Wow... seriously you guys have these great answers, Mr. or Ms. Panja, gave a great speech right there about why do we have to keep our hair. I really don't know why, people ask that why should we throw away something that god gave us? Panja gave a great explanation with a scientific explanation, I have another scientific "question" right here hair is a dead cell, as far as i know everyone who believe in Sikhism including me also cut their nails. Nails are also dead cells. Now tell me how come we can't cut our hair, but we can cut our nails. As far as the scientific explanation goes on how hair benefits your body, we should be in the guiness (dunno the spelling) world record book already, we should be the ones with the longest life span on this planet already. Why don't we have the longest life span on this planet? Is there any "scientific" explanation to that. I would say there's no scientific explanation to why we can't cut our hair, we don't cut our hair so that we can stay in the society; I mean if you observe the society when someone cut his hair then they would start the gossip about how this person is bad. So what I would say is that this not cutting hair thing is completely irrational and I have no idea why can't we cut our hair.