Sexual dimorphism is the differences between males and females in size, appearance and some other characteristics. Sexual dimorphism is the condition where males and females of the same species exhibit different characteristics beyond the differences in their sexual organs. Sexual dimorphism occurs in many animals and some plants. In 1871, Charles Darwin Darwinism advanced the theory of sexual selection, which related sexual dimorphism with sexual selection. Some plant species also exhibit sexual dimorphism in which the females are significantly larger than the males, such as in the moss Dicranum and the liverwort Sphaerocarpos. There is some evidence that, in these genera, the dimorphism may be tied to a sex chromosome, or to chemical signalling from females.
According to Clark Spencer Larsen, modern day Homo sapiens show a range of sexual dimorphism, with average body mass difference between the sexes being roughly equal to 15%. - Larsen, Clark Spencer (2003). "Equality for the sexes in human evolution? Early hominid sexual dimorphism and implications for mating systems and social behavior."
Sexual dimorphism among humans includes differentiation among gonads, internal genitals, external genitals, breasts, muscle mass, height, the endocrine systems and their physiological and behavioral effects. Sexual dimorphism in humans is greater than in some animals and less than in many. Evolutionary psychologists and biologists are intrigued to understand the function of sexual dimorphism. Depression is twice as common in women as in men, but the reason for this sexual dimorphism is unknown.
Another complicated example of sexual dimorphism is in Vespula squamosa, the southern yellowjacket. In this wasp species, the female workers are the smallest, the male workers are slightly larger, and the female queens are significantly larger than her female worker and male counterparts. Sexual dimorphism and mating choice are also observed in many fish species. Male guppies have colorful spots and ornamentations while females are generally grey in color.
Snips and Snails and Theorists' Tales: Classical Sociological Theory and the Making of 'Sex' - Exploring how the emerging discipline of sociology both drew on and contributed to the construction of a scientifically grounded sexual dimorphism. Barbara L. Marshall, Trent University, Canada. This article locates classical sociology within the context of widely circulating scientific 'truths' about sexed bodies, exploring how the emerging discipline of sociology both drew on and contributed to the construction of a scientifically grounded sexual dimorphism.
Normal Sexual Dimorphism
of the Adult Human Brain Assessed by In Vivo Magnetic Resonance Imaging
Jill M. Goldstein, Larry J. Seidman, Nicholas J. Horton, Nikos Makris, David N. Kennedy, Verne S. Caviness, Jr, Stephen V. Faraone and Ming T. Tsuang.
The etiology and consistency of findings on normal sexual dimorphisms of the adult human brain are unresolved. In this study, we present a comprehensive evaluation of normal sexual dimorphisms of cortical and subcortical brain regions, using in vivo magnetic resonance imaging, in a community sample of 48 normal adults.
Sexual dimorphisms of adult brain volumes were more evident in the cortex, with women having larger volumes, relative to cerebrum size, particularly in frontal and medial paralimbic cortices. These findings have implications for developmental studies that would directly test hypotheses about mechanisms relating sex steroid hormones to sexual dimorphisms in humans.
Regulation of Sexual Dimorphism in Mammals
CHRISTOPHER M. HAQQ AND PATRICIA K. DONAHOE.
Haqq, Christopher M., and Patricia K. Donahoe. Regulation of Sexual Dimorphism in Mammals. Physiol. Rev. 78: 1-33, 1998. Sexual dimorphism in humans has been the subject of wonder for centuries. In 355 BC, Aristotle postulated that sexual dimorphism arose from differences in the heat of semen at the time of copulation.
Sexual Dimorphism in
Counterregulatory Responses to Hypoglycemia after Antecedent Exercise -
Pietro Galassetti, Anthony R. Neill, Donna Tate, Andrew C. Ertl, David H. Wasserman and
Stephen N. Davis
Departments of Medicine and Molecular Physiology and Biophysics, Vanderbilt University School of Medicine and Nashville Veteran Affairs Medical Center, Nashville, Tennessee 37232-6303.
Age, Gender, and Non-modulation - A Sexual Dimorphism in Essential Hypertension.
Naomi D. L. Fisher; Claudio Ferri; Cesare Bellini; Anna Santucci; Ray Gleason; Gordon H. Williams; Norman K. Hollenberg; Ellen W. Seely.
Childhood Sexual Abuse as a Risk Factor for Depression in Women: Psychosocial and
Erica L. Weiss, M.D., James G. Longhurst, M.D. and Carolyn M. Mazure, Ph.D.
OBJECTIVE: Depression is twice as common in women as in men, but the reason for this sexual dimorphism is unknown. This article reviews recent studies of the role of childhood sexual abuse in the subsequent development of major depressive disorder, and the biological and psychosocial mechanisms by which early stressors may contribute to adult-onset depression in women. Particular attention is paid to investigations of the long-term effects of early stress on hypothalamic-pituitary-adrenal (HPA) axis function.
Brain Development, XI, Sexual Dimorphism - JILL M. GOLDSTEIN, PH.D., DAVID N. KENNEDY, PH.D. and Verne S. CAVINESS, JR., M.D., D.PHIL., Boston, Mass.
Pelvic Politics: Sexual Dimorphism and Racial Difference - Sally Markowitz, Signs, Vol. 26, No. 2 (Winter, 2001).