Size Of Genitalia Research Articles

Character Displacement in Stag Beetles (Coleoptera: Lucanidae)

I quantitatively analyzed male morphology of two closely related stag beetles species (Odontolabis mouhoti Hope and O. cuvera Parry) in 11 allopatric and two sympatric locations in the Asian tropics and subtropics. Across allopatric locations, body size and genitalia size nearly completely overlapped between O. mouhoti and O. cuvera, and body color was more similar between the two species in allopatric locations. In sympatric locations the differences between the two species in these characters were highly noticeable, genitalia size being most signiÞcant. The body color difference between the two species was most striking in sympatric locations. It is probable that the interaction between the two species induced character displacement in sympatry. Character displacement may enable species to maintain themselves as integrated units by minimizing interspeciÞc competition and enhancing reproductive isolation.

Character Displacement in Giant Rhinoceros Beetles

I quantitatively analyzed male morphology of two closely related rhinoceros beetles species (Chalcosoma caucasus F. and Chalcosoma atlas L.) in 12 allopatric and seven sympatric locations throughout Southeast Asia. The qualitative features and the magnitude of intraspecific variation of each species were unaltered between allopatric and sympatric locations. Across allopatric locations, body size, horn size, dimorphic dimension, and genitalia size nearly completely overlapped between C. caucasus and C. atlas. Yet, in all sympatric locations, the differences between the two species in these characters were highly significant. While the enlarged difference between the two species in body size in sympatry could be attributed to habitat differentiation, that in genitalia size far exceeded what was expected from the general body-size displacement. These results indicate that morphological character displacement in sympatry was most complete in sexual organs. This may account for the process of existing species conserving themselves as integrated units by avoiding interspecific competition and enhancing reproductive isolation.

Character Displacement in Giant Rhinoceros Beetles

I quantitatively analyzed male morphology of two closely related rhinoceros beetles species (Chalcosoma caucasus F. and Chalcosoma atlas L.) in 12 allopatric and seven sympatric locations throughout Southeast Asia. The qualitative features and the magnitude of intraspecific variation of each species were unaltered between allopatric and sympatric locations. Across allopatric locations, body size, horn size, dimorphic dimension, and genitalia size nearly completely overlapped between C. caucasus and C. atlas. Yet, in all sympatric locations, the differences between the two species in these characters were highly significant. While the enlarged difference between the two species in body size in sympatry could be attributed to habitat differentiation, that in genitalia size far exceeded what was expected from the general body‐size displacement. These results indicate that morphological character displacement in sympatry was most complete in sexual organs. This may account for the process of existing species conserving themselves as integrated units by avoiding interspecific competition and enhancing reproductive isolation.

Sexuality, delinquency and r/ K reproductive strategies: Data from a Canadian University sample

Across species, r/K reproductive strategies have been postulated to underlie a tradeoff that exists between mating effort and parental effort, also hypothesized to mediate encephalization, longevity, rate of maturation, and altruism. Recent analyses have extrapolated this framework to human differences. Here a test is provided with data gathered from university students in which measures of family size, intelligence, head circumference, and longevity are related to strength of sex drive, genitalia size, sexual attitudes and delinquency. The results indicate that, although the magnitude of the effects are small, many of the variables cohere in a pattern interpretable as an r/K dimension. For example, aggregate scores on one set of measures were predictive of both delinquency and sexual permissiveness, which were also related to each other.

Race differences in behaviour: A review and evolutionary analysis

Racial differences exist on numerous heritable behaviour traits such that Caucasoids fall between Mongoloids and Negroids. Across samples, ages, and time periods, this pattern is observed on estimates made of brain size and intelligence (cranial capacity=1448, 1408, 1334 cm 3., brain weight=1351, 1336, 1286 g; IQ scores=107, 100, 85); maturation rate (age to walk alone, age of puberty, age of death); personality and temperament (activity level, anxiety, sociability); sexual restraint (gamete production, intercourse frequency, size of genitalia); and social organization (marital stability, mental health, law abidingness). These observations may be explained in part in terms of gene-culture coevolutionarily based r/K reproductive strategies.

Race differences in sexual behavior: Testing an evolutionary hypothesis

Population differences exist in personality and sexual behavior such that, in terms of restraint, Orientals > whites > blacks. This ordering is predicted from an evolutionary theory of r K reproductive strategies in which a tradeoff occurs between gamete production and parental care. Literature is reviewed on differences between the three groups in rate of ovulation, intercourse frequencies, sexual attitudes, developmental precocity, size of genitalia, secondary sexual characteristics, and biologic control of behavior that accord with this formulation. Novel analyses of data from the Institute for Sex Research are also carried out, indicating that American blacks, compared to American whites, are more precocious and less restrained. Their parents were younger when they were born, had more children, and had an earlier mortality. Blacks left home earlier, experienced a variety of premarital, marital, and extramarital sexual events earlier, had a greater number of premarital and extramarital partners, had a greater frequency of marital intercourse, used fewer contraceptives, and had a greater incidence of pregnancy, at a faster rate. The men had larger penises, at a different angle of erection, and maintained intromission longer, while the women had shorter menstrual cycles, more periodicity of sexual response, and a greater number of orgasms per act of coitus. Whites varied their sexual activity more, both with spouses and with prostitutes, although blacks consorted with prostitutes more frequently. Finally, blacks had a shorter duration of marriage and more permissive sexual attitudes.

Age of appearance of secondary sex characters in Ajmer school children.

In 1000 healthy school boys of Ajmer urban area, aged 8–16 years, an increase in the size of genitalia (Tanner’s stage G2) at the median age of 11.2 years was the earliest secondary sex character to appear. Pubic, axillary and facial hair growth (stage PH2, AX2, and FH2) appeared at the median ages of 11.7, 12.7 and 13.7 years, respectively. Nonappearance of stage G2 by 13.5 years and stage PH2 by the age of 14 years may suggest delayed onset of genital maturation and pubarche respectively.

Plasma 5α-dihydrotestosterone (17β-hydroxy-5α-androstan-3-one) in adolescent males at different stages of sexual maturation

A method for the estimation of 5α-dihydrotestosterone (5α-DHT; 17β-hydroxy-5α-androstan-3-one) by competitive protein binding assay in the plasma of pre-adolescent and adolescent boys is described. Plasma testosterone could also be estimated simultaneously by the method. Boys were grouped into 5 stages according to their sexual maturation in relation to their genitalia size and pubic hair. Adult males had significantly higher concentration of 5α-DHT (64.7 ng/100 ml) than that of stage 5 boys. Chorionic gonadotrophin therapy in 5 boys with undescended testes showing clinical success, also resulted in an increase in plasma 5α-DHT concentration.

A psychoanalytic study of contraception

This study tries to highlight the unconscious meaning of contraception and how it mobilizes anxieties and conflicts in people. This objective is emphasized through case studies dealing with the fitting of a diaphragm the relationship of contraception with the size of genitalia the contraceptive device as an organ of the body coital significance of contraceptives how one may gain adult status through the use of contraceptives anxiety doubt and frustration as they are related to contraception and the misuse of contraceptives. The latter may be result from psychologically hidden motives such as aggressive impulses towards the partner or unconscious wished to become pregnant.