May 15, 2021
Updated January 3, 2022
• A shipment of viagra was stolen yesterday. Police are on the lookout for a gang of hardened criminals. • Q: What human body part is long, hard, most useful when erect, and contains the letters e, i, n, p, and s? A: The spine.
All kidding aside, the penile erection plays an essential role in sexual activities. Few people understand the physiological mechanics that cause erections. And circumcision opponents have made a number of claims related to erections. In this article we’ll, uh, rise to the challenge and address these topics.
How an erection happens
The corpora cavernosa are two chambers that run from the glans (head) of the penis into the pelvis. They contain a series of blood vessels shaped like a sponge.
"An erection begins with sensory and mental stimulation. During sexual arousal, nerve messages begin to stimulate the penis. Impulses from the brain and local nerves cause the muscles of the corpora cavernosa to relax, allowing blood to flow in and fill the open spaces. The blood creates pressure in the corpora cavernosa, making the penis expand and creating an erection.” 
Let’s take a look at three popular circumcision myths related to erections.
MYTH #1: Circumcision causes erectile dysfunction.
Erectile dysfunction (ED) is the inability to achieve or sustain an erection suitable for sexual intercourse. Approximately 10% of adult males suffer from long term ED.
There are several possible causes of ED. They include: vascular disease, neurological disorders, psychological states, chronic illness, trauma, stress, certain medications, high blood pressure, excess body weight, sleep disorders, low testosterone, smoking, alcohol consumption, and drug use.  
The myth that circumcision increases the risk that a man will suffer from ED may have originated from a 2011 study by Dan Bollinger and Robert Van Howe. Based on the results of an online survey, the researchers found that circumcised men were 4.53 times more likely than uncircumcised men to use a drug for erectile dysfunction. 
Both researchers are longtime anti-circumcision activists. Bollinger is the author of the infamous “117 deaths” study. As of 2022 he is vice chair of the Intact America board of directors. While researcher bias doesn’t automatically discredit a study, readers should be particularly skeptical when considering a paper in which data, analysis, and conclusions support the researcher‘s partisan agenda.
Study participants were invited to visit a men’s health website to complete the survey. Thus the results may have been skewed by self-selection bias. The authors cautioned, “We hope readers will heed our advice in not extrapolating these results to the general population from this preliminary investigation...” The Bollinger-Van Howe study conflicts with a 2008 study of 2,784 young men in Kenya. Researcher John Krieger reported, "Adult male circumcision was not associated with sexual dysfunction.”  (As Krieger supports circumcision, one should treat the results with similar skepticism.) A 2013 study of 10,000 men in Germany also found no correlation between circumcision and erectile dysfunction. 
For further analysis of the Bollinger-Van Howe study, see this post on the CircFacts website:
MYTH #2: Before the procedure a doctor must stimulate a baby‘s penis to erection.
Some circumcision opponents say that a baby boy’s first sexual experience occurs during the circumcision procedure. They claim that the circumcision practitioner deliberately fiddles with the baby’s penis in order to cause an erection. They may cite a 1904 book by Jacob Snowman, The Surgery of Ritual Circumcision.  (Snowman was a British doctor and mohel who would later be called in 1948 to circumcise Prince Charles.) Snowman wrote, "When the penis of an infant is in a state of erection the operation of circumcision can be more easily performed and the dressing more efficiently applied. The manipulation of the organ necessary to grasp the prepuce is generally sufficient to stimulate the increased blood supply requisite for an erection."
We were unable to find anything in the medical literature written in the past century to support Snowman’s assertion. A World Health Organization manual for early infant circumcision identifies infancy as an ideal time for the procedure precisely because “the procedure is not complicated by erections, which can be problematic in adolescent boys and men.” 
That said, it is normal for infant boys to get erections, often during diaper changes. A Boston, Mass. urologist explained, “In newborns, there is a surge of testosterone that occurs in the first few months of life which may cause erections.” 
While researching this subject we received conflicting reports on whether an erection would make the procedure easier or more difficult. A medical practitioner  explained that “erections actually make the procedure more difficult to perform because it changes the landmarks and makes the skin tighter and more difficult to manipulate.” But a religious practitioner  said that an erect penis would be easier to circumcise. He told us that while there is no deliberate intent to cause an erection, it can happen, for example when cleaning the penis with a gauze pad.
Based on the above, we grade this myth MOSTLY FALSE.
MYTH #3: A function of the foreskin is to make the glans a visual signal of sexual arousal.
We examined this myth four years ago in our analysis of the 16 foreskin functions. The argument goes as follows:
During the normal, flaccid state the glans of an uncircumcised man is covered by the foreskin. As sexual arousal begins the foreskin will retract to expose his glans. When a partner sees the glans, she knows that the man is aroused. By contrast the glans of a circumcised man is always exposed, making it appear as if he is always sexually aroused. Therefore a partner cannot determine just by seeing the glans whether the man is actually aroused.
This “function” is laughably ridiculous. With one ironic exception,  we are unaware of any culture - even among the most foreskin-friendly countries on earth - where glans visibility is considered a sign of sexual arousal. An erection is the universally recognized sign of male sexual arousal. An erection is the sign irrespective of a man’s circumcision status. And a partner can detect an erection regardless of whether the man is naked or fully clothed. Any additional “sign” would be redundant.
An erection is caused by increased blood flow into the penis. There is no strong evidence that circumcision increases the risk of erectile dysfunction. While a baby can have an erection, doctors do not deliberately stimulate a baby’s penis. An erection is the universal sign of male sexual arousal.
 "Erection Ejaculation: How It Occurs"; Cleveland Clinic; last reviewed November 27, 2020
 "Erectile Dysfunction"; Cleveland Clinic; last reviewed October 14, 2019
 Hims; "11 tips for a stronger erection"; Philly Voice; March 26, 2019
 Dan Bollinger and Robert S Van Howe MD; “Alexithymia and Circumcision Trauma: A Preliminary Investigation"; International Journal of Men's Health, pp 84-195; July, 2011
 JN Krieger; "Adult Male Circumcision: Effects on Sexual Function and Sexual Satisfaction in Kisumu, Kenya"; J Sex Med; November, 2008
 B Hoshke et al; "Male circumcision is not associated with an increased prevalence of erectile dysfunction: results of the Cottbus 10,000-men survey"; Der Urolege; April 2013
 Jacob Snowman MD; "The Surgery of Ritual Circumcision"; Medical Board of the Initiation Society, p 26; January 1, 1904
 "Manual for early infant male circumcision under local anaesthesia"; World Health Organization and Jhpiego; February, 2011
 Erin McNamara MD; "Private Parts: Things moms of newborn and toddler boys need to know"; Boston Children's Hospital; November 17, 2016
 Circumcision specialists spoke with us for this article on the condition of anonymity.
 Richie Gupta et al; "A Novel Procedure of Prepuce Reconstruction Contomized to the Religious Needs of Some Individuals"; Indian Journal of Plastic Surgery; April 2021. "There are many religious groups [in India] who need to shun all material objects including clothing. Any interaction ... must be in cloth-less state. Many of the group members have a congentally short prepuce, leaving a portion of glans exposed, or have undergone circumcision in childhood in villages for unknown indications. Among these groups, such a condition is an ineligibility. One such religious group approached the authors to device [sic] a procedure, which would enable them to achieve complete glans penis coverage at all times."
 Gupta, email to Andrew Gross - July 29, 2021. Gupta explained that to begin his religious journey, a member must be complete in all physical aspects. Lacking even a finger would be a disqualification. Ethical considerations prevented Gupta from naming the group, but it is probably the Digambara monks that belong to a sect of Jainism known as the sky-clad. Members are forbidden to engage in sexual activities. A visible glans might be mistakenly inferred as sexual arousal - a disqualification in that culture.