Could Africans Dominate Distance Running Because They Are "Saltier?"

Old friend Anonymous Economist responds to a post earlier this week on the science of electrolytes:

An article in the American Journal of Human Genetics suggests (if I've interpreted it correctly—and I'm an economist, not a medical professional) that populations with genetic roots in hot, humid climates tend to retain more salt than populations with roots in cooler climates. The relevant genes are CYP3A5 and AGT. Populations from cooler climates carry a mutated form of CYP3A5 that produces a nonfunctional protein, inhibiting salt retention.

In addition, research by up-and-coming Harvard economist Roland Fryer (along with Ed Glaeser and David Cutler) links a higher rate of salt sensitivity among African-Americans to higher rates of hypertension and other diseases. Slave traders, according to Fryer, may have licked the faces of prospective slaves. "Saltier" Africans may have been selected for the voyage from Africa to America—because slaves with higher capacities for salt retention may also have retained more water, decreasing their chance of death by dehydration during the long trip.

I may be reaching, but put that all together with the post on electrolytes and one can perhaps begin to see why Africans dominate long-distance running events—they may be saltier. Unfortunately, they may also suffer higher rates of cardiovascular, stroke, and kidney disease than their otherwise equally fit white counterparts.

The theory appears testable, though I don't recommend the experiment. The theory suggests that if you were to lick marathon runners' cheeks, the winners would taste saltiest.

Mmm…marathon runner cheek salt. Thanks, Anonymous Economist—for this provocative post you have once again been "activated," which as you know is our highest honor.

Ladies: I'll try to convince Activeness's Jan to make his face available for salt licking in the neighborhood of 10.A.M. (the race starts at 7:00 A.M.) on April 10 at the finish line of the St. Louis Marathon. - John