Why do Caucasians have the color variations in their hair?

From: Aquatic DubMonkey (rewindme_at_lunarmagazine.com)
Date: 10/05/04 

Date: Tue, 5 Oct 2004 06:01:35 +0000 (UTC)

If it were solely from climate, wouldnt some Asian cultures also have
groups of people with natural blond or red hair?? Anybody know if any
study has been done on this, any ideas? Any insight would be greatly
appreciated.