A study has looked into human penis size as depicted in paintings throughout the centuries, finding that the appendage has grown significantly over the last seven centuries, particularly in the 20th century.

The team wanted to assess the ideal penis size throughout the ages, and how the male ideal has been altered by cultural differences.

"It seems logical that these alterations in the perception of ideal penis size would be reflected in paintings in which the penis is depicted," the team writes in their study. "Thus, this study investigates the depiction of penis size in art and evaluates the perception of penis size in a historical context over the past seven centuries."

The researchers first attempted to find as many paintings of nude males throughout the centuries as possible, searching for variations of "nude male" on several popular art websites, organizing them by time timeframe. Thankfully, there was no shortage of depictions of nude males from the Renaissance onward, and the team identified 232 paintings from 21 countries which were suitable for the study, albeit with a European bias. Any depictions of erect penises were rejected, as were paintings of children. 

As scale and distance is difficult to gauge in paintings (is that man's penis gigantic or is he just standing near a tiny horse?) the researchers instead measured penis-to-ear ratio, or penis-to-nose ratio given that they are equivalent "according to the golden ratio". This gave a number that could be compared across time periods, with a number less than 1 meaning that the penis size was depicted as smaller than its owner's ear or nose, and 1 being equal sizes.

"During the 15th and 16th centuries, although the number of naked human paintings increased considerably, the penis continued to be depicted as rather small," the team found, noting that the depicted penis length did not change much over the next few centuries, into the 1800s. 

"However, from the 19th century onwards, images of the penis began to become proportionally larger."

Why the sudden increase in penis size over the last century? 

"One explanation behind the exaggerated perceived penis size in paintings produced in this century could be the widespread use of the internet and exposure to other media, which perpetuate the association between penis size and masculinity, strength, and partner satisfaction," the team suggests, adding that pornography may have changed the "ideal" penis size for men. 

"With the ubiquity of porn, supersized penises and exaggerated female reactions towards them could make men compare their own penis size to that of others, including those men who are featured in pornographic content."

The team points out that males tend to overestimate the average penis size, while also underestimating their own (you may be surprised by the average penis size), with a "considerable number of men" seeking potentially hazardous penis enhancements and enlargements in recent years. 

The team notes that the study has limitations, including how the paintings were found and the European bias to them. However, if the findings are accurate they say it could add to men's body image problems. 

"Evolutions of artistic representation of the penis towards a larger, possibly unrealistic, ideal in contemporary media might contribute to feelings of inadequacy and dissatisfaction with penis size in modern men," the team concludes.

The study was published in the medical journal BJU International.