The intelligence of six-year-olds in Hong Kong

Evidence has accumulated to suggest that the mean IQs of Orientals in the United States and in the countries of the Pacific Basin are higher than those of Whites (Caucasoids) in the United States and Britain. This paper presents evidence from IQ tests on 4858 6-year-old Chinese children in Hong Kong. On the Coloured Progressive Matrices these children obtained a mean IQ of 116. Samples from Australia, Czechoslovakia, Germany, Romania, the UK and the US obtain IQs in the range 95-102. It is suggested that these results pose difficulties for the environmentalist explanations commonly advanced to explain the low mean IQs obtained by some ethnic minorities in the United States.     

Intelligence in Taiwan: Progressive Matrices means and sex differences in means and variances for 6- to 17-year-olds

Data for Raven's Progressive Matrices are reported for a sample of 6290 6- to 17-year-olds in Taiwan. The Taiwanese obtained a mean IQ of 109.5, in relation to a British mean of 100. There was no difference in mean scores of boys and girls at age 7 years. At age 10 years girls obtained significantly higher scores than boys, and at ages 13 and 16 years boys obtained significantly higher scores than girls. There was no sex difference in variance at age 7 years. At ages 10, 13 and 16 years variance was significantly greater in boys.     

Requiem for nutrition as the cause of IQ gains: Raven's gains in Britain 1938-2008

The hypothesis that enhanced nutrition is mainly responsible for massive IQ gains over time borrows plausibility from the height gains of the 20th century. However, evidence shows that the two trends are largely independent. A detailed analysis of IQ trends on the Raven's Progressive Matrices tests in Britain dramatizes the poverty of the nutrition hypothesis. A multiple factor hypothesis that operates on three levels is offered as an alternative instrument of causal explanation.The Raven's data show that over the 65 years from circa 1942 to the present, taking ages 5-15 together, British school children have gained 14 IQ points for a rate of 0.216 points per year. However, since 1979, gains have declined with age and between the ages of 12-13 and 14-15, small gains turn into small losses. This is confirmed by Piagetian data and poses the possibility that the cognitive demands of teen-age subculture have been stagnant over perhaps the last 30 years.     

The growth of IQ among Estonian schoolchildren from ages 7 to 19

The Standard Progressive Matrices test was standardized in Estonia on a representative sample of 4874 schoolchildren aged from 7 to 19 years. When the IQ of Estonian children was expressed in relation to British and Icelandic norms, both demonstrated a similar sigmoid relationship. The youngest Estonian group scored higher than the British and Icelandic norms: after first grade, the score fell below 100 and remained lower until age 12, and after that age it increased above the mean level of these two comparison countries. The difference between the junior school children and the secondary school children may be due to schooling, sampling error or different trajectories of intellectual maturation in different populations. Systematic differences in the growth pattern suggest that the development of intellectual capacities proceeds at different rates and the maturation process can take longer in some populations than in others.     

The Effects of Birth Order and Birth Interval on the Phenotypic Expression of Autism Spectrum Disorder

A rise in the prevalence of diagnosed cases of autism spectrum disorder (ASD) has been reported in several studies in recent years. While this rise in ASD prevalence is at least partially related to increased awareness and broadened diagnostic criteria, the role of environmental factors cannot be ruled out, especially considering that the cause of most cases of ASD remains unknown. The study of families with multiple affected children can provide clues about ASD etiology. While the majority of research on ASD multiplex families has focused on identifying genetic anomalies that may underlie the disorder, the study of symptom severity across ASD birth order may provide evidence for environmental factors in ASD. We compared social and cognitive measures of behavior between over 300 first and second affected siblings within multiplex autism families obtained from the Autism Genetic Resource Exchange dataset. Measures included nonverbal IQ assessed with the Ravens Colored Progressive Matrices, verbal IQ assessed with the Peabody Picture Vocabulary Test, and autism severity assessed with the Social Responsiveness Scale (SRS), an instrument established as a quantitative measure of autism. The results indicated that females were more severely impacted by ASD than males, especially first affected siblings. When first and second affected siblings were compared, significant declines in nonverbal and verbal IQ scores were observed. In addition, SRS results demonstrated a significant increase in autism severity between first and second affected siblings consistent with an overall decline in function as indicated by the IQ data. These results remained significant after controlling for the age and sex of the siblings. Surprisingly, the SRS scores were found to only be significant when the age difference between siblings was less than 2 years. These results suggest that some cases of ASD are influenced by a dosage effect involving unknown epigenetic, environmental, and/or immunological factors.     

The Hemogram,Serum Biochemistry,and Electrolyte Profile of Aged Rhesus Monkeys (Macaca mulatto)

The hemogram, scrum biochcmicals, and electrolytes of aged (15- to 28-year-old) rhesus monkeys were compared with values for younger adults (4-14 years old) maintained under identical conditions. Aged males had lower mean corpuscular volume, serum iron and magnesium, and higher percentages of eosinophils, globulins, and triglycerides than adult males. Aged females had lower mean corpuscular hemoglobin, total leukocyte count, percentage of neutrophils, alkaline phosphatase and magnesium, and higher percentages of lymphocytes and eosinophils, globulins, and uric acid than adult females.     

Sex differences in nutritional modulation of gonadotropin secretion during development: studies in the growth-retarded lamb

This study determined whether changes in nutrition during development alter LH secretion in males in a manner similar to that in females; sheep were used as an experimental model. Studies were conducted in the absence of gonadal steroid negative feedback. First, we compared the effect of chronic growth restriction on LH secretion in male and female lambs. Second, we determined whether the gonadotropic response to acute increases and decreases in nutrition is sexually differentiated. Seven male and 8 female Suffolk lambs, gonadectomized, and weaned by 8 wk of age were maintained at a target weight of 20 kg by level of nutrition. After 7 wk of chronic low nutrition (15 wk of age), LH pulse frequency was equally low in males (2.0 +/- 0.7 pulses/4 h) and females (2.0 +/- 0.4 pulses/4 h) relative to that (ca. hourly pulses) in normally growing gonadectomized lambs. Seven weeks later, at 22 wk of age, LH pulse frequency dropped further (males 0.9 +/- 0.3/4 h; females 0.9 +/- 0.4 pulses/4 h). The results of this first experiment, in which we observed no sex difference in gonadotropin secretion under chronic growth restriction, imply equal neuroendocrine sensitivity in males and females to long-term low nutrition. In the second experiment, however, a sex difference was evident in the response to increased and decreased nutrition. Both sexes responded to feeding ad libitum with a rapid increase in LH pulse frequency, but the response was greater in the males than in the females.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sex difference in the saturable binding of low-density lipoprotein by liver membranes in ageing rats

It is well documented that women of child-bearing age tend to have lower serum low-density lipoprotein (LDL) concentrations than men. In order to explore the metabolic basis of this sex difference, we have compared the saturable binding of 125I-labeled LDL (d 1.02-1.05 g/ml) at 37 degrees C by liver membranes from healthy male and female Wistar rats of different ages (15-213 days). Woolf plots of saturable binding curves over the concentration range 15-65 micrograms LDL protein/ml were linear and compatible with a single class of binding sites. Maximum binding capacity (Bmax) was not significantly different in male and female animals of 15-19 days of age (respectively, 0.331 +/- 0.018 vs. 0.427 +/- 0.044 micrograms LDL protein/mg membrane protein, mean +/- S.E.). Thereafter, Bmax increased in females, reaching a peak of 0.635 +/- 0.042 micrograms LDL protein/mg membrane protein at 60 days. As no increase in Bmax occurred in males, values were significantly higher (P less than 0.02) in females than in males (by a mean of 61-117%) at all ages after 30 days. During ageing, serum cholesterol concentration changed reciprocally with Bmax in females (Pearson's correlation coefficient, r = -0.761, P less than 0.01) and remained essentially constant in males. The equilibrium dissociation constant for 125I-labelled LDL binding to the hepatic membranes was unaffected by both age and sex. These results provide evidence that the sex difference in the plasma total and LDL cholesterol concentrations is related, at least in part, to a greater mean LDL receptor density in the livers of females.     

Sexual dimorphism in the renin-angiotensin system in aging spontaneously hypertensive rats

In young adult spontaneously hypertensive rats (SHR), mean arterial pressure (MAP) is higher in males than in females and inhibition of the renin-angiotensin system (RAS) eliminates this sex difference. After cessation of estrous cycling in female SHR, MAP is similar to that in male SHR. The purpose of this study was to determine the role of the RAS in maintenance of hypertension in aging male and female SHR. At 16 mo of age, MAP was similar in male and female SHR (183+/-5 vs. 193+/-8 mmHg), and chronic losartan (40 mg.kg-1.day-1 po for 3 wk) reduced MAP by 52% (to 90+/-8 mmHg, P<0.05 vs. control) in males and 37% (to 123+/-11 mmHg, P<0.05 vs. control) in females (P<0.05, females vs. males). The effect of losartan on angiotensin type 1 (AT1) receptor blockade was similar: MAP responses to acute doses of ANG II (62.5-250 ng/kg) were blocked to a similar extent in losartan-treated males and females. F2-isoprostane excretion was reduced with losartan more in males than in females. There were no sex differences in plasma renin activity, plasma angiotensinogen or ANG II, or renal expression of AT1 receptors, angiotensin-converting enzyme, or renin. However, renal angiotensinogen mRNA and protein expression was higher in old males than females, whereas renal ANG II was higher in old females than males. The data show that, in aging SHR, when blood pressures are similar, there remains a sexual dimorphism in the response to AT1 receptor antagonism, and the differences may involve sex differences in mechanisms responsible for oxidative stress with aging.     

Sex differences in energy metabolism and performance of teleost cardiac tissue

This study examined the effects of different oxygenation levels and substrate availability on cardiac performance, metabolism, and biochemistry in sexually immature male and female rainbow trout (Oncorhynchus mykiss). Ventricle strips were electrically paced (0.5 Hz, 14 degrees C) in hyperoxic or hypoxic Ringer solution. Our results demonstrate that 1) males sustain isometric force production (F) longer than females under hyperoxia (P O2 = 640 mmHg) with exogenous glucose present; 2) contractility is not maintained under moderate (P O2 = 130 mmHg) or severe hypoxia (P O2 = 10-20 mmHg) with glucose in either sex; however, following reoxygenation, F is higher in females compared with males; and 3) female tissue has higher lactate levels, net lactate efflux, and lactate dehydrogenase activity than males, whereas males have higher glycogen, citrate synthase, and beta-hydroxy acyl-CoA dehydrogenase activities, and greater inotropic responses to exogenous glucose and octanoate. No sex differences were detected in responsiveness to epinephrine and inhibitors of glucose transport or activities of hexokinase and pyruvate kinase. We conclude that sex differences exist in rainbow trout cardiac tissue: females appear to prefer glycolysis for ATP production, whereas males have a higher capacity for aerobic and lipid metabolism.     

Sex differences in Seoul virus infection are not related to adult sex steroid concentrations in Norway rats

Field studies of hantavirus infection in rodents report that a higher percentage of infected individuals are males than females. To determine whether males were more susceptible to hantavirus infection than females, adult male and female Long Evans rats (Rattus norvegicus) were inoculated with doses of Seoul virus ranging from 10(-4) to 10(6) PFU. The 50% infective doses (ID(50)) were not significantly different for male and female rats (10(0.05) and 10(0.8) PFU, respectively). To determine whether sex differences in response to infection were related to circulating sex steroid hormones, sex steroid concentrations were manipulated and antibody responses and virus shedding were assessed following inoculation with the ID(90). Regardless of hormone treatment, males had higher anti-Seoul virus immunoglobulin G (IgG) and IgG2a (i.e., Th1) responses than females and IgG1 (i.e., Th2) responses similar to those of females. Males also shed virus in saliva and feces longer than females. Manipulation of sex steroids in adulthood did not alter immune responses or virus shedding, suggesting that sex steroids may organize adult responses to hantavirus earlier during ontogeny.     

Role of Catecholamines in the Reproduction of Romanomermis culicivorax

The relative concentrations of catecholamine in the nervous system of the entomophilic nematode Romanomermis culicivorax were measured under different experimental conditions by a glyoxylic acid-induced fluorescence procedure. A greater concentration of catecholamine was recorded in the nervous system of adult males and females than in postparasitic juveniles. A higher concentration of catecholamine occurred in adults maintained in physical contact with the opposite sex than in those maintained in isolation. Adult males maintained with females in the same aqueous medium but physically separated by a barrier displayed a greater concentration of catecholamine in their nervous systems than did males maintained in isolation, but the catecholamine fluorescence intensity of such males was less than in males allowed physical contact with females. In adult males, the fluorescence intensity of catecholamine declined progressively during and after copulation. In adult females, the intensity of catecholamine remained constant before, during, and after copulation. Catecholamine(s) may play a role in regulating copulatory behavior, egg production, or oviposition.     

The maintenance of gynodioecy and androdioecy in angiosperms

Algebraic models of gynodioecy show that the effects on the equilibrium sex ratio of the relative survival and seed production of the sexes and of inbreeding of male-fertile plants are identical for all genic modes of inheritance, provided that different genotypes among male-fertile plants (or among females) do not differ in average fitness. The effects of three modes of inbreeding on equilibrium sex ratios are examined. If there is competition between self- and cross-fertilization of male-fertile individuals, a stable sexual dimorphism can be maintained by an outbreeding advantage of females if both the proportion of cross-fertilized seeds among those borne on male-fertile individuals,t, and the inbreeding depression (fitness inbred/outbred seeds),i, are less than one half. A lower frequency of females is obtained for the same values oft andi if self-fertilization precedes cross-fertilization. If self-fertilization follows cross-fertilization, gynodioecy cannot be maintained by an outbreeding advantage of females. When the sex phenotypes of gynodioecious populations are determined by cytoplasmic inheritance, females need only a slight advantage over males in survival, ovule production or outbreeding to persist at equilibrium. When determined by nuclear genes, androdioecy can be maintained by greater fecundity or a higher survival rate of males than of female-fertile plants, but not by an outbreeding advantage. Androdioecy cannot be maintained with cytoplasmic inheritance of sex. The models suggest explanations for the more frequent occurrence of gynodioecy than of andrdioecy, the high frequency of gynodioecy in Hawaii and New Zealand, and the origin of gynodioecy from hermaphrodite but not from monoecious ancestors.     

Role of the renal nerves in blood pressure in male and female SHR

Female spontaneously hypertensive rats (SHR) have lower blood pressures than males. The renin-angiotensin system plays an important role in the sexual dimorphism of blood pressure in SHR. The sympathetic nervous system can stimulate renin release, and, therefore, the present study was performed to determine whether the renal sympathetic nerves play a role in the sexual dimorphism of blood pressure in SHR. Male and female SHR underwent bilateral kidney denervation or sham surgery, and, 2 wk later, mean arterial pressure (MAP) and pulse interval were recorded, and baroreflex sensitivity (BRS) was measured by the sequence technique. Left ventricle index (LVI) was also calculated. MAP was higher in sham-operated males than females (182 +/- 5 vs. 169 +/- 4 mmHg; P < 0.01), but, despite the higher MAP in males, LVI was significantly greater in female rats. BRS was not different between sham-operated male and female SHR. Following bilateral renal denervation, MAP was decreased by a similar percentage (8-10%) in males (169 +/- 2 mmHg) and females (152 +/- 3 mmHg), whereas LVI was reduced only in female SHR. BRS was not altered by renal denervation in either sex. These data indicate that renal nerves play a role in the control of blood pressure in SHR independent of sex, but do not play a role in mediating the sex differences in blood pressure.     

Patterns of infection by lungworms, Rhabdias ranae and Haematoloechus spp., in northern leopard frogs: a relationship between sex and parasitism

We examined a population of northern leopard frogs to determine whether sex biases in investment in immunity, previously reported for this host species under controlled exposures to lung nematodes, is predictive of patterns of parasitism in nature. We examined Rhabdias ranae and Haematoloechus spp. infections in 74 breeding adult, 28 non-breeding adult, and 53 juvenile frogs. Contrary to our predictions, R. ranae prevalence and mean abundance were higher in breeding female frogs (prevalence: 39.4%, abundance: 3.05 +/- 0.85) than on breeding males (prevalence: 26.0%, abundance: 1.17 +/- 0.52), although no sex bias was observed among non-breeding adults or juvenile frogs. Female frogs also carried larger R. ranae worms, on average, than did males (females: 6407.38 microm +/- 153.80; males: 5198 microm +/- 131.09), regardless of age or breeding condition. We observed no sex-linked patterns of parasitism by Haematoloechus spp. worms in either adult or juvenile frogs. Alternative hypotheses, such as differences among sexes in the selection of thermal clines for hibernation, may explain the observed female bias in parasitism by nematode lungworms in nature and, thus, need to be considered.     

Biological Studies on Agamermis unka (Nematoda: Mermithidae), a Parasite of the Brown Planthopper Nilaparvata lugens

The mermithid parasite, Agamermis unka, is the most important natural enemy of the brown planthopper (BPH), Nilaparvata lugens, in Korean rice fields. Very little is known about many aspects of the mermithid's life cycle and behavior, and a study was undertaken to close the data gap. The sex ratio of A. unka isolated from field-collected BPH showed a strong female bias. Even when several A. unka occurred within a BPH, the majority were females. Similarly, the sex ratio of field-collected A. unka adults that were in the soil was strongly biased towards females and, in many instances, the females were found in the absence of males. Females collected from the field from January to May and maintained in water at 25 C had a mean pre-oviposition period of 17-28 days and a mean oviposition period of 17-37 days, and averaged 543-1851 eggs/female. The eggs averaged 20, 17 and 36 days to hatch at 30, 25 and 20 C respectively, but none hatched at 15 C. Most of the eggs (96%) hatched at 25 and 20 C, but only 64% hatched at 30 C. Agamermis pre-parasites could be found on rice stems in the field and laboratory. In the field, BPH-susceptible and BPH-resistant rice cultivars showed no significant difference in the numbers of pre-parasites on the stem. In the laboratory, the number of pre-parasites recovered/rice stem was significantly higher in two out of three trials when BPH nymphs and adults were present. When BPH nymphs were exposed to the pre-parasites in the laboratory, 39% of the brachypterous females and 4.5% of the brachypterous males were parasitized, whereas 0.3% of the macropterous females and 0% of the macropterous males were parasitized. The parasitism data obtained under field conditions showed similar trends. The reason(s) for these differences in parasitism between the BPH sex and wing types that have been observed both in the laboratory and field is unknown. Because brachypterous males and macropterous females and males occur in lesser numbers than the brachypterous females, this may, in part, account for the differences in parasitism observed. However, BPH behavior cannot be discounted as a factor in the differential parasitism.     

Sex ratios, size distributions, and sexual dimorphism in the dioecious tree Ilex aquifolium (Aquifoliaceae)

Sex ratio and sexual dimorphism in physiology and growth were studied in the dioecious tree Ilex aquifolium at two localities in northern Spain. Genet sex ratio was significantly male biased in one locality but not in the other. However, ramet and flowering ramet sex ratios were male biased at both study sites. Males had significantly thicker main trunks than females in one locality and produced more ramets in the other. Growth rate, estimated from mean width of annual rings, did not differ between localities, but males produced wider rings than females at both sites. Mean annual growth rates over the last 10, 20, and 30 yr were significantly higher for males. Measurements of chlorophyll fluorescence indicated that the efficiency of photosynthesis of leaves on nonfruiting branches of females was higher than for leaves on branches of male plants under low-light conditions, though not under saturating-light conditions. Efficiency of photosynthesis was significantly lower on fruiting branches of female plants than on nonfruiting branches. We discuss whether the observed between-sex differences are attributable to the higher cost of reproduction in females and/or to pollen competition.     

Heritability of human hookworm infection in Papua New Guinea

Hookworms infect approximately 740 million humans worldwide and are an important cause of morbidity. The present study examines the role of additive genetic effects in determining the intensity of hookworm infection in humans, and whether these effects vary according to the sex of the host. Parasitological and epidemiological data for a population of 704 subjects in Papua New Guinea were used in variance components analysis. The 'narrow-sense' heritability of hookworm infection was estimated as 0.15+/-0.04 (P<0.001), and remained significant when controlling for shared environmental (household) effects. Allowing the variance components to vary between the sexes of the human host consistently revealed larger additive genetic effects in females than in males, reflected by heritabilities of 0.18 in females and 0.08 in males in a conservative model. Household effects were also higher in females than males, although the overall household effect was not significant. The results indicate that additive genetic effects are an important determinant of the intensity of human hookworm infection in this population. However, despite similar mean and variance of intensity in each sex, the factors responsible for generating variation in intensity differ markedly between males and females.     

Male Ornamentation in a Sex‐Role Reversed Pipefish Corythoichthys haematopterus

Sexual selection theory predicts that mating competition in sex‐role reversed animals acts more strongly on females than males and consequently females are expected to develop secondary sexual traits. However, in a sex‐role reversed pipefish Corythoichthys haematopterus (family: Syngnathidae), only males develop an ornamental trait on the thorax, consisting of approx. 3–5 speckles alternated by lateral stripes of brilliant light blue and orange. To understand the function of this male ornament, we examined whether the presence of females affects the expression of this trait, and whether the expression of this trait depends on the male’s physical condition. Individual males were reared in a tank for a month in four different conditions: in high or low food supply and in the presence or absence of a female. After 1 mo, males in better condition expressed larger and deeper blue and yellow speckles, and males maintained with a female expressed larger and deeper blue speckles than solely reared males. These results indicated that the male ornament functions as a signal conveying information on the phenotypic quality of its holder and that females are potential receivers of this signal. Because C. haematopterus exhibits strict monogamy and competition for a mate occurs only among females, we concluded that the male ornament is not displayed in the context of mating competition but rather it is used as a cue for partner recognition to maintain pair bond.     

The systemizing quotient: an investigation of adults with Asperger syndrome or high-functioning autism,and normal sex differences

Systemizing is the drive to analyse systems or construct systems. A recent model of psychological sex differences suggests that this is a major dimension in which the sexes differ, with males being more drawn to systemize than females. Currently, there are no self-report measures to assess this important dimension. A second major dimension of sex differences is empathizing (the drive to identify mental states and respond to these with an appropriate emotion). Previous studies find females score higher on empathy measures. We report a new self-report questionnaire, the Systemizing Quotient (SQ), for use with adults of normal intelligence. It contains 40 systemizing items and 20 control items. On each systemizing item, a person can score 2, 1 or 0, so the SQ has a maximum score of 80 and a minimum of zero. In Study 1, we measured the SQ of n = 278 adults (114 males, 164 females) from a general population, to test for predicted sex differences (male superiority) in systemizing. All subjects were also given the Empathy Quotient (EQ) to test if previous reports of female superiority would be replicated. In Study 2 we employed the SQ and the EQ with n = 47 adults (33 males, 14 females) with Asperger syndrome (AS) or high-functioning autism (HFA), who are predicted to be either normal or superior at systemizing, but impaired at empathizing. Their scores were compared with n = 47 matched adults from the general population in Study 1. In Study 1, as predicted, normal adult males scored significantly higher than females on the SQ and significantly lower on the EQ. In Study 2, again as predicted, adults with AS/HFA scored significantly higher on the SQ than matched controls, and significantly lower on the EQ than matched controls. The SQ reveals both a sex difference in systemizing in the general population and an unusually strong drive to systemize in AS/HFA. These results are discussed in relation to two linked theories: the 'empathizing-systemizing' (E-S) theory of sex differences and the extreme male brain (EMB) theory of autism.