the U.S. is genetically much less homogenous than the rift valley. yes, i think those from the highlands of east africa are more genetically predisposed to being good runners than those of lowlands west africa, who’re probably more predisposed to being sprinters.
but in the U.S., those whites, blacks, hispanics, genetically more akin to “east highlands” population (so to speak) and our “west lowlands” population are spread all over the continent. i suspect that there is a typical runner physiology that you’d find in england, ireland, spain, italy, that is every bit the equal of an east african. those people are also found all over the U.S., but sprinkled in amidst those genetically suited for other activities.
if you look at the U.S. in running right now, we’re in the middle of a big upsurge. ritzenhein and webb started it, and galen rupp, ryan hall are following in their wake. ryan’s younger brother leads the next wave, and we’ll have a lot of 8:45 2-milers and 4:03 milers this year. there are four reasons for this, and neither is genetically based. reason one is that we’re in a population upsurge, that is, the baby boomers’ kids are in high school. after the ‘primary sports’ are filled up (you can only put so many players on a football team) the secondary sport (XC) gets the overcapacity. so instead of 35 kids on a XC team you get 60 or 70.
the second reason is akin to the first. when you have 70 kids, you have a better chance of producing a 4:10 miler. once you get one of these, it lets the others know what’s possible, and they gaze higher. the 4:40 miler becomes a 4:25 miler because of that 4:10 miler on his team.
third, you get that sort of thing occurring across leagues and areas. a couple of years ago there was one overcoming program in southern california, royal high school in simi valley. the team is just as good now as it was two years ago, but you have trabuco hills, el toro, and others who’ve lifted themselves up and give as good as they get from royal. that sort of thing is happening all over the country.
finally, one wonders how many really good runners are buried in football or swimming or baseball programs. i remember coley candaele from carpenteria hs some years back. his brother was a pro baseball player, he himself was a star quarterback. but in track he was a 4:10 miler. what if he would’ve dropped the other stuff and just run?