Not everyone conceals underwear =)

You mean like batman? :-)

I haven't seen one in the streets of KL or Sg. Well, except those saggy jeans where ppl reveal their butt cracks...

Sorry I came late to this interesting discussion but on the OP part that says "if we stay in a warm place, and there isnt anything in the environment to that can harm us, why cant we walk around naked?"

Ever tried sitting under the hot sun in your shorts for longer than 15 minutes, without sunscreen? That's one reason to wear clothes. Ever tried walking through the bushes with shorts and getting scratched? Or sitting around outside in the evening and getting bitten by insects? That's another reason to wear clothes.

Concealing our modesty I think is a later invention due to social pressure. It had nothing to do with the environment. If we've progressed beyond hunting for our food, we have the luxury to be creative and feed our egos so we can buy Donna Karan and all that stuffs. Other societies like those tribes in Papua New Guinea, clothes are decorative - to indicate status in the clan, helps people get organized. Not much different from us in that sense, except the fashion taste is different.

i think its more for hygiene purposes..

imagine we do not have any clothes on and we are taking the LRT which is packed to the brim..

and there's this guy next to you..his hand holding the handle and his armpit if right in front of you...............................................

Haha, I took a packed LRT once and someone farted. Want to pengsan man. But dunno who's the culprit coz everyone's so nicely dressed n look like angels.