Why do giant pandas poop a lot? This is the question plaguing the minds of scientists, prompting a study on the matter published Tuesday in the American Society for Microbiology’s open-access journal, mBio.
Giant pandas’ diets consist almost exclusively of bamboo, and they’ve been eating this for about 2 million years. With such a long track record of eating bamboo, it is quite curious that their gut bacteria isn’t really equipped to process all that plant matter. In fact, giant pandas only digest about 17 percent of the nearly 30 pounds of bamboo they eat throughout the day, the new study found.
This means no matter how much giant pandas eat, most of their efforts go into pooping undigested bamboo.
Study co-author Xiaoyan Pang of Shanghai Jiao Tong University said in a statement that their findings imply “the giant panda’s gut microbiota may not have well adapted to its unique diet, and places pandas at an evolutionary dilemma.”
The situation is curious, since pandas used to eat both meat and plants before switching to a solely bamboo diet. “Unlike other herbivores 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 authors wrote.
Another article by the same authors, published this week in Scientific Reports, compared the gut bacteria in giant pandas to that in red pandas, who also consume bamboo. The researchers discovered that giant pandas have gut bacteria more closely comparable to black bears. What’s more, a giant panda’s gut is completely different from that of a red panda.
When both studies are looked at together underscore the giant pandas place as a bear in the animal kingdom, while red pandas are more closely related to the raccoon, Mike Maslanka, head of the nutrition science department at the Smithsonian’s National Zoo in Washington D.C., told the Washington Post.
“Regardless of their diet, giant pandas are bears. They’re cool and fuzzy, black and white, but they’re bears,” said Maslanka, who did not work on these particular studies. “It just reinforces that, from the inside out.”