History of Circumcision

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Introduction

Does circumcision have a history?

There is no single history of circumcision. A number of pre-literate societies adopted cutting procedures on the genitals of males and females (usually as children), at different times and for different reasons. At the end of the nineteenth century Britain (followed by its white colonies) and the USA took it up as a “health” measure for infants and young boys. Today the most likely reason for a male to be circumcised is because his parents are Muslims or Americans: together, these two categories account for the vast bulk of the 25 per cent or so of the world’s male population who are circumcised.

The two sorts of circumcision – ritual and medical – thus have different histories, though in recent times they have influenced each other. Defenders of ritual circumcision point to the health benefits claimed by those who perform it for medical reasons; while those who perform it for medical reasons try to justify it as an ancient operation, performed by many different cultures. The whole thing ends up rather circular. When doubt is thrown on the medical benefits of circumcision, supporters of the operation stress its cultural importance; when its cultural necessity is questioned, they stress the alleged health benefits.

Although circumcision is not mentioned in the Koran and the prophet Mohammed did not name it as a pillar of the faith, Muslims inherited the custom from the tribal ritual of the desert Arabs. A boy born to Muslim parents may be circumcised any time between the ages of a few days and twelve years, though the traditional age is eight years. Yet Islam places no obligation on parents to circumcise their children: the prophet described circumcision as meritorious in both men and women, though required for neither; and he said nothing about parents having to do it to their sons or daughters, though these days many do it. Some Islamic societies (Egypt, the Sudan, Somalia, parts of Malaysia and Indonesia, for example) also practise circumcision of girls, though this is far less frequent than the operation on boys.

For a boy born to American parents, the reason he is circumcised is because the USA, alone among English-speaking countries, has retained the nineteenth century practice of neonatal male circumcision as a heath precaution. Medically justified circumcision arose in the Anglo-American world in late Victorian times; but while Britain lost faith in the procedure in the 1940s and dropped it in the 1950s, to be followed by the British dominions (Australia, Canada and New Zealand) at a generation’s delay, the incidence of circumcision in the USA continued to rise until the 1970s, when it affected as many of 90 per cent of males. Since then the rate has declined to between 50 and 60 per cent, but it has been a very slow process, despite repeated advice from the American Academy of Pediatrics that there is no significant medical benefit to be gained.

How did this strange situation come about?

Sovereignty of the individual

… every Man has a Property in his own Person. This no Body but himself has any Right to but himself. The Labour of his Body, and the work of his Hands, we may say, are properly his.

— John Locke, An essay concerning the true, original extent and end of civil government (Second treatise on government), Book II, Chapter V

The demonisation of the foreskin

To overturn millennia of tradition, both religious and secular, in favour of the normal and unaltered body was a slow and laborious process. The odd medico (usually a surgeon) can be heard muttering about the “benefits” of amputating the foreskin as early as the mid-eighteenth century, but it was not until the Victorian age - notorious for its anti-sexual impulses – that the mutterings grew to a chorus. The crucial step in forcing the acceptance of preventive circumcision (that is, the amputation of a normal body part in the absence of any medical indication or problem) was to blacken the reputation of the foreskin and blame it for the most feared diseases of the period. As Geoffrey Miller has pointed out, the essential precondition for routine circumcision was the demonization of the foreskin as a source of moral and physical decay.

Between the mid-eighteenth and the late nineteenth century, but only in English-speaking countries, the status of the male foreskin fell disastrously. It was transformed from “the best of your property”, as a popular rhyme of the period put it, and an adornment which brought pleasure to its owner and his partners, to “a useless bit of flesh”, an enemy of man, and a “harbour for filth”, as Dr Remondino and other scissors-happy doctors of the late Victorian period asserted. It is hard to think of any body part whose standing fell so far and so rapidly, nor one which came to be treated with such savage hostility; even today in countries with a history of routine circumcision doctors seem to regard the foreskin as guilty until proven innocent. Yet, as the Canadian pathologists Chris Cold and John Taylor point out, the prepuce has been a prominent feature of the external genitals of all primate species for 65 million years, and the species in which it has developed most luxuriantly is precisely the one which has been most successful in the struggle for existence; despite this, since the nineteenth century it has been “the most vilified normal anatomical structure of the human body”.

But aside from calling the foreskin nasty names, have the supporters of involuntary circumcision really made much of a case for their favourite surgery? It is not, after all, the opponents of routine male circumcision who need to make a case against the procedure, but its supporters who must prove its necessity: they need to explain why a natural part of the human body, and one common to all primates, is so dangerous that it must be amputated before a baby can talk, crawl or do anything much except scream. As both William Paley and Charles Darwin appreciated, what has naturally evolved must be presumed to be beneficial or harmless unless there is overwhelming evidence to the contrary.

In all cases [of masturbation] circumcision is undoubtedly the physician's closest friend and ally, offering as it does a certain means of alleviation and pronounced benefit …. Those cases in which the glans presents a moist, semi-oily appearance … long thickened foreskin, pliant and giving, large and often tortuous dorsal veins, go to make up a picture that is exceedingly tempting to the surgeon's scissors.

- Dr Edgar Spratling, "Masturbation in the adult", Medical Record, Vol. 48, 1895, p. 443

What is the foreskin?

The penis consists of several major parts, but one useful way of looking at it is to divide it into an erectile portion (the part that gets stiff) and a non-erectile portion (the part that does not). The foreskin is the non-erectile portion. A more conventional definition would be to describe it as the soft, sensitive double-fold of tissue which covers the lower half of the penis shaft, extends in a sleeve over the head (glans) and usually ends in a tapering nozzle or spout. The outer layer is tender skin, the inner layer a sensitive mucous membrane. There is no agreed anatomical definition about where the foreskin ends and the skin of the penis shaft begins, and hence no exact surgical definition of what circumcision is meant to remove. As a consequence, the amount of tissue cut off by the operation is highly variable (some doctors take more, some less), but a typical circumcision carried out in a western hospital will remove about 50 per cent of the surface tissue of the penis.

The foreskin is not just a flap of skin, but a complex web of mucous membrane, muscle fibres, blood vessels and nerves: in fact, it supports one of the densest concentrations of nerves in the whole body. The underside of the penis (just beneath the glans) is called the fraenum, and this carries ridged bands which are densely packed with fine-touch nerve receptors and a very rich blood supply. The main nerve supplying the penis goes down to the end and then doubles back, allowing the foreskin to slide backwards and forwards, and showing that this is exactly what it evolved to be able to do. To operate at its best, the penis is meant to be covered with a mobile sheath of responsive flesh.

Further information:

Development of the normal foreskin

Anatomy of the adult penis

What is routine male circumcision?

Circumcision is the surgical amputation of a some or all of this tissue. By routine male circumcision we mean the removal of the foreskin from the penis of normal male babies or boys, on the decision of adults (usually parents or guardians), without the boy's consent, and in the absence of any genuine medical indication, and particularly in the absence of the sort of critical injury, malformation or disease which would be required for the amputation of any other part of the body without the subject's consent. In the past the procedure was referred to as Routine Neonatal Circumcision or Routine Infant Circumcision, abbreviated here as RNC.

Strictly speaking, RNC is no longer practised even in places where it was once common, since most doctors are opposed to the practice and only do it in response to parental insistence. Each case today is thus an individual decision, not a matter of mere routine. In the heydey of circumcision in the 1950s, doctors pressured parents to agree to have their baby boys circumcised and would automatically do it unless they strenuously objected; sometimes they did it without even parental consent, as still occurs in the United Sates from time to time. The essential elements of routine (medically unnecessary) circumcision as practised today are (1) decision by adults; (2) absence of medical indication or need; (3) lack of consent on the part of the boy.

Why is it an issue all of a sudden?

Although Britain abandoned RNC in the 1950s, New Zealand in the 1960s, Australia in the 1980s (with very little fuss or controversy), and Canada in the 1990s, the issue has suddenly become topical and controversial. A few die-hard circumcision enthusiasts and medical researchers, mainly from the USA and other cultures where routine male circumcision is the rule, are making strident claims for the protective effect of circumcision against a number of diseases which defy normal control strategies, and particularly the one for which there is still no cure and of which everybody is afraid: AIDS. They attempt to exploit this fear by demanding widespread (indeed, universal) circumcision of male infants as a public health measure, on the feeble and misleading analogy that it is just like immunisation, and thus the sort of harmless and effective medical intervention which should be made compulsory. The main objective of this propaganda is to halt the decline of RNC in the USA and to revive it in Australia, Canada and Britain.

Recent extravagant claims that circumcison is the long-desired "silver bullet" against AIDS are mainly wish fulfilment: they reflect the wish for an effective means of halting the spread of AIDS, and they express the wish of circumcision enthusiasts to have an unanswerable reason to circumcise as many boys as possible. In South Africa, experts in public health cast doubt on the first hope, and question the ethics of the second.

The cat which keeps coming back

Circumcision was a Victorian medical fad which should have gone out with neck-to-knee bathing costumes, phrenology and the idea that children should be seen and not heard. Instead, a small band of medical researchers and moral fanatics keep coming up with new reasons for doing it. First there was the claim that it would stop masturbation and the imaginary disease of spermatorrhoea. Then it was suggested that it would protect men from syphilis. Then doctors forgot that all baby boys have a tight and non-retractable foreskin (phimosis) and declared that the natural condition of the infant penis was a pathological abnormality requiring urgent surgical correction. After that it was asserted that circumcision would give immunity to cancer of the penis in men and of the cervix in women. Some doctors seriously believed that circumcision would cure various forms of muscular paralysis, brass poisoning and whooping cough; others claimed it would prevent tuberculosis, polio, epilepsy and wet dreams. Then there was a lot of vague talk about hygiene, as though boys and men were too stupid to wash themselves, and ridiculous references to embarrassment in locker rooms.

At no time did more than a handful men choose to have themselves circumcised; it was always something to done to babies and boys without their agreement or permission.

In the 1990s the myth about syphilis was revived in a new form: that uncircumcised men having unprotected intercourse with an infected partner have a higher risk of catching HIV-AIDS (and that therefore all boys should be circumcised soon after birth). Most recently there has been an attempt to resuscitate the old claim (dating from the 1930s, refuted by studies in the 1960s and 70s) that early male circumcision is necessary so as reduce the incidence of cervical cancer in any female partners they may later consort with.

One by one these claims for the harmfulness of the foreskin and the benefits of its amputation have been proven false or misguided, but new reasons keep being invented.

Personal freedom

The sole end for which mankind are warranted, individually or collectively, in interfering with the liberty of action of any of their number, is self-protection. The only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others. His own good, either physical or moral, is not a sufficient arrant. He cannot rightfully be compelled to do or forbear because it will be better for him to do so, because it will make him happier, because, in the opinion of others, to do so would be wise, or even right. … The only part of the conduct of any one, for which he is amenable to society, is that which concerns others. In the part which merely concerns himself, his independence is, of right, absolute. Over himself, over his own body and mid, the individual is sovereign.

— John Stuart Mill, On Liberty

Burden of proof

It is not the opponents of routine male circumcision who need to make a case against the procedure, but its supporters who must prove its necessity: they need to explain why a natural part of the human body, and one common to all primates, is so dangerous that it must be amputated before a baby can talk, crawl or do anything much except scream. But since the operation has become entrenched in the medical culture of English-speaking countries over the past 120 years, it has come to be seen as reasonable, customary or even normal. As the sorcerer's apprentice found to his alarm and cost, starting a practice ("seemed like a good idea at the time …") is often much easier than stopping it. All you need is to get a majority of males over two generations circumcised, and the circumcised penis will come to be seen as both normal and normative. The main reason for circumcision of children is a population of circumcised adults.

Advocates of RNC particularly have to

demonstrate (1) that the benefits of the operation significantly outweigh (a) the risks of the procedure; (b) the injury inflicted; (c) the disadvantages of being deprived of the normal anatomy of the penis; and (2) that the operation must be done before the child is able to give legal consent;
explain how a part of the body which has evolved over millions of years could be pathogenic (disease-producing) and must be removed to ensure a normal level of health.

Human evolution

Advocates of RNC have never been able to explain why all primates (monkeys, chimps etc) have foreskins, or how humans became the most successful mammal on the planet while carrying this supposedly pathogenic burden. For 99 per cent of the million or so years during which modern humans have prospered, males have lived and died with their foreskins intact, and in that time our species managed to colonise just about every corner of the earth. Perhaps the foreskin was a factor in that triumph. There is good evidence that the human foreskin became longer, more luxuriant and more richly networked with sensory nerves than those of our near relatives, suggesting that it must have conferred a selective advantage: the more foreskin you had, the more offspring you left behind, and the more your extra-foreskin genes spread through the population. [1] This could not have happened if the foreskin had been as troublesome as its enemies claim: what has naturally evolved must be presumed to be beneficial or harmless unless there is overwhelming evidence to the contrary. [2]

An individual choice

The only freedom which deserves the name, is that of pursuing our own good in our own way, so long as we do not attempt to deprive others of theirs, or impede their efforts to obtain it. Each is the proper guardian of his own health, whether bodily, or mental and spiritual.

— John Stuart Mill, On Liberty

Trying to come up with the goods

It is this proof that circumcision advocates are obliged to provide, and which they have been struggling unsuccessfully to manufacture since the 1850s (when Jonathan Hutchinson announced that his statistics showed that circumcised men were all but immune to syphilis). The world is still waiting for them to make a convincing case. Although there have been mountains of reports and studies (more than anybody could read in a lifetime), the issue is still inconclusive. The most that even a scaremongering evangelist like the Queensland GP Terry Russell can say is that RNC "may reduce the risk of STDs (syphilis, gonorrhoea, herpes and candida) and carcinoma of the cervix in female partners", as well as phimosis, paraphimosis, HIV-AIDS, neonatal UTIs and carcinoma of the penis”. [3] These are the traditional Victorian excuses, but they are not good enough: "may" is not much different from "may not". Nor is it enough to claim that circumcision will reduce the risk if the risk is non-existent or infinitesimal in the first place. The issue is not whether circumcision can or might offer protection against these disease, but whether it is a necessary measure of protection, and so necessary that it must be performed without consent. It's pretty ridiculous, after all, to amputate part of the penis merely in the hope of reducing the risk of a minor infection, such as chlamydia, when the infection can be cleared up with a single pill.

Further information on HIV-AIDS and cervical cancer.

Australia's other prominent crusader for RNC, Professor Brian Morris, cites several studies which purport to show a higher incidence of gonorrhoea and syphilis among uncut males and reaches the dithering conclusions that (1) "based on the bulk of evidence it would seem that at least some STDs could be more common in uncircumcised males under some circumstances"; but that (2) "there may be little difference in most STDs between those with and those without a foreskin". [4] That's really helpful.

Can these guys be serious? They want to circumcise all boys at birth because retention of the foreskin "may" increase the risk of their getting a few diseases they most likely would not get anyway; most of which are curable; and which, even if they did get them, do not strike until many years later. Except for infantile UTIs (which are usually cured easily by antibiotics), there is plenty of time for a boy to reach maturity and make his own assessment of the risks and choose the best means, for him, of managing them. To make a convincing case for RNC Russell, Morris and Co must do much better than they have done so far: we need proof that that if the foreskin is not cut off urgently the child will get seriously ill or die before he is old enough to make his own health decisions. Nothing like this has ever been achieved by the circumcision lobby, or even seriously attempted. Statistics are not available, but it is quite likely that more boys under the age of eighteen die as a result of circumcision, or its complications, than from any of the diseases circumcision is supposed to protect them against. Certainly this is true in South Africa, where scores of boys each year die as a result of tribal circumcision and hundreds are seriously injured.

There are no proven cases of an infant, child or adult becoming sick or dyng because he had not been circumcised; but here are thousands of recorded cases where infants, children and men have been seriously injured, become sick or have died as a direct result of circumcision.

Further information on complications and on deaths and recent news items

Medical scaremongering

Both Dr Russell and Professor Morris are frequently seen in the media urging parents to have their boys circumcised, and much of their routine is just a long list of nasty diseases, designed to terrify people into seeking urgent medical aid. How different it is from the rantings of a Victorian quack is a matter of personal judgement. In 1891 Dr Peter Charles Remondino wrote:

"The prepuce seems to exercise a malign influence in the most distant and apparently unconnected manner; where, like some of the evil genii or sprites in the Arabian tales, it can reach from afar the object of its malignity, striking him down unawares in the most unaccountable manner; making him a victim to all manner of ills, sufferings and tribulations; unfitting him for marriage or the cares of business; making him miserable and an object of continual scolding and punishment in childhood, through its worriments and nocturnal enuresis; later on, beginning to affect him with all kinds of physical distortions and ailments, nocturnal pollutions, and other conditions calculated to weaken him physically, mentally, and morally; to land him, perchance, in jail or even in a lunatic asylum." [5]

Drs Russell and Morris are radicals and extremists: most doctors the world over (except for Islamic countries and parts of the USA) are opposed to RNC or undecided on the issue, and the Royal Australasian College of Physicians has recently issued yet another statement against the practice . The truth is that RNC has never been supported by more than a small fraction of the world's medical establishment and remains a controversial and unproven therapy. Back in the 1890s an early opponent of RNC noted this confusion and uncertainty, not only over the risks and touted benefits of the operation but when and how to do it, how much tissue to excise, how to stop bleeding etc, and asked: "Where doctors differ, who shall decide?" [6]

There can be only one answer to that question.

References

1. J.R.Taylor, A.P. Lockwood and A.J.Taylor, “The prepuce: specialized mucosa of the penis and its loss to circumcision”, British Journal of Urology, Vol. 77,1996, pp. 291-295; C.J. Cold and J.R. Taylor, "The prepuce", BJU International, Vol. 83, Supplement 1 (January) 1999, pp. 34-44; C.J. Cold and K.A. McGrath, "Anatomy and histology of the penile and clitoral prepuce in primates: Evolutionary perspective of specialised sensory tissue in the external genitalia", in George C. Denniston, Frederick Hodges and Marilyn Milos (eds), Male and female circumcision: Medical, legal and ethical considerations in pediatric practice (New York and London, Kluwer Academic/Plenum Publishers, 1999), pp. 19-30

2. The argument holds even if you believe in the creationist account of human origins. If God created men with a foreskin it must be presumed that He intended them to have one.

3. Terry Russell, "Debate: Male circumcision remains a valid procedure - Yes", Australian Doctor, 24 May 1996, p. 54

4. Brian Morris, In favour of circumcision (Sydney 1999), pp. 38 and 39. See the scathing review by Basil Donovan in Venereology, Vol. 12 (1999), pp. 68-9. Professor Donovan describes Morris as "a man on a mission to rid the world of the male foreskin" and some of his claims as "so dangerous" that the publishers ought to withdraw the book.

5. P.C. Remondino, History of circumcision from the earliest times to the present: Moral and physical reasons for its performance (Philadelphia and London 1891), pp. 54-5

6. Herbert Snow, The barbarity of circumcision as a remedy for congenital phimosis (London 1890), p. 32

Why does this Victorian invention persist?

The reasons for the persistence of routine circumcision (that is, medically unnecessary circumcision of normal infants or boys at the request of parents) have been much debated. Only a few old fashioned fanatics seriously believe the various “health justifications”, and the tendency is to see the operation as a cultural practice, not very different from a tribal ritual, which needs to be explained by sociologists and cultural theorists rather than doctors. As a result of US influence after the Korean war, circumcision also became prevalent in South Korea, though performed on boys between the ages of ten and thirteen rather than at birth. The continuing popularity of circumcision among American doctors is also connected with strong financial incentives for performing it, with the result that the USA remains a kind of centre for infection: American medical journals continue to publish articles extolling the health advantages of circumcision and minimising the adverse effects, and these are eagerly quoted by crusaders for circumcision in other countries. The vast weight of the American medical industry ensures that its cultural values have far more influence than their scientific value warrants.

The strongest focus of this website will be on the medically rationalised variety of circumcision in Anglophone countries, as it emerged in the late nineteenth century, and as it faded away towards the end of the twentieth, but it will also offer leads on the other forms.

Myths of smegma

Despite the importance of avoiding smegma so frequently stressed by enthusiasts for routine circumcision, there is no evidence at all that smegma is harmful. Why would it be? It's just a natural secretion like saliva, found in the genitals of both males and females.

The carcinogenicity of smegma: Debunking a myth

RS Van Howe,* FM Hodges‡
*Department of Pediatrics, Michigan State University School of Human Medicine, Marquette, MI and ‡Berkeley, CA, USA, in Journal of the European Academy of Dermatology and Venereology, Vol. 20, 2006, pp. 1046-1054

Abstract

Background: Smegma is widely believed to cause penile, cervical and prostate cancer. This nearly ubiquitous myth continues to permeate the medical literature despite a lack of valid supportive evidence.

Methods: A historical perspective of medical ideas pertaining to smegma is provided, and the original studies in both animals and humans are reanalysed using the appropriate statistical methods.

Results: Evidence supporting the role of smegma as a carcinogen is found wanting.

Conclusions: Assertions that smegma is carcinogenic cannot be justified on scientific grounds.

Extract from the conclusion

The evidence does not support the theory that smegma is a cause of genital cancer.

The smegma theory of disease was best stated by Boczko and Freed: "Smegma, a sterol, produced by Tyson’s glands in the epithelium of the retroglandular sulcus, has been implicated as the causative agent. It may be converted to a carcinogen by the action of the Mycobacterium smegmatis." [69] From the medical literature we have found that smegma is not a sterol, that there are no Tyson’s glands, that smegma is not converted to a carcinogen by M. smegmatis, and that M. smegmatis is not part of the normal genital flora. The myth is sustained only by its popularity among circumcision advocates.

Some have extrapolated the smegma theory by hypothesizing that men with inadequate circumcisions may be at risk for cancer because smegma can accumulate under any foreskin remnants. [70] In similar fashion, Abraham Ravish expanded the smegma theory to indict smegma as the cause of prostate cancer by travelling upstream through the urethra to invade the prostate gland. [71] Davis-Daneshfar and Trueb speculated that chronic infection with M. smegmatis is the cause of plasma cell (Zoon’s) balanitis, [72] but Yoganathan et al. could not isolate the organism in any of their cases. [73]

Some have shown an unwillingness to abandon the smegma theory. When it was postulated that sperm proteins caused cervical cancer, it was the smegma mixing with the sperm proteins that were to blame. [74] When diaphragm use was found to decrease cervical cancer, it was postulated that it provided a barrier to contact with smegma. [75] When it was clear that cervical cancer resulted from a viral infection, some still postulated that smegma was a necessary part for the viral exposure to be carcinogenic. [45] Those promoting the ‘cocoon’ theory prefer to think of smegma as a cofactor in the development of penile cancer.

There are two reasons to dismiss this speculation. First, there is no scientific evidence to support the assertion. Second, it is analogous to declaring saliva a cofactor in the development of lip cancer in those who chew tobacco. Both saliva and smegma are bodily fluids that serve a function and, like any other bodily fluid, are present in organs than can develop a malignancy. The purpose of the scientific method is to distinguish between wishful thinking, strongly held pinion, and provable fact. The smegma theory of disease, which began as wishful thinking on the part of circumcision zealots such as Abraham Wolbarst and Abraham Ravich, has evolved into irrefutable dogma, but as modern physicians, we need to recognize that, until proved otherwise, smegma is harmless.

References

69. Boczko S, Freed S. Penile carcinoma in circumcised males. N Y State J Med 1979; 79: 1903–1904.

70. Culp D. Penile cancer. J Iowa Med Soc 1973; 63: 201–202.

71. Ravich A, Ravich RA. Prophylaxis of cancer of the prostate, penis and cervix by circumcision. N Y J Med 1951; 51: 1519– 1520.

72. Davis-Daneshfar A, Trueb RM. Bowen’s disease of the glans penis (erythroplasia of Queyrat) in plasma cell balanitis. Cutis 2000; 65: 395–398.

73. Yoganathan S, Bohl TG, Mason G. Plasma cell balanitis and vulvitis (of Zoon). A study of 10 cases. J Reprod Med 1994; 39: 939–944.

74. Sandler B. Sperm basic proteins in cervical carcinogenesis. Lancet 1978; 2: 208–209.

75. Sandler B. Contraceptives and cervical carcinoma. Br Med J 1969; 1: 356–357.

Full text available from CIRP.

Why mice don't live in the foreskins of horses

The article by Boczko and Freed relied heavily on an eccentric experiment from 1947 in which A. Plaut and A. C. Kohn-Speyer tried to induce cancer in mice by doses of smegma harvested from horses. Despite persistent applications, it appears that they were successful in producing cancerous lesions in only about 60 of 400 victims, and I say “appears” because the presentation of their results is so confusing that it is very difficult to work out just what the results were. They also reported that up to 500 days the smegma-treated mice actually fared better than those who missed out: a survival rate of 47% and 30% respectively. Had they stopped the experiment at that point they would have been forced to conclude that horse smegma boosted mouse health. The most one can say about this preposterous exercise is that it explains one of the great puzzles of zoology: why mice don't live inside equine prepuces.

Plaut A, Kohn-Speyer AC. Carcinogenic action of smegma. Science 1947; 105: 391–392.