Looking beyond the obvious genetic element, let's continue to other aspects. I saw this because they aren't the only ones born at high altitude and walk to and from school everyday. I'd argue Native Americans in Wyoming/Colorado/Utah/Montana/Norther Arizona probably covered as much ground and lived in higher altitudes in historic times before horses.
The Valencia race had 7 guys under 59. Watching the race, the Africans look like scrawny dudes with relaxed faces out on just another tempo run. We have thousands of runners that graduate through our highschool and collegiate ranks and you'd be pressed to find a super efficient form wasting as little energy as these Africans.
My assumption here is we, as US runners, are missing the memo on running efficiency and not necessarily raw speed (as the distance goes up we fall further behind Africans but we're closer to parity in the shorter stuff).
1. Body mass index -- Africans are skinny as hell. They make our skinny runners look obese. There is peer-reviewed research associated with weight and performance.
2. Diameter of ankles -- think of the energy requires to swing each leg thousands of times.
3. Body's ability to dissipate heat -- this goes along with #1 and #2 but also notice most Africans are practically bald further optimizing heat release. How many Americans were bald in the Valencia race?
4. Diet - hardcore high carb diets. We, as westerners, are trending towards salads and paleo. Bring back the pasta loading?
We're going to have the science the sh*t out of this to figure their secret out. We have the talent. We need to figure out the efficiency equation.