A part of Tibetan life for centuries, the revered animals provide food, clothing, labor and transport.

Over 40 years ago, Wu Yuchu was trapped in a blizzard in the Tibet autonomous region.

It was 1977, two years after Wu had started working in Tibet. He and more than 50 other people took shelter in a mud-brick house while the blizzard raged. The outside temperature dropped to-30 C, and food was running out.

When the rescue team finally arrived with yaks carrying lifesaving supplies, Wu immediately bonded with the beasts.

He could not have imagined that the bond would last for decades. Yaks saved his life, and he has spent most of his life promoting the animals.

"I have watched and studied them ever since," Wu says. "I grew really fond of them, and I wanted to learn more about the species." His yak studies remained a hobby until 2014, when he became the curator of the Yak Museum in Lhasa, Tibet's capital.