scholarly journals Variation in Chin and Mandibular Symphysis Size and Shape in Males and Females: A CT-Based Study

2020 ◽  
Vol 17 (12) ◽  
pp. 4249
Author(s):  
Tatiana Sella Tunis ◽  
Israel Hershkovitz ◽  
Hila May ◽  
Alexander Dan Vardimon ◽  
Rachel Sarig ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Anatomical Landmark ◽  
Anatomical Structure ◽  
Sexually Dimorphic ◽  
Selection Theory ◽  
Size And Shape ◽  
Size Index ◽  
Sexual Selection Theory ◽  
Males And Females ◽  
Anthropological Literature

The chin is a unique anatomical landmark of modern humans. Its size and shape play an important role from the esthetic perspective. However, disagreement exists in the dental and anthropological literature regarding the sex differences in chin and symphysis morphometrics. The “sexual selection” theory is presented as a possible reason for chin formation in our species; however, many other contradictory theories also exist. This study’s aims were therefore to determine how chin and symphysis size and shape vary with sex, and to discuss “sexual selection” theory as a reason for its formation. Head and neck computed tomography (CT) scans of 419 adults were utilized to measure chin and symphysis sizes and shapes. The chin and symphysis measures were compared between the sexes using an independent-samples t-test, a Mann–Whitney test, and the F-statistic. The chin width was significantly greater in males than in females (p < 0.001), whereas the chin height, area, and size index were significantly greater in females (p < 0.001). Symphysis measures did not differ significantly between the sexes. Size accounted for 2–14% of the chin variance and between 24–33% of the symphysis variance. Overall, the chin was found to be a more heterogeneous anatomical structure than the symphysis, as well as more sexually dimorphic.

scholarly journals Sexual selection in females across the animal tree of life

2021 ◽  
Author(s):  
Salom&eacute Fromonteil ◽  
Lennart Winkler ◽  
Lucas Marie-Orleach ◽  
Tim Janicke
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Sexual Reproduction ◽  
Tree Of Life ◽  
Selection Theory ◽  
Sexual Selection Theory ◽  
Males And Females

The pioneers of sexual selection theory proposed that males are generally "eager" whereas females are rather "coy" with respect to mating. This male-centred perspective on sexual selection continues to permeate our perception of sex differences across disciplines. Despite an increased awareness that females also compete for mating partners, we still tend to consider sexual selection in females a rare peculiarity. Here we present meta-analytic evidence from 72 species across a broad range of animal taxa to show that sexual selection in females is widespread and should be considered the norm rather than the exception. Thereby, our results extend our general understanding of sexual reproduction and may contribute to a more balanced perspective of how sexual selection operates in both males and females.

scholarly journals Food availability differentially influences young males' and females' cognitive processes in accordance with sexual selection theory

2009 ◽  
Vol 6 (2) ◽  
pp. 250-252 ◽  
Author(s):  
Joyce F. Benenson ◽  
Ryan Rivard ◽  
Henry Markovits
Keyword(s):  
Working Memory ◽  
Sexual Selection ◽  
Food Availability ◽  
Cognitive Processes ◽  
Resource Availability ◽  
Opposite Effect ◽  
Young Males ◽  
Selection Theory ◽  
Sexual Selection Theory ◽  
Males And Females

Sexual selection theory predicts that additional resources will have a greater impact on males’ compared with females’ reproductive success. Consequently, we expected that strong cues signalling increased resource availability should augment cognitive functioning associated with long-term maximization of reproductive outcomes (inhibition, working memory) in human males. In human females, who can rely on assistance in resource-rich environments, we expected the opposite effect. We tested this prediction in lower socio-economic status children, since their poverty increased the relative salience of the cues available in a limited experimental situation. We show that cues indicative of food availability increased impoverished young males’ inhibitory and working memory capacities compared with males who viewed photographs of food. By contrast, cues indicating food availability exerted the opposite effect on females. These results indicate that cues related to resource availability have differential effects on basic cognitive functions associated with strategic behaviour in males and females. The findings also demonstrate remarkable plasticity in fundamental cognitive processes in young children, even those from impoverished backgrounds.

scholarly journals Darwin's bawdy: the popular, gendered and radical reception of the Descent of Man in the US, 1871–1910

BJHS Themes ◽  
2021 ◽  
pp. 1-17
Author(s):  
Kimberly A. Hamlin
Keyword(s):  
Sexual Selection ◽  
Selection Theory ◽  
Scientific Establishment ◽  
Scientific Institutions ◽  
The Us ◽  
Sexual Selection Theory ◽  
Descent Of Man

Abstract Most studies of the American reception of Darwin have focused on the Origin. The Descent of Man, however, was even more widely read and discussed, especially by those outside the emerging scientific establishment. This essay maps the varied, popular and radical responses to the Descent and suggests that these unauthorized readers helped shape the formation of American scientific institutions (by encouraging scientists to close ranks), as well as ordinary Americans’ perceptions of gender and sex. I argue that the radical – freethinkers, socialists and feminists – embrace of sexual selection theory provides one explanation for naturalists’ scepticism of the theory.

scholarly journals Reluctant males: why blue monkey males reject female sexual advances

Behaviour ◽  
2019 ◽  
Vol 157 (1) ◽  
pp. 33-58 ◽  
Author(s):  
Sofia Schembari ◽  
Marina Cords
Keyword(s):  
Sexual Selection ◽  
Social Context ◽  
Wild Population ◽  
Market Models ◽  
Selection Theory ◽  
Sexual Selection Theory ◽  
Blue Monkey ◽  
To Receive ◽  
Number Of Males

Abstract Classical sexual selection theory predicts that males should mate eagerly, yet blue monkey males often reject females’ sexual invitations. We evaluated how males’ responses to female solicitations related to female characteristics, number of males and conceptive females present, and the male’s recent copulations. Using 12 years of data from a wild population, we found that males accepted only 20% of female solicitations. Odds of acceptance (copulation) increased for conceptive females, for females with whom the male copulated recently, and when fewer males were present. Odds of accepting nulliparous females decreased when more conceptive females were available, consistent with market models. Male responses did not relate to female rank or matings with other females the same day. When males responded negatively, nulliparous females were especially likely to receive aggression vs. mere refusal. Overall, males’ decisions to mate with willing females depended both on female characteristics, especially fertility, and on social context.

Sexual selection does not provide an adequate theory of sex differences in aggression

2009 ◽  
Vol 32 (3-4) ◽  
pp. 276-277 ◽  
Author(s):  
Alice H. Eagly ◽  
Wendy Wood
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Social Role ◽  
Adequate Account ◽  
Selection Theory ◽  
Biosocial Theory ◽  
Adequate Theory ◽  
Sexual Selection Theory ◽  
Physical Attributes ◽  
Reproductive Activities

AbstractOur social role/biosocial theory provides a more adequate account of aggression sex differences than does Archer's sexual selection theory. In our theory, these sex differences arise flexibly from sociocultural and ecological forces in interaction with humans' biology, as defined by female and male physical attributes and reproductive activities. Our comments elaborate our theory's explanations for the varied phenomena that Archer presents.

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