Humans have been slipping into animal skins to protect their own for about the last 500,000 years-a few weeks before the original Harley-Davidson V-twin was designed on the inside of a cave near what is now Milwaukee. So what could be more appropriate when you're looking to set off those chic retro wheels with something that only looks old? Vintage-style motorcycle jackets have found their way into mainstream fashion lately, garments from Bates and Schott and China and Pakistan gracing the display windows of stores in the Beverly Center and on Melrose Avenue. Not all are up to the actual rigors of riding, however. What follows are five we've found to be both functional and stylish.