scholarly journals Stay or stray? Evidence for alternative mating strategy phenotypes in both men and women

2015 ◽  
Vol 11 (2) ◽  
pp. 20140977 ◽  
Author(s):  
Rafael Wlodarski ◽  
John Manning ◽  
R. I. M. Dunbar
Keyword(s):  
Mixture Models ◽  
Mating Strategy ◽  
Digit Ratio ◽  
Human Populations ◽  
Complex Frequency ◽  
Men And Women ◽  
Frequency Dependent Selection ◽  
Comparative Analyses ◽  
Prenatal Testosterone ◽  
Alternative Mating Strategy

In all comparative analyses, humans always fall on the borderline between obligate monogamy and polygamy. Here, we use behavioural indices (sociosexuality) and anatomical indices (prenatal testosterone exposure indexed by 2D : 4D digit ratio) from three human populations to show that this may be because there are two distinct phenotypes in both sexes. While males are more promiscuous and display higher prenatal testosterone exposure than females overall, our analyses also suggest that the within-sex variation of these variables is best described by two underlying mixture models, suggesting the presence of two phenotypes with a monogamous/promiscuous ratio that slightly favours monogamy in females and promiscuity in males. The presence of two phenotypes implies that mating strategy might be under complex frequency-dependent selection.

Reproduction by Captive Unplumed Male Lesser Bird of ParadiseParadisaea minor: Evidence for an Alternative Mating Strategy?

1992 ◽  
Vol 92 (2) ◽  
pp. 108-111 ◽  
Author(s):  
Mark S. Laska ◽  
Michael Hutchins ◽  
Christine Sheppard ◽  
Wendy Worth ◽  
Kurt Hundgen ◽  
...  
Keyword(s):  
Mating Strategy ◽  
Alternative Mating Strategy

scholarly journals A parametric model for estimating nuptiality patterns in modern populations

2015 ◽  
Vol 42 (1-2) ◽  
pp. 130 ◽  
Author(s):  
Anastasia Kostaki ◽  
Paraskevi Peristera
Keyword(s):  
Mixture Models ◽  
Parametric Model ◽  
Parametric Models ◽  
Human Populations ◽  
Marriage Rates ◽  
First Marriage ◽  
Flexible Parametric Model ◽  
Typical Shape

Nuptiality is a phenomenon closely related to fertility. The age-specific marriage distribution has a typical shape common in all human populations. In order to estimate this pattern, alternative parametric models have been proposed. However recent evidence suggests that mixture models are required to estimate nuptiality patterns. In this paper, a flexible parametric model is proposed in three versions, appropriate to describe the age pattern of first marriage rates. For evaluation purposes the models as well as the alternative existing models are fitted to a variety of empirical datasets.

Null Effects of Game Violence, Game Difficulty, and 2D:4D Digit Ratio on Aggressive Behavior

2019 ◽  
Vol 30 (4) ◽  
pp. 606-616 ◽  
Author(s):  
Joseph Hilgard ◽  
Christopher R. Engelhardt ◽  
Jeffrey N. Rouder ◽  
Ines L. Segert ◽  
Bruce D. Bartholow
Keyword(s):  
Video Games ◽  
Aggressive Behavior ◽  
Digit Ratio ◽  
Acute Exposure ◽  
First Person ◽  
Large Sample ◽  
Prenatal Testosterone ◽  
Play Session ◽  
Game Violence ◽  
First Person Shooter

Researchers have suggested that acute exposure to violent video games is a cause of aggressive behavior. We tested this hypothesis by using violent and nonviolent games that were closely matched, collecting a large sample, and using a single outcome. We randomly assigned 275 male undergraduates to play a first-person-shooter game modified to be either violent or less violent and hard or easy. After completing the game-play session, participants were provoked by a confederate and given an opportunity to behave aggressively. Neither game violence nor game difficulty predicted aggressive behavior. Incidentally, we found that 2D:4D digit ratio, thought to index prenatal testosterone exposure, did not predict aggressive behavior. Results do not support acute violent-game exposure and low 2D:4D ratio as causes of aggressive behavior.

Intermolt Insemination, an Alternative Mating Strategy for the American Lobster (Homarus americanus)

1990 ◽  
Vol 47 (12) ◽  
pp. 2402-2406 ◽  
Author(s):  
S. L. Waddy ◽  
D. E. Aiken
Keyword(s):  
Reproductive Strategy ◽  
Carapace Length ◽  
Homarus Americanus ◽  
Mating Strategy ◽  
American Lobster ◽  
Male Aggression ◽  
Female Receptivity ◽  
Molt Stage ◽  
Alternative Mating Strategy ◽  
Ovarian Stage

American lobster (Homarus americanus) have a dual mating strategy. Although most females mate when they are newly molted, mating can occur at any molt stage if necessary, in the laboratory, virtually all uninseminated preovigerous females mate prior to spawning. Male aggression is a major factor in the success of intermolt mating and males can discriminate between immature and mature females, and between inseminated and uninseminated females. Female receptivity is affected by both ovarian stage and the presence of stored sperm, but not by molt stage. Most females become unreceptive after insemination, but their receptivity returns once the supply of stored sperm is exhausted. Intermolt mating occurs in smaller lobster that for some reason did not mate at molt, and it is an important part of the reproductive strategy of larger lobster. Lobster s[Formula: see text] carapace length frequently spawn twice without molting and often fail to store sufficient sperm to fertilize consecutive spawnings. Intermolt mating ensures these females will produce fertile second broods.

Influence of density and major histocompatibility genotype on sexual selection in a salmonid alternative mating strategy

2012 ◽  
Vol 69 (4) ◽  
pp. 670-680 ◽  
Author(s):  
Laura K. Weir ◽  
Jeffrey A. Hutchings ◽  
Daniel D. Heath
Keyword(s):  
Sexual Selection ◽  
Salmo Salar ◽  
Fertilization Success ◽  
Mating Strategy ◽  
Male Mating ◽  
Salmonid Fishes ◽  
Major Histocompatibility ◽  
Main Determinant ◽  
Alternative Mating Strategy

Various mechanisms of sexual selection can occur at both the whole organism and gamete levels. Fertilization success in salmonid fishes is largely determined by behavioural competition within and between “fighter” and “sneaker” male strategies, but is also influenced by interactions among gametes. We investigated the influence of density, fighter male presence, and major histocompatibility (MH) genotype on patterns of fertilization success in sneaker Atlantic salmon ( Salmo salar ). At low density and in the absence of fighter males, monopolization by single sneaker males occurred, suggesting that male–male competition was the main determinant of fertilization success. By contrast, at high density and (or) in the presence of fighter males, several sneakers succeeded in fertilizing eggs. Our study, the first to investigate the role of MH-mediated fertilization for a genetically based alternative male mating strategy, suggests that a larger proportion of eggs were fertilized by sneakers whose MH genotypes were more similar to those of the female than expected by chance. These findings highlight the importance of examining sexual selection under different competitive conditions.

scholarly journals Parental income inequality and children’s digit ratio (2D:4D): a ‘Trivers-Willard’ effect on prenatal androgenization?

2021 ◽  
pp. 1-9
Author(s):  
J.T. Manning ◽  
B. Fink ◽  
L. Mason ◽  
R. Trivers
Keyword(s):  
Income Inequality ◽  
Low Income ◽  
Online Survey ◽  
Ring Finger ◽  
Total Sample ◽  
Digit Ratio ◽  
Average Income ◽  
Parental Income ◽  
Prenatal Testosterone ◽  
Internet Study

Abstract Income inequality is associated positively with disease prevalence and mortality. Digit ratio (2D:4D) – a negative proxy for prenatal testosterone and a positive correlate of prenatal oestrogen – is related to several diseases. This study examined the association of income inequality (operationalized as relative parental income) and children’s 2D:4D. Participants self-measured finger lengths (2D=index finger, and 4D=ring finger) in a large online survey conducted in July 2005 (the BBC Internet Study) and reported their parents’ income. Children of parents of above-average income had low 2D:4D (high prenatal testosterone, low prenatal oestrogen) while the children of parents of below-average income had high 2D:4D (low prenatal testosterone, high prenatal oestrogen). The effects were significant in the total sample, present among Whites (the largest group in the sample), in the two largest national samples (UK and USA) and were greater for males than females. The findings suggest a Trivers-Willard effect, such that high-income women may prenatally masculinize their sons at the expense of the fitness of their daughters. Women with low income may prenatally feminize their daughters at the fitness expense of their sons. The effect could, in part, explain associations between low income, high 2D:4D (low prenatal testosterone) and some major causes of mortality such as cardiovascular disease.

scholarly journals Digit Ratio (2D:4D), Aggression, and Testosterone in Men Exposed to an Aggressive Video Stimulus

2013 ◽  
Vol 11 (5) ◽  
pp. 147470491301100 ◽  
Author(s):  
Liam P. Kilduff ◽  
Renato N. Hopp ◽  
Christian J. Cook ◽  
Blair T. Crewther ◽  
John T. Manning
Keyword(s):  
Negative Correlation ◽  
Free Testosterone ◽  
Digit Ratio ◽  
Testosterone Levels ◽  
Prenatal Testosterone ◽  
Before And After ◽  
Video Stimulus ◽  
The Difference ◽  
And Control ◽  
The Impact

The relative lengths of the 2nd and 4th digits (2D:4D) is a negative biomarker for prenatal testosterone, and low 2D:4D may be associated with aggression. However, the evidence for a 2D:4D-aggression association is mixed. Here we test the hypothesis that 2D:4D is robustly linked to aggression in “challenge” situations in which testosterone is increased. Participants were exposed to an aggressive video and a control video. Aggression was measured after each video and salivary free testosterone levels before and after each video. Compared to the control video, the aggressive video was associated with raised aggression responses and a marginally significant increase in testosterone. Left 2D:4D was negatively correlated with aggression after the aggressive video and the strength of the correlation was higher in those participants who showed the greatest increases in testosterone. Left 2D:4D was also negatively correlated to the difference between aggression scores in the aggressive and control conditions. The control video did not influence testosterone concentrations and there were no associations between 2D:4D and aggression. We conclude that 2D:4D moderates the impact of an aggressive stimulus on aggression, such that an increase in testosterone resulting from a “challenge” is associated with a negative correlation between 2D:4D and aggression.

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