Secondary sexual characteristics are characteristics that are sex related but are not directly connected with the physiology of reproduction (the sex organs). The body image depends a good deal on the secondary sexual characteristics.
Statistically, men tend to be heavier with more muscle mass and physical strength than women although there are some women heavier, more muscular and stronger than some men. Darwin did not limit his discussion of sex differences in variability to obviously secondary sexual characteristics.
Of humans he suggested that "the numerous measurements of various other races with respect to stature, the circumference of the neck and chest, and the length of the back-bone and arms, which were carefully made, nearly all showed that the males differed much more from each other than did the females." He also discussed studies in which various abnormalities, such as supernumerary digits, occurred more frequently in men, noting that the data might be biased if women were more likely to conceal such effects.
Darwin wrote of "the frequent and extraordinary amount of variability presented by secondary sexual characters" of males and he concluded from his studies of domesticated animals that "the male is more liable to vary than the female. He reasoned that all these contingencies are highly favorable for sexual selection.
Human female breasts are secondary sexual characteristics that evolved to attract mates. - Desmond Morris (The Naked Ape, 1967).
An imbalance of maternal hormonal levels and some chemicals may alter the secondary sexual characteristics of fetuses.
Ellis, H. 1894. Man and woman: A study of human secondary sexual characteristics. Walter Scott, London.
The Psychological Significance of
Secondary Sexual Characteristics in Nine- to Eleven-Year-Old Girls. -
Brooks-Gunn, J.; Warren, Michelle P. - Child Development, v59 n4 p1061-69 Aug
Abstract: Studied the onset of puberty in girls aged nine to eleven as represented by breast, pubic hair growth, and height. Breast growth, but not pubic hair growth was associated with a positive body image, positive peer relationships, and superior adjustment. Height was linked to superior adjustment and rating of career as important.
Beyond Gender-Specific Intervention: Theory-driven Praxis - by Laurie Schaffner
Extract: In sociology, sex and gender are distinguished in theoretical discussion. Sex is used to describe the biological, physiological differences between boys/men and girls/women, although even these binary categories are now under serious challenge. Some of the biological or physiological characterizations utilized to differentiate among sexes are presence of mammary glands and breasts, uterus, ovaries, vaginas, testicles, penises and the like, as well as what are sometimes called secondary sexual characteristics, such as amount of facial hair, pitch of voice, size of Adam's apple, and such.
Sexual maturation in Turkish girls - Neyzi, Olcay; Alp, H�lya; Orhon, Alper
Source: Annals of Human Biology, Volume 2, Number 1, Number 1/January 1975.
Abstract: The time intervals from onset to completion of secondary sexual characteristics were comparable to those reported for European girls for pubic and axillary hair development, but relatively longer for the development of the breast. They differed little between the socioeconomic classes.
Onset of secondary sexual characteristics and of menarche in the highest socioeconomic class were early as compared to other population groups.
Sexual precocity in girls. An association with sexual abuse? Herman-Giddens ME, Sandler AD, Friedman NE. - Child Protection Team, Duke University Medical Center, Durham, NC 27710.
Am J Dis Child. 1988 Apr;142(4):431-3.
The development of secondary sexual characteristics before 8 years of age in girls is uncommon and little is known of its epidemiology. In a retrospective study of a population of 105 girls 10 years old and younger who were victims of confirmed or suspected sexual abuse, we found a one in 15 prevalence of early development of one or more secondary sexual characteristics. We speculate on possible associations between early development of secondary sexual characteristics and sexual abuse. The data suggest that further research explore this possible association.
A study of developmental order of secondary sexual characteristics in Beijing girls. - Li JJ., Haidian Health and Epidemic Prevention Station, Beijing. - Zhonghua Yu Fang Yi Xue Za Zhi. 1991 Jan;25(1):23-5.
A six-year (1980-1986) study of the developmental status of the secondary sexual characteristics was made among 937 girls in Beijing. The mean age of the first appearance of the secondary sexual characteristics was measured. The individual variation was very great.
Secondary Sexual Characteristics in Boys
Estimates From the National Health and Nutrition Examination Survey III, 1988-1994
Marcia E. Herman-Giddens, PA, MPH, DrPH; Lily Wang, MS; Gary Koch, PhD.
Arch Pediatr Adolesc Med.