Penis size has increased over decades. Study link
This is the study conclusion
"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.
Conclusions: The average erect penis length has increased over the past three decades across the world. Given the significant implications, attention to potential causes should be investigated.
Why do you think it happens?