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Introduction Gender dysphoria (GD) is associated with several psychiatric conditions, but the causal links are not known. We note that some of these conditions are associated with physiological masculinisation. Methods Here, we explore this association through a series of systematic reviews, using Google Scholar, on original studies that test the relationship between GD and at least one correlate of androgens, namely autism spectrum disorder, left-handedness, 2D:4D ratio, being male and male heterosexuality. Results Individuals with GD tend to exhibit scores that reflect heightened levels of androgens and masculinity compared with non-GD individuals. We further show that these same androgen indices are also associated with other identity disorders (or dysphoriae). Conclusions Autism is associated with masculinisation, and we argue that GD may reflect autism spectrum disorder traits that indirectly lead to anxiety and to one questioning one’s sense of self. We note that this is consistent with Blanchard’s transsexualism typology, which successfully integrates a wide range of empirical findings.

Following the Developmental Theory of Sex Differences, males and females have roughly the same IQ during childhood. However, because females enter puberty earlier their general IQ exceeds that of males during early adolescence, after which males enter puberty. By their late teens, males have a small IQ advantage. To test this model, we administered the SPM+ to a sample of 701 male and 705 female school students aged 10 to 19 years from different schools in the Dhofar Governorate in the Sultanate of Oman. Our results broadly validated Lynn's model, as males scores exceeded those of females from the age of 16 onwards. However, we note that there are also alternative explanations for our findings.

Many groups differ in their mean intelligence score. Spearman’s hypothesis states that the differences are a function of cognitive complexity. There tend to be large differences on subtests of high cognitive complexity and small differences on subtests of low cognitive complexity. Spearman’s hypothesis has been supported by a large number of studies. Can Spearman’s hypothesis be generalized to regions of a country, where these regions differ in mean intelligence? We utilized data from 86 different cognitive tests from all 47 Japanese prefectures and correlated the g loadings of 86 subtests with standardized differences on the same subtests. Spearman’s hypothesis was clearly supported: the biggest differences between the regions were on the tests that were of the greatest complexity, meaning that Spearman’s hypothesis may be generalizable from groups to regions. In Japan, g loadings offer a better explanation of group differences in intelligence than cultural differences. Future research should explore whether Spearman’s hypothesis is also supported for differences between regions of other countries.

Research is increasingly finding that stereotypes about the average intelligence or personality of different groups, when actually tested, have a substantial degree of empirical accuracy. This has been explored with regard to more incendiary stereotypes — such as about races and nationalities — but in no great detail with regard to different religious groups. In this study, we draw upon the Midlife in the United States study (MIDUS) to discern the most important values held by atheists and agnostics. We compare these to stereotypes about atheists and agnostics in terms of personality or interests. We find that the stereotypes are accurate to a strong degree. Item ambiguity and other problems with the instrument may have impacted the results, leading to suggestions on how to overcome these problems in future research.

Numerous studies have found a negative relationship between religiousness and IQ. It is in the region of − 0.2, according to meta-analyses. The reasons for this relationship are, however, unknown. It has been suggested that higher intelligence leads to greater attraction to science, or that it helps to override evolved cognitive dispositions such as for religiousness. Either way, such explanations assume that the religion–IQ nexus is on general intelligence (g), rather than some subset of specialized cognitive abilities. In other words, they assume it is a Jensen effect. Two large datasets comparing groups with different levels of religiousness show that their IQ differences are not on g and must, therefore, be attributed to specialized abilities. An analysis of the specialized abilities on which the religious and non-religious groups differ reveals no clear pattern. We cautiously suggest that this may be explicable in terms of autism spectrum disorder traits among people with high IQ scores, because such traits are negatively associated with religiousness.

Sex differences in intelligence are of great importance with regard to understanding intelligence's underlying evolutionary forces. Previous research in this area has had a strong focus on Western ...

Impulsivity (or impulsiveness) is a psychological trait with a long history in research and a large amount of accepted associations with other traits and with life outcomes. But it is rarely studied outside of the Western world, raising questions as to whether it can be generalized beyond this. In this study the Barratt Impulsiveness Scale 11 (BIS-11) was administered on two university student samples; one Egyptian (N = 450) and one Saudi (N = 396), in order to close this gap and to observe differences between sexes and cultures. We compared the Saudi samples with samples from typical Western countries (Germany, USA) by using Hofstede’s cultural dimensions as a means of assessing cultural differences. We found no indicators of sex differences or cultural differences along the superficial division between countries from the Western and Arab-Muslim world. Also, more differentiated cultural dimensions were predominantly unrelated to BIS-11 factor scores. Implications for further research and limitations, such as the inclusion of more samples from Arab-Muslim countries and the use of samples more representative for the whole population, were discussed.

Communicating intelligence research : media misrepresentation, the Gould Effect and unexpected forces

Patterns of adoption behaviour are starkly asymmetric across populations. To better understand this phenomenon we conducted a systematic review of transracial adoption and adoption in general. We f ...

It has been argued that Raven's tests are problematic in the context of Sub-Saharan Africa. No discussion of Raven's in South Sudan, one of the least developed countries in Africa, has been presented. We present all known administrations of Raven's to South Sudanese samples. We find that Raven's in South Sudan is problematic. The scores are so low that they may imply that the subjects had little understanding of the test and simply guessed the answers. It is argued that the undeveloped nature of South Sudan means that a test based around shapes and analytic thinking is unsuitable. It is likely to heavily under-estimate their average intelligence.

Kevin MacDonald (1998) has argued that a series of twentieth century ideologies which have challenged European traditions should be understood as part of a Jewish evolutionary strategy to promote Jewish interests in the West, as evidenced by Jewish leadership of and disproportionate involvement in these movements. Cofnas Human Nature 29, 134–156 (Cofnas 2018a) has critiqued this model and countered that the evidence can be more parsimoniously explained by the high average intelligence and urban location of Jews in Western countries. This, he avers, should be the ‘default hypothesis.’ In this response, I argue that it is MacDonald’s model that is the more plausible hypothesis due to evidence that people tend to act in their ethnic group interest and that group selectedness among Jews is particularly strong, meaning that they are particularly likely to do so.

SummaryTwo administrations of the Coloured Progressive Matrices in Egypt were compared. The first was administered to a large, representative national sample between 2011 and 2013. The second was administered to primary school pupils in villages in Menoufia in northern Egypt in 2017. Adjusting for the Flynn Effect, the IQ of the rural northern Egyptians was shown to be statistically significantly higher than the national average. It is demonstrated that this is consistent with regional socioeconomic differences in Egypt, which strongly imply that northern Egypt has a higher average IQ than southern Egypt.

Three recent studies have summarized evidence for Negative Flynn Effects (Dutton et al., 2016; Flynn & Shayer, 2018; Woodley of Menie, Penaherrera-Aguirre, Fernandes, and Figueredo, 2017), that is secular deceases in IQ scores. To develop this important line of research, as many instances of this effect must be reported and understood as possible. Dutton, Bakhiet, Ziada, Essa, and Blahmar (2017) reported, in Intelligence, a Negative Flynn Effect in Khartoum, where education was voluntary for some cohorts. This study reports an increase in IQ, as assessed by the Colored Progressive Matrices, in Khartoum between 2004 and 2016. The increase in IQ amounted to 8 to 13 points, based on assessments of children between the ages of 6 and 9. Thus, the original negative Flynn Effect reflected schooling not being compulsory for some of the earlier sample.

Previous research indicates that the typical increase in IQ during childhood is greater in European countries than in Arab countries. A systematic literature review of age-dependent IQ in Arab coun ...

There are elevated levels of non-heterosexual orientation and pedophilia among male religious celibates, such as Catholic priests and certain shamans. Based on cross-cultural empirical studies, it is argued that the most likely explanation is that male homosexuality is associated not only with elevated religiousness, but also with pathologies which themselves predict hyper-religiosity and intense religious experiences. This is supported by evidence of elevated religiousness among homosexual males, elevated Neuroticism among Catholic priests, and evidence of schizophrenia among shamans. The discussion also observes an erotic dimension to intense religiousness, which may aid the maintenance of celibacy. Finally, it is suggested that these findings may partially explain how male homosexuality may have been an adaptive trait: a group with an associated optimum level of fervent, celibate religious devotees would have a higher average level of religiosity and be more successful in terms of group selection.

Industrialisation leads to relaxed selection and thus the accumulation of fitness-damaging genetic mutations. We argue that religion is a selected trait that would be highly sensitive to mutational ...

The results of two previously published Arabic language administrations of the Standard Progressive Matrices (SPM) are compared. The first is an administration of the SPM in 2006 to a probability sample of 6529 Kuwaitis aged between 8 and 15 from all regions of Kuwait. The second is an administration to a comparable sample of 6431 Kuwaitis in 2015. We find a significant Negative Flynn Effect in each age cohort and an overall Negative Flynn Effect amounting to a loss of 6.2 points in a decade. Possible reasons for this are discussed. It is proposed that the most persuasive explanation is increasing religious emphasis in the Kuwaiti school curriculum.

Frost and Harpending, Evolutionary Psychology, 13 (2015), have argued that the increasing use of capital punishment across the Middle Ages in Europe altered the genotype, helping to create a less violent and generally more law-abiding population. Developing this insight, we hypothesise that the same system of violent punishments would also have helped to genotypically create a more religious society by indirectly selecting for religiousness, through the execution of men who had not yet sired any offspring. We estimate the selection differential for religiousness based on genetic correlation data for conceivably related traits, and compare that to the actual increase in religiosity across the Middle Ages. We further explore other mechanisms by which religiousness was being selected for in Medieval England, and conclude that executions most likely contributed substantially to the increase in religiosity, but that other selection pressures also played a role.

We compare the results of the Standard Progressive Matrices on two samples from Khartoum, one from 1999 (N 6877) and the other from 2010 (N 5659), both aged between 9 and 25. We show that in 7 out of 12 age groups there has been a significant Negative Flynn Effect over this period. Among those aged 9 to 18 - directly comparable as they are population samples - we found a significant aggregate loss of 2.13 IQ points between 1999 and 2010 comparing these two groups. The sample, in part, is elite and we note that a cessation of the Flynn Effect has also been reported in an elite Brazilian sample; another developing country. We examine a number of factors which may be behind our finding, in particular changes in the Sudanese education system, changes in the Khartoum population, and dysgenic fertility in Sudan.

For over a century, social scientists have predicted declines in religious beliefs and their replacement with more scientific/naturalistic outlooks, a prediction known as the secularization hypothesis. However, skepticism surrounding this hypothesis has been expressed by some researchers in recent decades. After reviewing the pertinent evidence and arguments, we examined some aspects of the secularization hypothesis from what is termed a biologically informed perspective. Based on large samples of college students in Malaysia and the USA, religiosity, religious affiliation, and parental fertility were measured using self-reports. Three religiosity indicators were factor analyzed, resulting in an index for religiosity. Results reveal that average parental fertility varied considerably according to religious groups, with Muslims being the most religious and the most fertile and Jews and Buddhists being the least. Within most religious groupings, religiosity was positively associated with parental fertility. While cross-sectional in nature, when our results are combined with evidence that both religiosity and fertility are substantially heritable traits, findings are consistent with view that earlier trends toward secularization (due to science education surrounding advancements in science) are currently being counter-balanced by genetic and reproductive forces. We also propose that the inverse association between intelligence and religiosity, and the inverse correlation between intelligence and fertility lead to predictions of a decline in secularism in the foreseeable future. A contra-secularization hypothesis is proposed and defended in the discussion. It states that secularism is likely to undergo a decline throughout the remainder of the twenty-first century, including Europe and other industrial societies.

We present three models which attempt to explain the robust negative association between religion and intelligence: the Irrationality of Religion Model, the Cultural Mediation Hypothesis, and the Savanna-IQ Interaction Hypothesis. We highlight problems with each of them and propose that the negative religion-IQ nexus can be understood through substantially revising the Savanna-IQ Interaction Hypothesis. We argue that religion should be regarded as an evolved domain or instinct. Intelligence, by contrast, involves rising above our instincts. It follows that an inclination toward the non-instinctive will thus be an aspect of intelligence because it will help us to solve problems. Thus, intelligence will involve being attracted to evolutionary mismatch, to that which we would not be instinctively evolved to be attracted to. It is this, we argue, that is behind the negative religion-intelligence nexus. We respond to potential criticisms of our model and we examine how this model can be further tested.

We administered the SPM to a sample of 1614 pupils aged between 9 and 18 in 2018 in the Dhofar region of Oman. Our results were compared to a previous administration of the SPM to 5139 pupils aged 9 to 18 in the capital region of Muscat which took place in 2001. We found that the IQ of Muscat in 2001 is substantially higher than the IQ of Dhofar is 17 years later. As there are only a small number of studies on the mean IQ in Oman, we did not apply a Flynn-effect correction. It is found that these regional IQ differences are paralleled by regional differences on many correlates of IQ such as life expectancy and years spent in schooling. We suggest three key factors as likely explaining the difference in IQ: poorer conditions in Dhofar, the association between intelligence and urban migration, and the effects of the Dhofar Rebellion. Other possible explanations are also examined.

Previous research has attempted to understand why countries with relatively favorable conditions and high estimated average IQs (such as Finland and Japan) have a relatively low per capita number o ...

There are national differences in scientific activity that are not well accounted for by economic and intellectual factors alone. We examine the novel hypothesis that androgen levels may also play ...

Many studies have found a small negative correlation between religiousness and intelligence measured by IQ tests, and many others have found that females are more religious than males. Still other studies have demonstrated that the IQ profile of females is different from that of males, with females tending to be higher than males in some abilities and lower in others. This raises the intriguing question of whether religiousness may be correlated with a more stereotypically female intelligence profile. We tested whether this was the case using the NLSY 79 (N = 12,686). The NLSY shows that religiousness, using the proxy of regular church attendance, is not only higher among females but is also associated with a female profile of abilities even among males (r = 0.92). We argue that this is potentially consistent with evidence that Autism Spectrum Disorder is negatively associated with religiosity.

Meta-analyses have found a negative relationship between religiousness and IQ of around r = −0.2, including in samples of elderly Westerners. However, there have been few attempts to directly test the existence of the religion-IQ nexus in non-Western societies. We administered a cognitive test to a representative sample of elderly South Koreans who were also surveyed about their religion and tested whether elderly nonreligious people had higher mean IQ scores than elderly religious people. Using a broad cognitive test battery, we computed mean IQ scores of n = 589 non-religious, n = 494 Protestants, n = 520 Catholics, n = 347 Buddhists, and n = 17 Confucianists. Elderly South Koreans who claimed to have ‘no religion’ had lower mean IQs than religious Koreans. This finding is not consistent with previous findings from meta-analyses. We argue that it is explicable in terms of differences in how the concept of religion is understood when comparing Western and Northeast Asian societies. Many of the ‘non-religious’ category would be adherents to Korean folk religion, something expected to be associated with lower mean IQ.

We conducted a review of factors associated with individual and group level differences in positive ethnocentrism (PE) and negative ethnocentrism (NE). We inter-correlated datasets on national diff ...

Male and female Finns who contracted cross-national marriages had spouses from very different countries. We tested the possibility that this might reflect sexual selection, with nationality being a ...

It was hypothesized that religiosity is positively associated with religious in-group favoritism. This hypothesis was tested using the second wave of data from the Midlife in the United States representative survey of middle adulthood. The sample included White participants from four religious groups (Baptists, Catholics, Methodists, and Jews). Consistent with the hypothesis, when analyzing the full sample and within each of the four religious groups, religiosity was predictive of in-group favoritism. However, while differences between religious groups in in-group favoritism emerged, and remained when controlling for the previously found group differences in intelligence and personality, the group differences in in-group favoritism were not mediated by religiosity. For example, while Baptists scored high in both religiosity and in-group favoritism, Jews scored low in religiosity yet high in in-group favoritism. Possible explanations for these findings are discussed, such as genetic similarity among group members.

The Flynn Effect (rising performance on intelligence tests in the general population over time) is now an established phenomenon in many developed and less developed countries. Recently, evidence has begun to amass that the Flynn Effect has gone into reverse; the so-called ‘Negative Flynn Effect.’ In this study, we present a systematic literature review, conducted in order to discover in precisely how many countries this reverse phenomenon has been uncovered. Using strict criteria regarding quality of the sample and the study, we found nine studies reporting negative Flynn Effects in seven countries. We also discuss several possible explanations for the negative Flynn Effect as an attempt to understand its most probable causes.

Differential-K theory proposes that levels of androgen, i.e. male hormone, differ across three large racial groups with Sub-Saharan Africans having the highest levels, East Asians the lowest, and Caucasians (Europeans, North Africans and South Asians) being intermediate. In this study, we found that most of the national-level indicators of androgen – CAG repeats on the AR gene, androgenic hair, prostate cancer incidence, sex frequency and number of sex partners – are positively correlated at the population (country) level. East Asians showed signs of the lowest androgen level for most indicators and were lower than Caucasians on all of them. Sub-Saharan Africans showed inconsistent results. The results provide a partial validation of Differential-K theory.

The relationship between the general factor of intelligence (g) and handedness is investigated using a combined sample of 23511 respondents from three large databases: the NLSY’79 (US), NLSY’97 (US) and NCDS (UK). Dextrals – those who use their right hands were found to be 1.22 IQ points higher than sinistrals (left handers) after controlling for sex and age and correcting for sources of measurement error. To see if the association between IQ and handedness was strongest on the abilities that were the best measures of g, the method of correlated vectors was used to test for moderation. Across the three studies, g was found to very weakly negatively moderate the association between ability measure and handedness (ρ = −.023, K = 3, N = 23511), however in the NLSY’79, the coding speed subtest was an outlier in terms of the strength of its association with handedness. Its removal yielded indications of positive moderation in this dataset, which when aggregated boosted the overall vector correlation value to .539 (K = 3, N = 23511), suggesting that g might be an important moderator of this relationship. Secondary analysis of secular trend data on the changing percentage of sinistrals in Western populations indicates that overall, sinistrality has increased, entailing a g decline of .106 points over 150 years (.006 points per decade). The secular increase in sinistrality is consistent with other data indicating long-term declines in developmental stability and may stem from some combination of increasing mutation load and environmental stress in Western populations.

Why is social bias and its depressing effects on low-status or low-performing groups exaggerated? We show that the higher intelligence of academics has at best a very weak effect on reducing their bias, facilitates superficially justifying their biases, and may make them better at understanding the benefits of social conformity in general and competitive altruism specifically. We foresee a surge in research examining these mechanisms and recommend, meanwhile, reviving and better observing scientific ideals.

There is evidence that Finland's Swedish-speaking minority (Finland-Swedes) may have a distinct intelligence-personality profile from the Finnish-speaking Finns (Finns). We test this through an exa ...

The gods of monotheistic religions, which began amongst pastoralists and defeated exiles, are closer to Big Gods than those associated with ancient city-based polities. The development of Big Gods is contingent upon a need to reduce uncertainty and negative feelings in combination with a relatively high level of prosociality, rather than a need to induce or assess prosociality.

Life history speed has been argued to differ across the three main races, with Sub-Saharan Africans adopting the fastest (most r) strategy, Northeast Asians adopting the slowest (most K) strategy and Caucasians being intermediate, but closer to Northeast Asians (Rushton, 1995). Differential-K theory would predict that puberty begins earlier in the more r-strategy groups. Here, we extend this hypothesis to the length of puberty rather than its onset. Examining previously published data, we find that puberty is shortest amongst Caucasians and longest amongst Sub-Saharan Africans, and argue that this pattern is consistent with Differential-K theory. Key Words: Puberty, Race, Group Differences, Differential K Theory