Puzzling research suggests pandas can't digest their favorite food

New research suggests that despite subsisting on it for two million years, pandas haven't actually adapted to digest the bamboo they famously eat.

Researchers in China looked at the bacteria in panda poop and compared what they found to 54 other mammals, including herbivores and other bears.

The researchers found the panda's microorganisms much more closely resembled those of other carnivores and omnivores, and were missing the bacteria that helps other animals digest plant fiber, suggesting they're still not adapted to eating bamboo.

The process is so inefficient that while panda spend up to 14 hours per day chowing down on bamboo, they only digest about 17% of it.

But some scientists call that conclusion into question.

"Some of the microbes in the panda gut might still be highly efficient at breaking down cellulose," Jonathan Eisen, a microbial biologist at the University of California Davis, told Nature.

Eisen argues the scientists only looked at what microorganisms were found in the panda, and not what functions they actually carry out in the panda's digestive system.

Scientists theorize pandas started eating bamboo when they first moved to the higher elevation of the Chinese mountains where they live today, as a way of avoiding competition for prey with the predators already established there.

Like most bears, pandas are actually omnivores, and while they mostly eat bamboo, they will also eat meat if presented with it.