Contary to myth, pandas are not 'evolutionary dead ends'. They may now just eat bamboo, but their digestive system betrays their carnivorous roots and shows that they are very efficient at extracting the protein they need from bamboo.
Yonggang Nie and Fuwen Wei of the Chinese Academy of Sciences have spent years tracking wild pandas, analyzing exactly what kinds of bamboo they eat, and measuring the chemicals within those mouthfuls. And they found that the nutrient profile of a panda’s all-bamboo diet—very high in protein, and low in carbohydrates—is much closer to that of a typical carnivore than to that of other plant-eating mammals. “It was a surprise,” Wei says. Nutritionally, “bamboo looks like a kind of meat.”

In other words, “the giant panda does what human vegetarians do,” says Silvia Pineda-Munoz of the Georgia Institute of Technology. “We have high protein requirements, so we wouldn’t be able to survive if we just ate kale salad. Thus, we choose to eat tofu, beans, nuts, and other plant-based foods that compensate for the protein we aren’t getting from animal products. In the end, vegetarians and nonvegetarians don’t have such different diets when it comes to nutrients.” And so it is with China’s black-and-white bear.
This suggests that the move from meat to plants might have been easier for ancestral pandas than commonly assumed. By simply choosing parts of plants that are richer in protein, they could switch to vegetarianism without needing to radically overhaul their bodies. “If you’re going to switch to a specific plant, bamboo isn’t too bad, as it does have respectable plant protein levels, as well as a swath of different vitamins,” says Garret Suen of the University of Wisconsin at Madison.

These results should help to counter the tiresome myth that pandas are evolutionary dead ends: lazy, poorly adapted creatures that eat deficient diets, are inept at sex, and should be allowed to go extinct. Nonsense. Pandas have beautifully adapted to eat an extremely plentiful food source—bamboo—and they go to great, careful lengths to get exactly the right balance of nutrients.
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