Why did humans evolve big penises but small testicles?

We have the penis of a monogamous primate yet our body sizes suggest our ancestors slept around a lot.

Why Is the Penis Shaped Like That?

Are My Penis & Testicles Normal?

Why Is the Penis Shaped Like That?: And Other

Why did humans evolve so that males' testicles are exposed? - Quora

What Happened to the Openly Gay Athlete? - Gayety

sexual selection UCL Researchers in Museums

Why do mammals have two testicles? When did it start on evolutionary history? - Quora

Testicles – News, Research and Analysis – The Conversation – page 1

Why humans have big penises but small testicles

Male Infertility: Practice Essentials, Background, Pathophysiology

How come you never see any gorillas who are hung like a horse below the belt? - Quora

WATCH: Why Have Humans Evolved Such Large Penises? : ScienceAlert

Human evolution - Noticias, Investigaciones y Análisis - The Conversation - página 7

The Evolution of Testicles: Why Do They Hang So Low?