[Warning: Vastly overlong book review. Casual reader beware.]
Race Differences in Intelligence: An Evolutionary Analysis, by Richard Lynn (Augusta, GA: Washington Summit, 2006)
Richard Lynn’s ‘Race Differences in Intelligence’ is structured around his massive database of IQ studies conducted among different populations. This collection seems to be largely recycled from his earlier IQ and the Wealth of Nations, and subsequently expanded, revised and reused again in IQ and Global Inequality, The Global Bell Curve, and The Intelligence of Nations (as well as a newer edition of Race Differences in Intelligence, published in 2015).
Thus, despite its subtitle, “An Evolutionary Analysis”, the focus is very much on documenting the existence of race differences in intelligence, not explaining how or why they evolved. The “Evolutionary Analysis” promised in the subtitle is actually almost entirely confined to the last three chapters.
The choice of this as a subtitle is therefore misleading and presumably represents an attempt to cash in on the recent rise in, and popularity of, evolutionary psychology and other sociobiological explanations for human behaviours.
However, whatever the inadequacies of Lynn’s theory of how and why race differences in intelligence evolved (discussed below), his documentation of the existence of these differences is indeed persuasive. The sheer number of studies and the relative consistency over time and place suggests that the differences are indeed real and there is therefore something to be explained in the first place.
In this respect, it aims to do something similar to what was achieved by Audrey Shuey’s The Testing of Negro Intelligence, first published in 1958, which brought together a huge number of studies, and a huge amount of data, regarding the black-white test score gap in the US.
However, whereas Shuey focused almost exclusively on the black-white test score gap in North America, Lynn’s ambition is much broader and more ambitious – namely, to review data relating to the intelligences of all racial groups everywhere across the earth.
Thus, Lynn declares that:
“The objective of this book [is] to broaden the debate from the local problem of the genetic and environmental contributions to the difference between whites and blacks in the United States to the much larger problem of the determinants of the global differences between the ten races whose IQs are summarised” (p182).
Therefore, his book purports to be:
“The first fully comprehensive review… of the evidence on race differences in intelligence worldwide” (p2).
Consistent with this, Lynn includes in his analysis data for many racial groups that rarely receive much if any coverage in previous works on the topic of race differences in intelligence.
Relying on both morphological criteria and genetic data gathered by Cavalli-Sforz et al in The History and Geography of Human Genes, Lynn identifies ten separate human races. These are:
3) “Bushmen and Pygmies”;
4) “South Asians and North Africans”;
5) “Southeast Asians”;
6) “Australian Aborigines”;
7) “Pacific Islanders”;
8) “East Asians”;
9) “Artic Peoples”; and
10) “Native Americans”.
Each of these racial groups receives a chapter of their own, and, in each of the respective chapters, Lynn reviews published (and occasionally unpublished) studies that provide data on each group’s:
- Reaction times when performing elementary cognitive tasks; and
- Brain size
The average IQs reported by Lynn are, he informs us, corrected for the Flynn Effect – i.e. the rise in IQs over the last century (p5-6).
However, the Flynn Effect has occurred at different rates in different regions of the world. Likewise, the various environmental factors that have been proposed as possible explanations for the phenomenon (e.g. improved nutrition and health as well as increases in test familiarity, and exposure to visual media) have varied in the extent to which they are present in different places. Correcting for the Flynn Effect is therefore easier said than done.
IQs of “Hybrid populations”
Lynn also discusses the average IQs of racially-mixed populations, which are, he reports, consistently intermediate between the average IQs of the two (or more) parent populations.
However, both, on the one hand, hybrid vigour or heterosis and, on the other, hybrid incompatibility or outbreeding depression could potentially complicate the assumption that racial hybrids should have average IQs intermediate between the average IQs of the two (or more) parent populations.
However, Lynn only alludes to the possible effect of hybrid vigour in relation to biracial people in Hawaii, not in relation to other hybrid populations whose IQs he discusses, and never discusses the possible effect of hybrid incompatibility or outbreeding depression at all.
Finally, Lynn also purports to estimate what he calls the “genotypic IQ” of at least some of the races discussed. This is a measure of genetic potential, distinguished from their actual realized phenotypic IQ.
He defines the “genotypic IQ” of a population as the average score of a population if they were raised in environments identical to those of the group with whom they are being compared.
Thus, he writes:
“The genotypic African IQ… is the IQ that Africans would have if they were raised in the same environment as Europeans” (p69).
The fact that lower-IQ groups generally provide their offspring with inferior environmental conditions is therefore irrelevant for determining their “genotypic IQ”. However, as Lynn himself later points out:
“It is problematical whether the poor nutrition and health that impair the intelligence of many third world peoples should be regarded as a purely environmental effect or as to some degree a genetic effect arising from the low intelligence of the populations that makes them unable to provide good nutrition and health for their children” (p193).
Also, Lynn does not explain why he uses Europeans as his comparison group – i.e. why the African genotypic IQ is “the IQ that Africans would have if they were raised in the same environment as Europeans”, as opposed to, say, if they were raised in the same environments East Asians, Middle Eastern populations or indeed their own environments.
Presumably this reflects historical reasons – namely, Europeans were the first racial group to have their IQs systematically measured – the same reason that European IQs are arbitrarily assigned an average score of 100.
Reaction times refer to the time taken to perform so-called elementary cognitive tasks. These are tests where everyone can easily work out the right answer, but where the speed with which different people get there correlates with IQ.
Arthur Jensen has championed reaction time as a (relatively more) direct measure of one key cognitive process underlying IQ, namely speed of mental processing.
Yet individuals with quicker reaction times would presumably have an advantage in sports, since reacting to, say, the speed and trajectory of a ball in order to strike or catch it is analogous to an elementary cognitive task.
However, despite lower IQs, African-Americans, and blacks resident in other western economies, are vastly overrepresented among elite athletes.
To explain this paradox, Lynn distinguishes “reaction time proper” – i.e. when one begins to move one’s hand towards the correct button to press – from “movement time” – how long one’s hand takes to get there.
Whereas whites generally react faster, Lynn reports that blacks have faster movement times (p58-9). Thus, Lynn concludes:
“The faster movement times of Africans may be a factor in the fast sprinting speed of Africans shown in Olympic records” (p58).
However, psychologist Richard Nisbett reports that:
“Across a host of studies, movement times are just as highly correlated with IQ as reaction times” (Intelligence and How to Get It: p222).
Lynn also reviews data regarding the brain-size of different groups.
The correlation between brain-size and IQ as between individuals is well-established (Rushton and Ankney 2009).
As between species, brain-size is also thought to correlate with intelligence, at least after controlling for body-size.
Thus, in the late-1960s, biologist HJ Jerison developed an equation to estimate an animal’s intelligence from its brain- and body-size alone. This is called the animal’s encephalization quotient.
However, comparing the intelligence of different species poses great difficulties.
In short, if you think a ‘culture fair’ IQ test is an impossibility, then try designing a ‘species fair’ test!
Moreover, dwarves have smaller absolute brain-sizes but usually larger brains relative to body-size, but usually have normal IQs.
Sex differences in IQ, meanwhile, are smaller than those between races even though differences in brain-size are greater, at least before one introduces controls for body-size.
Also, Neanderthals had larger brains than modern humans, despite a shorter, albeit more robust, stature.
One theory has it that population differences in brain-size reflect a climatic adaptation that evolved in order to regulate temperature, in accordance with Bermann’s Rule. This seems to be the dominant view among contemporary biological anthropologists, at least those who deign (or dare) to even discuss this politically charged topic.
Thus, in one recent undergraduate textbook in biological anthropology, authors Mielke, Konigsberg and Relethford contend:
“Larger and relatively broader skulls lose less heat and are adaptive in cold climates; small and relatively narrower skulls lose more heat and are adaptive in hot climates” (Human Biological Variation: p285).
On this view, head size and shape represents a means of regulating the relative ratio of surface-area-to-volume, since this determines the proportion of a body that is directly exposed to the elements.
Thus, Stephen Molnar, the author of another competing undergraduate textbook in biological anthropology, observes
“The closer a structure approaches a spherical shape, the lower will be the surface-to-volume ratio. The reverse is true as elongation occurs—a greater surface area to volume is formed, which results in more surface to dissipate heat generated within a given volume. Since up to 80 percent of our body heat may be lost through our heads on cold days, one can appreciate the significance of shape” (Human Variation: Races, Types and Ethnic Groups, 5th Ed: p188).
For example, Eskimos tend to be short and stocky, with short arms and legs and flat faces. This minimizes the ratio of surface-area-to-volume, ensures only a minimal proportion of the body is directly exposed to the elements, and also minimizes the extent of extremities (e.g. arms, legs, noses), which are especially vulnerable to the cold.
In contrast, populations from tropical climates, such as African blacks and Australian Aboriginals, tend to have relatively long arms and legs as compared to trunk size, a factor which likely contributes towards their success in some athletic events.
Yet, interestingly, Beals et al report that:
“Braincase volume is more highly correlated with climate than any of the summative measures of body-size” (Beals et al 1984: p305).
Yet, contrary to popular wisdom, humans do not lose an especially high proportion of our body heat through our heads, certainly not “up to 80 percent of our body heat”, as claimed in Stephen Molnar’s anthropology textbook as quoted above, a preposterous figure given that the head comprises only about 10% of the body’s overall surface area.
Indeed, the amount of heat lost through our head is relatively higher than that lost through other parts of the body only because other parts of the body are typically covered by clothes.
At any rate, it is surely implausible that an increase in brain tissue, which is metabolically highly expensive, would have evolved solely for the purpose of regulating temperature, when the same result could surely have been achieved by modifying only the external shape of the skull.
Conversely, even if race differences in brain-size did evolve purely for temperature regulation, differences in intelligence could still have emerged as a by-product of such selection.
In other words, if larger brains did evolve among populations inhabiting colder latitudes solely for the purposes of temperature regulation, the extra brain tissue that resulted may still have resulted in greater levels of cognitive ability among these populations, even if there was no direct selection for increased cognitive ability itself.
The first racial group discussed by Lynn are those he terms “Europeans” (i.e. white Caucasians). He reviews data on IQ both in Europe and among diaspora populations elsewhere in the world (e.g. North America, Australia).
The results are consistent, almost always giving an average IQ of about 100 – though this figure is, of course, arbitrary and reflects the fact that IQ tests were first normed by reference to European populations. This is what James Thompson refers to as the ‘Greenwich mean IQ’ and the IQs of all other populations in Lynn’s book are calculated by reference to this figure.
Southeast Europeans, however, score slightly lower. This, Lynn argues, is because:
“Balkan peoples are a hybrid population or cline, comprising a genetic mix between the Europeans and South Asians in Turkey” (p18).
Therefore, as a hybrid population, their IQs are intermediate between those of the two parent populations, and, according to Lynn, South Asians score somewhat lower in IQ than do white European populations (see below).
In the newer 2015 edition, Lynn argues that IQs are somewhat lower elsewhere in southern Europe, namely southern Spain and Italy, for much the same reason, namely because:
“The populations of these regions are a genetic mix of European people with those from the Near East and North Africa, with the result that their IQs are intermediate between the parent populations” (Preface, 2015 Edition).
An alternative explanation is that these regions (e.g. Balkan countries, Southern Italy) have lower living-standards.
However, instead of viewing differences in living standards as causing differences in recorded IQs as between populations, Lynn argues that differences in innate ability themselves cause differences in living standards, because, according to Lynn, more intelligent populations are better able to achieve high levels of economic development (see IQ and the Wealth of Nations).
Moreover, Lynn observes that in Eastern Europe, living standards are substantially below elsewhere in Europe as a consequence of the legacy of communism. However, populations from Eastern Europe score only slightly below those from elsewhere in Europe, suggesting that even substantial differences in living-standards may have only a minor impact on IQ (p20).
The Portuguese also, Lynn claims, score lower than elsewhere in Europe.
However, he cites just two studies. These give average IQs of 101 and 88 respectively, which Lynn averages to give an average of 94.5 (p19).
Yet these two results are actually highly divergent, the former being slightly higher than the average for north-west Europe. This suggests an inadequate basis on which to posit a genetic difference in ability.
However, Lynn provocatively concludes:
“Intelligence in Portugal has been depressed by the admixture of sub-Saharan Africans. Portugal was the only European country to import black slaves from the fifteenth century onwards” (p19).
This echoes Arthur De Gobineau’s infamous theory that empires decline because, through their empires, they conquer large numbers of inferior peoples, who then inevitably interbreed with their conquerors, which, according to De Gobineau, results in the dilution the very qualities that permitted their imperial glories in the first place.
Ireland and ‘Selective Migration’
IQs are also, Lynn reports, somewhat lower than elsewhere in Europe in Ireland.
Lynn cites four studies of Irish IQs which give average scores of 87, 97, 93 and 91 respectively. Again, these are rather divergent but nevertheless consistently below the European average, all but one substantially so.
Of course, in England, in less politically correct times, the supposed stupidity of the Irish was once a staple of popular humour, Irish jokes being the English equivalent of Polish jokes in America.
This seems anomalous given the higher average IQs recorded elsewhere in North-West Europe, especially the UK, Ireland’s next-door neighbour, whose populations are closely related to those in Ireland.
Of course, historically Ireland was, until relatively recently, quite poor by European standards.
It is also sparsely populated and a relatively high proportion of the population live in rural areas, and there is some evidence that people from rural areas have lower average IQs than those from urban areas.
However, economic deprivation cannot explain the disparity. Today, despite the 2008 economic crash, and inevitable British bailout, Ireland enjoys, according to the UN, a higher Human Development Index than does the UK, and has done for some time. Indeed, by this measure, Ireland enjoys one of the highest standards of living in the world.
Moreover, although formerly Ireland was much poorer, the studies cited by Lynn were published from 1973 to 1993, yet show no obvious increase over time.
Lynn himself attributes the depressed Irish IQ to what he calls ‘selective migration’, claiming:
“There has been some tendency for the more intelligent to migrate, leaving less intelligent behind” (p19).
Of course, this would suggest, not only that the remaining Irish would have lower average IQs, but also that the descendants of Irish émigrés in Britain, Australia, America and other diaspora communities would have relatively higher IQs than other white people.
In support of this, Americans reporting Irish ancestry do indeed enjoy higher relative incomes as compared to other white American ethnicities.
Interestingly, Lynn also invokes “selective migration” to explain the divergences in East Asian IQs. Here, however, it was supposedly the less intelligent who chose to migrate (p136; p138; p169).
Meanwhile, other hereditarians have sought to explain away the impressive academic performance of recent African immigrants to the West, and their offspring, by reference to selective immigration of high IQ Africans, an explanation which is wholly inadequate on mathematical grounds alone (see Chisala 2015b; 2019).
It certainly seems plausible that migrants differ in personality from those who choose to remain at home. It is likely that they are braver, have greater determination, drive and willpower than those who choose to stay behind. They may also perhaps be less ethnocentric, and more tolerant of foreign cultures.
However, I see no obvious reason they would differ in intelligence.
As Chanda Chisala writes:
“Realizing that life is better in a very rich country than in your poor country is never exactly the most g-loaded epiphany among Africans” (Chisala 2015b).
Likewise, it likely didn’t take much brain-power for Irish people to realize during the Irish Potato Famine that they were less likely to starve to death if they emigrated abroad.
Of course, wealth is correlated with intelligence and may affect the decision to migrate.
The rich usually have little economic incentive to migrate, while the poor may be unable to afford the often-substantial costs of migration (e.g. transportation).
However, without actual historical data showing certain socioeconomic classes or intellectual ability groups were more likely to migrate than others, Lynn’s claims regarding ‘selective migration’ represent little more than a post-hoc rationalization for IQ differences that are otherwise anomalous and not easily explicable in terms of heredity.
Ireland, Catholicism and Celibacy
Interestingly, in the 2015 edition of ‘Race Differences in Intelligence’, Lynn also proposes, in addition, a further explanation for the low IQs supposedly found in Ireland, namely the clerical celibacy demanded under Catholicism. Thus, Lynn argues:
“There is a dysgenic effect of Roman Catholicism, in which clerical celibacy has reduced the fertility of some of the most intelligent, who have become priests and nuns” (2015 Edition; see also Lynn 2015).
Of course, this theory presupposes that it was indeed the most intelligent among the Irish people who became priests. However, this is a questionable assumption, especially given the well-established inverse correlation between intelligence and religiosity (Zuckerman et al 2013).
However, it is perhaps arguable that, in an earlier age, when religious dogmas were relentlessly enforced, religious scholarship may have been the only form of intellectual endeavour that it was safe for intellectually-minded people to engage in.
Anyone investigating more substantial matters, such as whether the earth revolved around the sun or vice versa, was liable to be burnt at the stake if he reached the wrong (i.e. the right) conclusion.
However, such an effect would surely also apply in other historically Catholic countries as well.
Yet there is little if any evidence of depressed IQs in, say, France or Austria, although the populaions of both these countries were, until recently, like that of Ireland, predominantly Catholic.
The next chapter is titled “Africans”. However, Lynn uses this term to refer specifically to black Africans – i.e. those formerly termed ‘Negroes’. He therefore excludes from this chapter, not only the predominantly ‘Caucasoid’ populations of North Africa, but also African Pygmies and the Khoisan of southern Africa, who are considered separately in a chapter of their own.
Lynn’s previous estimate of the average sub-Saharan African IQ as just 70 provoked widespread incredulity and much criticism. However, undeterred, Lynn now goes even further, estimating the average African IQ even lower, at just 67.
Therefore, just as populations from Southern Europe have lower average IQs than other Europeans because, according to Lynn, they are genetically intermediate between Europeans and Middle Eastern populations, so populations from the Horn of Africa should score higher than those from elsewhere in sub-Saharan Africa because of intermixture with Middle Eastern populations.
However, Lynn’s data gives average IQs for Ethiopia and Somalia of just 68 and 69 respectively – no higher than elsewhere in sub-Saharan Africa (The Intelligence of Nations: p87; p141-2).
On the other hand, blacks resident in western economies score rather higher, with average IQs around 85.
The only exception, strangely, are the Beta Israel, who also hail from the Horn of Africa, but are now mostly resident in Israel, yet who score no higher than those blacks still resident in Africa. From this, Lynn concludes:
“These results suggest that education in western schools does not benefit the African IQ” (p53).
However, why then do blacks resident in other western economies score higher? Are blacks in Ethiopia somehow treated differently than those resident in the UK, USA or France?
For his part, Lynn attributes the higher scores of blacks resident in these other Western economies to both superior economic conditions and, more controversially, to racial admixture.
Therefore, Lynn argues that the higher IQs of African-Americans reflect, in part, the effect of the European portion of their ancestry.
However, this explanation is difficult to square with the observation that recent African immigrants to the US, themselves presumably largely of unmixed African descent, actually consistently outperform African-Americans (and sometimes whites as well) both academically and economically (Chisala 2015a; 2015c; Anderson 2015).
Lynn also reviews the evidence pertaining to one class of specific mental ability not covered in most previous reviews on the subject – namely, race differences in musical ability.
The accomplishments of African-Americans in twentieth century jazz and popular music are, of course, much celebrated. To Lynn, however, this represents a paradox, since musical abilities are known to correlate with general intelligence and African-Americans generally have low IQs.
In addressing this perceived paradox, Lynn reviews the results of various psychometric measures of musical ability. These tests include:
- Recognizing a change in pitch;
- Remembering a tune;
- Identifying the constituent notes in a chord; and
- Recognizing whether different songs have similar rhythm (p55).
In relation to these sorts of tests, Lynn reports that African-Americans actually score somewhat lower in most elements of musical intelligence than do whites, and their musical ability is indeed generally commensurate with their general low IQs.
The only exception is for rhythmical ability.
This is, of course, congruent with the familiar observation that black musical styles place great emphasis on rhythm.
However, even with respect to rhythmical ability, blacks score no higher than whites. Instead, blacks’ scores on measures of rhythmical ability are exceptional only in that this is the only form of musical ability on which blacks score equal to, but no higher than, whites (p56).
For Lynn, the low scores of African-Americans in psychometric tests of musical ability are, on further reflection, little surprise.
“The low musical abilities of Africans… are consistent with their generally poor achievements in classical music. There are no African composers, conductors, or instrumentalists of the first rank and it is rare to see African players in the leading symphony orchestras” (p57).
However, who qualifies as a composer, conductor or instrumentalist “of the first rank” is, ultimately, unlike the results of psychometric testing, a subjective assessment, as are all artistic judgements.
Moreover, why is achievement in classical music, an obviously distinctly western genre of music, to be taken as the sole measure of musical accomplishment?
Even if we concede that the ability required to compose and perform classical music is greater than that required for other genres (e.g. jazz and popular music), musical intelligence surely facilitates composition and performance in other genres too – and, given the financial rewards offered by popular music often dwarf those enjoyed by players and composers of classical music, the more musically-gifted race would have every incentive to dominate this field too.
Perhaps, then, these psychometric measures fail to capture some key element of musical ability relevant to musical accomplishment, especially in genres other than classical.
In this context, it is notable that no lesser champion of standardized testing than Arthur Jensen has himself acknowledged that intelligence tests are incapable of measuring creativity (Langan & LoSasso 2002: p24-5).
Thus, Dinesh D’Souza speculates tentatively that:
“Blacks have certain inherited abilities, such as improvisational decision making, that could explain why they predominate in… jazz, rap and basketball” (The End of Racism: p440-1).
Steve Sailer rather less tentatively expands upon this theme, positing an African advantage in:
“Creative improvisation and on-the-fly interpersonal decision-making” (Sailer 1996).
On this basis, Sailer concludes that:
“Beyond basketball, these black cerebral superiorities in ‘real time’ responsiveness also contribute to black dominance in jazz, running with the football, rap, dance, trash talking, preaching, and oratory” (Sailer 1996).
“Bushmen and Pygmies”
Quite why these two populations are grouped together by Lynn in a single chapter is unclear.
He cites Cavalli-Sforza et al in The History and Geography of Human Genes as providing evidence that:
“These two peoples have distinctive but closely related genetic characteristics and form two related clusters” (p73).
However, although both groups are obviously indigenous to sub-Saharan Africa and quite morphologically distinct from the other black African populations who today represent the great majority of the population of sub-Saharan Africa, they share no especial morphological similarity to one another.
Moreover, since Lynn acknowledges that they have “distinctive… genetic characteristics and form two… clusters”, they presumably should each of merited chapters of their own.
One therefore suspects that they are lumped together more for convenience than on legitimate taxonomic grounds.
In short, both are marginal groups of hunter-gatherers, now few in number, few if any of whom have been exposed to the sort of standardized testing necessary to provide a useful estimate of their average IQs. Therefore, since his data on neither group alone is really sufficient to justify its own chapter, he groups them together in a single chapter.
However, the lack of data on IQ for either group means that even this combined chapter remains one of the shorter chapters in Lynn’s book, and, as we will see, the paucity of reliable data on the cognitive ability of either group almost leads one to suspect that he might almost have been better omitting both groups from his survey of race differences in cognitive ability altogether.
It may be some meagre consolation to African blacks that, at least in Lynn’s telling, they no longer qualify as the lowest scoring racial group when it comes to IQ. Instead, this dubious honour is now accorded their sub-Saharan African neighbours, San Bushmen.
In Race: The Reality of Human Differences (which I have reviewed here and here), authors Vincent Sarich and Frank Miele quote anthropologist and geneticist Henry Harpending as observing:
“All of us have the impression that Bushmen are really quick and clever and are quite different from their [Bantu] neighbors… Bushmen don’t look like their black African neighbors either. I expect that there will soon be real data from the Namibian school system about the relative performance of Bushmen… and Bantu kids – or more likely, they will suppress it” (Race: The Reality of Human Differences (reviewed here): p227).
Today, however, some fifteen or so years after Sarich and Miele published this quotation, the only such data I am aware of is that reported by Lynn in this book, which suggests, at least according to Lynn, a level of intelligence even lower than that of other sub-Saharan Africans.
Unfortunately, however, the data in question is very limited and, in my view, inadequate to support Lynn’s controversial conclusions regarding Bushman ability.
It also consists of just three studies, none of which remotely resemble a full IQ test (p74-5).
Yet, from this meagre dataset, Lynn does not hesitate to attribute to Bushmen an average IQ of just 52.
If Lynn’s estimate of the average sub-Saharan African IQ at around 70 provoked widespread incredulity, then his much lower estimate for Bushmen is unlikely to fare better.
Lynn anticipates such a reaction, and responds by pointing out:
“An IQ of 54 represents the mental age of the average European 8-year-old, and the average European 8-year-old can read, write, and do arithmetic and would have no difficulty in learning and performing the activities of gathering foods and hunting carried out by the San Bushmen. An average 8-year-old can easily be taught to pick berries put them in a container and carry them home, collect ostrich eggs and use the shells for storing water and learn how to use a bow and arrow” (p76).
Indeed, Lynn continues, other non-human animals survive in difficult, challenging environments with even lower levels of intelligence:
“Apes with mental abilities about the same as those of human 4-year olds survive quite well as gatherers and occasional hunters and so also did early hominids with IQs around 40 and brain sizes much smaller than those of modern Bushmen. For these reasons there is nothing puzzling about contemporary Bushmen with average IQs of about 54” (p77).
Here, Lynn makes an important point. Many non-human animals survive and prosper in ecologically challenging environments with levels of intelligence much lower than that of any hominid, let alone any extant human race.
On the other hand, however, I suspect Lynn would not last long in Kalahari Desert – the home environment of most contemporary Bushmen.
Lynn’s data on the IQs of Pygmies is even more inadequate than his data for Bushmen. Indeed, it amounts to just one study, which again fell far short of a full IQ test.
Moreover, the author of the study, Lynn reports, did not quantify his results, reporting only that Pygmies scored much “much worse” than other populations tested using the same test (p78).
However, while the other populations tested using the same test and outperforming Pygmies included “Eskimos, Native American and Filipinos”, Lynn conspicuously does not mention that they included other black Africans, or indeed other very low IQ groups such as Australian Aboriginals (p78).
Thus, Lynn’s assumption that Pygmies are lower in cognitive ability than other black Africans is not supported even by the single study that he cites.
Lynn also infers a low level of intelligence for Pygmies from their lifestyle and mode of sustenance:
“Most of them still retain a primitive hunter-gatherer existence while many of the Negroid Africans became farmers over the last few hundred years” (p78).
Thus, Lynn assumes that whether a population has successfully transitioned to agriculture is largely a product of their intelligence (p191).
In contrast, most historians and anthropologists would emphasize the importance of environmental factors in explaining whether a group transitions to agriculture.
Finally, Lynn also infers a low IQ from the widespread enslavement of Pygmies by neighbouring Bantus:
“The enslavement of Pygmies by Negroid Africans is consistent with the general principle that the more intelligent races generally defeat and enslave the less intelligent, just as Europeans and South Asians have frequently enslaved Africans but not vice versa” (p78).
However, while it may be a “general principle that the more intelligent races typically defeat and enslave the less intelligent” (p78), this is hardly a rigid rule.
Interestingly, it is notable that Pygmies are the only racial group whom Lynn includes in his survey for whom he does not provide an actual figure as an estimate their average IQ, which presumably reflects a tacit admission of the inadequacy of the available data.
Curiously, unlike for all the other racial groups discussed, Lynn also fails to provide any data on Pygmy brain-size.
Presumably, Pygmies have small brains as compared to other races, if only on account of their smaller body-size – but what about their brain-size relative to body-size? Is there simply no data available?
Another group who are barely mentioned at all in most previous discussions of the topic of race differences in intelligence are Australian Aborigines. Here, however, unlike for Bushmen and Pygmies, data from Australian schools are actually surprisingly abundant.
These give, Lynn reports, an average Aboriginal IQ of just 62 (p104).
Unlike his estimates for Bushmen and Pygmies, this figure seems to be reliable, given the number of studies cited and the consistency of their results. One might say, then, that Australian Aboriginals have the lowest recorded IQs of any human race for whom reliable data is available.
Interestingly, in addition to his data on IQ, Lynn also reports the results of Piagetian measures of development conducted among Aboriginals. He reports, rather remarkably, that a large minority of Aboriginal adults fail to reach what Piaget called the concrete operational stage of development – or, more specifically, fail to recognize a substance, transferred to a new container, necessarily remains of the same quantity (p105-7).
Perhaps even more remarkable, however, are reports of Aborigine spatial memory (p107-8). This refers to the ability to remember the location of objects, and their locations relative to one another.
Thus, he reports, one study found that, despite their low general cognitive ability, Aborigines nevertheless score much higher than Europeans in tests of spatial memory (Kearins 1981).
Another study found no difference in the performance of whites and Aborigines (Drinkwater 1975). However, since Aborigines have much lower IQs overall, even equal performance on spatial memory as against Europeans is still out of sync with the performance of whites and Aborigines on other types of intelligence test (p108).
Lynn speculates that Aboriginal spatial memory may represent an adaptation to facilitate navigation in a desert environment with few available landmarks.
The difference, Lynn argues, seems to be innate, since it was found even among Aborigines who had been living in an urban environment (i.e. not a desert) for several generations (p108; but see Kearins 1986).
Two other studies reported lower scores than for Europeans. However, one was an unpublished dissertation and hence must be treated with caution, while the and the other (Knapp & Seagrim 1981) “did not present his data in such a way that the magnitude of the white advantage can be calculated” (p108).
Intriguingly, Lynn reports that this ability even appears to be reflected in neuroanatomy. Thus, despite smaller brains overall, Aborigines’ right visual cortex, implicated in spatial ability, is relatively larger than in Europeans (Klekamp et al 1987; p108-9).
New Guineans and Jared Diamond
In his celebrated Guns, Germs and Steel, Jared Diamond famously claimed:
“In mental ability New Guineans are probably genetically superior to Westerners, and they surely are superior in escaping the devastating developmental disadvantages under which most children in industrialized societies grow up” (Guns, Germs and Steel: p21).
Diamond bases this claim on the fact that, in the West, survival, throughout most of our recent history, depended on who was struck down by disease, which was largely random.
In contrast, in New Guinea, he argues, people had to survive on their wits, with survival depending on one’s ability to procure food and avoid homicide, activities in which intelligence was likely to be at a premium (Guns, Germs and Steel: p20-21).
He also argues that the intelligence of western children is likely reduced because they spend too much time watching television and movies (Guns, Germs and Steel: p21).
However, there is no evidence television has a negative impact on children’s cognitive development. Indeed, given the rise in IQs over the twentieth century has been concomitant with increases in television viewing, it has even been speculated that increasingly stimulating visual media may have contributed to rising IQs.
On the basis of two IQ studies, plus three studies of Piagetian development, Lynn concludes that the average IQ of indigenous New Guineans is just 62 (p112-3).
This is, of course, exactly the same as his estimate for the average IQ of Australian Aboriginals.
It is therefore consistent with Lynn’s racial taxonomy, since, citing Cavalli-Sforza et al, he classes New Guineans as in the same genetic cluster, and hence as part of the same race as Australian Aboriginals (p101).
They also, Lynn reports, score rather higher in IQ, with most such populations having average IQs of about 85 (p117). However, the Māoris of New Zealand score rather higher, with an average IQ of about 90 (p116).
Hawaiians and Hybrid Vigor
For the descendants of the inhabitants of one particular Pacific Island, namely Hawaii, Lynn also reports data regarding the IQs of racially-mixed individuals, both those of part-Native-Hawiian and part-East Asian ancestry, and those of part-Native-Hawiian and part-European ancestry.
These racial hybrids, as expected, score on average between the average scores for the two parent populations. However, Lynn reports:
“The IQs of the two hybrid groups are slightly higher than the average of the two parent races. The average IQ of the Europeans and Hawaiians is 90.5, while the IQ of the children is 93. Similarly, the average IQ of the Chinese and Hawaiians is 90, while the IQ of the children is 91. The slightly higher than expected IQs of the children of the mixed race parents may be a hybrid vigor or heterosis effect” (p118).
Actually, the difference between the “expected IQs” and the IQs actually recorded for the hybrid groups is so small (only one point for the Chinese-Hawaiians), that it could easily be dismissed as mere noise, and I doubt it would reach statistical significance.
Nevertheless, Lynn’s discussion begs the question as to why hybrid vigor has not similarly elevated the IQs of the other hybrid, or racially-mixed, populations discussed in other chapters, and why Lynn has not discussed this issue when reporting the average IQs of other racially-mixed populations in other chapters.
Presumably, then, which of these countervailing effects outweighs the other for different types of hybrid depends on the degree of genetic distance between the two parent populations. This, of course, varies for different races.
It is therefore possible that some racial mixes may tend to elevate intelligence, whereas others, especially between more distantly-related populations, may tend, on average, to depress intelligence.
For what it’s worth, Pacific Islanders, including Hawiians, are thought to be genetically closer to East Asians than to Europeans.
“South Asians and North Africans”
Another group rarely treated separately in earlier works are those whom Lynn terms “South Asians and North Africans”, though this group also includes populations from the Middle East.
Physical anthropologists often lumped these peoples together with Europeans as collectively “Caucasian” or “Caucasoid”. However, while acknowledging that they are “closely related to the Europeans”, Lynn cites Cavalli-Sforza et al as showing they form “a distinctive genetic cluster” (p79).
He also reports that they score substantially lower in IQ than do Europeans. Their average IQ in their native homelands is just 84 (p80), while South Asians resident in the UK score only slightly higher with an average IQ of just 89 (p82-4).
This conclusion is surely surprising and should, in my opinion, be treated with caution.
For one thing, all of the earliest known human civilizations – namely, Mesopotamia, Egypt and the Indus Valley civilization – surely emerged among these peoples, or at least in regions today inhabited primarily by people of this race.
Moreover, people of Indian ancestry in particular are today regarded as a model majority in both Britain and America, whose overrepresentation in the professions, especially medicine, is widely commented upon.
Indeed, according to some measures, British-Indians are now the highest earning ethnicity in Britain, or the second-highest earning after the Chinese, and Indians are also the highest earners in the USA.
Interestingly, in this light, one study cited by Lynn showed a massive gain of 14-points for children from India who had been resident in the UK for more than four years as compared to those who had been resident for less than four years, the former scoring almost as high in IQ as the indigenous British, with an average IQ of 97 (p83-4; Mackintosh & Mascie-Taylor 1985).
In the light of this study, it would be interesting to measure the IQs of a sample composed exclusively of people who traced their ancestry to India but who had been resident in the UK for the entirety of their lives (or even whose ancestors had been resident in the UK for several generations), since all of the other studies cited by Lynn of the IQs of Indian children in the UK presumably include both recent arrivals and long-term residents grouped together.
Interestingly, the high achievement of immigrants, and their descendants, from India is not matched by those from neighbouring countries such as Bangladesh or Pakistan. Indeed, the same data suggesting that Indians are the highest earning ethnicity in Britain also show that British-Pakistanis and Bangladeshis are among the lowest earners.
The primary divide between these three countries is, of course, not racial but rather religious. This suggests a religion as a causal factor in the difference.
Perhaps, then, cultural practices in Muslim countries are responsible for reducing IQs.
For example, the prevalence of consanguineous (i.e. incestuous) marriage, especially cross-cousin marriage may have an effect on intelligence due to inbreeding depression (Woodley 2009).
However, Lynn’s own data show little difference between IQs in India and those in Pakistan and Bangladesh, nor indeed between IQs in India and those in Muslim countries in the Middle East or North Africa. Nor, according to Lynn’s data, do people of Indian ancestry resident in the UK score noticeably higher in IQ than do people who trace their ancestry to Bagladeshi, Pakistani or Middle Eastern countries.
This is possible because, although male slaves in the Islamic world were routinely castrated and hence incapable of procreation, female slaves outnumbered males and were often employed as concubines, a practice which, unlike in puritanical North America, was regarded as perfectly socially acceptable on the part of slave owners.
This would be consistent with the finding that Arab populations from the Middle East show some evidence of sub-Saharan African ancestry in their mitochondrial DNA, which is passed down the female line, but not in their Y-chromosome ancestry, passed down the male line (Richards et al 2003).
In contrast, in the United States, the use of female slaves for sexual purposes, although it certainly occurred, was, at least in theory, very much frowned upon.
In addition, in North America, due to the one-drop rule, all mixed-race descendants of slaves with any detectable degree of black African ancestry were classed as black. Therefore, at least in theory, the white bloodline would have remained ‘pure’, though some mixed-race individuals may have been able to ‘pass’.
Therefore, sub-Saharan African genes may have entered the Middle Eastern, and North African, gene-pools in a way they were not able to do so among whites in North America.
This might explain why genotypic intelligence among North African and Middle Eastern populations may have declined in the period since the great civilizations of Mesopotamia and ancient Egypt and even since the Golden Age of Islam, when the intellectual achievements of Middle Eastern and North African peoples seemed so much more impressive.
Besides Indians, another economically and intellectually overachieving model minority who derive, at least in part, from the race whom Lynn classes as “South Asians and North Africans” are the Jews.
Lynn has recently written a whole book on the topic of Jewish intelligence and achievement, titled The Chosen People: A Study of Jewish Intelligence and Achievement (review forthcoming).
However, in ‘Race Differences in Intelligence’, Jews do not even warrant a chapter of their own. Instead, they are discussed only at the end of the chapter on “South Asians and North Africans”, although Ashkenazi Jews also have substantial European ancestry.
The decision not to devote an entire chapter to the Jewish people is surely correct, because, although even widely disparate groups (e.g. Ashkenazim, Sephardic and Mizrahim, even the Lemba) do indeed share genetic affinities, Jews are not racially distinct (i.e. reliably physically distinguishable on phenotypic criteria) from other peoples.
However, the decision to include them in the chapter on “South Asians and North Africans” is potentially controversial, since, as Lynn readily acknowledges, the Ashkenazim in particular, who today constitute the majority of world Jewry, have substantial European as well as Middle Eastern ancestry.
Lynn claims British and US Jews have average IQs of around 108 (p68). His data for Israel are not broken down by ethnicity, but give an average IQ for Israel as a whole of 95, which Lynn, rather conjecturally, infers scores of 103 for Ashkenazi Jews, 91 for Mizrahi Jews and 86 for Palestinian-Arabs (p94).
Lynn’s explanations for Ashkenazi intelligence, however, are wholly unpersuasive.
First, he observes that, despite Biblical and Talmudic admonitions against miscegenation with Gentiles, Jews inevitably interbred to some extent with the host populations alongside whom they lived. From this, Lynn infers that:
“Ashkenazim Jews in Europe will have absorbed a significant proportion of the genes for higher intelligence possessed by… Europeans” (p95).
It is indeed true that, if, as Lynn claims, Europeans are indeed a more intelligent race than are populations from the Middle East, then interbreeding with Europeans may indeed explain how Ashkenazim came to score higher in IQ than do other populations tracing their ancestry to the Middle East.
However, interbreeding with Europeans can hardly explain how Ashkenazi Jews came to outscore, and outperform academically and economically, even the very Europeans with whom they are said to have interbred!
This explanation therefore fails to explain why Ashkenazim have higher IQs than do Europeans.
Lynn’s second explanation for high Ashkenazi Jewish IQs is equally unpersuasive. He suggests that:
“The second factor that has probably operated to increase the intelligence of Ashkenazim Jews in Europe and the United States as compared with Oriental Jews is that the Ashkenazim Jews have been more subject to persecution… Oriental Jews experienced some persecution sufficient to raise their IQ of 91, as compared with 84 among other South Asians and North Africans, but not so much as that experienced by Ashkenazim Jews in Europe.” (p95).
On purely theoretical grounds, the idea that persecution selects for intelligence may seem reasonably plausible, if hardly compelling.
However, there is no evidence that persecution does indeed reduce a population’s level of intelligence. On the contrary, other groups who have been subject to persecution throughout much of their histories – e.g. the Roma (i.e. Gypsies) and African-Americans – are generally found to have relatively low IQs.
East and South-East Asians
Excepting Jews, the highest average IQs are found among East Asians, who have, according to Lynn’s data, an average IQ of 105, somewhat higher than that of Europeans (p121-48).
However, it is important to emphasize that this relatively high figure applies only to East Asians – i.e. Chinese, Japanese Koreans, Taiwanese etc.
It does not apply to the related populations of Southeast Asia (i.e. Thais, Filipinos, Vietnamese, Malaysians, Cambodians, Indonesians etc.), who actually score much lower in IQ, with average scores of only around 87 in their indigenous homelands, but rising to 93 among those resident in the US.
Thus, Lynn distinguishes the East Asians from Southeast Asians as a separate race, on the grounds that the latter, despite “some genetic affinity with East Asians” form a distinct genetic cluster in data gathered and analyzed by Cavalli-Sforza et al, and also have distinct morphological features, with “the flattened nose and epicanthic eye-fold… [being] less prominent” than among East Asians (p97).
This is an important point, since many previous writers on the topic have implied that the higher average IQs of East Asians applied to all ‘Asians’ or ‘Mongoloids’, which would presumably include South-East Asians.
Yet, in Lynn’s opinion, it is just as misleading to group all these groups together as ‘Mongoloid’ or ‘Asian’ as it was to group “Europeans” and “South Asians and North Africans” together as ‘Caucasian’ or ‘Caucasoid’.
However, that low scores throughout South-East Asia are entirely genetic in origin is unclear. Thus, Vietnamese resident in the West have sometimes, but not always, scored considerably higher, and Jason Malloy suggests that Lynn exaggerates the overrepresentation of ethnic Chinese among Vietnamese immigrants to the West so as attribute such results to East Asians rather than South-East Asians (Malloy 2014).
Moreover, in relation to Lynn’s ‘Cold Winters Theory’ (discussed below), whereby it is claimed that populations were exposed to colder temperatures during their evolution evolved higher levels of intelligence in order to cope with the adaptive challenges that surviving cold temperatures posed, it is notable that climate varies greatly across China, reflecting the geographic size of the country, with Southern China having a subtropical climate with mild winters.
However, perhaps East Asians, like the Han Chinese, are to be regarded as only relatively recent arrivals in what is now Southern China. This would be consistent with claim of some physical anthropologists that the some aspects of the morphology of East Asians reflects adaptation to the extreme cold of Siberia and the Steppe, and also with the historical expansion of the Han Chinese.
More problematic for ‘Cold Winters Theory’ is the fact that, although Lynn classifies them as East Asian (p121), the higher average IQ scores of East Asians (as compared to whites), does not even extend to the people after whom the Mongoloid race was named – namely the Mongols themselves.
According to Lynn, Mongolians score only around the same as whites, with an average IQ of only 101 (Lynn 2007).
This report is based on just two studies. Moreover, it had not been published at the time the first edition of ‘Race Differences in Intelligence’ came off the presses.
However, Lynn infers a lower IQ for Mongolians from their lower level of cultural, technological and economic development (p240).
Lynn’s explanation for this anomaly is that the low population-size of the Mongols, and their isolation from other populations, meant that the necessary mutations for higher IQ never arose (p240).
This is the same explanation that Lynn provides for the related anomaly of why Eskimos (“Arctic Peoples”), to whom Mongolians share some genetic affinity, also score low in IQ, an explanation that is discussed in the final part of this review.
Another group sometimes subsumed with Asian populations as “Mongoloids” are the indigenous populations of the American continent, namely “Native Americans”.
However, on the basis of both genetic data from Cavalli-Sforza et al and morphological differences (“darker and sometimes reddish skin, hooked or straight nose, and lack of the complete East Asian epicanthic fold”), Lynn classifies them as a separate race and hence accords them a chapter of their own.
His data suggest average IQs of about 86, for both Native Americans resident in Latin America, and also for those resident in North America, despite the substantially higher living standards of the latter (p158; 162-3; p166).
Mestizo populations, however, have somewhat higher scores, with average IQs intermediate between those of the parent populations (p160).
Like the Asian populations with whom they share their ancestry, Native Americans score rather higher on spatio-visual intelligence than on verbal intelligence (p156).
In particular, they also have especially high visual memory (p159-60).
As he did for African-Americans, Lynn also discusses the musical abilities of Native Americans. Interestingly, psychometrical testing shows that their musical ability is rather higher than their general cognitive ability, giving a MQ (Musical Quotient) of approximately 92 (p160).
They also show the same pattern of musical abilities as do African-Americans, with higher scores for rhythmical ability than for other forms of musical ability (p160).
However, whereas blacks, as we have seen, only score as high as Europeans for rhythmical ability, but no higher, Native Americans, because of higher IQs (and MQs) overall, actually outscore both Europeans and African-Americans when it comes to rhythmical ability.
These results are curious. Unlike African-Americans, Native Americans are not, to my knowledge, known for their contribution to any genres of western music, and neither are their indigenous musical traditions especially celebrated.
“Artic Peoples” (i.e. Eskimos)
Distinguished from other Native Americans are the inhabitants of the far north of the American landmass. These, together with other indigenous populations from the area around the Bering straight, namely those from Greenland, the Aleutian Islands, and the far north-east of Siberia, together form the racial group whom Lynn refers to as “Arctic Peoples”, though the more familiar, if less politically correct, term would be ‘Eskimos’.
As well as forming a distinctive genetic cluster per Cavalli-Sforza et al, they are also morphologically distinct, not least in their extreme adaptation to the cold, with, Lynn reports:
“Shorter legs and arms and a thick trunk to conserve heat, a more pronounced epicanthic eye-fold, and a nose well flattened into the face to reduce the risk of frostbite” (p149).
As we will see, Lynn is a champion of what is sometimes called ‘Cold Winters Theory’ – namely the theory that the greater environmental challenges, and hence cognitive demands, associated with living in colder climates selected for increased intelligence among those races inhabiting higher latitudes.
Therefore, on the basis of this theory, one might imagine that Eskimos, who surely evolved in one of the most difficult, and certainly in the coldest, environment of any human group, would also have the highest IQs.
This conclusion would also be supported by the observation that, according to the data cited by Lynn himself, Eskimos also have the largest average brain-size of any race (p153).
Interestingly, some early reports did indeed suggest that Eskimos had high levels of cognitive ability as compared to whites. However, Lynn now reports that Eskimos actually have rather lower IQ scores than do whites and East Asians, with results from 15 different studies giving an average IQ of around 90.
Actually, however, viewed in global perspective, this average IQ of 90 for Eskimos is not that low. Indeed, of the ten major races surveyed by Lynn, only Europeans and East Asians score higher.
It is an especially high score for a population who, until recently, lived exclusively as hunter-gatherers. Other foraging groups, or descendants of peoples who, until recently, subsisted as foragers, tend, according to Lynn’s data, to have low IQs (e.g. Australian Aboriginals, San Bushmen, Pygmies).
One obvious explanation for the relatively low IQs of Eskimos as compared to Europeans and East Asians would be their deprived living conditions.
However, Lynn is skeptical of the claim that environmental factors are entirely to blame for the difference in IQ between Eskimos and whites, since he observes:
“The IQ of the Arctic Peoples has not shown any increase relative to that of Europeans since the early 1930s, although their environment has improved in so far as in the second half of the twentieth century they received improved welfare payments and education. If the intelligence of the Arctic Peoples had been impaired by adverse environmental conditions in the 1930s it should have increased by the early 1980s” (p153-4).
He also notes that all the children tested in the studies he cites were enrolled in schools (since this was where the testing took place), and hence were presumably reasonably familiar with the procedure of test-taking (p154).
Visual Memory, Spatial Memory and Hunter-Gathering
This is a proficiency they share in common with Native Americans (p159-60), to whom they are obviously closely related.
However, as we have seen, Australian Aboriginals, who are not closely related to either group, also seem to possess a similar ability, though Lynn refers to this as “spatial Memory” rather than “visual Memory” (p107-8).
These are, strictly speaking, somewhat different abilities, although they may not be entirely separate either, and may also be difficult to distinguish between in tests.
If Aboriginals score high on spatial memory, they may then also score high on visual memory, and vice versa for Eskimos and Native Americans. However, since Lynn does not provide comparative data on visual memory among Aboriginals, or on spatial memory among Eskimos or Native Americans, this is not certain.
Interestingly, one thing all these three groups share in common is a recent history of subsisting, at least in part, as hunter-gatherers.
One is tempted, then, to attribute this ability to the demands of a hunter-gatherer lifestyle, perhaps reflecting the need to remember the location of plant foods which appear only seasonally, or to find one’s way home after a long hunting expedition.
It would then be interesting to test the visual and spatial memories of other groups who either continue to subsist as hunter-gatherers or only recently transitioned to agriculture or urban life, such as Pygmies and San Bushmen. However, since tests of spatial and visual memory are not included in most IQ tests, the data is probably not yet available.
For his part, Lynn attributes Eskimo visual memory to the need to “find their way home after going out on long hunting expeditions” (p152-3).
Thus, just as the desert environment of Australian Aboriginals provides few landmarks, so:
“The landscape of the frozen tundra [of the Eskimos] provides few distinctive cues, so hunters would need to note and remember such few features as do exist” (p153).
Proximate Causes: Heredity or Environment?
Chapter fourteen discusses the proximate causes of race differences in intelligence and the extent to which the differences observed can be attributed to either heredity or environmental factor, and, if partly the latter, which environmental factors are most important.
Lynn declares at the beginning of the chapter that the objective of his book is “to broaden the debate” from an exclusive focus on the black-white test score gap in the US, to instead looking at IQ differences among all ten racial groups across the world for whom data on IQ or intelligence is presented in Lynn’s book (p182).
Actually, however, in this chapter alone, Lynn does indeed focus primarily on black-white differences, if only because it is in relation to this difference that most research has been conducted, and hence to this difference that most available evidence relates.
Downplaying the effect of schooling, Lynn identifies malnutrition as the major environmental influence on IQ (p182-7).
However, he rejects malnutrition as an explanation for the low scores of American blacks, noting there is no evidence of short stature in black Americans and nor have surveys have found a greater prevalence of malnutrition (p185).
As to global differences, he concludes that:
“The effect of malnourishment on Africans in sub-Saharan Africa and the Caribbean probably explains about half of the low IQs, leaving the remaining half to genetic factors” (p185).
However, it is unclear what is meant by “half of the low scores” as he has identified no comparison group.
He also argues that the study of racially mixed individuals further suggests a genetic component to observed IQ differences. Thus, he claims:
“There is a statistically significant association between light skin and intelligence” (p190).
As evidence he cites his own study (Lynn 2002) to claim:
“When the amount of European ancestry in American blacks is assessed by skin color, dark-skinned blacks have an IQ of 85 and light-skinned blacks have an IQ of 92” (p190).
However, he fails to explain how he managed to divide American blacks into two discrete groups by reference to a trait that obviously varies continuously.
More importantly, he neglects to mention altogether two other studies that also investigated the relationship between IQ and degree of racial admixture among African-Americans, but used blood-groups rather than skin tone to assess ancestry (Loehlin et al 1973; Scarr et al 1977).
This is surely a more reliable measure of ancestry than is skin tone, since the latter is affected by environmental factors (e.g. exposure to the sun darkens the skin), and could conceivably have an indirect psychological effect.
Meanwhile, Lynn mentions the Eyferth study (1961) of the IQs of German children fathered by black and white US servicemen in the period after World War II, only to report, “the IQ of African-Europeans [i.e. those fathered by the black US servicemen] was 94 in relation to 100 for European women” (p63).
However, he fails to mention that the IQ of those German children fathered by black US servicemen (i.e. those of mixed race) was actually almost identical to that of those fathered by white US servicemen (who, with German mothers, were wholly white). This finding is, of course, evidence against the hereditarian hypothesis with respect to race differences.
Yet Lynn can hardly claim to be unaware of this finding, or its implications with respect to race differences, since this is actually among the studies most frequently cited by opponents of the hereditarian hypothesis with respect to the black-white test score gap for precisely this reason.
Lynn’s presentation of the evidence regarding the relative contributions of heredity and environment to race differences in IQ is therefore highly selective and biased.
“An Evolutionary Analysis”
Only in the last three chapters does Lynn provide the belated “Evolutionary Analysis” promised in his subtitle.
Lynn’s analysis is evolutionary in two senses.
First, he presents both a functionalist explanation of why race differences in intelligence (supposedly) evolved (Chapter 16). This is the sort of ultimate evolutionary explanation with which evolutionary psychologists are usually concerned.
However, in addition, Lynn also traces evolution of intelligence over evolutionary history, both in humans of different races (Chapter 17) and among our non-humans and our pre-human ancestors (Chapter 15).
In discussing the former of these two questions (namely, why race differences in intelligence evolved: Chapter 16), Lynn identifies climate as the ultimate environmental factor responsible for the evolution of race differences in intelligence.
Thus, he claims that, as humans spread out beyond Africa towards regions further from the equator and hence generally with colder temperatures, especially during winters, the colder climates that these pioneers encountered posed greater challenges for the humans who encountered them in terms of feeding themselves and obtaining shelter etc., and that different human races evolved different levels of intelligence in response to the adaptive challenges posed by such difficulties.
Hunting vs. Gathering
The greater problems supposedly posed by colder climates included not just difficulties of keeping warm (i.e. the need for clothing, fires, insulated homes), but also the difficulties of keeping fed.
Thus, Lynn emphasizes the dietary differences between foragers inhabiting different regions of the world:
“Among contemporary hunter-gatherers the proportions of foods obtained by hunting and gathering varies by hunting and by gathering varies according to latitude. Peoples in tropical and subtropical latitudes are largely gatherers, while peoples in temperate environments rely more on hunting, and peoples in arctic and sub-arctic environments rely almost exclusively on hunting and fishing and have to do so because plant foods are unavailable except for berries and nuts in the summer and autumn” (p227).
I must confess that I was previously unaware of this dietary difference. However, in my defence, this is perhaps because many anthropologists seem all too ready to overgeneralize from the lifestyles of the most intensively studied tropical groups (e.g. the San of Southern Africa) to imply that what is true of these groups is true of all foragers, and was moreover necessarily also true of all our hunter-gatherer ancestors before they transitioned to agriculture.
Thus, for example, feminist anthropologists seemingly never tire of claiming that it is female gatherers, not male hunters, who provide most of the caloric demands of foraging peoples.
Actually, however, this is true only for tropical groups, where plant foods are easily obtainable all year round, not of hunter-gatherers in general (Ember 1978).
It is certainly not true, for example, of Eskimos, among whom females are almost entirely reliant on male hunters to provision them for most of the year, since plant foods are hardly available at all except for during a few summer months.
Similarly, radical-leftist anthropologist Marshall Sahlins famously characterized hunter-gatherer peoples as “The Original Affluent Society”, because, according to his data, they do not want for food and actually have more available leisure-time than do most agriculturalists, and even most modern westerners.
Unfortunately, however, he relied primarily on data from tropical peoples such as the !Kung San to arrive at his estimates, and these findings do not necessarily generalize to other groups such as the Inuit or other Eskimos.
However, it has now fallen into disfavour, if only because it put accorded male hunters the starring role in hominid evolution, with female gatherers relegated to a supporting role, and hence offended the sensibilities of feminists, who have become increasingly influential in academia, even in science.
Nevertheless, it is seems to be true that, across taxa, carnivores tend to have larger brains than herbivores.
Of course, non-human carnivores did not evolve the exceptional intelligence of humans.
However, Desmond Morris in The Naked Ape argued that, because our hominid ancestors only adopted a primarily carnivorous diet relatively late in their evolution, they were unable to compete with such specialized hunters as lions and tigers in terms of their fangs and claws. They therefore had to adopt a different approach, using intelligence instead or claws and fangs, hence inventing handheld weapons and cooperative group hunting.
Thus, in the traditional version, it is the intelligence of early hominids, the descendants all populations of contemporary humans, that increased as a result of the increasing cognitive demands that hunting placed upon us.
However, Lynn argues that it is only certain races that were subject to such selection, as their dependence on hunting increased as they populated colder regions of the globe.
Indeed, Lynn’s arguments actually cast some doubt on the traditional version of the Hunting Ape Theory.
After all, anatomically modern humans are thought to have first evolved in Africa. Yet if African foragers actually subsisted primarily on a diet of wild plant foods, and only occasionally hunted or scavenged meat to supplement this primarily herbivorous diet, then the supposed cognitive demands of hunting can hardly be invoked to explain the massive increase in hominid brain-size that occurred during the period before our ancestors left Africa to colonize the remainder of the world.
Indeed, Lynn is seemingly clear that he rejects the ‘Hunting Ape Hypothesis’, writing that the increases in hominid brain-size after our ancestors “entered a new niche of the open savannah in which survival was more cognitively demanding” occurred, not because of the cognitive demands of hunting, but rather that:
“The cognitive demands of the new niche would have consisted principally of finding a variety of different kinds of foods and protecting themselves from predators” (p202)
‘Cold Winters Theory’
There are several problems with so-called ‘Cold Winters Theory’ as an explanation for the race differences in IQ reported by Lynn.
For one thing, other species have adapted themselves to colder climates without evolving a level of intelligence as high as human population, let alone of Europeans and East Asians.
Indeed, I am not aware of any studies even suggesting a relationship between brain-size or intelligence and the temperature or latitude of their species-ranges among non-human species. However, one might expect to find an association between temperature and brain-size, if only because of Bergmann’s rule.
Similarly, Neanderthals were ultimately displaced and driven to extinction throughout Eurasia by anatomically-modern humans, who, at least according to the conventional account, outcompeted Neanderthals due to their superior intelligence and tool-making ability.
Yet, whereas anatomically modern humans are thought to have evolved in tropical Africa before spreading outwards to Eurasia, the Neanderthals were a cold-adapted species of hominid who had evolved and thrived in Eurasia during the last Ice age.
At any rate, even if the conditions were indeed less demanding in tropical Africa than in temperate or arctic latitudes, then, according to basic Darwinian (and Malthusian) theory, in the absence of some other factor limiting population growth (e.g. warfare, predation, homicide, disease), this would presumably mean that humans would respond to greater resource abundance in the tropics by reproducing until they reached the carrying capacity of the environment.
By the time the carrying capacity of the environment was reached, however, the environment would no longer be so resource-abundant given the greater number of humans competing for its resources.
This leads me to believe that the key factors selecting for increases in the intelligence of hominids were not ecological but rather social – i.e. not access to food and shelter etc., but rather competition with other humans.
Also, I remain unconvinced that the environments inhabited by the two races that have, according to Lynn, the lowest average IQs, namely, San Bushmen and Australian Aborigines, are cognitively undemanding.
Meanwhile, the Eskimos occupy what is certainly the coldest, and also undoubtedly one of the most demanding, environments anywhere in the world, and also have, according to Lynn’s own data, the largest brains.
However, according to Lynn’s data, their average IQ is only about 90, high for a foraging group, but well below that of Europeans and East Asians.
For his part, Lynn attempts to explain away this anomaly by arguing that Arctic Populations were precluded from evolving higher IQs by small and dispersed populations, reflecting of the harshness of the environment. This meant the necessary mutations either never arose or never spread through the population (p153; p239-40; p221).
On the other hand, he explains their large brains as reflecting visual memory rather than general intelligence, as well as a lack of mutations for neural efficiency (p153; p240)
However, these seem like post-hoc rationalizations
After all, if conditions were harsher in Eurasia than in Africa, then this would presumably also have resulted in smaller and more dispersed populations in Eurasia than in Africa. However, this evidently did not prevent mutations for higher IQ spreading among Eurasians.
Why then, when the environment becomes even harsher, and the population even more dispersed, would this pattern suddenly reverse itself?
Likewise, if whole-brain-size is related to general intelligence, it is inconsistent to invoke specific abilities to explain Inuit brains.
Thus, according to Lynn, Australian Aborigines have high spatial memory, which is closely related to visual memory. However, also according to Lynn, only their right visual cortex is enlarged (p108-9) and they have small overall brain-size (p108-9; p210; p212).
 Curiously, Lynn reports, this black advantage for movement-time does not appear in the simplest form of elementary task (simple reaction time), where the subject simply has to press a button on the lighting of a light, rather than hitting a specific button, rather than alternative buttons, on the lighting of a particular light rather than other lights (p58). These latter forms of elementary cognitive test presumably involve some greater degree of cognitive processing.
 First, there are the practical difficulties. Obviously, non-human animals cannot use written tests, or an interview format. Designing a maze for laboratory mice may be relatively straightforward, but building a comparable maze for elephants is rather more challenging. Second, and more important, different species likely have evolved different specialized abilities for dealing with specific adaptive problems. For example, migratory birds may have evolved specific spatio-visual abilities for navigation. However, this is not necessarily reflective of high general intelligence, and to assess their intelligence solely on the basis of their migratory ability, or even their general spatio-visual ability, would likely overestimate their general level of cognitive ability. In other words, it reflects a modular, domain-specific adaptation.
Admittedly, the same is true to some extent for human races. Thus, some races score relatively higher on certain types of intellectual ability. For example, East Asians tend to score higher on spatio-visual ability than on verbal ability; Ashkenazi Jews show the opposite pattern, scoring higher in verbal intelligence than in spatio-visual ability; while American blacks score relatively higher in tests involving rote memory than in those requiring abstract reasoning ability. Similarly, as discussed by Lynn, some races seem to have certain quite specific abilities not commensurate to their general intelligence (e.g. Aborigine visual memory). However, in general, both between and within races, most variation in human intelligence loads onto the ‘g-factor’ of general intelligence.
 American anthropologist Carleton Coon is credited as the first to first to propose that population differences in skull size reflect a thermoregulatory adaptation to climatic differences (Coon 1955). An alternative theory, less supported, is that it was differing levels of ambient light that resulted in differences in brain-size as between different populations tracing their ancestry to different parts of the globe (Pearce & Dunbar 2011). On this view, the larger brains of populations who trace their descent to areas of greater latitude presumably reflect only the demands of the visual system, rather than any differences in general intelligence. Yet another theory, less politically-correct than these, is so-called ‘Cold Winters Theory’, which posits that colder climates placed a greater premium on intelligence, which caused populations inhabiting colder regions of the globe to evolve larger brains and higher levels of intelligence. This is, of course, the theory championed by Lynn himself, and I will discuss the problems with this theory below.
 Conversely, Lynn also suggests that Turkish people score slightly higher than other Middle-Eastern populations, because they are somewhat intermixed with Europeans (p80).
 Actually, Lynn acknowledges causation in both directions, possibly creating a feedback loop. He also acknowledges other factors in contributing to differences in economic development and prosperity, including the effects of the economic system adopted. For example, countries that adopted communism tend to be poorer than comparable countries that have capitalist economies (e.g. Eastern Europe is poorer than Western Europe, and North Korea poorer than South Korea).
 Incidentally, Lynn cites two studies of Polish IQ, whose results are even more divergent than those of Portugal or Ireland, giving average IQs of 106 and 91 respectively. One of these scores is substantially below the European average, while the other the substantially above.
 Essayist Ron Unz has argued that IQs in Ireland have risen in concert with living standards in Ireland (Unz 2012a; Unz 2012b). However, judging from dates when the studies cited by Lynn in ‘Race Differences in Intelligence’ were published, there is no obvious increase over time. True the earliest study, an MA thesis, published in 1973 gives the lowest figure, with an average IQ of just 87 (Gill and Byrt 1973). This rises to 97 in a study published in 1981 that provided little details on its methodology (Buj 1981). However, it declines again for in the latest study cited by Lynn on Irish IQs, which was published in 1993 but gives average IQs of just 93 and 91 for two separate samples (Carr 1993). In the more recent 2015 edition, Lynn cites a few extra studies, eleven in total. Again, however, there is no obvious increase over time, the latest study cited by Lynn, which was published in 2012, giving an average IQ of just 92 (2015 edition).
 While this claim is made in reference to immigrants to America and the West, it is perhaps worth noting that East Asians in South-East Asia, namely the Overseas Chinese, largely dominate the economies of South-East Asia, and are therefore on average much wealthier than the average Chinese person still residing in China (see World on Fire by Amy Chua). Given the association of intelligence with wealth, this would suggest that Chinese immigrants to South-East Asia are not substantially less intelligent than those who remained in China. Did the more intelligent Chinese migrate to South-East Asia, while the less intelligent migrated to America? If so, why would this be?
 According to Daniel Nettle in Personality: What Makes You the Way You Are, in the framework of the five-factor model of personality, a liking for travel is associated primarily with extraversion. One study found that an intention to migrate was positively associated with both extraversion and openness to experience, but negatively associated with agreeableness, conscientiousness, and neuroticism (Fouarge et al 2019). A study of migration within the United States found a rather more complex set of relationships between migration and each of the big five personality traits (Jokela 2009).
 Other Catholic countries, namely those in Southern Europe, such as Italy and Spain, may indeed have slightly lower IQs, at least in the far south of these countries. However, as we have seen, Lynn explains this in terms of racial admixture from Middle-Eastern and North African populations. Therefore, there is no need to invoke priestly celibacy in order to explain it. The crucial test case, then, is Catholic countries other than Ireland from Northern Europe, such as Austria and France.
 In the 2006 edition, Lynn cites no studies from the Horn of Africa. However, in the 2015 edition, he cites five studies from Ethiopia, and, in The Intelligence of Nations, he and co-author David Becker also cite a study on Somalian IQs.
“The ‘Aethiopid’ race of Ethiopia and Somaliland are an essentially Europid subrace with some Negrid admixture” (Race: p225).
This may be an exaggeration. However, recent genetic studies indeed show affinities between populations from the Horn of Africa and those from the Middle East (e.g. Ali et al 2020; Khan 2011a; Khan 2011b; Hodgson 2014).
 However, it is not at all clear that the same is true for black African minorities resident in other western polities, whose IQs are also, according to Lynn’s data, also considerably above those for indigenous Africans. Here, I suspect black populations are more diverse. For example, in Britain, Afro-Caribbean people, who emigrated to Britain by way of the West Indies, are probably mostly mixed-race, like African-Americans, since both descend from white-owned slave populations. However, Britain also plays host to many immigrants direct from Africa, most of whom are, I suspect, of relatively unmixed sub-Saharan African descent. Yet African immigrants to the UK outperform Afro-Caribbeans in UK schools (Chisala 2015a).
 Blogger John ‘Chuck’ Fuerst suggests, the higher scores for Somali immigrants might reflect the fact that the peoples of the Horn of Africa actually, as we have seen, have substantial Caucasoid ancestry, and genetic affinities with North African and Middle Eastern populations (Fuerst 2015). However, the problem with attributing the relatively high scores of Somali refugees and immigrants to Caucasoid-admixture is that, as we have seen, according to the data collected by Lynn, IQs are no higher in the Horn of Africa than elsewhere in sub-Saharan Africa.
 If anything, “Bushmen” should presumably be grouped, not with Pygmies, with rather the distinct but related Khoikhoi pastoralists. However, the latter are now all but extinct as an independent people and are not mentioned by Lynn.
 For example, Lynn also acknowledges that those whom he terms “South Asians and North Africans” are “closely related to the Europeans” (p79). However, they nevertheless merit a chapter of their own. Likewise, he acknowledges that “South-East Asians” share “some genetic affinity with East Asians with whom they are to some degree interbred” (p97). Nevertheless, he justifies considering these two ostensible races in separate chapters, partly on the basis that “the flattened nose and epicanthic eye-fold are less prominent” among the former (p97). Yet the morphological differences between Pygmies and Khoisan are even greater, but they are lumped together in the same chapter.
 There is indeed, as Lynn notes, a correlation between a group’s IQ and their lifestyle (i.e. whether they are foragers or agriculturalists). However, the direction of causation is unclear. Does high intelligence allow a group to transition to agriculture, or does an agriculturalist lifestyle somehow increase a group’s average IQ? And, if the latter, is this a genetic or a purely environmental effect?
 Indeed, Lynn could hardly have arrived at an actual figure for the average Pygmy IQ, since, as we have seen, he reports the results of only a single actual study of Pygmy intelligence, the author of which did not present his results in a quantitative format.
 Thus, he suggests that the lower performance of the Aboriginals tested by Drinkwater (1975), as compared to those tested by Kearins (1981), may reflect the fact that the latter were the descendants of coastal populations of Aborigines, for whom the need to navigate in deserts without landmarks would have been less important.
 The fact that the earliest civilization emerged among Middle Eastern, North African and South Asian populations is attributed by Lynn to the sort of environmental factors that, elsewhere in his book, he largely discounts. Thus, Lynn writes:
“[Europeans] were not able to develop early civilizations like those built by the South Asians and North Africans because Europe was still cold, was covered with forest, and had heavy soils that were difficult to plough unlike the light soils on which the early civilizations were built, and there were no river flood plains to provide annual highly fertile alluvial deposits from which agricultural surpluses could be obtained to support an urban civilization and an intellectual class” (p237).
 An interesting question is whether there exist differences in IQ as between different caste groups within the Indian subcontinent, since, at least in theory, these represented endogamous breeding populations between whom strict separation was maintained. Thus, it would be interesting to know the average IQ of Brahmins or of the high-achieving Parsi people (though the latter are not strictly a caste, since they are not Hindu).
 However, all of these comparisons, in both Britain and America, omit to include Jewish people as a separate ethnicity, instead grouping them with other whites. Jews earn more, on average, than any other religion in Britain and America, including Hindus.
 I assume that this is the study that Lynn is citing, since this is the only matching study included in his references. However, curiously, Lynn refers to this study here as “Mackintosh et al 1985” (p83-4), despite their being only two authors listed in his references, such that “Mackintosh & Mascie-Taylor 1985” would be the more usual citation. Indeed, Lynn uses this latter form of citation (i.e. “Mackintosh & Mascie-Taylor 1985”) elsewhere when citing what seems to be the same paper in his earlier chapter on Africans (p47; p49).
 In order to determine whether religion or national origin is the key determining factor, it would be interesting to have data on the incomes (and IQs) of Pakistani Hindus, Bangladeshi Hindus and Muslim Indians resident in the West.
 An alternative possibility is that it was the spread of Arab genes, as a result of the Arab conquests, and resulting spread of Islam, that depressed IQs in the Middle-East and North Africa, since Arabs were, prior to the rise of Islam, a relatively backward group of desert nomads, whose intellectual achievements were minimal compared to those of many of the groups whom they conquered (e.g. Persians, Mesopotamians, Assyrians, and Egyptians). Indeed, even the achievements of Muslim civilization during the Islamic Golden Age were disproportionately those of the Persians, not the Arabs.
 One might, incidentally, question Lynn’s assumption that Oriental Jews were less subject to persecution than were the Ashkenazim in Europe. This is, of course, the politically correct view, which sees Islamic civilization as, prior to recent times, more tolerant than Christendom. On this view, anti-Jewish sentiment only emerged in the Middle East as a consequence of Zionism and the establishment of the Jewish state in what was formerly Palestine. However, for alternative views, see The Myth of the Andalusian Paradise. See also Robert Spencer’s The Truth About Muhammad (which I have reviewed here), in which he argues that Islam is inherently antisemitic (i.e. anti-Jewish). Interestingly, Kevin Macdonald, in A People That Shall Dwell Alone (which I have reviewed here and here) makes almost the opposite argument to that of Lynn. Thus, he argues that it was precisely because Jews were so discriminated against in the Muslim world that their culture, and ultimately their IQs, were to decline, as they were, according to Macdonald, largely excluded from high-status and cognitively-demanding occupations, which were reserved for Muslims (p301-4). Thus, Macdonald concludes:
“The pattern of lower verbal intelligence, relatively high fertility, and low-investment parenting among Jews in the Muslim world is linked ultimately to anti-Semitism” (A People That Shall Dwell Alone (reviewed here): p304).
 For example, one might speculate that only the relatively smarter Jews were able to anticipate looming pogroms and hence escape. Alternatively, since wealth is correlated with intelligence, perhaps only the relatively richer, and hence generally smarter, Jews could afford the costs of migration, including bribes to officials, in order to escape pogroms. These are, however, obviously speculative, post-hoc ‘just-so stories’ (in the negative Gouldian sense), and I put little stock in them.
 This pattern among East Asians of lower scores on the verbal component of IQ tests was initially attributed to a lack of fluency in the language of the test, since the first East Asians to be tested were among diaspora populations resident in the West. However, the same pattern has now been found even among East Asians tested in their first language, in both the West and East Asia.
 For example, Sarich and Miele, in Race: The Reality of Human Differences (which I have reviewed here and here) write that “Asians have a slightly higher IQ than do whites” (Race: The Reality of Human Differences: p196). However, in actuality, this applies only to East Asians, not to South-East Asians (nor to South Asians and West Asians, who are “Asian” in at least the geographical, and the British-English, sense.) Similarly, in his own oversimplified tripartite racial taxonomy in Race, Evolution and Behavior (which I have reviewed here), Philippe Rushton seems to imply that the traits he attributes to ‘Mongoloids’, including high IQs and large brain-size, apply to all members of this race, including South-East Asians and even Native Americans.
 Ethnic Chinese were overrepresented among Vietnamese boat people, though less so among later waves of immigrants. However, perhaps a greater problem is that they were disproportionately middle-class and drawn from the business elite, and hence unrepresentative of the Vietnamese as a whole, and likely of disproportionately high cognitive ability.
 In his paper on Mongolian IQs, Lynn also suggests that Mongolians have lower IQs than other East Asians because they are genetically intermediate between East Asians and Eskimos (“Arctic Peoples”), who themselves have lower IQs (Lynn 2007). However, this merely begs the question as to why Eskimos themselves have lower IQs than East Asians, another anomaly with respect to ‘Cold Winters Theory’, which is discussed in the final part of this review.
 With regard to the population of Colombia, Lynn writes:
“The population of Colombia is 75 percent Native American and Mestizo, 20 percent European, and 5 percent African. It is reasonable to assume that the higher IQ of the Europeans and the lower IQ of the Africans will approximately balance out and that the IQ of 84 represents the intelligence of the Native Americans” (p58).
However, this assumption that the African and European genetic contributions will balance out seems dubious since, by Lynn’s own reckoning, the European contribution to the Colombian gene-pool is three times greater than that of Africans.
 The currently-preferred term ‘Inuit’ is not sufficiently inclusive, because it applies only to those Eskimos indigenous to the North American continent, not the related but culturally distinct populations inhabiting Siberia or the Aleutian Islands. I continue to use the term Eskimos, because it is more accurate, not obviously pejorative, probably more widely understood, and also because I deplore the euphemism treadmill. Elsewhere, I have generally deferred to Lynn’s own usage, for example mostly using ‘Aborigine’, rather than the now preferred ‘Aboriginal’, a particularly preposterous example of the euphemism treadmill since the terms are so similar, comparable to how, today, it is acceptable to say ‘people of colour’, but not ‘coloured people’.
 For example, Hans Eysenck made various references in his writings to the fact that Eskimo children performed as well as European children in IQ tests as evidence for his claim that economic deprivation did not necessarily reduce IQ scores (e.g. The Structure and Measurement of Intelligence: p23). See also discussion in: Jason Malloy, A World of Difference: Richard Lynn Maps World Intelligence (Malloy 2016).
 Certain specific subpopulations also score higher (e.g. Ashkenazim and Māoris, though the latter only barely). However, these are subpopulations within the major ten races that Lynn identifies, not races in and of themselves.
 Actually, by the time Columbus landed in the Americas, many Native Americans had already partly transitioned to agriculture. However, not least because of a lack of domesticated animals that they could use as a meat source, most supplemented this with hunting and sometimes gathering too.
 However, Lynn reports that Japanese also score high on tests of visual memory (p143). However, excepting perhaps the Ainu, the Japanese do not have a recent history of subsisting as foragers. This suggests that foraging is not the only possible cause of high visual memory in a population.
 Presumably the comparison group Lynn has in mind are Europeans, since, as we have seen it is European living standards that he takes as his baseline for the purposes of estimating a group’s ”genotypic IQ” (p69), and, in a sense, all the IQ scores that he reports are measured against a European standard in so far as they are calculated by reference to an arbitrarily assigned average of 100 for European populations.
 Thus, it is at least theoretically possible that a relatively darker-skinned African-American child might be treated differently than a lighter-skinned child, especially one whose race is relatively indeterminate, by others (e.g. teachers) in a way that could conceivably affect their cognitive development and IQ. In addition, a darker skinned African-American child might, as a consequence of their darker complexion, come to identify as an African American to a greater extent than a lighter skinned child, which might affect who they socialize with, which celebrities they identify with and the extent to which they identify with broader black culture, all of which could conceivably have an effect on IQ. I do not contend that these effects are likely or even plausible, but they are at least theoretically possible. Using blood group to assess ancestry, especially if one actually introduces controls for skin tone (since this may be associated with blood-group, since both are presumed to be markers of degree of African ancestry), obviously eliminates this possibility. Today, this can also be done by looking at subjects’ actual DNA, which obviously has the potential to provide a more accurate measure of ancestry than either skin-tone or blood-group (e.g. Lasker et al 2019).
 More recently, a better study has been published regarding the association between European admixture and intelligence among African-Americans, which used genetic data to assess ancestry, and actually sought to control for the possible confounding effect of skin-colour and appearance (Lasker et al 2019). Unlike the blood-group studies, this largely supports the hereditarian hypothesis. However, this was not available at the time Lynn authored his book. Also, it ought to be noted that it was published in a controversial pay-to-publish academic journal, and therefore the quality of peer review to which the paper was subjected may be open to question. No doubt in the future, with the reduced costs of genetic testing, more studies using a similar methodology will be conducted, finally resolving the question of the relative contributions of heredity and environment to the black-white test score gap in America, and perhaps disparities between other ethnic groups too.
 It is a fallacy, however, to assume that what is true for those foraging peoples that have managed to survive as foragers in modern times and hence come to be studied by anthropologists was necessarily also true of all foraging groups before the transition to agriculture. On the contrary, those foraging groups that have survived into modern times, tend to have done so only in the ecologically most marginal and barren environments (e.g. the Kalahari Desert occupied by the San), since these areas are of least use to agriculturalists, and therefore represent the only regions where more technologically and socially advanced agriculturalists have yet to displace them (see Ember 1978). However, this would seem to suggest that African hunter-gatherers, prior to the expansion of Bantu agriculturalists, would have occupied more fertile areas, and therefore might have had even less need to rely on hunting than do contemporary hunter-gatherers such as the San, who are today largely restricted to the Kalahari Desert.
 Here, interestingly, Lynn departs from the theory of fellow race realist, and fellow exponent of ‘Cold Winters Theory’, Philippe Rushton. The latter, in his book, Race, Evolution and Behavior (which I have reviewed here), argues that:
“Hunting in the open grasslands of northern Europe was more difficult than hunting in the woodlands of the tropics and subtropics where there is plenty of cover for hunters to hide in” (Race, Evolution and Behavior: p228).
In contrast, Lynn argues “open grasslands”, albeit on the African Savannah rather than in Northern Europe, actually made things harder, not for predators, but rather for prey – or at least arboreal primate prey. Thus, Lynn writes:
“The other principle problem of the hominids living in open grasslands would have been to protect themselves against lions, cheetahs and leopards. Apes and monkeys escape from the big cats by climbing into trees and swinging or jumping form one tree to another. For the Autralopithecines and the later hominids in open grasslands this was no longer possible” (p203).
 To clarify, this is not to say that either San Bushmen or Australian Aborigines evolved primarily in these desert environments. On the contrary, many of them formerly occupied more fertile areas, before being displaced by more advanced neighbours, Bantu agriculturalists in the case of Khoisan, and European (more specifically British) colonizers, in the case of Aborigines. However, that they are nevertheless capable of surviving in these demanding desert environments suggests either:
(1) They are more intelligent than Lynn concludes; or
(2) That surviving in challenging environments does not require the level of intelligence that Lynn’s ‘Cold Winters Theory’ supposes.
 Besides Eskimos, another potential test case for ‘Cold Winters Theory’ are the Sámi (or Lapps) of Northern Scandinavia. Like Eskimos, they have inhabited an extremely cold, northern environment for many generations and are genetically quite distinct from other populations. Also, again like Eskimos, they maintained a foraging lifestyle until modern times. According to Armstrong et al (2014), the only study of Sámi cognitive ability of which I am aware, the average IQ of the Sámi is almost identical to that of neighbouring populations of Finns (about 101).
 Lynn gives the same explanation for the relatively lower recorded IQs of Mongolians, as compared to other East Asians (p240).
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