by Unknown
‘Coca-Cola douches had become a part of contraceptive folklore during the 1950s and 1960s, when other birth-control methods were hard to come by,’ Anderson told New Scientist. ‘It was believed that the carbonic acid in Coke killed sperm, and the method came with its own “shake and shoot applicator”—the classic Coke bottle.’
To see if Coke really worked, Anderson, Umpierre and their colleague, gynaecologist Joe Hill, mixed four different types of Coke with sperm in test tubes. A minute later, all sperm were dead in the Diet Coke, but 41 per cent were still swimming in the just-introduced New Coke. But that’s not good enough, Anderson warned. Sperm ‘can make it into the cervical canal, out of reach of any douching solution, in seconds’—faster than anyone could shake and apply a bottle of Diet Coke.
The three researchers shared the chemistry prize with Chuang-Ye Hong of the Taipei Medical University in Taiwan and his colleagues, whose similar experiment found both Coca-Cola and its arch-rival Pepsi-Cola useless as spermicides.
But, even with cola as protection, you still need to be very careful whom you choose to kiss.
Read my lips
In 1993, the journal Nature suggested that the phrase ‘kiss and tell’ might take on a new meaning when it reported that after humans have done the kissing, bacteria and fungi do the telling. The article alleged that each of us has a different ‘lip fauna’, as individual as our fingerprints. When people kiss, there is a veritable battle of the bacteria as the two microscopic populations come into contact.
Close family members who touch frequently share many of the same skin bacteria, but a stranger has a totally different fauna.
The ‘locals’ eventually come out on top, as they are better suited to their environment. So, by comparing the ratios of ‘foreign’ and ‘native’ microbes remaining, scientists could not only tell who had been kissing whom but also when they kissed.
The techniques were devised for forensic work in legal cases involving bodily contact. But with the number of high-profile personages implicated in extramarital indiscretions, how long might it be before forensic scientists are called in to read their lips?
Scientists, we note with some pride, are prepared to ask the questions others only dare think about, or indeed do not even consider at all. Otherwise, how would we know that, instead of stunting your growth, this almost universal practice might actually be good for you…
Masturbating may protect against prostate cancer
It will make you go blind. It will make your palms grow hairy. Such myths about masturbation are largely a thing of the past. But research conducted in 2003 had even better news for young men: frequent self-pleasuring could protect against the most common kind of cancer.
A team in Australia led by Graham Giles of The Cancer Council Victoria in Melbourne asked 1079 men with prostate cancer to fill in a questionnaire detailing their sexual habits, and compared their responses with those of 1259 healthy men of the same age. The team concluded that the more men ejaculated between the ages of 20 and 50, the less likely they were to develop prostate cancer. The protective effect was greatest while men were in their twenties: those who had ejaculated more than five times per week in their twenties, for instance, were one-third less likely to develop aggressive prostate cancer later in life.
The results contradicted those of previous studies, which suggested that having had many sexual partners, or a high frequency of sexual activity, increased the risk of prostate cancer by up to 40 per cent. The key difference was that these earlier studies defined sexual activity as sexual intercourse, whereas the more recent study focused on the number of ejaculations, whether or not intercourse was involved.
The team speculated that infections caused by intercourse may increase the risk of prostate cancer. ‘Had we been able to remove ejaculations associated with sexual intercourse, there should have been an even stronger protective effect of other ejaculations,’ they suggested. ‘Men have many ways of using their prostate which do not involve women or other men,’ Giles added.
But why should ejaculating more often cut the risk of prostate cancer? The team speculated that ejaculation prevents carcinogens building up in the gland. The prostate, together with the seminal vesicles, secretes the bulk of the fluid in semen, which is rich in substances such as potassium, zinc, fructose and citric acid. Generating the fluid involves concentrating these components from the bloodstream up to 600-fold—and this could be where the trouble starts. Studies in dogs showed that carcinogens such as 3-methylcholanthrene, found in cigarette smoke, are also concentrated in prostate fluid. ‘It’s a prostatic stagnation hypothesis,’ said Giles. ‘The more you flush the ducts out, the less there is to hang around and damage the cells that line them.’
‘All these mechanisms are totally speculative,’ cautioned breast cancer expert Loren Lipworth of the International Epidemiology Institute in Rockville, Maryland.
But if the findings were ever confirmed, future health advice from doctors might no longer be restricted to diet and exercise. ‘Masturbation is part of people’s sexual repertoire,’ said Anthony Smith, deputy director of the Australian Research Centre in Sex, Health and Society at La Trobe University in Melbourne. ‘If these findings hold up, then it’s perfectly reasonable that men should be encouraged to masturbate,’ he said.
We later discovered that sex generally may help prevent prostate cancer.
Frequent ejaculation may protect against cancer
Frequent sexual intercourse and masturbation could protect men against a common form of cancer, suggested a 2004 study of the issue. The US study, which followed nearly 30,000 men over eight years, showed that those who ejaculated most frequently were significantly less likely to get prostate cancer. The results backed the findings of the Australian study cited above which asserted that masturbation was good for men.
In the US study, the group with the highest lifetime average of ejaculation—21 times per month—were a third less likely to develop the cancer than the reference group, who ejaculated four to seven times a month. Michael Leitzmann, at the National Cancer Institute in Bethesda, Maryland, and colleagues set out to test a long-held theory that suggested the opposite—that a higher ejaculation rate raises the risk of prostate cancer. ‘The good news is it is not related to an increased risk,’ he said. In fact, it ‘may be associated with a lower risk’.
‘It goes a long way to confirm the findings from our recent case-control study,’ said Graham Giles, who led the Australian study. He praised the study’s large size—including about 1500 cases of prostate cancer. Furthermore, it was the first study to begin by following thousands of healthy men. This ruled out some of the biases which might be introduced by asking men diagnosed with prostate cancer to recall their sexual behaviour retrospectively.
At the start of the study, the men filled in a history of their ejaculation frequency and then filled in further questionnaires every two years. Men of different ages varied in how often they ejaculated, so the team used a lifetime average for comparisons. Compared with the reference group who ejaculated four to seven times a month, ‘each increase of three ejaculations per week was associated with a 15 per cent decrease in the risk of prostate cancer’, said Leitzmann.
‘More than twelve ejaculations per month would start conferring the benefit—on average every second day or so,’ he said. However, whilst the findings were statistically significant, Leitzmann remained cautious. ‘I don’t believe at this point our research would warrant suggesting men should alter their sexual behaviour in order to modify their risk.’
A further caveat was that the benefit of ejaculation was less clear in relation to the most dangerous, metastasising form of prostate cancer, compared with the organ-confined or slow-growing types.
Giles noted that neither study examined ejaculation during the teenage years—which may be a crucial factor. But he said: ‘Although much more research remains to be done, the take-home message is that ejaculation is not harmful, and very probably protectiv
e of prostatic health—and it feels good!’
Sadly, research released in 2009 seems to have shown that the added protection only occurs if frequent ejaculation takes place in those aged 40 or over, which rather confuses the issue. Indeed, as was once thought, it is possible that prostate cancer may be more common in men who are sexually active at a young age. There was always bound to be a downside wasn’t there? Clearly, more research needs to be done to ascertain the true picture. All we can do is present the evidence and leave it in readers’ hands…And there’s something else you should think twice about doing too.
Oral sex linked to mouth cancer
Oral sex can lead to oral tumours. That was the conclusion of researchers who, in 2004, proved what had long been suspected—that the human papilloma virus can cause oral cancers.
The risk, thankfully, is tiny. Only around 1 in 10,000 people develop oral tumours each year, and most cases are probably caused by two other popular recreational pursuits: smoking and drinking. The researchers were not recommending any changes in behaviour.
The human papilloma virus (HPV), an extremely common sexually transmitted infection, had long been known to cause cervical cancers. Several small studies suggested it also plays a role in other cancers, including oral and anal cancers.
‘There has been tremendous interest for years on whether it has a role in other cancers. Many people were sceptical,’ said Raphael Viscidi, a virologist at Johns Hopkins University School of Medicine in Baltimore, Maryland, a member of the team which did the latest work.
The researchers, working for the International Agency for Research on Cancer in Lyon, France, compared 1670 participants who had oral cancer with 1732 healthy volunteers. The patients lived in Europe, Canada, Australia, Cuba and Sudan. HPV16, the strain seen most commonly in cervical cancer, was found in most of the oral cancers too. The people with oral cancers containing the HPV16 strain were three times as likely to report having had oral sex as those whose tumour did not contain HPV16. There was no difference between men and women in terms of how likely the virus was to be present in the cancers. The researchers thought both cunnilingus and fellatio could infect people’s mouths.
Patients with mouth cancer were also three times as likely to have antibodies against HPV as the healthy controls. For cancers of the back of the mouth, the link was even stronger.
Cancer specialist Newell Johnson of King’s College London agreed. ‘We have known for some time that there is a small but significant group of people with oral cancer whose disease cannot be blamed on decades of smoking and drinking, because they’re too young,’ he said. ‘In this group there must be another factor, and HPV and oral sex seems to be one likely explanation. This study provides the strongest evidence yet that this is the case.’
Genital HPV infections are common. At any one time, around a third of 25-year-old women in the US are infected. It is thought that only 10 per cent of infections involve cancer-causing strains, and that 95 per cent of women will get rid of the infection within a year. But even this does not explain why so few develop cancer.
And if you thought you’d had enough bad news, it turns out that the old adage about the bad guys and their girls really is true.
Bad guys really do get the most girls
Nice guys already knew it, and in 2008 two studies confirmed it: bad boys get the most girls. The finding may help explain why a nasty suite of antisocial personality traits known as the ‘dark triad’ persists in the human population, despite their potentially grave cultural costs.
The traits are the self-obsession of narcissism; the impulsive, thrill-seeking and callous behaviour of psychopaths; and the deceitful and exploitative nature of Machiavellianism. At their extreme, these traits would be highly detrimental for life in traditional human societies. People with these personalities risk being shunned by others and shut out of relationships, leaving them without a mate, hungry and vulnerable to predators. But being just slightly evil could have an upside: a prolific sex life, according to Peter Jonason at New Mexico State University in Las Cruces. ‘We have some evidence that the three traits are really the same thing and may represent a successful evolutionary strategy.’
Jonason and his colleagues subjected 200 college students to personality tests designed to rank them for each of the dark triad traits. They also asked about their attitudes to sexual relationships and about their sex lives, including how many partners they’d had and whether they were seeking brief affairs. High ‘dark triad’ scorers are more likely to try to poach other people’s partners for a brief affair. The study found that those who scored higher on the dark triad personality traits tended to have more partners and a greater desire for short-term relationships. But the correlation only held in males.
James Bond epitomises this set of traits, Jonason said. ‘He’s clearly disagreeable, very extroverted and likes trying new things—killing people, new women.’ Just as Bond seduces woman after woman, people with dark triad traits may be more successful with a quantity-style or shotgun approach to reproduction, even if they don’t stick around for parenting. ‘The strategy seems to have worked. We still have these traits,’ Jonason said.
This observation seemed to hold across cultures.
But questions remained as to its effectiveness. ‘They still have to explain why it hasn’t spread to everyone,’ said Matthew Keller of the University of Colorado in Boulder. ‘There must be some cost of the traits.’ One possibility, both Keller and Jonason suggested, is that the strategy is most successful when dark triad personalities are rare. Otherwise, others would become more wary and guarded.
But, finally, take comfort in the fact that bizarre sexuality is not confined to humans.
Female beetles have a thirst for sex
Buying a lady a drink to win her favour is a trick not confined to men. Some beetle females will mate simply to quench their thirst.
The bean weevil Callosobruchus maculatus feeds on dry pulses. With a diet like this, the male’s ejaculate is a valuable water source for females. In 2007, Martin Edvardsson at Uppsala University, Sweden, tested the idea that females tap into this by keeping them on dry beans with or without access to water. Females living on beans alone accepted more matings, presumably to secure the water in the seminal fluid.
Edvardsson said that the energy used to produce the ejaculate, which makes up a whopping 10 per cent of a male’s weight, is well spent. Once impregnated, females lose interest in sex—probably to avoid further injury from the male’s spiny penis. They are more likely to mate again if they are thirsty. ‘This is a massive investment for the male,’ Edvardsson said. ‘It buys them time before the females remate and their sperm have to compete with that of other males.’
Females with access to water lived on average for a day and a half longer than those without water. Since average lifespan is only around nine days, this makes quite a difference to the total number of eggs they can lay.
Turkey turn-ons
While researching the sexual behaviour of turkeys in the 1960s, Martin Schein and Edgar Hale of Pennsylvania State University discovered that male members of that species truly are not fussy. When placed in a room with a lifelike model of a female turkey, the birds mated with it as eagerly as they would the real thing.
Intrigued by this observation, Schein and Hale embarked on a series of experiments to determine the minimum stimulus it takes to excite a male turkey. This involved removing parts from the turkey model one by one until the male bird eventually lost interest. Tail, feet and wings—Schein and Hale removed them all, but still the clueless bird waddled up to the model, let out an amorous gobble, and tried to do his thing. Finally, only a head on a stick remained. The male turkey was still keen. In fact, it preferred a head on a stick to a headless body.
The researchers speculated that the males’ head fixation stemmed from the mechanics of turkey mating. When a male turkey mounts a female, he is so much larger than her that he covers her completely, except for her head. There
fore, they suggested, it is her head that serves as his focus of erotic attention.
Schein and Hale then went on to investigate how minimal they could make the head before it failed to excite the turkey. They discovered that a freshly severed head on a stick worked best. Next in order of preference was a dried-out male head, followed by a two-year-old ‘discolored, withered, and hard’ female head. Last place went to a plain balsa wood head, but even that elicited a sexual response. They published their results in 1965 in a book called Sex and Behavior.
Before we humans snigger at the sexual predilections of turkeys, we should remember that our species stands at the summit of the bestial pyramid of the perverse. Humans will attempt to mate with almost anything. A case in point is Thomas Granger, the teenage boy who in 1642 became one of the first people to be executed in puritan New England. His crime? He had sex with a turkey.
Double the fun
Male lizards and snakes have to make a choice when they mate: which penis should they use? They have two. One is connected to their right testis, and one to their left. In 1990, two biologists from the US found that some lizards alternate their penises when each is depleted of sperm. In this way, they maximise their chance of fertilising a female. Richard Torkaz and Joseph Slowinski of Miami University studied the lizard Anolis carolinensis. They found that the penis a lizard used depended on which they had used last time they mated, and how long ago they had last used it.
Torkaz and Slowinski believed that such behaviour could be explained by ‘sperm competition’. Zoologists have realised that competition for a female’s favour does not simply involve fights among males or displays of bright plumage; it can continue inside the female’s reproductive tract as sperms compete to be first to the egg.
