More Science but less math

Last night, as I was failing to sleep, I wondered if human evolution, a process which rewarded those species members who had mutations which were advantageous to survival, could be the result of sociological developments. As I lay there, I considered where to put my arms and I noticed that their length was less ape like than, for example, ape arms. They fall, with the slight change in angle because of the natural bend in the elbow (note, if your elbow doesn't bend, you should probably consult some sort of professional) naturally resting on the genital region. Why would humans have developed to cover their private bits? I have a number of theories which range in their level of appropriateness, so please choose accordingly:

1. innocent: We, as a species, are the only one that has evolved to play soccer

2. innocent but informed: We, as a species, are the only one that includes a free kick in our version of soccer

3. more realistic but less appropriate: We are the only species on God's green earth to have unlocked a sense of humor that celebrates the nut shot

So less math in this version of science but it seems to me that we should do some field experientation. Would someone who is friends with a large number of apes of all sorts please arrange to hit one in the private parts and see if the other apes laugh or if they just go back onsides and prepare for the resumption of play? You know, I was about to call them "primate parts" but that would make light of this serious scientific endeavor.

As a control, please hit the apes in other parts of their bodies and check for laughter or signs of rugby. Then try it with lions. We aren't evolved from lions but I suspect that they have fully developed, but latent senses of humor. Report back on your findings when you recover.