scholarly journals A test of oscillation in the human secondary sex ratio

2020 ◽  
Vol 2020 (1) ◽  
pp. 225-233 ◽  
Author(s):  
Ralph Catalano ◽  
Joan A Casey ◽  
Tim A Bruckner
Keyword(s):  
Time Series ◽  
Sex Ratio ◽  
Female Offspring ◽  
Vital Statistics ◽  
Birth Cohorts ◽  
Reproductive Suppression ◽  
Female Ratio ◽  
Secondary Sex Ratio ◽  
Male To Female ◽  
Human Birth

Abstract Background and objectives The sex ratio of human birth cohorts predicts the health and longevity of their members. Most literature invokes natural selection in support of the argument that heritable tendencies to produce male or female offspring induce oscillation in the sex ratio and its sequelae. Tests of the argument remain exceedingly rare because they require vital statistics describing many generations of a population both unaffected by migration and exposed to an exogenous stressor virulent enough to change the sex ratio at birth. We contribute to the literature by using time-series modeling to detect oscillation in the best data currently available for such a test. Methodology We apply rigorous time-series methods to data describing Sweden from 1751 through 1830, a period when the population not only aged in place without migration, but also exhibited the effects of an Icelandic volcanic eruption including a historically low secondary sex ratio. That very low sex ratio should have induced oscillation if heritable mechanisms appear in humans. Results We detected oscillation in the ratio but not that predicted by heritable tendencies to produce males or females. We found peak-to-trough oscillation at 14 rather than the approximately 32 years expected from the heritable tendencies argument. Conclusions and implications Our findings suggest that mechanisms other than perturbation of heritable tendencies to produce males or females induce oscillation in the human secondary sex ratio. These other mechanisms may include reproductive suppression and selection in utero. LAY SUMMARY The male to female ratio in human birth cohorts predicts longevity but its variation over time remains unexplained. We test the long-held theory that the ratio oscillates due to heritable tendencies to produce males or females. We find oscillation, but it appears due to social processes rather than heritable mechanisms.

scholarly journals Do differences in Toxoplasma prevalence influence global variation in secondary sex ratio? Preliminary ecological regression study

Parasitology ◽  
2016 ◽  
Vol 143 (9) ◽  
pp. 1193-1203 ◽  
Author(s):  
MADHUKAR S. DAMA ◽  
LENKA MARTINEC NOVÁKOVÁ ◽  
JAROSLAV FLEGR
Keyword(s):  
Sex Ratio ◽  
Female Offspring ◽  
Human Populations ◽  
Offspring Sex Ratio ◽  
Global Variation ◽  
Ecological Regression ◽  
Large Populations ◽  
Secondary Sex Ratio ◽  
Genetically Determined ◽  
Male To Female

SUMMARYSex of the fetus is genetically determined such that an equal number of sons and daughters are born in large populations. However, the ratio of female to male births across human populations varies significantly. Many factors have been implicated in this. The theory that natural selection should favour female offspring under suboptimal environmental conditions implies that pathogens may affect secondary sex ratio (ratio of male to female births). Using regression models containing 13 potential confounding factors, we have found that variation of the secondary sex ratio can be predicted by seroprevalence of Toxoplasma across 94 populations distributed across African, American, Asian and European continents. Toxoplasma seroprevalence was the third strongest predictor of secondary sex ratio, β = −0·097, P < 0·01, after son preference, β = 0·261, P < 0·05, and fertility, β = −0·145, P < 0·001. Our preliminary results suggest that Toxoplasma gondii infection could be one of the most important environmental factors influencing the global variation of offspring sex ratio in humans. The effect of latent toxoplasmosis on public health could be much more serious than it is usually supposed to be.

Influence of latent toxoplasmosis on the secondary sex ratio in mice

Parasitology ◽  
2007 ◽  
Vol 134 (12) ◽  
pp. 1709-1717 ◽  
Author(s):  
Š. KAŇKOVÁ ◽  
P. KODYM ◽  
D. FRYNTA ◽  
R. VAVŘINOVÁ ◽  
A. KUBĚNA ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Human Subjects ◽  
Congenital Toxoplasmosis ◽  
Protozoan Parasite ◽  
Developed Countries ◽  
Female Offspring ◽  
Intermediate Hosts ◽  
Female Ratio ◽  
Secondary Sex Ratio ◽  
Retrospective Cohort Studies

SUMMARYThe sex ratio may be influenced by many factors, such as stress and immunosuppression, age of parents, parity and sex of preceding siblings. In animal systems, parasitism often changes the sex ratio of infected hosts, which can increase the probability of their transmission. The most common human protozoan parasite in developed countries,Toxoplasma gondii(prevalence 20%−80%), is known to change the behaviour of its intermediate hosts, thereby increasing the probability of transmission to its definitive host (the cat) by predation. The intermediate hosts, which under natural conditions are rodents, serve as the vector forToxoplasma. Therefore, we speculate thatToxoplasmacan alter the secondary sex ratio (i.e. male to female ratio in the offspring) of infected females to increase the proportion of (congenitally infected) male offspring, which are the more migratory sex in most rodent species. Here we studied the sex ratio of experimentally infected laboratory mice, expressed here as the proportion of males in the litter. In accordance with our hypothesis and results of previous retrospective cohort studies on human subjects, mice with toxoplasmosis produced a higher sex ratio than controls, in the early phase of latent infection. In the later phase of infection, mice with congenital toxoplasmosis had a lower sex ratio than controls, which is in accord with the Trivers-Willard hypothesis of sex ratio manipulation, suggesting that females in poor physical condition give birth to more female offspring.

scholarly journals Ascitic Fluid Cytology Seen in a Tertiary Hospital in Nigeria

2020 ◽  
pp. 345-350
Author(s):  
CC Nwafor ◽  
K Obioha ◽  
TO Akhiwu
Keyword(s):  
Sex Ratio ◽  
Patient Care ◽  
Ascitic Fluid ◽  
Age Groups ◽  
Tertiary Hospital ◽  
Age Group ◽  
Malignant Cells ◽  
Female Ratio ◽  
Male To Female ◽  
Fluid Cytology

Ascites is a symptom that can originate due to diverse pathologies. A lot of investigations including ascitic fluid cytology (AFC) can be done on it to help determine its origin. The aim of this study, is to document the findings and highlight the importance of AFC in patient care in Uyo. All AFC reports and slides in the Department of Histopathology, University of Uyo were retrieved, reviewed and used for this study. The age ranged from 1.5 – 80 years with mean age, 41.79 (±17.23) years. About 71.8% of the ascitic fluid (AF) specimens were from patients between the 3rd and 6th decade. Females predominated in all age groups expect 10-19 year's group, with a male to female sex ratio of 1:2.4. Malignant cells were seen in 28.7% of all the samples, while 51.2% were negative for malignant cells. Malignant cells were seen in 4 (6.7%), 11 (18.3%) and 6 (10%) of the AFC performed due to various liver pathologies, ovarian malignancies and intra-abdominal malignancies respectively. Malignant cells were found more in females with a male to female ratio of 1: 3.6. Age group 40-49 years accounted for most of the malignant cases (26.6%). The pattern of AFC in Uyo is similar to the pattern in other parts of Nigeria

Reproductive suppression and longevity in human birth cohorts

2019 ◽  
Vol 32 (3) ◽  
Author(s):  
Katherine B. Saxton ◽  
Alison Gemmill ◽  
Joan A. Casey ◽  
Holly Elser ◽  
Deborah Karasek ◽  
...  
Keyword(s):  
Birth Cohorts ◽  
Reproductive Suppression ◽  
Human Birth

Sex Ratio in Sibships With Twins

2008 ◽  
Vol 11 (2) ◽  
pp. 204-214 ◽  
Author(s):  
Johan Fellman ◽  
Aldur W. Eriksson
Keyword(s):  
Sex Ratio ◽  
Effective Means ◽  
Vital Statistics ◽  
Influential Factors ◽  
Sex Composition ◽  
Secondary Sex Ratio ◽  
Female Pair ◽  
Birth Data ◽  
The 19Th Century ◽  
Male Twin

AbstractIn national birth registers of Caucasians, the secondary sex ratio, that is, the number of boys per 100 girls at birth, is almost constant at 106. Variations other than random variation have been noted, and attention is being paid to identifying presumptive influential factors. Studies of the influence of different factors have, however, yielded meagre results. An effective means of identifying discrepancies is to investigate birth data compiled into sibships of different sizes. Assuming no inter- or intra-maternal variations, the distributions of the sex composition are binomial. Varying parental tendencies for a specific sex result in discrepancies from the binomial distribution. Over a century ago, the German scientists Geissler and Lommatzsch analyzed the vital statistics of Saxony, including twin maternities, for the last quarter of the 19th century. They considered sibships ending with twin sets. Their hypothesis was that in sibships ending with male–male twin pairs, the sex ratio among previous births is higher than normal, while in sibships with female–female twin pairs, the sex ratio is lower than normal. If the sibship ended with a male-female pair, then the sex ratio is almost normal. Consequently, a same-sex twin set indicated, in general, deviations in the sex ratio among the sibs within the sibship. Our analyzes of their data yielded statistically significant results that support their statements.

scholarly journals Optimization of reproduction of ricefish endemic to Southeast Sulawesi Oryzias woworae Parenti & Hadiaty, 2010 through different sex ratios in spawning

2021 ◽  
Vol 21 (3) ◽  
pp. 235-251
Author(s):  
Mohamad Ayip Firmansyah ◽  
Mustahal Mustahal ◽  
Mas Bayu Syamsunarno ◽  
Muh Herjayanto
Keyword(s):  
Water Quality ◽  
Sex Ratio ◽  
Ornamental Fish ◽  
Egg Hatching ◽  
Female Ratio ◽  
Male And Female ◽  
Status Information ◽  
The Difference ◽  
Endangered Status ◽  
Male To Female

Oryzias woworae has a beautiful color and has been traded as ornamental fish. This species is an endemic ricefish from Muna Island, Southeast Sulawesi, and is threatened with endangered status. Information on the optimal spawning sex ratio in O. woworae is unknown. This study aimed was to examine the optimization of reproduction based on the sex ratio of male: female broodstock O. woworae involved in spawning. The sex ratio of male: female spawning broodstock used were 1:1, 1:2, 1:3, and 1:4. The male and female brooders used had a total length of 3,1 ± 0,5 cm and 2,5 ± 0,5 cm. After adaptation, the broodstock of O. woworae was put into aquariums according to the treatment, and each container contained three spawning substrates. The harvesting of eggs on the substrate is carried out two times a day. The results showed that spawning O. woworae with a ratio of 1♂: 4♀ produced the lowest number of eggs and was significantly different with ratios of 1♂: 1♀ and 1♂: 2♀ (P<0,05). The ratio of 1♂ : 3♀ gave the highest egg hatching of 55% but was not significantly different from other treatments (P>0,05). The difference in male and female ratios did not affect the survival rate of O. woworae larvae (P>0,05), with values from 91,9-100%. The highest larvae produced was found in the spawning ratio of 1♂ : 3♀ with 37 larvae but not significantly different from other treatments (P>0,05). The water quality values during the study were temperature 26,5-310C, pH 5,5-8,8, and dissolved oxygen 5,3-6,0 mg L-1. O. woworae broodstock spawning can be optimized with a male to female ratio of 1:3.

scholarly journals On the fecundity and sex-ratio of Botia Dario (Hamilton) (Cypriniformes : Cobitidae)

1970 ◽  
Vol 26 ◽  
pp. 27-29 ◽  
Author(s):  
M Afzal Hussain ◽  
Mst Rehana Khatun ◽  
M Altaf Hossain
Keyword(s):  
Body Weight ◽  
Sex Ratio ◽  
Standard Length ◽  
Female Ratio ◽  
Ovary Weight ◽  
Total Length ◽  
Length Standard ◽  
The Mean ◽  
The Relationship ◽  
Male To Female

A total of 1183 Botia Dario (Hamilton) samples were collected from Rajshahi (Shaheb Bazar, Binodpur Bazar, Talaimari Bazar, Kazla Bazar and Godagari) during the period from January, 2002 to August, 2003 to study the fecundity, sex-ratio, relationship between fecundity and total length, standard length, body weight, ovary length as well as ovary weight. The mean fecundity was calculated as 31833.50±10313.42 with a range of 5245 to 53754 in fishes ranging in total length from 96 mm to 135 mm (mean 115.50±12.11 mm) and in body weight from 14.51 g to 43.29 g (mean 29.71±6.91 g). The relationship between the fecundity (F) and total length (TL), standard length (SL), body weight (BW), ovary length (OL) and ovary weight (OW) were found to be linear with the ‘r’ values 0.94, 0.94, 0.95, 0.92 and 0.98, respectively. The ovum diameter ranged from 0.3 to 0.72 mm and the mean diameter was calculated as 0.518±0.06 mm. The male to female ratio was 1:0.61. Key words: Botia dario, fecundity, sex-ratio. Univ. j. zool. Rajshahi Univ. Vol. 26, 2007. pp. 27-29

GEOGRAPHIC CLUSTERING OF THE SECONDARY SEX RATIO IN JAPAN: ASSOCIATION WITH DEMOGRAPHIC ATTRIBUTES

2012 ◽  
Vol 45 (2) ◽  
pp. 279-284 ◽  
Author(s):  
YOSUKE INOUE ◽  
MASAHIRO UMEZAKI ◽  
CHIHO WATANABE
Keyword(s):  
Life Expectancy ◽  
Sex Ratio ◽  
Type I Error ◽  
Divorce Rate ◽  
Vital Statistics ◽  
Scan Statistics ◽  
Type I ◽  
Geographic Clustering ◽  
Secondary Sex Ratio ◽  
Demographic Attributes

SummaryThe secondary sex ratio (SSR) has been suggested to decrease with adverse physical and psychological environments. Previous studies have focused on reduced SSR under adverse conditions, such as war, terrorism attack and earthquake, but few studies have investigated fluctuations in SSR in moderately adverse environments. This study analysed municipality-level vital statistics records in Japan collected between 1998 and 2002 to identify high-SSR clusters and low-SSR clusters with spatial-scan statistics. In 999 runs of simulation, high- and low-SSR clusters were detected but fewer than 950 times, indicating that SSR was not geographically clustered in Japan if type I error of 5% was adopted. Explorative analyses comparing demographic attributes between high-SSR clusters and low-SSR clusters that were detected more than 500 times in 999 runs of simulation, showed that rate of spontaneous abortion, rate of artificial abortion and divorce rate were higher in low-SSR clusters, while male life expectancy, female life expectancy and total fertility rate were higher in a high-SSR cluster.

Declining Frequency of Circumcision: Implications for Changes in the Absolute Incidence and Male to Female Sex Ratio of Urinary Tract Infections in Early Infancy

PEDIATRICS ◽  
1987 ◽  
Vol 79 (3) ◽  
pp. 338-342
Author(s):  
Thomas E. Wiswell ◽  
Robert W. Enzenauer ◽  
Mark E. Holton ◽  
J. Devn Cornish ◽  
Charles T. Hankins
Keyword(s):  
Urinary Tract ◽  
Sex Ratio ◽  
Urinary Tract Infections ◽  
Early Infancy ◽  
Female Ratio ◽  
Male Predominance ◽  
Female Sex ◽  
Frequency Rate ◽  
Tract Infections ◽  
Male To Female

The results of an investigation examining the circumcision frequency rate and its effect on the incidence of urinary tract infections in a large, widely dispersed population base during the 10-year period since the 1975 report of the American Academy of Pediatrics Ad Hoc Task Force on Circumcision are reported. Our study population included the 427,698 infants born in all United States Army hospitals, worldwide, from Jan 1, 1975, through Dec 31, 1984. There was an initial plateau in the circumcision frequency rate at approximately 85% during the first 4 years of the study period. In the subsequent 6 years there was a steady, significant decrease (P &lt; .001) of 1.4% to 4.0% per year through 1984, when the circumcision frequency rate reached its nadir of 70.5%. There was a concomitant increase in the total number of urinary tract infections among male infants (P &lt; .02) as the circumcision rate declined. This increase was due to the increase in the overall number of uncircumcised boys (who had a greater than 11-fold increased infection rate compared with circumcised boys). During the first half of the study period, there was a female predominance for urinary tract infections from birth onward. As the number of circumcised boys decreased (with a resultant increase in the total number of boys with infection), the male to female ratio of urinary tract infections during the first 3 months of life reversed, reflecting a movement toward a male predominance for infection in early infancy. This is the first, well-documented report of a decreasing rate of circumcisions performed on the American male population. We conclude that the number of urinary tract infections in male infants, as well as the male to female sex ratio, is affected by the circumcision practices of the population examined.

scholarly journals The Age Pattern of the Male- to- Female Ratio in Mortality from COVID-19 Mirrors that of Cardiovascular Disease but not Cancer in the General Population

2020 ◽  
Author(s):  
Ila Nimgaonkar ◽  
Linda Valeri ◽  
Ezra S. Susser ◽  
Sabiha Hussain ◽  
Jag Sunderram ◽  
...  
Keyword(s):  
Cardiovascular Disease ◽  
General Population ◽  
Sex Ratio ◽  
Sex Ratios ◽  
Adult Life ◽  
European Countries ◽  
Female Ratio ◽  
Age Related ◽  
The Us ◽  
Male To Female

Background: Males are at a higher risk of dying from COVID-19. Older age and cardiovascular disease are also associated with COVID-19 mortality. We compared the male-to-female (sex) ratios in mortality by age for COVID-19 with cardiovascular mortality and cancer mortality in the general population. Methods: We obtained data from official government sources in the US and five European countries: Italy, Spain, France, Germany, and the Netherlands. We analyzed COVID-19 deaths by sex and age in these countries and similarly analyzed their deaths from cardiovascular disease (coronary heart disease or stroke) and cancer, the two leading age-related causes of death in middle-to-high income countries. Findings: In both the US and European countries, the sex ratio of deaths from COVID-19 exceeded one throughout adult life. The sex ratio increased up to a peak in midlife, and then declined markedly in later life. This pattern was also observed for the sex ratio of deaths from cardiovascular disease, but not cancer, in the general populations of the US and European countries. Interpretation: The sex ratios of deaths from COVID-19 and from cardiovascular disease exhibit similar patterns across the adult life course. The underlying mechanisms are poorly understood, but could stem partially from sex-related biological differences that underlie the similar pattern for cardiovascular disease. These include, we propose, comparatively longer telomeres in females, ovarian hormones, and X chromosome mosaicism.

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