Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World Has Never Seen centers around two "tribes:--one a literal tribe of hunter-gatherers hidden in an inaccessible area of Mexico, while the other is a collection of "superathletes" scattered about in our own country. The connection between these two groups is that both regularly gather to run 50-100 miles (or more!) at a time. 
 I've written before about an interview I saw with Christopher McDougal. The tribe around which the book centers are the Tarahumara, who more or less spend their whole lives running, with men and women up into their 90s able to "run hundreds of miles without rest and chas down anything from a deer to an Olympic marathoner while enjoying every mile of it. Their superhuman talenet is matched by uncanny health and serenity." We get just as much, however, about the culture and the individuals involved in ultramarathons and similar races here in the United States. 
 The central organizing feature of the book is McDougall's own search for the Tarahumara and for an understanding of the "secrets" of long-distance running, which morphs into a quest to understand human origins as a species "born to run." There were a few times where McDougall's presence seemed intrusive, but the overwhelming effect was to bring in an important personal element, to make this not only a fascinating read in cultural anthropology, athletic science, and evolutionary speculation, but also a personal, human story not only about McDougall but--and more importantly--also about an interesting cast of characters to whom we are introduced over the book's course. 
 There's fascinating stuff here, about the way we appear to have evolved to be the world's greatest distance-running species; about the way that modern, "advanced" running shoes tend to promote more injuries, not fewer injuries, than the cheapest shoes on the the market, than the shoes of yesteryear, than no shoes at all; about a tribe of people who--every single one of them--can achieve feats of endurance running that seem superhuman to us, but probably are in reach of all human beings. 
 I found this book absolutely fascinating, and I'm sure I will recommend it to many people before I'm done, starting right here.