What your ball size says about you (Level 1)

Human testicles are very interesting parts of the body. They are different from other animals. For example, they are larger than a gorilla’s but smaller than a chimpanzee’s. Scientists study their size to understand human history. They look at physical signs called "badges of status." These are traits like a big nose on a monkey or a beard on a man. Research shows a trade-off in nature. Animals with big noses or loud voices often have smaller testicles. The body uses energy for one or the other. If a male looks very strong to attract a mate, he might not need large testicles. Temperature is also important. Sperm needs to be cool to survive. This is why the testicles hang outside the body. Muscles move them up and down to change the temperature. Also, it is normal for one side to hang lower than the other. This helps them stay cool and healthy.