Although giant pandas are technically carnivores, they have adapted to eating a diet of 99% bamboo, which they can barely digest. Pandas are genetically unable to turn cellulose into energy, so they must eat up to 38kg (84lbs) of the fibrous plant every day to get enough calories to survive. The task requires 12-16 hours of foraging and eating.
The panda’s gut has developed a thick layer of mucus to protect against bamboo splinters. So, aside from the rare rodent or bird, why don’t pandas eat meat? Clues in the recently sequenced panda genome point to a genetic mutation that may render them unable to taste flesh. Fossil studies show that the giant panda’s ancestors swapped meat for bamboo between 2 and 7 million years ago – perhaps due to a major environmental event wiping out their prey. Being forced to change their diet may have caused the gene responsible for tasting savoury to become obsolete, and without it they might not have wanted to eat meat even when it became plentiful.