For example: not a single woman has been world champion; only 1 per cent of Grandmasters, the best players in the world, are female; and there is only one woman among the best 100 players in the world.

Averaged over the 100 top players, the expected male superiority is 341 Elo points and the real one is 353 points. Therefore 96 per cent of the observed difference between male and female players can be attributed to a simple statistical fact -- the extreme values from a large sample are likely to be bigger than those from a small one.

Once participation rates of men and women are controlled for, there is little left for biological, environmental, cultural or other factors to explain. This simple statistical fact is often overlooked by both laypeople and experts.

Whatever the final resolution of these debates [on "gender differences in cognitive abilities"], there is little empirical evidence to support the hypothesis of differential drop-out rates between male and females. A recent study of 647 young chess players, matched for initial skill, age and initial activity found that drop-out rates for boys and girls were similar (Chabris & Glickman 2006).

The fourth column reports that in regions where more people report regularly attending religious services (per National Election Studies 2004), overall subscription rates are not statistically significantly different from subscriptions elsewhere...However, in such regions, a statistically significantly smaller proportion of subscriptions begin on Sundays, compared with other regions. In particular, a 1 percent increase in the proportion of people who report regularly attending religious services is associated with a 0.10 percent reduction in the proportion of purchases that occur on Sunday. This analysis suggests that, on the whole, those who attend religious services shift their consumption of adult entertainment to other days of the week, despite on average consuming the same amount of adult entertainment as others.

the categories of intelligence, race and gender are not definable within the framework required for natural scientific research, failing my first criterion of being well-founded. They also fail the second criterion of being answerable: we lack the theoretical or technical tools to study them.

to try to capture the many forms of socially expressed intelligent behaviour in a single coefficient — and to rank an entire population in a linear mode, like soldiers on parade lined up by height — excludes most richly intelligent human activities. Social intelligence, emotional intelligence, the intelligent hands of the craftsman or the intelligent intuition of the scientist all elude the 'g' straightjacket

Group comparisons of IQ are even more problematic. Attempts have been made to make 'culture-fair' or 'culture-free' tests, as if such a thing were possible, to allow comparisons of 'g' between people from very different societies.

As for 'race', the problem is whether it is a biologically, as opposed to socially, meaningful category. Among geneticists interested in differences in gene frequencies between populations, there is increasing consensus that the word obscures more than it reveals, and should be replaced by the concept of biogeographic ancestry, which makes possible the study of subpopulations for relevant genetic and phenotypic characteristics... Broad divisions between 'white' or 'Caucasian' and 'black' or 'Asian', the groups generally discussed in the context of the IQ debate, especially in the United States, hide genetically important subpopulation differences within these groups.

the crucial question is whether it is possible to identify a biological — presumably genetic or neurodevelopmental — cause to any difference in the way men and women think and act. The problem is that from the moment of birth, boys and girls are treated differently, which shapes both their growing bodies and brains and how they are expected to behave... Thus, although there are minor average structural and biochemical variations between Western men's and women's brains (such as the volume of some nuclei and the distribution of hormone receptors), speculations on their implications for how men and women may think or behave lack any empirical basis.

The standard approach of population biologists to estimating the potential genetic contribution to a trait is to make a heritability estimate. Whatever the strengths and weaknesses of this measure within a population, it is essentially just that: a within-population measure, only valid for a given environment. The nature of the equations means that if the environment changes, the heritability estimate changes too...Even if reliable correlations were found between some intelligence test score and a measure of brain physiology or activity held by a specific group, such a correlation says nothing about the direction of causation.

It would be interesting to know, if it could be ascertained, as throwing light on this question with respect to man, what occurs with the higher anthropomorphous apes - whether the young males and females soon wander away from their parents, or whether the old males become jealous of their sons and expel them, or whether any inherited instinctive feeling, from being beneficial, has been generated, leading the young males and females of the same family to prefer pairing with distinct families, and to dislike pairing with each other. A considerable body of evidence has already been advanced, showing that the offspring from parents which are not related are more vigorous and fertile than those from parents which are closely related; hence any slight feeling, arising from the sexual excitement of novelty or other cause, which led to the former rather than the latter unions, would be augmented through natural selection, and thus might become instinctive; for those individuals which had an innate preference of this kind would increase in number. It seems more probable that degraded savages should thus unconsciously have acquired their dislike and even abhorrence of incestuous marriages, rather than that they should have discovered by observation and reasoning the evil results. The abhorrence occasionally failing is no valid argument against the feeling being instinctive, for any instinct may occasionally fail or become vitiated, as sometimes occurs with parental love and the social sympathies. In the case of man, the question whether evil follows from close interbreeding will probably never be answered by direct evidence, as he propagates his kind so slowly and cannot be subject to experiment; but the almost universal practice of all races at all times of avoiding closely-related marriages is an argument of considerable weight; and whatever conclusion we arrive at in regard to the higher animals may safely be extended to man (1868, vol.2, pp.123-4)

It has been clearly shown by Mr Huth that there is no instinctive feeling against incest in man any more than in gregarious animals. We know also how readily any prejudice or feeling may give rise to abhorrence, as shown by Hindus in regard to objects causing defilement. Although there seems to be no strong inherited feeling in mankind against incest, it seems possible that men during primeval times may have been more excited by strange females than by those with whom they habitually lived; in the same manner as according to Mr Cupples, male deerhounds are inclined towards strange females, while the females prefer dogs with whom they have associated. If any such feelings formerly existed in man, this would have led to a preference for marriages beyond the nearest kin, and might have been strengthened by the offspring of such marriages surviving in greater numbers, as analogy would lead us to believe would have occurred (1875, vol.2, pp.103-4)

The breach of a rule held sacred by the tribe, will thus, as it seems, give rise to the deepest feelings, - and this quite apart from the social instincts, excepting in so far as the rule is grounded on the judgement of the community. How so many strange superstitions have arisen throughout the world we know not; nor can we tell how some great and real crimes, such as incest, have come to be held in abhorrence (which is not however quite universal) by the lowest savages. It is even doubtful whether in some tribes incest would be looked on with greater horror, than would the marriage of a man with a woman bearing the same name, though not a relation....[quotes examples from E. B. Tylor] We may therefore reject the belief, lately insisted on by some writers, that the abhorrence of incest is due to our possessing a special God-implanted conscience.(1874, p.176)

To this I can only answer by remarking, that a new mode of attack with new weapons might be a great advantage, as shown by the case of the Ovis cycloceros [described earlier] who thus conquered a domestic ram famous for his fighting power. Though the branched antlers of the stag are well adapted for fighting with his rivals, and though it might be an advantage to the prong-horned variety slowly to acquire long and branched horns, if he had to fight only with others of the same kind, yet it by no means follows that branched horns would be the best fitted for conquering a foe differently armed. In the foregoing case of the Oryx leucoryx, it is almost certain that the victory would rest with an antelope having short horns, and who therefore did not have to kneel down, though an oryx might profit by having still longer horns, if he fought only with his proper rivals. (1874, p.783)

As everyone knows, male deer have branched antlers. During the breeding season, two stags fight by lowering their heads so that their antlers interlock. Each then attempts to force the other backwards, until at last the weakest is forced to break away and flee. Because of the branching structure of the antlers it is rare for a stag to be pierced by its opponent's antlers. Occasionally, however, a stag grows antlers without branches; such a stag may wound and kill its adversary.... Why should natural selection have favoured a device - the branching of antlers - which appears to reduce the chances a stag may have of winning fights? (1972, p.8)

These results therefore point to the importance of inherited factors in the association between prenatal smoking and offspring antisocial behavior and suggest that gene-environment correlation is important in explaining this association