Head, Heart and Balls
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In one controversial study, UCLA psychologist Neil Malamuth had male college students, none of whom had ever been arrested for a sex crime, read accounts of two sexual encounters, one consensual, the other coerced.
The students were asked to give a written response to what they read, then they were hooked up to a plethysmograph and asked to read the same accounts again.
In their written reports, the students claimed to be far more turned on by the consensual encounter. But the readings on the plethysmograph showed they were equally turned on by the rape.
This finding was trumpeted by some feminists to prove that all men, no matter what they say in polite company, have a propensity for sexual violence.
But scientists without a political agenda to advance - including, eventually, Malamuth himself - noted that such tests do not establish a link between arousal and behavior and therefore have no predictive significance.
It is, after all, the behavior that is the crime, not the arousal, some of which can be attributed to unconscious fantasies that a wired-up man, no matter how aroused his penis might get during the experiment, would never act out in real life.
It is also relevant to note that nearly all the phallometric experiments in the scientific literature took place in prison, an environment raising two serious validity issues.
First, it is by definition a place inhabited by men who have already demonstrated a lack of self-control second, it is occupied by men with little (or no) exposure to heterosexual stimulation at all - therefore any depiction of women and sex, coerced or not, would be likely to raise an erection.
For reasons such as this, evidence from the so-called penile lie detector, just like the "real" one, the polygraph, is not admissible in court.
In a 1993 case covered by the Wall Street journal, a police officer in Maine lost his job, and then successfully sued to get it back, when he refused to submit to a penile plethysmograph after he was accused - falsely, it turned out - of taking part in a sex orgy with local teenagers.
The officer refused the test
not on Fifth Amendment grounds, but because he found the methodology
Client space must be separated from the clinician's work area by at least an opaque wall, which is a minimum of seven feet high. A stationary wall is preferred.
A disposable cover on the chair seat is required for each client.
Gauges will be disinfected prior to use.
Disgusting or not, disinfected or not, reliable or not, the penile plethysmograph continues to be used in some psychiatric hospitals to screen out " potential" pedophiles from easy access to minors.
It is also used in behavior-modification centers that employ aversion therapy to rehabilitate sex offenders.
These centers use electric shocks or other unpleasant sensations to treat patients who, according to the plethysmograph, respond to inappropriate sexual stimuli with an erection.
The long-term success rate of such treatment is, like the penile plethysmograph itself, a matter of some controversy.
One interesting idea is that sexual conflict might contribute to evolution just as surely as the usual suspects - climate, landscape, vegetation, and so on.
Several years ago a geneticist decided to test the idea that one's environment influences the sexual behavior of the opposite sex.
If the erotic activities of males affect the evolution of females, and vice versa, William Rice thought, there should be a way to prove it with the geneticist's favorite guinea pig - the fruit fly.
Exploiting that species' short life span, which enables a scientist to breed many generations (and see many mutations) in just months, Professor Rice used genetic engineering-unnatural selection-to breed " super-fly" males exhibiting a hyper-aggressive sexuality.
These little tough guys totally dominated normal males, denying them access to female flies, who were similarly intimidated.
These " super-males" were so ultra-macho, in fact, they often fathered only males. They thus became the fittest of the fit - recreating themselves abundantly in subsequent generations - while killing most of the females in the process.
This happened because of a peculiar aspect of fruit fly semen which, even under normal circumstances, is slightly toxic.
Evolution has enabled female flies to cope with standard toxicity levels. But the levels reached by Rice's super-studs were way beyond - and, equally important, arrived at much faster - than anything those females could adapt to in so short a time.
So they died, Rice reported, like flies. This experiment, as Deborah Blum notes in her book Sex on the Brain, reminds us that males and females do not necessarily work as partners, even when coming together to reproduce.
Feminists may be happy to know there are " super-females" in the insect world who flaunt a similarly imposing superiority.
During copulation, some female biting midges trap the male inside her. Then, after he releases his sperm, she eats him - except for his penis - which remains packed in her genital opening to facilitate fertilization.
We are not biting midges, thank God. Nor, of course, are we fruit flies.
But Professor Rice's research with that second species raises some intriguing questions: Is there anything in or about human semen that tells us something about our sexual behavior? Or male aggression?
Is it possible that it is in sperm, a substance produced exclusively by male genitalia, that the penis's true " pathological" nature is revealed?
Fascinating answers to those questions were proposed by British scientists R. Robin Baker and Mark A. Bellis in their book Human Sperm Competition: Copulation, Masturbation and Infidelity, published in 1995.
The authors' interest in the subject emerged from one of biology's great mysteries:
Why is it that during copulation the human penis expels enough sperm - about 350 million - to theoretically fertilize every woman in the United States twice?
Their answer is " sperm competition," a theory that says the sperm of one man must be prepared to do battle with the sperm of another inside a woman's vagina because of the real possibility that she has " double-mated."
By that term Baker and Bellis mean that the female had unprotected sex with another man within ten days, the outer limit of a sperm's fertility, in the same reproductive cycle.
Evolution, the authors suggest, has selected all sperm cells, and the entire penis, to fight that battle-a conflict that requires a huge army of sperm with specially trained " soldiers" for different aspects of combat.
Based on a sex survey done by a British women's magazine, Baker and Bellis guessed that between 4 and 20 percent of British children are conceived to a sperm that prevailed over rivals from another male.
The idea of sperm competition was conceived in 1970 by British scientist Geoffrey Parker, who was studying the sex lives of insects.
Baker and Bellis's highly controversial contribution was to declare that Parker's theory unequivocally applies to humans.
Along with the quantity of sperm in human ejaculate, the authors' investigation was prompted by the equally impressive variety of shapes exhibited by those cells.
The man on the street may think all human spermatozoa resemble tiny tadpoles, each with an oval head at one end, a mid-piece, and a long tail at the other end.
But Baker and Bellis identified at least eight different types of sperm head, four types of tall, and two types of mid-piece, with many variations among those types, not to mention in size.
Why such variety? is a question that has many scientists scratching their heads.
Baker and Bellis were also intrigued by a related question: Why
do so many of those sperm cells appear to be " mistakes" - that is, sperm with
misshapen heads and/or tails?
The manufacturing process, which takes almost eleven weeks, starts in the seminiferous tubules inside the testes-the same ones described by Regnier de Graaf in 1668-where the sperm head is made, and then moves to the epididymis, a comma like structure adjoining each testicle where the sperm cells slowly mature, gaining motility and the biochemical properties necessary to fertilize an egg.
The optimal temperature for sperm-cell manufacture is three or four degrees lower than the rest of the human body.
This is why testicles are enclosed outside the body in the scrotum, stored in a cool, dark place, just as you might read on a warning label.
Unfortunately, natural selection is not so powerful as to make that assembly line totally efficient, no matter what the temperature.
Like birth defects in humans, developmental errors in sperm-sperm with misshapen bodies-are inevitable, says the conventional wisdom, which is one reason we emit so many: the greater the number, the greater the chance of having more perfect sperm in that ejaculate, swimming next to all those mistakes.
But Baker and Bellis say it is wrong to think of those " mistakes" as mistakes.
They argue in their controversial " Kamikaze Sperm Hypothesis" that the great variation in size and shape of human sperm cells reflects a brilliant division of labor.
Some sperm cells, usually the younger well-formed ones with large heads, are " egg getters" others are " kamikaze sperm" , whose job is to block sperm from other men, or " seek-and destroyers," whose function is to disable a rival's sperm by spearing them in the head, then injecting a tiny dose of acrosomal enzyme, the same substance used by the successful egg getter to melt the membranes surrounding the female egg.
Sperm competition not only affects the amount of sperm in an ejaculation-more if the male intuitively suspects the presence of another man's sperm, less if he does not-but the types of sperm inside that ejaculation.
If competition is likely, the more likely it Is there will be more kamikazes. The authors speculate the purpose of masturbation by males is to maximize the number of young, fit, egg-getting sperm available for the next competition.
A typical man has 1 to 3 billion sperm cells. in production at any given moment. Roughly 300 million finished cells emerge from that assembly line every day. Some of them could grow old and weak waiting to be used.
Baker and Bellis argue that women double-mate to promote sperm competition so that their sons will inherit the ability to make victorious sperm from their victorious-sperm-making fathers.
In this view, women are not being promiscuous they are being genetic entrepreneurs. The authors speculate that the purpose of the female orgasm, as well as " flowback," the process in which a woman expels some of the semen a man has just ejaculated in her, is to influence that competition.
This influence occurs because the orgasm helps to retain, and flowback discards, some or all of the sperm that a woman is rooting for or against.
The male, of course, is never a bystander in sperm competition. Baker and Bellis propose that, along with the make up of his sperm, something else has evolved to help him get an edge over his rivals-the very shape of his penis and the way he likes to use it.
Other biologists have pointed to the length of the shaft and the weight of human testicles as evidence of natural selection at work.
Baker And Bellis added three more items to that list: the hefty girth of the human penis (thicker than any primate, including the much larger gorilla and orangutan) its large smooth, acorn-shaped head and the repetitive, plunging fashion in which men use it during intercourse.
To see the evolutionary advantages of these adaptations, we must look at other mammals. The penis of a male rat, after copulating with a female, ejects a substance into her reproductive tract that coagulates into a hard plug.
The point of this is to emerge as the undisputed champion in sperm competition.
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