Tuesday, January 04, 2011 6:15:27 AM
Countdowns - Why So Many Animals Evolved to Masturbate
Porcupines prefer sex toys, and moose get off by rubbing their antlers on trees. While scientists debate the evolutionary reason for masturbation, there's no doubt that humans are not alone in their self-pleasure from time to time. Here are some other creatures that partake in solo sex.
-- Clara Moskowitz, LiveScience Senior Writer
*
10 Monkeys
Perhaps not surprisingly, our closest animal relatives, primates, are also known to take matters into their own hands. "It does seem to be relatively widespread in primates (we have a paper just out online in International Journal of Primatology showing it occurs in wild golden-backed uacaris)," biologist Gareth Jones of the University of Bristol in England wrote in an e-mail to LiveScience. "The exciting thing... is that scientists are now exploring potential evolutionary reasons for its occurrence."
Besides uacaris, masturbatory behavior has been studied in rhesus monkeys, gray-cheeked mangabeys monkeys, colobus monkeys, Japanese macaques and other animals.
*
Credit: Charles Foley, Wildlife Conservation Society
9 Elephants
Elephants have been known to rub up against rocks for pleasure. However, to collect semen from captive elephants for artificial insemination, zookeepers must manually stimulate a bull's rectum to massage its prostate (yep, that means some poor zoo worker has to don a glove and reach up there).
Fun fact: Elephant penises are curved like an S, and can reach 3-5 feet (1 to 1.5 meters) in length with a 6-inch (16-centimeters) girth. Meanwhile, elephant clitorises can reach more than a foot long (40 cm)!
*
8 Porcupines
Prickly porcupines apparently like it rough -- and use toys.
"As the mating season approached, the female porcupine would often rub her genitals on structures such as food and water dishes, sticks, and the cage wire," researcher Albert R. Shadle reported in a 1946 paper.
Shadle also found that lady porcupines were wont to "seize, straddle, and ride sticks about the cage."
*
These ground squirrels may get off in the name of STD protection.
Credit: Hans Hillewaert / CC-BY-SA-3.0
7 Squirrels
A new study on African ground squirrels tried to probe the possible adaptive benefits of masturbation. After all, if solo love is so common, there must be an evolutionary reason for it, right?
In a September 2010 paper in the journal PLoS ONE, Jane M. Waterman of the University of Central Florida found that all 20 of the male squirrels observed masturbated to ejaculation and consumed the ejaculate. The researchers observed 105 squirrel masturbation sessions in total.
An analysis of the results suggests male squirrel "masturbation could function as a form of genital grooming," because saliva has anti-bacterial properties, and the act may also reduce their risk of catching a sexually transmitted disease. The ejaculation could also serve as "postcopulatory urination, as a more thorough mechanism to clean vital reproductive tracts after mating than just external genital grooming. Consuming the ejaculate may prevent moisture loss," the researchers wrote.
*
Credit: John Rowe
6 Turtles
Self-stimulation is not reserved just for mammals, though. A whole genre of YouTube videos will attest to rampant turtle masturbation.
Male turtles will often rub or buck up against a wall, rock or step and repeatedly thrust his penis out of its sheath. The reptiles also emit telltale squeaks of pleasure.
*
5 Walruses
Male walruses are among those flexible animals that enjoy not only manual self-stimulation, but also oral. The marine mammals have been known to use their flippers to get the job done, and their mouths for so-called self-fellation.
*
Credit: Dreamstime
4 Birds
Most birds have an opening called a cloaca used for both sexual and waste-excretion purposes. Male birds masturbate by bending their tails under an object -- such as a toy, perch, or even a human's hand -- and then rubbing their cloacas on it, explained Dr. Marge Wissman on BirdChannel.com, a resource for pet owners.
A female bird will lift her tail to one side and back up onto an object to rub her cloaca on it.
"If done infrequently, behaviorists say masturbation is healthy, allowing the bird a natural release. If your bird is masturbating too often, you can often stop the behavior by removing the favored object," Wissman wrote.
*
Credit: Patricia Moehlman/IUCN
3 Horses
Autoeroticism in both male and female horses is common. While males like to slide their penises against their underbellies, females are known to rub up against posts or other objects -- and they have even been observed secreting a type of female ejaculate mucus.
At least in males, these self-pleasing practices do not reduce sperm count or inhibit a stallion's ability to impregnate a female, studies have found.
In related news, moose can reportedly bring themselves to orgasm simply by rubbing their antlers on nearby trees.
*
Credit: Caroline Kjall/stock.xchng
2 Dogs
As most pet owners know, even domesticated dogs and cats are fond of doing the deed.
"Mounting, thrusting (humping) and masturbation are normal behaviors exhibited by most dogs," according to the American Society for the Prevention of Cruelty to Animals (ASPCA).
Dogs like to thrust and rub against objects, people and animals, and also enjoy licking themselves. Cats, too, enjoy self-fellation.
*
Credit: dreamstime
1 Humans
While our shared interest with the animal kingdom highlights some similarities between Homo sapiens and the rest of Earth's fauna, scientists say there are some differences in how we go about it.
For one, many animals that masturbate don't continue the deed until orgasm (humans seem to be rather goal-oriented on this point). That means that some of the best theories for why masturbation evolved in humans are off the table for other animals.
For example, studies have found that masturbation can increase a man's sperm count by getting rid of old semen that's lost its vitality, and therefore boosting the chances that young, lively sperm will be ejaculated during intercourse.
But since this discharge doesn't seem to occur as often in animals, then there must be some other benefits to the practice, scientists say.
*
Copyright © TechMediaNetwork.com
http://www.livescience.com/animals/ten-masturbating-animals-sex-science-101019.html [with comments]
=====
The Scientific Case for Masturbation
O’Donnell’s mid-’90s crusade against autoeroticism wasn’t based on science.
youtube.com
Why O’Donnell gets it wrong: being ‘master of your domain’ does not help procreation.
embedded video:
Late Night Obsession
The Anti-Self-Service Candidate
Christine O’Donnell has shown she can hold her own at the polls in Delaware, but she’s apparently against people 'holding their own’ in other respects. The late-night comics can’t help but react.
by Sharon Begley
October 07, 2010
Since Christine “I’m Not a Witch [ http://www.newsweek.com/blogs/the-gaggle/2010/10/05/great-political-ad-watch-christine-o-donnell-and-russ-feingold.html ]” O’Donnell is campaigning for the U.S. Senate and not the directorship of the Kinsey Institute [ http://www.kinseyinstitute.org/ ], maybe we should give her a pass when it comes to her views on sex and, specifically, masturbation. But that would be a mistake: the stakes are simply too high, going all the way up the very survival of our species. For while O’Donnell crusaded against masturbation in the mid-1990s, denouncing [ http://www.msnbc.msn.com/id/21134540/vp/39203840#39203840 ] it as “toying” with the organs of procreation and generally undermining baby making, the facts are to the contrary. Evidence from elephants to rodents to humans shows that masturbating is—counterintuitively—an excellent way to make healthy babies, and lots of them. No one who believes in the “family” part of family values can let her claims stand.
The science is straightforward. Whenever a behavior is common in the animal kingdom, biologists suspect it has an adaptive function. That is, the behavior enabled individual animals to survive better and leave more offspring than animals that did not engage in the behavior. As a result, genes for the behavior spread throughout that population until it became essentially ubiquitous. And so it is with autoeroticism, which is common—really common. As the Science in Seconds blog [ http://www.scienceinseconds.com/blog/Spanking-the-Monkey (below)] noted this week, what with “spanking the monkey,” “charming the snake,” and “freeing willy,” a remarkable number of the slang terms for pleasuring oneself refer to animals. That reflects reality: the practice has been documented in Japanese macaques [ http://www.springerlink.com/content/k7508l6033g17187/ ], gibbons, baboons, chimps, elephants, dogs, cats, horses, lions, donkeys, “and walruses that manage to flog the bishop with their fins.” (Bonus for clicking on the blog link above: excellent photo of an elephant in flagrante dilecto.)
What, then, might be its adaptive function? How can autoeroticism help animals triumph in the war of survival of the fittest? Lucky for us, scientists have been pondering this. There are four basic theories, each with some support in one or another animal species (I’m not counting the sexual-outlet hypothesis, which posits that masturbation is not adaptive but is just a byproduct of sexual arousal, which is definitely adaptive):
1. Masturbation might remove old, worn-out, broken sperm from the reproductive tract. That would increase the fraction of healthy, speedy sperm, improving a male’s chance of becoming a father. “In humans, masturbation increases sperm quality (by promoting younger sperm) without affecting sperm numbers in the female reproductive tract,” notes biologist Jane Waterman of the University of Central Florida in a new paper in the journal PLoS One. As far back as 1993, biologists had observed that masturbating decreased the number of sperm a man delivered the next time he had sex with his partner, but not the number of sperm the woman retained. They concluded that “masturbation is a male strategy to increase sperm fitness.”
Research presented at a science meeting last year [ http://www.eshre.eu/01/default.aspx?pageid=757 ] offered support for the fitter-sperm idea. Ejaculating daily for seven days improved sperm quality as measured by the amount of DNA damage: levels of damage averaged 34 percent on a standard measurement index after three days’ abstinence, but after a week of ... um, non-abstinence, the level of damage dropped to 26 percent, in the “fair” range for sperm quality. Looking only at men whose sperm damage decreased (in a few, damage got worse for some reason), the average damage level fell to just under 23 percent—putting them in the “good” range. In addition, sperm motility rose significantly. Result: healthier and possibly more babies.
2. Masturbation might be a form of advertising. According to this idea, males that engage in autoeroticism signal to possible mates as well as competitors how much they have to offer. “Males may advertise their high quality,” explains Waterman, “signaling that they have high quantities of sperm and can afford to waste some.” Result: more mating, more babies, more families. We hasten to add that masturbation as advertising does not apply (we really, really hope) to humans.
3. Masturbation might be a sort of victory lap. Some animals masturbate after they mate. Since other members of a group know this, then masturbation signifies that the male engaging in this behavior was the chosen partner of other females. Females who are still shopping for a mate might be inspired by that information to copy their choice, as in, “if he was good enough for her ...” Result: more mating, more babies.
4. Masturbation can serve a hygiene function. According to this idea, males engage in autoeroticism because it cleans the reproductive tract and reduces the chance of acquiring a sexually transmitted disease from a female that he mated with and who had other recent partners. Result: a lower incidence of STDs, better sexual hygiene, more mating, more babies.
The STD function is what Waterman inferred about masturbation after she spent 2,000 (!) hours observing the Cape ground squirrel (Xerus inauris) of Namibia. As she explains in PLoS One, “an oral masturbation was recorded when a male sat with head lowered and an erect penis in his mouth, being stimulated with both mouth (fellatio) and forepaws (masturbation), while the lower torso moved forward and backwards in thrusting motions, finally culminating in an apparent ejaculation.” The behavior was much more frequent on days when females were fertile, and mostly occurred after mating. That would seem odd, since it wastes huge numbers of sperm just when they have the best chance of finding a willing egg. Odd, too, is the observation that males masturbated more when their mate had had a lot of other suitors (female Cape ground squirrels mate with up to 10 males in their three-hour fertile period). But there is one explanation that makes sense of a behavior that occurs after mating, and more often when a male has mated with a particularly promiscuous female: masturbation is a way for males to reduce the chance of infection, since saliva has antibacterial properties. Since STDs can destroy fertility, sexual hygiene through masturbation is a way for male squirrels to keep making babies.
And what about females? There have been far fewer observations of females masturbating in the wild, though bonobos are well known for this form of eroticism (and every other, it seems). One popular theory for why females might indulge, however, is incorrect—namely, the idea that orgasm (during or right after mating) might propel sperm to the egg. To the contrary, scientists reported [ http://www.springerlink.com/content/p4j5u02611713712/ ] in a 2002 paper, “vaginal and uterine contractions ... have been misinterpreted as powering rapid sperm transport to facilitate fertilization, but such fast transport would lead to the tubal deposition of noncapacitated, incompetent spermatozoa,” which would not lead to conception. Instead, primatologists conclude, in the case of females the purpose is simply to “produce enjoyable sensations [ http://books.google.com/books?id=oW64qjzGv-AC&pg=PA104&lpg=PA104&dq=female+bonobo+masturbation&source=bl&ots=Kk9GOeC65o&sig=9L69eaoy2ZIq0qdxmCIwrNuu0Ps&hl=en&ei=vPStTKzxH8TJceOM0d4K&sa=X&oi=book_result&ct=result&resnum=5&ved=0CCUQ6AEwBA#v=onepage&q=female%20percent20bonobo%20percent20masturbation&f=false ]”.
All in all, and across species great and small, autoeroticism (at least among males) is a cornerstone of procreation and thus the formation of families. Were O’Donnell’s unscientific views of the practice to spread, it would be a worrisome threat to family values.
© 2010 Harman Newsweek LLC
http://www.newsweek.com/2010/10/07/why-masturbation-helps-procreation.html [with comments]
=====
Spanking the Monkey
October 4, 2010
Torah Kachur
Charming the Snake. Choking the Chicken. Freeing Willy. The amount of slang for masturbation with animal references should be seriously disconcerting. Except that a wide-range of animals including dogs, cats, horses, all apes, lions, bears... and the list ["Slate - Animals Maturbating: A YouTube Gallery", http://www.slate.com/id/2223013/slideshow/2223004/ ] goes on... have been found to Jack off. Included on the list are elephants, donkeys and walruses that manage to flog the bishop with their fins. Even birds have been shown to rub their cloaca against pretty much anything.
This phenomenon isn't restricted to males either - female organgutans were observed exhibiting inspiring creativity by fashioning home-made dildos from lianas. Female horses during breeding season will rub up against fence posts, barn doors and seemingly anything made of wood.
Discovering that a species can milk the moose is fun and entertaining and often awe-inspiring. You have to respect a macaque for committing 1-6% of its daily metabolism to producing ejaculate and the ability for 'self-directed oral sex' in a variety of mammals. But the bigger question is why? If masturbation is so widespread among all animals then it must provide an evolutionary advantage.
A new study has found ground squirrels [ http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0013060 ] can be added to the list of those that shake hands with the devil. Previous explanations to this blatant waste of sperm in and around a females oestrus period were that masturbation provided a way to display fertility to potential mates or as a deterrant to rivals.
In contrast, it was also thought that masturbation could provide a sexual release or as a way to refresh sperm. Studies done on the ground squirrles of Namibia concluded that masturbation was likely used as a method of cleansing the genitalia. This is likely species dependent when genitalia are more accessible to the environment and likely to be dirtier. In other words, they kept clean by getting down and dirty.
For most animals, the more likely reason for whacking off is that sperm quality improves the more a man pleasures his loins - a recent study [ http://www.eshre.eu/01/default.aspx?pageid=757 ] suggests that daily masturbation and ejaculation can reduce the amount of accumulated DNA damage in sperm by 12%. Therefore wasting sperm into a sock can actually improve the mobility of sperm and increase fertility. A continuation of this theory is the idea of sperm competition. This is when sperm from multiple males have a race to the egg and undergo various forms of chemical competition to see who gets to be the lucky shizz. Most women likely don't have sex with multiple males during their ovulatory phase... we aren't like the chimpanzee, where a single female chimp was observed to have sex with 50 male partners in a single day (ouch).
One consequence of shining the pole so often is that the testis enlarges to accomodate the demand for sperm. It's personal preference if this is desirable but there may be an evolutionary significance to larger balls. And that is the biggest balls gets the worm. There is precendent amongst several different species, including our ape cousins, that larger testes actually attract mates. Though it is unlikely that larger ball size relates to the desirability of a human male as most men don't go around showing off their packages.
The idea of refreshing sperm seems to account for the evolution of masturbation from turtles to donkeys. It is unclear if these species have hairy palms.
© 2010 Science in Seconds
http://www.scienceinseconds.com/blog/Spanking-the-Monkey [with comments]
=====
in addition to (items linked in) the post to which this is a reply and preceding and (other) following (including http://investorshub.advfn.com/boards/read_msg.aspx?message_id=52390097 ), see also (items linked in:
http://investorshub.advfn.com/boards/read_msg.aspx?message_id=54562899 and preceding
http://investorshub.advfn.com/boards/read_msg.aspx?message_id=54812980 and preceding and following
http://investorshub.advfn.com/boards/read_msg.aspx?message_id=54510168 and preceding and following
http://investorshub.advfn.com/boards/read_msg.aspx?message_id=58337514 and preceding
http://investorshub.advfn.com/boards/read_msg.aspx?message_id=57342847 and preceding (and http://investorshub.advfn.com/boards/read_msg.aspx?message_id=57667156 and preceding and following)
http://investorshub.advfn.com/boards/read_msg.aspx?message_id=50595333 and preceding
http://investorshub.advfn.com/boards/read_msg.aspx?message_id=56838300 and preceding and following
Porcupines prefer sex toys, and moose get off by rubbing their antlers on trees. While scientists debate the evolutionary reason for masturbation, there's no doubt that humans are not alone in their self-pleasure from time to time. Here are some other creatures that partake in solo sex.
-- Clara Moskowitz, LiveScience Senior Writer
*
10 Monkeys
Perhaps not surprisingly, our closest animal relatives, primates, are also known to take matters into their own hands. "It does seem to be relatively widespread in primates (we have a paper just out online in International Journal of Primatology showing it occurs in wild golden-backed uacaris)," biologist Gareth Jones of the University of Bristol in England wrote in an e-mail to LiveScience. "The exciting thing... is that scientists are now exploring potential evolutionary reasons for its occurrence."
Besides uacaris, masturbatory behavior has been studied in rhesus monkeys, gray-cheeked mangabeys monkeys, colobus monkeys, Japanese macaques and other animals.
*
Credit: Charles Foley, Wildlife Conservation Society
9 Elephants
Elephants have been known to rub up against rocks for pleasure. However, to collect semen from captive elephants for artificial insemination, zookeepers must manually stimulate a bull's rectum to massage its prostate (yep, that means some poor zoo worker has to don a glove and reach up there).
Fun fact: Elephant penises are curved like an S, and can reach 3-5 feet (1 to 1.5 meters) in length with a 6-inch (16-centimeters) girth. Meanwhile, elephant clitorises can reach more than a foot long (40 cm)!
*
8 Porcupines
Prickly porcupines apparently like it rough -- and use toys.
"As the mating season approached, the female porcupine would often rub her genitals on structures such as food and water dishes, sticks, and the cage wire," researcher Albert R. Shadle reported in a 1946 paper.
Shadle also found that lady porcupines were wont to "seize, straddle, and ride sticks about the cage."
*
These ground squirrels may get off in the name of STD protection.
Credit: Hans Hillewaert / CC-BY-SA-3.0
7 Squirrels
A new study on African ground squirrels tried to probe the possible adaptive benefits of masturbation. After all, if solo love is so common, there must be an evolutionary reason for it, right?
In a September 2010 paper in the journal PLoS ONE, Jane M. Waterman of the University of Central Florida found that all 20 of the male squirrels observed masturbated to ejaculation and consumed the ejaculate. The researchers observed 105 squirrel masturbation sessions in total.
An analysis of the results suggests male squirrel "masturbation could function as a form of genital grooming," because saliva has anti-bacterial properties, and the act may also reduce their risk of catching a sexually transmitted disease. The ejaculation could also serve as "postcopulatory urination, as a more thorough mechanism to clean vital reproductive tracts after mating than just external genital grooming. Consuming the ejaculate may prevent moisture loss," the researchers wrote.
*
Credit: John Rowe
6 Turtles
Self-stimulation is not reserved just for mammals, though. A whole genre of YouTube videos will attest to rampant turtle masturbation.
Male turtles will often rub or buck up against a wall, rock or step and repeatedly thrust his penis out of its sheath. The reptiles also emit telltale squeaks of pleasure.
*
5 Walruses
Male walruses are among those flexible animals that enjoy not only manual self-stimulation, but also oral. The marine mammals have been known to use their flippers to get the job done, and their mouths for so-called self-fellation.
*
Credit: Dreamstime
4 Birds
Most birds have an opening called a cloaca used for both sexual and waste-excretion purposes. Male birds masturbate by bending their tails under an object -- such as a toy, perch, or even a human's hand -- and then rubbing their cloacas on it, explained Dr. Marge Wissman on BirdChannel.com, a resource for pet owners.
A female bird will lift her tail to one side and back up onto an object to rub her cloaca on it.
"If done infrequently, behaviorists say masturbation is healthy, allowing the bird a natural release. If your bird is masturbating too often, you can often stop the behavior by removing the favored object," Wissman wrote.
*
Credit: Patricia Moehlman/IUCN
3 Horses
Autoeroticism in both male and female horses is common. While males like to slide their penises against their underbellies, females are known to rub up against posts or other objects -- and they have even been observed secreting a type of female ejaculate mucus.
At least in males, these self-pleasing practices do not reduce sperm count or inhibit a stallion's ability to impregnate a female, studies have found.
In related news, moose can reportedly bring themselves to orgasm simply by rubbing their antlers on nearby trees.
*
Credit: Caroline Kjall/stock.xchng
2 Dogs
As most pet owners know, even domesticated dogs and cats are fond of doing the deed.
"Mounting, thrusting (humping) and masturbation are normal behaviors exhibited by most dogs," according to the American Society for the Prevention of Cruelty to Animals (ASPCA).
Dogs like to thrust and rub against objects, people and animals, and also enjoy licking themselves. Cats, too, enjoy self-fellation.
*
Credit: dreamstime
1 Humans
While our shared interest with the animal kingdom highlights some similarities between Homo sapiens and the rest of Earth's fauna, scientists say there are some differences in how we go about it.
For one, many animals that masturbate don't continue the deed until orgasm (humans seem to be rather goal-oriented on this point). That means that some of the best theories for why masturbation evolved in humans are off the table for other animals.
For example, studies have found that masturbation can increase a man's sperm count by getting rid of old semen that's lost its vitality, and therefore boosting the chances that young, lively sperm will be ejaculated during intercourse.
But since this discharge doesn't seem to occur as often in animals, then there must be some other benefits to the practice, scientists say.
*
Copyright © TechMediaNetwork.com
http://www.livescience.com/animals/ten-masturbating-animals-sex-science-101019.html [with comments]
=====
The Scientific Case for Masturbation
O’Donnell’s mid-’90s crusade against autoeroticism wasn’t based on science.
youtube.com
Why O’Donnell gets it wrong: being ‘master of your domain’ does not help procreation.
embedded video:
Late Night Obsession
The Anti-Self-Service Candidate
Christine O’Donnell has shown she can hold her own at the polls in Delaware, but she’s apparently against people 'holding their own’ in other respects. The late-night comics can’t help but react.
by Sharon Begley
October 07, 2010
Since Christine “I’m Not a Witch [ http://www.newsweek.com/blogs/the-gaggle/2010/10/05/great-political-ad-watch-christine-o-donnell-and-russ-feingold.html ]” O’Donnell is campaigning for the U.S. Senate and not the directorship of the Kinsey Institute [ http://www.kinseyinstitute.org/ ], maybe we should give her a pass when it comes to her views on sex and, specifically, masturbation. But that would be a mistake: the stakes are simply too high, going all the way up the very survival of our species. For while O’Donnell crusaded against masturbation in the mid-1990s, denouncing [ http://www.msnbc.msn.com/id/21134540/vp/39203840#39203840 ] it as “toying” with the organs of procreation and generally undermining baby making, the facts are to the contrary. Evidence from elephants to rodents to humans shows that masturbating is—counterintuitively—an excellent way to make healthy babies, and lots of them. No one who believes in the “family” part of family values can let her claims stand.
The science is straightforward. Whenever a behavior is common in the animal kingdom, biologists suspect it has an adaptive function. That is, the behavior enabled individual animals to survive better and leave more offspring than animals that did not engage in the behavior. As a result, genes for the behavior spread throughout that population until it became essentially ubiquitous. And so it is with autoeroticism, which is common—really common. As the Science in Seconds blog [ http://www.scienceinseconds.com/blog/Spanking-the-Monkey (below)] noted this week, what with “spanking the monkey,” “charming the snake,” and “freeing willy,” a remarkable number of the slang terms for pleasuring oneself refer to animals. That reflects reality: the practice has been documented in Japanese macaques [ http://www.springerlink.com/content/k7508l6033g17187/ ], gibbons, baboons, chimps, elephants, dogs, cats, horses, lions, donkeys, “and walruses that manage to flog the bishop with their fins.” (Bonus for clicking on the blog link above: excellent photo of an elephant in flagrante dilecto.)
What, then, might be its adaptive function? How can autoeroticism help animals triumph in the war of survival of the fittest? Lucky for us, scientists have been pondering this. There are four basic theories, each with some support in one or another animal species (I’m not counting the sexual-outlet hypothesis, which posits that masturbation is not adaptive but is just a byproduct of sexual arousal, which is definitely adaptive):
1. Masturbation might remove old, worn-out, broken sperm from the reproductive tract. That would increase the fraction of healthy, speedy sperm, improving a male’s chance of becoming a father. “In humans, masturbation increases sperm quality (by promoting younger sperm) without affecting sperm numbers in the female reproductive tract,” notes biologist Jane Waterman of the University of Central Florida in a new paper in the journal PLoS One. As far back as 1993, biologists had observed that masturbating decreased the number of sperm a man delivered the next time he had sex with his partner, but not the number of sperm the woman retained. They concluded that “masturbation is a male strategy to increase sperm fitness.”
Research presented at a science meeting last year [ http://www.eshre.eu/01/default.aspx?pageid=757 ] offered support for the fitter-sperm idea. Ejaculating daily for seven days improved sperm quality as measured by the amount of DNA damage: levels of damage averaged 34 percent on a standard measurement index after three days’ abstinence, but after a week of ... um, non-abstinence, the level of damage dropped to 26 percent, in the “fair” range for sperm quality. Looking only at men whose sperm damage decreased (in a few, damage got worse for some reason), the average damage level fell to just under 23 percent—putting them in the “good” range. In addition, sperm motility rose significantly. Result: healthier and possibly more babies.
2. Masturbation might be a form of advertising. According to this idea, males that engage in autoeroticism signal to possible mates as well as competitors how much they have to offer. “Males may advertise their high quality,” explains Waterman, “signaling that they have high quantities of sperm and can afford to waste some.” Result: more mating, more babies, more families. We hasten to add that masturbation as advertising does not apply (we really, really hope) to humans.
3. Masturbation might be a sort of victory lap. Some animals masturbate after they mate. Since other members of a group know this, then masturbation signifies that the male engaging in this behavior was the chosen partner of other females. Females who are still shopping for a mate might be inspired by that information to copy their choice, as in, “if he was good enough for her ...” Result: more mating, more babies.
4. Masturbation can serve a hygiene function. According to this idea, males engage in autoeroticism because it cleans the reproductive tract and reduces the chance of acquiring a sexually transmitted disease from a female that he mated with and who had other recent partners. Result: a lower incidence of STDs, better sexual hygiene, more mating, more babies.
The STD function is what Waterman inferred about masturbation after she spent 2,000 (!) hours observing the Cape ground squirrel (Xerus inauris) of Namibia. As she explains in PLoS One, “an oral masturbation was recorded when a male sat with head lowered and an erect penis in his mouth, being stimulated with both mouth (fellatio) and forepaws (masturbation), while the lower torso moved forward and backwards in thrusting motions, finally culminating in an apparent ejaculation.” The behavior was much more frequent on days when females were fertile, and mostly occurred after mating. That would seem odd, since it wastes huge numbers of sperm just when they have the best chance of finding a willing egg. Odd, too, is the observation that males masturbated more when their mate had had a lot of other suitors (female Cape ground squirrels mate with up to 10 males in their three-hour fertile period). But there is one explanation that makes sense of a behavior that occurs after mating, and more often when a male has mated with a particularly promiscuous female: masturbation is a way for males to reduce the chance of infection, since saliva has antibacterial properties. Since STDs can destroy fertility, sexual hygiene through masturbation is a way for male squirrels to keep making babies.
And what about females? There have been far fewer observations of females masturbating in the wild, though bonobos are well known for this form of eroticism (and every other, it seems). One popular theory for why females might indulge, however, is incorrect—namely, the idea that orgasm (during or right after mating) might propel sperm to the egg. To the contrary, scientists reported [ http://www.springerlink.com/content/p4j5u02611713712/ ] in a 2002 paper, “vaginal and uterine contractions ... have been misinterpreted as powering rapid sperm transport to facilitate fertilization, but such fast transport would lead to the tubal deposition of noncapacitated, incompetent spermatozoa,” which would not lead to conception. Instead, primatologists conclude, in the case of females the purpose is simply to “produce enjoyable sensations [ http://books.google.com/books?id=oW64qjzGv-AC&pg=PA104&lpg=PA104&dq=female+bonobo+masturbation&source=bl&ots=Kk9GOeC65o&sig=9L69eaoy2ZIq0qdxmCIwrNuu0Ps&hl=en&ei=vPStTKzxH8TJceOM0d4K&sa=X&oi=book_result&ct=result&resnum=5&ved=0CCUQ6AEwBA#v=onepage&q=female%20percent20bonobo%20percent20masturbation&f=false ]”.
All in all, and across species great and small, autoeroticism (at least among males) is a cornerstone of procreation and thus the formation of families. Were O’Donnell’s unscientific views of the practice to spread, it would be a worrisome threat to family values.
© 2010 Harman Newsweek LLC
http://www.newsweek.com/2010/10/07/why-masturbation-helps-procreation.html [with comments]
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Spanking the Monkey
October 4, 2010
Torah Kachur
Charming the Snake. Choking the Chicken. Freeing Willy. The amount of slang for masturbation with animal references should be seriously disconcerting. Except that a wide-range of animals including dogs, cats, horses, all apes, lions, bears... and the list ["Slate - Animals Maturbating: A YouTube Gallery", http://www.slate.com/id/2223013/slideshow/2223004/ ] goes on... have been found to Jack off. Included on the list are elephants, donkeys and walruses that manage to flog the bishop with their fins. Even birds have been shown to rub their cloaca against pretty much anything.
This phenomenon isn't restricted to males either - female organgutans were observed exhibiting inspiring creativity by fashioning home-made dildos from lianas. Female horses during breeding season will rub up against fence posts, barn doors and seemingly anything made of wood.
Discovering that a species can milk the moose is fun and entertaining and often awe-inspiring. You have to respect a macaque for committing 1-6% of its daily metabolism to producing ejaculate and the ability for 'self-directed oral sex' in a variety of mammals. But the bigger question is why? If masturbation is so widespread among all animals then it must provide an evolutionary advantage.
A new study has found ground squirrels [ http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0013060 ] can be added to the list of those that shake hands with the devil. Previous explanations to this blatant waste of sperm in and around a females oestrus period were that masturbation provided a way to display fertility to potential mates or as a deterrant to rivals.
In contrast, it was also thought that masturbation could provide a sexual release or as a way to refresh sperm. Studies done on the ground squirrles of Namibia concluded that masturbation was likely used as a method of cleansing the genitalia. This is likely species dependent when genitalia are more accessible to the environment and likely to be dirtier. In other words, they kept clean by getting down and dirty.
For most animals, the more likely reason for whacking off is that sperm quality improves the more a man pleasures his loins - a recent study [ http://www.eshre.eu/01/default.aspx?pageid=757 ] suggests that daily masturbation and ejaculation can reduce the amount of accumulated DNA damage in sperm by 12%. Therefore wasting sperm into a sock can actually improve the mobility of sperm and increase fertility. A continuation of this theory is the idea of sperm competition. This is when sperm from multiple males have a race to the egg and undergo various forms of chemical competition to see who gets to be the lucky shizz. Most women likely don't have sex with multiple males during their ovulatory phase... we aren't like the chimpanzee, where a single female chimp was observed to have sex with 50 male partners in a single day (ouch).
One consequence of shining the pole so often is that the testis enlarges to accomodate the demand for sperm. It's personal preference if this is desirable but there may be an evolutionary significance to larger balls. And that is the biggest balls gets the worm. There is precendent amongst several different species, including our ape cousins, that larger testes actually attract mates. Though it is unlikely that larger ball size relates to the desirability of a human male as most men don't go around showing off their packages.
The idea of refreshing sperm seems to account for the evolution of masturbation from turtles to donkeys. It is unclear if these species have hairy palms.
© 2010 Science in Seconds
http://www.scienceinseconds.com/blog/Spanking-the-Monkey [with comments]
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Greensburg, KS - 5/4/07
"Eternal vigilance is the price of Liberty."
from John Philpot Curran, Speech
upon the Right of Election, 1790
F6
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