Puzzling Out Man's Ascent

It is one of the least hospitable places on earth. A steady wind moans over the crocodiles basking on the banks of blue-green Lake Turkana and flattens the knee-high beach grass where the long-horned oryx graze. Beyond stretches the desert of northeast Kenya, baked by the African sun. In a wadi, or dried-up stream bed, not far away, a sandy-haired man moves slowly, his loose shorts and shirt flapping in the breeze, his head bare to the sun, his eyes searching the arid soil at his feet. Some 50 ft. away, sandals scuffing dust into the air behind her. his wife...