Speculative Mechanisms Affecting Sex Ratio

Schuster, Donald H.; Schuster, Locky

doi:10.1080/00221325.1973.10532664

Cited by 8 publications

(4 citation statements)

References 12 publications

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“…The findings that stressed rats produced significantly more females than males and significantly fewer offspring than unstressed mother rats are presented as evidence that stress can contribute to the same phenomenon which has been reported for schizophrenic mothers. Of course, other factors, in addition to the well-known chromosomal one, have been related to sex determination such as temperature, nutrition, disease, acidity, radiation, etc., which are beyond the scope of this discussion (see reviews by Howard, McLaren, Michie, & Sander, 1955;Schuster & Schuster, 1972;Shettles, 1961;Stevenson & Bobrow, 1967). Whether stress affects sex ratios through one of these or through some other as yet unknown mechanism is uncertain from these data.…”

Section: Discussionmentioning

confidence: 88%

“…al., 1967;Taylor, 1969). An explanation in terms of stress also applies to variations in sex ratio in other human and animal populations (Schuster & Schuster, 1972). According to this theory, the male zygote and fetus are less likely than their more viable female counterparts to implant or to develop when the mother, such as a schizophrenic mother, is under stress.…”

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confidence: 99%

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Effect of maternal stress on fertility and sex ratio: A pilot study with rats.

Lane¹,

Hyde²

1973

Journal of Abnormal Psychology

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From a theory that stress accounts for the high proportion of daughters born to schizophrenic women, the relation of maternal stress to fertility and sex ratio was examined. Twelve female rats were stressed in wire-screen cocoons for four hours a day for one week before conception. The influence of the father on sex ratio and fertility was controlled by mating the same males with stressed and with unstressed females. Stressed females gave birth to significantly fewer males and significantly smaller litters than unstressed controls. The male zygote and fetus are evidently more vulnerable to stress than their female counterparts.

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Section: Discussionmentioning

confidence: 88%

mentioning

confidence: 99%

Effect of maternal stress on fertility and sex ratio: A pilot study with rats.

Lane¹,

Hyde²

1973

Journal of Abnormal Psychology

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“…Blanchard and Sheridan (1992) asked what the maternal stress hypothesis would predict about the family demographics of homosexual men. Citing findings that stressed mothers produce a predominance of male offspring (Schuster & Schuster, 1972; Wittels & Bornstein, 1974), they argued that if it is true that stressed mothers, for whatever reason, produce a predominance of sons, and if it is true that the mothers of homosexual men are relatively stress-prone, then the sibships of homosexual men should contain an excess of brothers. That is, of course, the finding of the present study and of the previous studies that it replicated (Blanchard & Sheridan, 1992; Jensch, 1941; Kallmann, 1952; Lang, 1960).…”

Section: Discussionmentioning

confidence: 99%

Birth order and sibling sex ratio in homosexual male adolescents and probably prehomosexual feminine boys.

Blanchard¹,

Zucker²,

Bradley³

et al. 1995

Developmental Psychology

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The purpose of this study was to extend the findings, previously limited to adults, that male homosexuals have a greater than average proportion of male siblings and a later than average birth order. There were 2 matched groups of 156 probands. The homosexual-prehomosexual (HP) group included boys referred to a specialty clinic because of persistent cross-gender behavior plus homosexual adolescents with or without gender identity problems. The controls were male child and adolescent patients referred for reasons other than gender identity disorder, homosexuality, or transvestism. Both predicted results were obtained in comparisons of the HP group with the controls and with expected values for the general population. Psychosocial and biological theories have been advanced to explain why male homosexuals have later births and more brothers, but none are well established.Previous investigations of the etiology of male homosexuality may be divided into two classes: studies showing that the erotic preference for male partners tends to be associated with other traits typical of the opposite sex, and studies relating male homosexuality to epidemiological and demographic variables of traditional interest in psychology and medicine.Investigations of the first class include prospective and retrospective studies showing that prehomosexual boys have a stronger interest in girls' games and toys, female playmates, feminine roles in fantasy play, and so on than do preheterosexual boys (

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“…More males are born during and after wars when there is decreased male-male competition for mates (James, 1987a;MacMahon 286 Williams and Gloster Social Biology and Pugh, 1954). Fewer males are born to fathers with high levels of stress (Little, Rigsby, and Little, 1987;Schuster and Schuster, 1972). Couples with low coital rates are less likely to produce males (James, 1983;19876) (less fit males, either because of age or dominance status, are likely to have lower coital rates).…”

mentioning

confidence: 99%

Human sex ratio as it relates to caloric availability

Williams

Gloster

1992

Biodemography and Social Biology

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ABSTRACT:The relationship between human sex ratios at birth and caloric availability per capita was examined across different countries. Significant positive correlations were obtained between the amount of food a country had available and the percentage of male births. Furthermore, increases or decreases in a country's caloric availability were related to corresponding changes in that country's sex ratio. These results provide evidence of adaptive sex ratio biasing in humans. The physiological mechanism by which this effect operates is probably higher mortality rates for male embryos and fetuses as a result of nutritional deficiencies and associated stressors.

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Speculative Mechanisms Affecting Sex Ratio

Cited by 8 publications

References 12 publications

Effect of maternal stress on fertility and sex ratio: A pilot study with rats.

Effect of maternal stress on fertility and sex ratio: A pilot study with rats.

Birth order and sibling sex ratio in homosexual male adolescents and probably prehomosexual feminine boys.

Human sex ratio as it relates to caloric availability

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