Why are the Testicles Kept Outside of the Body

Question

Why are the testicles kept outside of the body?
A) They lower the temperature for sperm production.
B) The testicles cushion the penis and stop it from hanging too low.
C) There's no reason for this.
D) Earlier in human evolution, visible testicles helped males to sexually attract females.

Accepted Answer

The testicles are kept outside of the body as they need to be at a slightly lower temperature than body temperature (about 2-4 degrees Celsius cooler) for sperm production to occur properly. If they were inside the body, they would be too warm, and the sperm might not develop as they should.