Those who have ridden yaks over mountain passes compare the animals' breathing to the chugging of locomotives. At high altitudes, a larger number of red blood cells are needed to combine with hemoglobin, which enables oxygen to travel in the blood. Yaks have almost three times the number of red blood cells found in lowland cows and a higher concentration of hemoglobin. Sharp cries pierce gorges dissected by the silver ribbon of a frozen stream. Their hooves churn the steep, dry slopes beneath the Himalayan peaks into clouds of dust.
Stones roll and fall into the chasm.
The ropes creak. The tinkling of bells echoes through barren mountains that will fall silent again after their passage. Though many experiments to introduce productive breeds have failed, such as the bulls brought to China in the 1950s, crossbreeds have been successful within limits. At lower altitudes, various crossbreeds yield more milk and provide transport. These animals are usually found close to villages on the southern rim of Dolpo.