anyway Reynolds indicates that assortative mating occurs as a result of social homogamy. What do you think about this? There was a time when Miller suggested that g evolved as a result of runaway sexual selection of the nonfunctional kind. The position he is coming from now is that g is a genuine indicator of fitness and not merely a decoration.

Peter Fros_ said...


Yes, it looks like verbal skills correlate imperfectly with abstract reasoning. This is one of the problems of "culture-free" tests. If you center the test on abstract reasoning, you're excluding a lot of crucial mental skills.


1) I agree that some kind of general mental property ("g") shows up across the board. But there are other mental properties. The ability to recognize human faces, for instance, seems to be independent of other mental abilities.

2) The more fields of interest we open up, the more people will take an interest in HBD. The success of a paradigm depends on its ability to mobilize interest within the academic community and among the public at large.

3) We all have interests that seem boring to most other people. I imagine hbd-chick finds much of my stuff boring. But the net result of encouraging different interests is to increase the overall number of people who take an active interest in HBD. We will also increase the probability that one of those fields of interest will lead to something really big.

4) Most Western countries are heavily in debt, but this debt crisis could go on indefinitely (look at Japan). Things will change when enough people can think outside the box and when even the elites realize that something is very, very wrong.


You may be on to something. The western coastline was under stronger Swedish influence than the rest of Finland. The market economy may have developed there at an earlier date, with an attendant increase in demand for literate and numerate individuals with a future-oriented time orientation.


I suspect that higher bone density is related to polygyny and male-male competition for mates.


It's a customer preference.


The problem is that geographic origin is less and less informative about ethnic origin. Most people now living in urban areas that tend to be multiethnic.


Yes, I read those posts. In fact, those posts and hbd-chick's interview were on my mind when I wrote this post.


Yes, I suspect that the degree of myelinization (as Ed Miller proposed) corresponds to this global property of mental functioning. I also suspect there are a lot of very specific mental modules, like face recognition and word recognition, that function pretty much on their own. Finally, there are probably mental abilities that merge into each other because they share many of the same neural networks.

I agree that human mental evolution continued after the advent of modern humans. In fact, most of the interesting stuff has happened since then.


Doing that Tay-Sachs study would require funding. Not a lot, but it's not something I could pay for out of my pocket. It would have to be a team project. From time to time I try to sound out different people on this idea, but so far no one has nibbled at the bait.


I agree that IQ and self-control correlate, but is this correlation a product of shared selection pressures or a product of shared neural networks?


I agree. There are big qualitative differences between dog and human intelligence. Humans can master the sequence: A causes B which causes C. Dogs can't. This is why dogs have a very limited capacity for tool use.

And, yes, humans are bathed in a cultural environment. We have had to adapt to culture.

Peter Fros_ said...


1. "G" is probably some property of brain tissue, like myelinization. It tells us little about brain organization.

2. Yes, since most of recent human evolution has been gene-culture co-evolution, the outcomes have necessarily been culture-bound. That's why cultural and physical anthropologists need to get together (at present, they aren't).

3. That higher IQ individuals are a more restricted and less heterogenous sample.

4-10. These questions seem to be aimed at another person.

11. In the Western World, evolution of mental capacity began to slow down in the late 19th century with the rise of industrial capitalism and the demise of cottage industry. If you needed new workers for your workshop, you could just hire them (instead of siring them). The rise of global capitalism will accentuate this trend. We will become a planet of helots.

Kiwiguy said...

@ Tyrion Lanister,

Regarding g, see this post by Steve Hsu which features papers by Duncan & Choi:

A Neural Basis for General Intelligence (Science)

Universal positive correlations between different cognitive tests motivate the concept of “general intelligence” or Spearman's g. Here the neural basis for g is investigated by means of positron emission tomography. Spatial, verbal, and perceptuo-motor tasks with high-g involvement are compared with matched low-g control tasks. In contrast to the common view that g reflects a broad sample of major cognitive functions, high-g tasks do not show diffuse recruitment of multiple brain regions. Instead they are associated with selective recruitment of lateral frontal cortex in one or both hemispheres. Despite very different task content in the three high-g–low-g contrasts, lateral frontal recruitment is markedly similar in each case. Many previous experiments have shown these same frontal regions to be recruited by a broad range of different cognitive demands. The results suggest that “general intelligence” derives from a specific frontal system important in the control of diverse forms of behavior....

Multiple Bases of Human Intelligence Revealed by Cortical Thickness and Neural Activation (Journal of Neuroscience)

"We hypothesized that individual differences in intelligence (Spearman’s g) are supported by multiple brain regions, and in particular that fluid (gF) and crystallized ( gC) components of intelligence are related to brain function and structure with a distinct profile of association across brain regions. In 225 healthy young adults scanned with structural and functional magnetic resonance imaging sequences, regions of interest (ROIs) were defined on the basis of a correlation between g and either brain structure or brain function. In these ROIs, gC was more strongly related to structure (cortical thickness) than function, whereas gF was more strongly related to function (blood oxygenation level-dependent signal during reasoning) than structure. We further validated this finding by generating a neurometric prediction model of intelligence quotient (IQ) that explained 50% of variance in IQ in an independent sample. The data compel a nuanced view of the neurobiology of intelligence, providing the most persuasive evidence to date for theories emphasizing multiple distributed brain regions differing in function."

Anonymous said...

"The problem is that geographic origin is less and less informative about ethnic origin. Most people now living in urban areas that tend to be multiethnic."

Yes but clustering of side-effects - if it occurred - would be interesting in itself and i'd imagine data to show that is true - or not - already exists.

Also if clustering did occur and if regional ancestry was behind it then the multiethnic point although it might initially make finding the ancestral region harder might help identify the region of DNA responsible once the geographical regions were figured out e.g. if you had two clusters which you found mapped onto French and German ancestry then which mixed French-Germans fell into which cluster might help to pinpoint which genes were involved.

I guess the ideal might be pills developed in the US which also underwent separate trials in individual countries and see if there was for example 10% of test subjects in the states were in a particular side-effect cluster whereas it was 20% in Germany and less than 10% elsewhere.

It might be nothing but given a lot of the preliminary data probably already exists from thousands of past medical trials this seems like a good candidate for *potential* low hanging fruit especially in the context of BiDil

I think there's bound to be more BiDils locked away in old data.

Sean said...

I think there is a need for a 12 step program called 'Commenters Anonymous'.

Mike said...

Tyrion Lanister, Im going to try to reply those questions that Peter was not able to answer:

4) This is a general and interesting phenomenon. It is something that people in evolutionary biology might tell someone like me a lot more about. Lykken & Tellegen (1993) looked at correlations between the spouses of MZ twins and DZ twins. We know that MZ twins are more alike primarily for genetic reasons, and that if people select spouses who are genetically similar to themselves you would expect the spouses of MZ twins to be similar in a way that the spouses of DZ twins are not. It turns out that across a large range of characteristics this is not the case. They argue that attraction to others is a kind of evolutionary mechanism to create genetic diversity, and people are simply attracted to people who are not necessarily genetically similar. People who study relationships often point out that it’s very hard to know why people are initially attracted. You can sometimes predict whether people will stay together or break up, by differences in political attitudes, for example. But the initial attraction seems almost like a random phenomenon.

5) Not with regard to the genetic variance, but more broadly with respect to the theory, yes. In evolutionary biology, life history theory is a fundamental framework for thinking about problems of selection. The adaptiveness of an organism’s activities is thought of in terms of trade-offs. One basic trade-off is that between current and future reproduction. Again, developing a bigger brain is an investment in the future at the expense of reproduction in the short term, which the energy used to build the bigger brain, could have been allocated to. But investment in the long-term future does not always pay, particularly if the long-term future cannot be counted upon. We think of low intelligence as being bad, but it’s quite possible that the brain size of everyone is optimal given their condition and their phenotype, which is some function of their genotype. For instance, suppose there is genetic variation in disease susceptibility, such that some individuals have the misfortune of not resisting the prevailing pathogens. From a life history standpoint, we might expect that selection would have designed organisms, whether humans or rats, to invest less in the future when they find themselves having that misfortune.

6) Efforts to breed animals for performance on particular tasks have not been particularly good at producing animals that are better across tasks. People looking for quantitative trait loci in humans have selected high performing populations and low performing populations on what we consider to be intelligence measures. If you could agree on a battery of tests in rodents of sufficient breadth, and you could somehow select for this, then that would probably be useful for the same reasons I think it’s useful in people.

7) I think there is an explicit connection between variation and the state of a population. Variation is how you got where you are now. You can’t think about evolution without thinking about variation. This is a separate issue from your point, which is saying that making inferences about variation is part of what mental architecture must be about.

8) I’m not quite sure how you’re using the term ‘mutations’. All genetic variations are in an ultimate sense ‘mutations’. Presumably, you are talking about new mutations that are deleterious. You are then postulating that these are functioning right across the range. It is not that you’re getting a jump up when you’re hitting the retarded range: you’re getting it within the normal range. I find it a surprising notion that the variations in g within the normal range are due to accumulation of abnormal mutations.

Mike said...


9) The best estimate of how much genetic variation mutation must account for, in terms of variance within Drosophila, is probably in the order of 20% (Houle et al 1996), and that’s a conservative estimate. The remaining 80% could well be accounted for by polymorphisms maintained by the sorts of things you’re talking about, such as disease interactions. However, an alternative is that mutation & selection balance maintains far more than 20%. There is lots of room for uncertainty about the quantitative importance of mutation.

10) If it is right that intelligent people are investing more in their fewer children, we would expect also to find a sex bias in their children. We would expect higher IQ to be correlated with a bias towards having boys. I don’t know about IQ, but a number of studies have shown that the richer sector of the population invests more heavily in their sons than daughters, and the poorer sector invests more heavily in their daughters. Various studies (e.g. Bereczkei & Dunbar 1997) have shown that this applies, even down to the level of how long mothers breast-feed their children for.

12) Although evolutionary theory suggests that when equilibrium is reached, additive genetic variance should be zero, I wonder whether that is actually borne out with empirical data. It seems such data have shown that in fact this does not happen. Some researchers point out two possible explanations as to why that might be so, in terms of selection for variance and condition dependence. There are other explanations in terms of how one knows when equilibrium has been reached, and what sort of assumptions one is making about the way it operates in the world.

Mike said...

regarding to (12) it does seem that the paradox posed is not a paradox any longer. Is this sort of extrapolation wrong? I think it is naive to believe the lek paradox as formulated that there will be no genetic variance. This has been shown to be wrong. What explains the existence of variance and if it happens to be higher in sexual traits is a matter for experimental investigation. The fact that both sexual traits and g may share high additive variance may have no signifficance, since these may have completely different explanations.

13) I have read some work of Miller & Todd on mate search strategies. In this work we predict that if there is general variation in fitness, then because of the mating market you are probably going to end up with someone of similar fitness since you cannot a¡ord to attract someone of higher mate value (they want someone at least equal to themselves). If this is true, then one would expect psychological adaptations to evolve that prefer similarity itself. This keeps you from wasting effort going after mates who won’t have you anyway.

14) For Miller´s argument to work, there doesn’t have to be variation in the sexual preference for intelligence, but I suspect there is variation, and I frankly would like to see studies that find no heritable variation in human mate preferences. The variation in the displays of g would be decorative, and this is where one would expect the sexual dimorphism. But the fact that there seems to be no sexual dimorphism in g itself suggests that it is a fittness indicator and not a consequence of runaway sexual selection.

Mike said...

Tyrion Lanister,let me point out my opinion on questions 1 to 3:

1) There is a lot more to differential psychology than g. There are group factors, interests and personality, and you can get at all of them through the Spearman & Brown formula (Lubinski 1996, Lubinski & Humphreys 1997). In terms of how g can help to understand low-order mechanisms, I think the jury is still out (but see Lubinski 2000). Science moves slowly sometimes. I think it can help to find and isolate different populations, look for genetic markers and look for individual differences in the CNS that can provide clues to the underlying structure. To be clear, the g construct is not a ‘thing’; it’s an abstraction like horsepower. There are different components to horsepower, such as carburettors and cylinders, but still there’s a general property. The overall functioning of this general property can be increased by tinkering with the components individually, tinkering with the whole system, or tinkering with fuel: there are a variety of different variables underlying ‘horsepower’ as there undoubtedly are with g. It helps to know where to look, just as Skinner’s principle of reinforcement helped to identify different areas of the brain for positive reinforcement centres and so on.

2) It is even more clear-cut than that I think. Anyone who just speaks one language is culture bound to being tested using that medium, if you’re going to use a language-based vehicle. This is why a lot of cross-cultural research uses things like the Raven matrices, which are just pictorial. There is strong evidence that g applies cross-culturally.

3) Yes that’s correct. Even comparing Berkeley students with mentally retarded people in institutions, their fastest reaction times do not differ all that much, but the retarded people produce many more slower reaction times. A more important correlate of g than reaction time is the intra-individual variance in reaction time: brighter people show less variation from trial-to-trial of a reaction time test than less bright people. There are hypotheses, such as the theory that there’s simply more noise in the nervous systems of lower IQ people, and that this variation from trialto- trial in reaction time tests reffects neural noise, whatever that may mean. This should be investigated, because it’s a more striking correlate of IQ than is reaction time itself.

Harold said...

Peter writes,

"Doing that Tay-Sachs study would require funding. Not a lot, but it's not something I could pay for out of my pocket."

Maybe you should consider crowdfunding. A quick web search discovered this site,

an article about it,

and a NYTimes article about crowdfunding research in general,

If Sailer or another with a higher traffic site gave a heads up I think it would get significant interest.

Anonymous said...

This is one of the problems of "culture-free" tests.

The notion of gene-culture co-evolution seems to surface a lot, but no one seems to be quantifying what culture is.

In my opinion, "culture" is behavioral complexity, and not some amorphous concept that people don't want to examine. We can measure it on a logarithmic scale.

If we set humans at a level of 10 for behavioral complexity, then chimps are at around 7, and gorillas are at around 5, while baboons are at around 6.

So, the more social the species, the higher the behavioral complexity.

We can also see that behavioral complexity increases when males co-operate. So, since among chimps they are mostly related males co-operating but among baboons you have a single dominant male in a troop, the chimps have an order of magnitude more complexity.

Among humans we have a new paradigm where largely unrelated males can co-operate, we see behavioral complexity ascend to great new heights.

PaganAtheist said...

Any erudite commentary from anyone?

Sean said...

Neanderthals were so stupid they thought erudite was a glue.

An Erudite Anon said...

Any erudite commentary from anyone?

All in all a pretty worthless paper.

1. Motor area size is connected to the complexity of muscle organisation, coordination and pattern firing, not really to muscle "size". Motor areas atrophy when a limb is amputed, they don't have to enlarge when people build muscle on a limb, or atrophy when all the muscles are still there but atrophied.

2. The eyeball size - orbital area correlation, relatively robust for very small mammals* really reduces in large mammals. It is is massively sublinear even in hominoidea, compared to the largely small primate sample which Stringer, Dunbar and Pearce uses as a model.

*(The reason is probably small mammals their body size is an evolutionary and physical constraint to having a more fitness optimal larger eye size, so their eyes increase in stepwise fashion to the maximum that they can support. Not the case in large mammals.)

Moreover, John Hawks cites (in his twitter) a paper which finds eyeball size has only 1.25% of its variation explained by orbit size in a modern human sample.

Finally, when actual axial lengths of eyeballs (a good proxy for eyeball size - the eyeball has to be more or less a sphere to function) are measured, there is no real good evidence Northern population consistently have larger eyeball sizes. In at least one sample, when populations in the same country are compared, Europeans have shorter axial lengths than Africans and South Asians (who have longer axial lengths than Africans), while East Asians have similar axial length to South Asians (and all this is perfectly in line with between population myopia rates, myopes having larger eyeballs with Europeans as the least myopic). Also, the differences in axial length are small (e.g. 0.5mm) compared to the increases in orbital volume Pearce et al previously described in their earlier work!


Neanderthals may have had expanded primary visual areas and motor areas compared to humans - having generally better senses and being more coordinated in their (probably gross rather than fine) body movements may have been their strategy.

(Although this is quite distinct from Pearce, Dunbar and Stringer's statement that Neanderthals had to have larger brains than humans to be effectively no better at perceptual or somatic abilities).

Its just Pearce, Dunbar and Stringer's paper is pretty damn awful evidence for this! And if this was the Neanderthal strategy, it certainly wasn't caused by the fact that Europe, Central Asia and the Near East was their EEA (as PDS moot).

Its also bad because Dunbar is using it as evidence to for push his "Change in language and perceptual abilities wasn't important - it was the Dunbar Number change in the frontal lobe, which allowed group size changes!" hypothesis, when it is still far more probable from the evidence that temporal and parietal expansion and language and perceptual ability enhancement was important in what made H Sap different, from actual direct brain evidence (as limited as that is by the condition of Neanderthal and archaic endocasts).