To the joy of my wife, human penises are getting longer all over the world. That is, according to a study that appeared last month in The World Journal of Men’s Health.
A research team lead by Michael Eisenberg, a professor of urology at Stanford Medicine, looked through 75 studies on penis size that were done between 1942 and 2021 on nearly 56,000 dudes. What they discovered was fascinating: that the average erect penile length is now 14 cm, a 24% increase over the past 29 years.
“Erect length increased significantly over time (QM=4.49, df=2, p=0.04) in several regions of the world and across all age groups, while no trends were identified in other penile size measurements. After adjusting for geographic region, subject age, and subject population; erect penile length increased 24% over the past 29 years.”
As far as any appendage is concerned, nearly a quarter increase in length over such a short period of time is remarkable — especially when it comes to one that is designed to be inserted into other people.
What influences penis size?
Penis sizes can be impacted by many factors — sexual selection over time, health and diet, but also environmental exposures. As we previously covered, the average testosterone level in men has been plummeting over the past few decades, as has sperm count. Meanwhile, incidences of male genital birth defects have been increasing. Contrasting the general trend of longer penises, micropenises — those that are under 2.5″ erect — are also becoming more common. There is something going on with male genitalia in the 21st century.
Eisenberg theorized that the rapid increase in penile length may be due to environmental factors, such as exposure to cosmetics, pesticides, and other chemicals, especially those related to plastics. While this would explain for such a drastic jump in size, the indicators of such exposure typically leads to smaller penises, not longer ones.
When I read about these findings of a 24% increase in penis length since the mid-nineties, these were my thoughts as to why this may be:
Inconsistent measurements?
My first thought when I read about this study was that it was more probable that the measurements / measuring protocols of some of the earlier studies to have been off than there was for the average human penis to get a quarter longer in such a short period of time. There are plenty of different ways to measure a penis: fully erect, bone-pressed, not bone-pressed, stretched, from the top, from the side … with each giving very different results.
However, this doesn’t seem to be the case with this one, as the researchers threw out 7,850 papers because they didn’t meet their strict measurement criteria, leaving them with just 75 studies from which to track penile length over time. So it seems as if penises may very well be getting significantly longer very quickly.
Sexual selection?
Humans have by far the largest penises in terms of volume in the primate world — both in raw size and size compared to height. For this distinction we have women to thank. Sexual selection is the primary driver of penis size in primates, and we can see remarkable differences in primate species where females have a role in the selection of mates and species where they don’t have this power.
The best example here is probably contrasting gorillas with bonobos and chimps. Gorillas are by far the largest primate by body size … but they also happen to have one of the smallest penises — coming in at around 3-6 cm erect. Meanwhile, the drastically smaller chimps and bonobos have erect penises that can range from 8 to 18 cm. Gorillas also have penises that are inconspicuous not only because of their size but color as well, as they are black and blend right into their fur. On the other end of the primate spectrum, chimps and bonobos have brightly colored penises that stand out, literally, as they intentionally display them to attract females.
The primary reason for this is a difference in mating patterns. Gorillas live in groups where there is a single male and a harem of females who the male does not need to compete for based on his sexual attributes … and the females do not have a choice of males. While chimps and bonobos live in multimale-multifemale types of communities, where both males and females sexually engage with many different members of the community and females have a big say in who they have sex with … and often decide based on sexual qualifications (i.e. penis size).
Ancestrally speaking, humans are more like chimps and bonobos, and “it has been theorised that ancestral hominid females sought out males who would sexually satisfy them. Through the mechanism of sexual selection, this will have increased penis size and altered structure,” wrote Carole Jahme in the Guardian.
“This unique adaptation is thought to have been selected through female mate choice, and by the time Homo erectus arrived on the scene, the hominid penis was significantly longer, fatter and more bendy than our ape cousins’… But the larger human penis suggests that hominids needed to keep females with choice sexually satisfied.”
There is also a theory that humans began walking upright to show off our penises to potential mates … While that seems a little far fetched — us dudes are probably not that into our dicks — it’s not difficult to see how this evolutionary adaption, where the penis is proudly put on display via anatomic positioning, could have put more of an emphasis on size as a selection criteria.
When extrapolated to modern times, humans are again returning to having visual representations of the penis being a primary criteria for sexual selection. Up until recently, the size of a man’s package was often an unknown until after intimacy begins — and sometimes not even until some form of a committed relationship was established. Now a dick pic is a customary part of the courtship process. In a 2017 Skyn Condoms survey of millennials, it was discovered that 42% of men send at least one naked picture of themselves to potential / current mates each week and half of the respondents claim to sext weekly. I’d say that I often exchange nudes with women that I meet on dating apps within one or two days of connecting. In other words, we now get to see the goods before committing to have sex and I strongly believe that penis size is a major selection criteria — kind of like it is for chimpanzees.
Men are perhaps obsessed with their penis size because deep down we instinctively know that it’s an evolutionary criteria for sexual selection.
While this could be a factor for the increasing of penis size moving forward, it doesn’t really explain the increase of the past 29 years, as the people reporting now would have had to of been conceived prior to the start of the smartphone era …
Better diet and lifestyle?
My main guess as to why average penis length is rapidly increasing is a whole less sexy than sexual selection: better diet. Over the past 30 years many regions of the world have seen not only an increase in penis size but also body height and mass.
29 years is the rough timeline of three era shifting developments: globalization, urbanization, and the internet. Rather suddenly, people all over the world began having access to different types of food, more nutrition, and a better knowledge of health.
This is clearly represented in the growth charts of countries like China, where the average height of a man increased by over three inches in the past 34 years. This was primarily due to better nutrition — i.e. access to animal foods like milk, eggs, and meat; things that most Chinese people rarely consumed through most of the 20th century.
Exercise, less arduous lifestyles, and a better health consciousness are also factors at play here. Intentional exercise and the gym is also something that’s new for many emerging markets in the world, as is masses of people converting to white collar, urban lifestyles that don’t destroy their bodies as much, as is an all-round better knowledge of what is considered healthy living. These all have major impacts on health and hormone levels, which in turn play a major role in body size and composition … which includes penis size.
Map of increased height around the world from 1985 to 2019:
It would only stand to reason that if men’s bodies have grown substantially over the past three decades then so too have their penises.
The authors of the The World Journal of Men’s Health paper queried that rapidly increasing penis sizes may be a cause for concern … not according to my wife.
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