In a desolate stretch of Nevada, teams have been competing all week to break speed records for human-powered locomotion. NPR's Scott Detrow talks with one of this year's competitors, Lizanne Wilmot.

From the rise of empires to the birth of global trade, no animal has shaped humanity quite like the horse. Domesticated around 4,200 years ago in the Pontiac-Caspian steppe — or around a thousand ...