This study examined how macaque monkeys living on the high Tibetan Plateau adapt to harsh conditions. Researchers found that high-altitude macaques have darker feces containing more stercobilin, a pigment from red blood cell breakdown. Their gut bacteria are specially adapted to process this increased bilirubin from the extra red blood cells produced at high altitude. Interestingly, high-altitude macaques also eat medicinal mushrooms like Ganoderma lucidum, which may help them cope with the stress and low oxygen levels.