An article on Science Daily (http://www.sciencedaily.com) talks about how Darwin thought all chickens descended from the Red Jungle Fowl, but scientific research has shown that is not quite the case. You who have yellow skinned chickens actually have chickens descended from Grey Jungle Fowl.
http://www.sciencedaily.com/releases/2008/02/080229102059.htm

http://www.sciencedaily.com/releases/2008/02/080229102059.htm