Gee - Jamaica I think was a British colony and became independent sometime in the 60s. For a small island with 3 million people that is so young to be on the map for its naturally beauty, reggae music and track and field is not too shabby at all.
And because I've been following track for a while I know Jamaica was always in the mix long before Beijing. I recall a documentary a while back on Jamaica's track and field history. They have this big track and field championship down there every year where 35,000 track fans fill a stadium for what is essentially a high school sports day, and it is a huge deal, people are that passionate about track and field and it is a top 3 sport there like football and baseball are in the US. So I think it is natural talent and not doping and if the US had more athletes choosing track over other sports it could dominate in the sprints again.