Talk:Human penis size

Penis enlargement

The article contains the sentence "At present there is no consensus in the scientific community of any non-surgical technique that permanently increases either the thickness or length of the erect penis that already falls into the normal range (4.5" to 7")." This probably needs to be revised; there now seems to be some some fairly good evidence that penile traction therapy has some effect, particularly in the treatment of Peyronie's disease, although consensus on this is still evolving. (eg [1], [2], [3]) All the other non-surgical treatments still seem to be worthless, though, and I don't know of any surgical treatments that are effective in increasing erect penis length in normal penises.

I'd greatly appreciate it if any editors with the relevant expertise could review this. — The Anome (talk) 16:48, 23 March 2024 (UTC)

All of those studies are pretty nonconclusive. LegalSmeagolian (talk) 21:05, 1 April 2024 (UTC)

Dubious validity of the BJU International review ?

This article relies significantly on that 2015 study to talk about the size of erect penises (the crux of the matter), but most of the measurements reviewed are of flaccid and stretched penises. 20 studies (n = 15 521) are included, of which only four (n = 692) measured erect penises. The two studies that measured both stretched and erect length showed a 2 and 4 inches difference between the measurements, showing that stretched length isn't a reliable proxy for erect length. The authors admit this :

"Limitations: relatively few erect measurements were conducted in a clinical setting and the greatest variability between studies was seen with flaccid stretched length." "This was found by Chen et al. [30] who reported that a minimal tension force of ≈450 g during stretching of the penis was required to reach a full potential erection length and that the stretching forces exerted by a urologist in their clinical setting were experimentally shown to be significantly less than the pressure required. " 2001:861:4B40:C8F0:2811:6845:A0B3:77E9 (talk) 21:49, 16 July 2024 (UTC)

Extremely questionable validity of Belladelli et al. 2023

Scroll down a bit for the points of dubious validity in the study, if you don't want to read my explanation for why blatantly unsound and just incorrect studies should not be cited, even if they are published in a journal.

I should preface this by saying there are no professional papers that have published anything regarding the validity of this specific meta-analysis, but it's illogical to automatically regard a study as valid since no "experts" have spoken on its erroneously derived findings yet. I'm claiming that the sheer amount and severity of the inaccuracies contained in this study, many that are easily able to be recognized even by an unsophisticated observer, should prevent it from being cited. I can't find on Wikipedia any recommendations on how to handle these studies that are flawed beyond any justifiable reason they should be included.

I'm presuming there must a guideline or at least an unspoken rule preventing them being cited, because the comparatively unscientific, infamous, "r-K life history theory" and the many studies descended from it are not cited. Funnily enough, a study based off "r-K life history theory" is cited in Belladelli's review as a prior investigation consistent with his own findings of penile length variation by geographic regions. Taking a quick look at the study Belladelli cited, the sole author is Richard Lynn, a self-described scientific racist, which "Many scientists criticised Lynn's work for lacking scientific rigour, misrepresenting data, and for promoting a racialist political agenda." (source: Wikipedia). If you know anything about r-k life history theory and Richard Lynn, Belladelli citing Lynn's study is very odd, since r-k life history theory is racist pseudoscience that is quite clear if you look at any of the studies pertaining it. Lynn's study tries to prove racial differences in penile length and cites penile measurements in varying countries from a random, non-credible website. All numbers from the website were literally fabricated and the supposed studies they were pulled from were non-existent. You can read about the creator of r-k theory on Wikipedia (J. Rushton in Scientific racism) and his role as president in a white supremacist organization, Pioneer Fund.

If we strictly go by the Wikipedia articles on how to judge reliable sources, the r-k theory and all studies based off it could be included. (At least through my brief analysis of the articles, WP:MEDRS and WP:RS) Many well-done papers ands books have since debunked and gone through the plentiful flaws in r-k life history theory due to its widespread controversy. Unlike r-k theory, Belladelli's meta-analysis has not gained any attention, which is needed to get "experts" to weigh in with their opinions. If the many critical flaws in a study are plainly obvious, are "expert" opinions truly needed? Does being published in a journal make a source immune to being incorrect? I believe in good faith that since Wikipedia's goal is providing a free encyclopedia through a neutral point of view of the best current information, as well as the fifth official Wikipedia pillar stating "Wikipedia has no firm rules", it is in the best intent to remove blatantly unsound sources. Disagreeing with this would enable the inclusion of well... blatantly unsound sources, as well as of the many pseudoscientific studies that are primarily influenced by "r-k life history". Studies that find spurious associations between penile length with IQ, race with penile length, and race with IQ (just to name a few) through disingenuousness or errors in the study design, similar to Belladelli with his temporal trends of penile length (association of time with penile length, as well as geographic variation in penile length).

I am not trying to imply there was any malicious intent in Belldelli's review, or anything other than that it is a extremely poorly done review. Many of my reasons against including Belladelli's meta-analysis can be found in an article by Cremiux Recueil named "No, Penises Haven't Gotten Longer". Cremiux Recueil is not an expert and from my quick examination, he is a blogger with an interest in scientific papers. One may argue that an "expert" is needed to evaluate the reliability of a source for it to be "proven" inaccurate, but as I discussed earlier, allowing blatantly unsound sources since no "experts" have yet to talk about it is disingenuous to the goal of Wikipedia. Also, there is no need for an expert to spot the glaring mistakes contained in this review. A lot of the mistakes have already been discussed in Recueil's article, so I may simply quote him. Recueil has many studies that are linked in his article, and if you wish to find the links, you can go to his article. I have bolded and underlined specific points that I find extremely important. Points that I find somewhat important are just underlined, and points that I find less important yet still raise concern for the meta-analysis' validity are italicized. I apologize in advance if this is a bit messy as the whole study is just full of errors and mistakes ranging from severe to minor and sometimes overlap.

Belladelli uses many studies on men specifically with ED, getting surgery for ED, or including men with ED (You can see the many studies in Table 1, and urology patients tend to include men with ED): Men with erectile dysfunction are shown to have lower penile length than normal controls (by about 0.6" - 0.8" Kamel et al 2009, Awwad et al 2005). Yet many of the studies included are done specifically on men getting surgery for ED (erectile dysfunction) and/or are diagnosed with ED. I would also like to add that there are also some studies that show no difference between ED and non-ED subjects, but the fact we are using studies specifically on men who literally have a penile disorder is the main issue. It is also hypothesized that the penile tissue itself is compromised in men with ED, especially within elderly men, so there are issues with that as well.

Belladelli uses studies containing exclusively self-reported measurements that influenced his meta-analysis: "Third, though the meta-analysis claimed to not use any self-report samples and to be comprehensive, both claims were clearly wrong: several samples were based on self-reports, like Kinsey’s (1948), as noted above, and many were excluded for no good reason. If we allow self-report studies like Kinsey (1948), we have to then include exact replications like Richters, Gerofi & Donovan (1995). But, self-report samples obviously cannot be used because people lie about their penis sizes. Lying is so pervasive that people lie about their heights in the same direction they lie about their penis size (bigger is better!). As an example of this, consider a study (see also) by one of the authors of a penis length study included here. This study showed height overestimation, and greater overestimation in bisexuals and homosexuals, coupled with lower objective but not self-reported heights."

Self-reported measurement cannot be used as studies consistently report larger penile length when self-reporting, significantly larger than researcher measured penile length. This is a very common and well-known phenomenon that happens with height as well. Many self-reported studies were included (even though they claimed they were not), which affected the results. From Belladelli himself, "Because of their inherent biases, self-reported lengths should be regarded with caution."

The studies that specifically consist of only self-reported measurements are "Kinsey AC. Sexual behavior in the human male", "Bogaert AF The relation between sexual orientation and penile size", "Herbenick. Erect penile length and circumference dimensions of 1,661 sexually active men in the United States." ,and "Di Mauro Penile length and circumference dimensions: a large study in young Italian men". There may be many more, since I'm not going to go through all the studies. I was literally able to recognize all of these studies as self-reported when I saw the titles, since I have already seen them. All these studies report means significantly above the norm. (Just went through the sole study in "Oceania" and it is self-reported. "Smith, Does penis size influence condom slippage and breakage?" And yes, the mean is significantly above average.)

A significant impact caused by this is the large increase of erect penile length in Europe. The most recent study was Di Mauro 2021 which self-reports an average of 16.8cm/6.6in. The studies from which Belladelli starts reporting the trend are Sengezer 2002 and Schneider 2001, and the pooled means of these 2 studies are about 5.3 inches. I'm not going to run a full separate analysis on all the studies without self-reported penile length, but it's quite obvious the self reports had a significant effect on the trends, since they are always reporting an average significantly higher. If you take a good look at everything, the trends Belladelli finds are from the bad study selection, which caused confounding and problems through mixing up pendulous/total penile length, including self-reported studies, including studies with men that are unrepresentative of the normal population, mysteriously excluding good studies, including unreliable studies, and lack of well-done studies in the past.

Belladelli does not differ between pendulous and total penile length, even though they are always significantly different from each other: The pendulous penile length is defined as measuring from the base of the pubo-penile skin junction without depressing the pubic fat pad. Total penile length is defined as measuring from the base of the penis while depressing the pubic fat pad. These two measurements are inherently different by the presence of the fat pad and can vary from around 2-5cm. (At least in these studies: Salama 2015, Salama 2015(2)) It is dependent on total fat mass and therefore BMI. Belladelli not differentiating between these two causes many errors and likely aided in the ludicrous 24% increase of erect penile length in 29 years by using pendulous length in older studies and total length in newer studies. Many studies, especially studies on Pca patients, exclusively measure pendulous length, which is always significantly shorter than the total penile length and therefore studies that report pendulous length will have lower averages than ones that report total length. This becomes a massive problem when trying to find temporal trends and geographical variation in penile length with the already very limited data.

Belladelli cites studies with exclusively prostate cancer patients. Prostate cancer patients likely received treatment that decreased penile length before the study, and these measurements cannot be extrapolated to the general population. They also almost exclusively measure pendulous stretched flaccid penile length, and there are no studies on erect length in Pca patients. Stretched flaccid length is consistently lower than erect length in Belladelli's meta-analysis. Belladelli himself finds that stretched penile length in Pca patients is lower than the average erect length found in his study by 0.6in/1.5cm. Nearly all studies on Pca patients measure pendulously, and higher BMI inherently causes a larger pubic fat pad. Higher BMI is associated with Pca.: "Fourth, there is a considerable literature on prostate cancer treatment effects on penis size, including studies about surgeries and hormones... For an example of both, see Brock et al. (2015). Because hormonal and radiation treatment are common in the run-up to surgery for various reasons (despite potentially not being useful; cf. Kadono et al., 2018), the baseline measurements from many of these studies cannot be taken for granted since they virtually all lack the relevant prior case history information needed to make the estimates interpretable as general population estimates. For all we know, prostate cancer treatment may have improved over time in such a way that penis size losses have become more minimal. Given how penis size loss is considered the “final indignity” of prostate cancer and a notable worry for many affected men, there’s clearly some reason for practitioners to have worked on this.

Since several of these studies were cited by the authors of the meta-analysis, it’s curious that they didn’t realize or even seem to care about their problems. But it’s more curious that, yet again, there were studies mentioned in the studies of prostate cancer sufferers that they cited that led to yet more work with penis measurements, and, if we consider prostate cancer patients to be usable for penile length measurements at all, they shouldn’t have been excluded, but mysteriously, that’s exactly what Belladelli et al. did."

Belladelli's meta-analysis does not have nearly enough information for his findings on geographic variation of penile length and seemingly fabricates a data point: Belladelli reports that there are 5 studies in South America and 8 in Africa. In reality, there are only 4 studies cited for SA and 7 in Africa. There are only 2 studies that report erect penile length in Africa and SA, so 1 each. Also note, if Salama 2018, the sole study on erect penile length in Africa, only used pendulous length and did not push down on the fat pad, the average erect length in Africa reported by Belladelli would have only been 10cm. A good example for how much pendulous versus total length differs. In Fig. 3A, there are at least 2 data points for Africa, but there is only 1 study in Africa on erect penile length. The only way Africa has a trend line in the figure is if Belladelli has added a data point for Africa that doesn't exist.

Belladelli's findings on significant geographic variation in Asia are majorly caused by poor selection of studies and could possibly be maliciously motivated: As previously discussed, Belladelli cites a study based off r-k life history theory by Richard Lynn as a prior study consistent with his current findings. R-k life history theory is commonly cited and used amongst scientific racists and Richard Lynn himself is a well-known racist. Any investigation into the study by Lynn would let you know that the racial differences in penile length claimed in his study are completely unfounded and are based off a non-credible website. Supposedly, the numbers were from many different studies, but the numbers are fabricated and no studies containing them can be found. These supposed variations of penile length by race/geography come from the belief of genetically different androgen levels by race/geography, which has been disproven (1, 2, 3). It is possible there is geographic variation in penile length due to malnutrition/poor environment, but Belladelli's results show significant differences in penile length in a specific region. The average for Asia is very low, and the rest of the regions do not have nearly as much variation between them. The extremely low average for Asia seems to be caused by the abysmal study selection. 1. The inclusion of older studies in Asia, some that are very unreliable, reporting very low average penile length, as well as the exclusion of older studies in Asia that report higher average penile length (There are several on the Wikipedia page that all report averages of 13-14cm, like Yoon 1998, Chung 1971, Weicheng 1990, Weicheng 1993, as well as Weicheng 1994 which is not currently cited). You can see in Figure 3 that the erect penile length in Asia has supposedly increased from below 10cm to around 14cm through 1990 - 2015. This is primarily caused by the unreliable Taiwanese study discussed afterwards in Belladelli fabricating a data point, since it is the only data point cited for erect length in Asia until Promodu 2007. Mind you, the trend for erect length in Asia is calculated between 1992-2015. There was only one study between 1992-2006 in Asia measuring erect length (at least in Belladelli's meta-analysis, although if you included other studies the average would increase between 1990-2006 and the trend would not be nearly as significant). Also, Belladelli does not include Turkish studies in Asia, although it is generally agreed upon as a West Asian country. 2. Belladelli's study selection overall is odd, but is even more so for studies in Asia. Belladelli cites Hosseini 2008, but there is nothing on penile measurements found in the study. Presumably, he must have cited the wrong study. Belladelli reports in "2. Description of studies" that there are 20 studies in Asia, but he only cites 15. 4/15 of the studies in Asia report pendulous stretched flaccid penile length in Pca patients, which as previously discussed always report lower averages. Belladelli cites a Taiwanese study with 20 men with ED, 10 of which failed to get a good erection, more on this is discussed in the next point. Nikoobakht 2010 is a study done specifically on men who complained on having a short penis and followed through with using a device to increase their penile length. Obviously, the averages from that study cannot be taken for granted. Kim 2019 is a study done specifically on men who have ED and needed a surgical implant for their erectile function. It also measures pendulous stretched flaccid length, which as previously discussed is always lower than the true total penile length due to the nature of the measurement. Canguven 2016 is done on elderly men with not only ED, but also low testosterone. The measurement is not specified as pendulous or total length. Mehraban 2007 is measuring pendulous stretched flaccid length and reports a lower value, and again, as we discussed, this should not be surprising. And I could go on and on about the poor study selection, but you get the point. Belladelli's results are influenced by mistakes in his study selection, and would not appear elsewise.

Belladelli fabricates a data point to find a positive result: "More interestingly, their erection trend (p = 0.04) was driven by the inclusion of a study of 20 Taiwanese men with erectile dysfunction who were given erections by injection. Belladelli et al. also improperly claimed this study had twice as many men (check their Table 1) as it did. Their erection trend was also apparently based on a nonexistent study conducted in the same year, because we see two dots in their plots, while the Taiwanese study was the only one with erection data in the year 1992 and their two other 1992 citations involved only flaccid and stretched measurements. Remove this study or even just correct the weight and they didn’t find any significant trends for erect, flaccid, or stretched flaccid length." Also note, the penile length measurement method in this Taiwanese study of only 20 impotent men was quite clear that they are measuring pendulous length: "The penile length was measured from base to midglans manually before and after PGE1 injection. In the determination of the penile erectile volume, the length of the unstretched penis from base to midglans was measured manually with a ruler." Belladelli including this study with only 20 impotent men was already odd enough, but the measurement is also pendulous, which fundamentally decreases penile length. Additionally, erection was chemical induced via PGE1 which induces full erection in only 70-80% of men and Chen found 10 patients had poor response to PGE1.

Belladelli includes several studies with dangerously low sample sizes, often these low sample size numbers are also exclusively accompanied by an unreliable demographic of men: Just to name a few: Da Silva 2002 (Cadavers, n=25), Moreira 1992 (Cadavers, n=17), Chen 1992 (Men with ED, n=20, falsely reported as 40 in the meta-analysis), Carceni 2014 (Men with ED getting surgery, n=19), and there are more. Belladelli does not even weigh the studies by sample size, but pools all the means together while including studies like these.

Belladelli uses dubious methodology and studies with specifically unreliable subjects that bias results: "A lot of samples have to be excluded. You cannot run a meta-analysis for changes in penile length over time with samples of men seeking penile implants, men who think their penises are small, men with erectile dysfunction (and thus most urological patient samples unless explicitly noted otherwise), or men seeking — often hormonal, as androgen suppression — treatment for prostate cancer. Because these people are so odd with respect to the average, we have no idea if it would be appropriate to include them even if there were time-invariant numbers of them.

Second, men seeking penile lengthening procedures or men who think their penises are small are not simply deluded about the average size or their self-perceptions: they are at least somewhat correct and they do tend to have below-average penises. Mondaini et al. (2002) sought to disprove this notion by alleging that people who thought they had small penises really did just have more serious misperceptions. But in reality, their sample showed they have a distribution of penis sizes that was shifted to the smaller side, even if not significantly due to the small sample. Other samples support these sorts of men being smaller than average, so this isn’t concerning. More importantly, people who think they have small penises often have ED, which is much more robustly associated with smaller size. Plus, if we’re doing a meta-analysis, why would we use qualitatively different groups for the flaccid, stretched, and erect groups, as an analysis involving men who have ED must be? Using samples of these people is simply a way to confound results and introduce problems with time-varying sample compositions."

Belladelli's findings are self-contradictory: Somehow, flaccid and stretched flaccid length has decreased, but erect length has increased. Belladelli's results contradict the very nature of the penile tissue, which should raise suspicion.

Belladelli's findings in geographic variation are contradictory (Caused by the very low amount of studies in both Africa and South America.): Not much to explain here. Africa has a significantly lower flaccid and stretched flaccid length than Europe, North America, and South America, yet higher erect length. South America has significantly higher flaccid and stretched flaccid length, yet lower erect length somehow.

Belladelli includes studies without any listed measurement method (The method of measurement can significantly impact findings): Ansell. 2001 "The penis size survey" does not list any measurement method/technique like many other studies Belladelli cites (See Table 1). Obviously, including these studies can cause unreliable results, since we don't know how the researchers measured and if they used different techniques. Specifically, studies using measurements that push down the pubic fat versus ones that do not (See Salama 2018, the difference between these two measurements can vary by up to 5cm on average, even in controls), and studies that stretch the flaccid penis gently versus until maximal extension. There are also differences between measuring the penile length parallel/perpendicular to the floor or body while standing versus in dorsal decubitus.

Belladelli did not include studies cited in studies he cited in his meta-analysis: "Some studies included proper measurement and were not in the meta-analysis at all, and the authors should have known, since they were cited within studies they cited! For example, the studies Spyropoulos et al. (2002), Chaurasia & Singh (1974), Farkas (1971),... and Awwad et al. (2004) were all cited within studies the meta-analysis cited, but they weren’t included in the meta-analysis."

Belladelli gets data and numbers wrong, as well as not factoring in the time from data collection to the study being published (He also uses cadaver studies that have very low sample sizes and does not factor in the effects of death on penile length): "All of this said, I hope readers don’t think the meta-analysis authors got everything besides these issues right. They didn’t: there are incorrect numbers in the meta-analysis for penile lengths, sample sizes, years, and ages. There was also evidence of arbitrary exclusions from certain studies. One study was also cited twice (Park et al., 2011) despite having only one available data point, so something else was presumably meant to be cited.

Regarding penile lengths, the errors were usually understandable, but readers wouldn’t notice because the authors of the meta-analysis didn’t provide their data. Readers would have had to look at their graphs and pull the data to know that the meta-analysis authors messed up in cases like with Shalaby et al. (2014). This study included the wrong measurement in the abstract (13.84cm) and the correct measurement in the body of the study (13.24cm), but the authors of the meta-analysis seem to have used the abstract’s errant number.

Regarding sample sizes, the errors were often harder to understand. For example, Tomova et al. (2010) was listed as having 310 people, but it actually had 310 per listed age, and the authors used ages 18-19, so the sample size should have been 620! But, because several studies used ages as young as 17, I don’t see why that age shouldn’t be included too, to bring the sample size up to 930. Alves Barboza et al. (2018) was more baffling, because those authors had a sample of 450, but the author’s proposed sample size for this study was double that for no apparent reason.

Regarding years and ages, the errors were usually less significant, but they could have been consequential in aggregate. For example, for year, Kinsey was cited incorrectly in their references and was listed with the citation year 1950 instead of the real year, 1948. Many studies were published several years after data collection, so this becomes a source of error because some studies are published closer to their data collection years. For age, studies with cadavers were not helpful since they didn’t list ages, and obviously cadavers tend to be older and thus stretchier for two reasons: age and death. But worse, other studies just had careless age number errors, like Söylemez et al. (2012), who reported a mean age of 21.1 (+/- 3.1) rather than the author’s reported 21.3. Needless to say, the conflation of age and cohort effects in this study was considerable and not able to be addressed due to the small number of studies. Known effects of age (i.e., greater penile elasticity, selection for normal samples related to lack of ED or prostate cancer) or location (geographic variation in size) simply had to be ignored for this reason."

Belladelli's findings should be viewed as almost certainly incorrect: "Belladelli et al.’s penile length meta-analysis produced a result that is almost certainly not true, and it should never have been taken for granted. Because of the absence of measurements conducted on samples that aren’t unusual over sometimes multiple decades, the ability to reliably discern a trend is also severely handicapped and any trends produced in newer studies will have to be unreliably computed based on differences from small numbers of past datapoints."

There are many other flaws within the extremely odd selection of studies Belladelli uses and with the meta-analysis itself, but this is already too long. If you take a good look at everything, the trends Belladelli finds are from the bad study selection, which caused confounding and problems through mixing up pendulous/total penile length, including self-reported studies, including studies with men that are not representative of the normal population, mysteriously excluding good studies, including very poorly done studies, and lack of well-done studies in the past.

PS: Apologize if this was cluttered. There's a lot of mistakes that Belladelli makes and there are many more not included here. Way6t (talk) 04:21, 27 August 2024 (UTC)

This meta-analysis is like death by 1000 little cuts. One problem by itself would not warrant the removal, but the whole study is unreliable. Way6t (talk) 04:50, 27 August 2024 (UTC)