Yak taking a rest. Adapted to high altitude with larger lungs and hearts than normal cattle, they continue to produce foetal haemoglobin their whole life to increase oxygen carrying capacity. Conversely at low altitudes or above 15 degrees C (59 F) they begin to suffer from heat exhaustion due to a thick layer of subcutaneous fat combined with a lack of functioning sweat glands. Nepalese Himalaya. Nepal . Shot with Fuji Velvia slide film.