Evolution Bungle? Panda Gut Better Suited for Meat Eating Not Bamboo, Study Finds

Pandas are known to be champion eaters but a new study reveals that the gentle giant's day-long munching does not do them much good.

The study showed that gut bacteria of pandas is similar to carnivores and omnivorous bears. It also argues that panda's digestive system is not anatomically designed to metabolize fiber like herbivores, implying that pandas cannot digest bamboo well. Instead, they are better suited to be meat-eaters, the study found.

"Unlike other plant-eating animals that have successfully evolved, anatomically specialized digestive systems to efficiently deconstruct fibrous plant matter, the giant panda still retains a gastrointestinal tract typical of carnivores. The animals also do not have the genes for plant-digesting enzymes in their own genome. This combined scenario may have increased their risk for extinction," said the study's lead author / Zhihe Zhang.

By analyzing fecal matter, gut bacteria and anatomy researchers have concluded that pandas can only absorb 17 percent of the bamboo they consume. The low absorption efficiency explains why pandas feed bamboo for more than 14 hours a day.

Pandas evolved from omnivorous bears and started feeding on bamboo about two million years ago. Modern pandas consume about 12.5 kg of bamboo a day. Their gut was found to have Escherichia, Shigella and Streptococcus bacteria, which can also be found in carnivores but not in herbivores.

"This result is unexpected and quite interesting, because it implies the giant panda's gut microbiota may not have well adapted to its unique diet, and places pandas at an evolutionary dilemma," said the study's coauthor Xiaoyan Pang.

The study has been published in the journal mBio.