[xg15]

I read this does have a functional reason: Sperm cells have to be kept at slightly lower temperature than the body temperature, so if the testicles were inside the body, the sperm wouldn't survive.

Of course you could ask why sperm is so temperature sensitive in the first place...

[volemo]

If elephants did it, I’m sure we can too.

[melagonster]

They have a complex system to mantain the specific temperature. Huaman and other smaller animal do not have enough space to it inside.

[polotics]

If we were as large as elephants, then yes.

[beAbU]

We did do it! It's called testicles!

[volemo]

But ours are outside. :(

[fastjack42]

Now that sounds like a design flaw in sperm cells