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Anthropologist Peter Frost has proposed that sexual selection for women with unusual hair or eye color was responsible for the evolution of pigmentary traits in European populations, [128] however this theory has since been refuted by data-based evidence from genetics and spectrophotometry, [129] [130] and multiple studies have shown that women ...
Sexual selection creates colourful differences between sexes in Goldie's bird-of-paradise.Male above; female below. Painting by John Gerrard Keulemans.. Sexual selection is a mechanism of evolution in which members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex ...
Sexual differentiation includes development of different genitalia and the internal genital tracts and body hair plays a role in sex identification. [ 2 ] The development of sexual differences begins with the XY sex-determination system that is present in humans, and complex mechanisms are responsible for the development of the phenotypic ...
Although males grow hair faster than females, baldness is more prevalent in males than in females. The main cause for this is male pattern baldness. Male pattern baldness is a condition where hair loss occurs in a typical pattern of a receding hairline and hair thinning on the crown. It is caused by hormones and genetic predisposition. [47]
A review authored by J. Michael Bailey states: "childhood gender nonconformity comprises the following phenomena among boys: cross-dressing, desiring to have long hair, playing with dolls, disliking competitive sports and rough play, preferring girls as playmates, exhibiting elevated separation anxiety, and desiring to be—or believing that ...
Nakedness and clothing use are characteristics of humans related by evolutionary and social prehistory. The major loss of body hair distinguishes humans from other primates. . Current evidence indicates that anatomically modern humans were naked in prehistory for at least 90,000 years before they invented clothi
Evidence for this explanation for the evolution of sex is provided by comparison of the rate of molecular evolution of genes for kinases and immunoglobulins in the immune system with genes coding other proteins. The genes coding for immune system proteins evolve considerably faster. [23] [24]
Sexual differentiation is the process of development of the sex differences between males and females from an undifferentiated zygote. [1] [2] Sex determination is often distinct from sex differentiation; sex determination is the designation for the development stage towards either male or female, while sex differentiation is the pathway towards the development of the phenotype.