Entwicklung der Vorhaut
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Millions of years of evolution have fashioned the human body into a model of refinement, elegance, and efficiency, with every part having a function and purpose. Evolution has determined that mammals' genitals should be sheathed in a protective, responsive, multipurpose foreskin. Every normal human being is born with a foreskin. In females, it protects the glans of the clitoris; in males, it protects the glans of the penis. Thus, the foreskin is an essential part of human sexual anatomy.
Over the last 65 million years, the prepuce has offered reproductive advantages. Although advocates of mass circumcision hypothesize that the prepuce represents a design flaw, it is more likely that sexual selection has refined the external genitalia of each primate species for reproductive excellence.
The reproductive advantages provided by the prepuce during the last 65 million years should not be taken lightly. The human prepuce is not "vestigial" but is, in fact, an evolutionary advancement over the prepuce of other primates.
The prepuce has been well conserved by evolution. In primates, the foreskin has been present in the genitalia of both sexes of mammals for at least 65 million years and likely has been present for over 100 millions years of evolution, based on its commonality as an anatomical feature in mammals. The evolution of complex penile morphologies like the foreskin may have been influenced by females. It has been proposed that the foreskin evolved to facilitate masturbation. The human prepuce has an increase in corpuscular innervation and concomitant decrease in corpuscular receptors in the human glans compared to the prepuce and glans of lower primates, demonstrating an evolutionary advancement. The human penis has retained and modified its prepuce over a period of extraordinarily evolution. The rapid divergence in external genital anatomy between humans and ancestral apes is thought to have occurred in the last seven million years.
The external genitalia of primates are marked by an astounding variety of specialized structures, but over the past 65 million years, the prepuce has not only withstood the test of time, it has also evolved in its complexity. The survival and further development of the human penile prepuce in the face of the extraordinarily rapid evolution of humans over the last 7 to 9 million years is particularly noteworthy, especially against the background of a fourfold increase in penile size.
A histologic study of the penile and clitoral prepuce, carried out on human and non-human primates, showed that corpuscular receptors are concentrated at the prepuce/glans penis and the prepuce/glans clitoridis interface in humans and rhesus monkeys. Surprisingly different patterns of innervation, however, are seen between human and non-human male primates.
The rhesus monkey has fewer corpuscular receptors in the prepuce (foreskin) and more corpuscular receptors in the glans (head). In humans, however, the glans penis has few corpuscular receptors and predominant free nerve endings, consistent with protopathic sensibility. Protopathic simply refers to a low order of sensibility (consciousness of sensation), such as to deep pressure and pain, that is poorly localised. The human glans penis has virtually no fine touch sensation and can only sense deep pressure and pain at a high threshold. While the human glans penis is protopathic, the prepuce contains a high concentration of touch receptors in the ridged band.
In the human penis, the prepuce is known to have ten times more corpuscular sensory receptors than the glans penis.
The male and female prepuce has persisted in all primates, which strongly supports the contention that the prepuce is valuable genital sensory tissue. The corpora cavernosa and the prepuce are the only two universally common characteristics of the primate penis.
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Functions of The Foreskin - Part 1
Functions of The Foreskin - Part 2
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