The average penis length worldwide has increased by 25 percent in recent decades — and the scientists who discovered this apparent growth spurt say it might not be a good thing.
In a paper published on Valentine's Day in the World's Journal of Men's Health, Stanford researchers observed that per their meta-analysis of decades of studies, the length of erect penises has increased 24 percent — from 4.8 inches to about six — over the past roughly 30 years, even as testosterone levels and sperm quality have declined.
To get there, the researchers sifted through 75 studies that went as far back as 1942 and comprised data on nearly 56,000 men. They were surprised to find that for the last 29 years of the period they studied, the reported length of erect penises began swelling.
What's more: this trend wasn't, as latent race science enthusiasts might speculate, isolated to any one part of the world, but seemed to be occurring all over the globe.
While the researchers were able to see the effect of this apparent trend, they're unsure as to its cause. That lack of clear causation is, as Stanford Medicine urologist Dr. Michael Eisenberg told USA Today, something of a red flag.
"The million-dollar question is why this would occur," said Eisenberg, who specializes in male fertility.
Given the underwhelming results of studies on sperm count and testosterone level trends in recent years, the Stanford research team behind the paper said in a school press release that they wouldn't have been surprised to see penis length declining alongside those data. Instead, they found the opposite.
"Given the trends we'd seen in other measures of men's reproductive health," the press release notes, "we thought there could be a decline in penile length due to the same environmental exposures."
While penis length isn't directly correlated to sexual health, the Stanford press release notes that it nevertheless is worthy of study because it's not positive on its face, either.
"The increase happened over a relatively short period of time," the school's update notes. "Any overall change in development is concerning."
It'll be fascinating to see where this line of inquiry goes next — and, of course, how the male enhancement industrial complex handles it.
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