From the website: 'A study, published in the Journal of Biological Chemistry, suggests that sperm could provide a vital clue to how diseases like cancer and HIV spread through the body.
UK researchers have identified markers on the surface of human sperm which prevent them being attacked by the female immune system. The markers are also found on cancer cells and HIV-infected blood cells and may help the diseases to take hold.
"If aggressive cancers and pathogens are using the same system of universally-recognisable markers to trick the immune system into thinking they're harmless, we need to work out exactly how this interaction works." (Professor Anne Dell)'
A very interesting essay from the journal of Evolutionary Psychology on sperm competition and its role in shaping the human penis, (size, length, width, forceful ejaculation), evolutionary strategies for successful fertilization i.e. semen displacement and coagulation. On sexual intercourse and evolutionary benefits of deep penis thrusting, function of the foreskin and effects of circumcision, premature ejaculation, female reproductive strategies i.e. copulation with multiple partners, human sexual behaviour and wife rape (males having sex with their partner if suspecting them of infidelity).
From the article: 'An examination of some of the implications that the human penis may have evolved to compete with sperm from other males by displacing rival semen from the cervical end of the vagina prior to ejaculation. The semen displacement hypothesis integrates considerable information about genital morphology and human reproductive behavior, and can be used to generate a number of interesting predictions.
... there is reason to believe that sperm competition played a role in shaping the human penis. The human penis, with a relatively larger glans and more pronounced coronal ridge than is found in many other primates, may function to displace seminal fluid from rival males in the vagina by forcing it back over/under the glans. During intercourse the effect of repeated thrusting would be to draw out and displace foreign semen away from the cervix. As a consequence, if a female copulated with more than one male within a short period of time this would allow subsequent males to 'scoop out' semen deposited by others before ejaculating.'
By Gordon G. Gallup, Jr., Department of Psychology, State
University of New York at Albany, Albany, NY 12222, USA.
Rebecca L. Burch, Department of Psychology, State University of New York at Oswego, Oswego, NY 13126, USA.
Violence is predominately a male phenomena. This is not intended to romanticize or idealize women, or to deny that they too can sometimes be nasty, brutal, even deadly. But the overall pattern is consistent: When it comes to violence, the two sexes simply are not in the same league. The same pattern is found, by and large, in animals.
... In brief, since sperm can be made in vast quantities, and with little mandated physiological follow-through, it is possible for males to have large numbers of offspring, the actual output limited by the number of females they succeed in fertilizing. By contrast, females are more likely to maximize their reproduction by producing successful offspring, rather than by outcompeting other females for the sexual attention of males.
To some degree, sexual competition is a replay of fertilization itself, in which numerous males, like hyperactive spermatozoa, compete among themselves for access to females. Just as it is now clear that the egg doesn't merely passively receive suitors, it is increasingly understood that females can be active participants in their own reproduction. Nonetheless, when it comes to sperm makers, success is likely to crown those who outcompete their rivals, and so, in species after species, it is the males who are larger, nastier, more likely to be armed with lethal weaponry and a violent disposition to match. Natural selection has outfitted males with the tools for success in male-male competition, much of it violent.
By David P. Barash. Chronicle of Higher Education, From the issue dated May 24, 2002
Page Title: 'Male Sexual Health: Sperm. Human Anatomy, Fertilization,
Reproductive System, Health Benefits of Swallowing Semen (Cum)'.
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Analyse any human emotion, no matter how far it may be removed from the sphere of sex, and you are sure to discover somewhere the primal impulse, to which life owes its perpetuation. ... The primitive stages can always be re-established; the primitive mind is, in the fullest meaning of the word, imperishable. ... Mans most disagreeable habits and idiosyncrasies, his deceit, his cowardice, his lack of reverence, are engendered by his incomplete adjustment to a complicated civilisation. It is the result of the conflict between our instincts and our culture. (Sigmund Freud)
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Karene (September, 2012)
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