Giant panda
(IN PHOTO)Yuan Zi, a male giant panda, bites on bamboo inside his enclosure at the ZooParc de Beauval in Saint-Aignan, Central France January 17, 2012. A pair of giant pandas, which have been loaned to the zoo by China, will be on public view for the first time on February 11, 2012. REUTERS

A new study has made a very surprizing revelation that giant pandas are not evolved to eat bamboos or any plant for that matter. The study findings published in the online US journal mBio indicate that the microbial flora of the intestine of giant pandas or Ailuropoda melanoleuca cannot efficiently breakdown the cellulose present in plants and show resemblance to that of carnivores, rather than other herbivores.

This observation was made after the study authors examined the fecal microbiomes of 45 giant pandas over the course of a year. They also found that the pandas have a digestive system which is "entirely differentiated from other herbivores.” Furthermore, they still retain the gut bacteria that are similar to that of omnivorous bears from whom they evolved.

According to researchers from Shanghai Jiao Tong University and the Chengdu Research Base of Giant Panda Breeding in China, the giant panda microbiome exhibited low microbial diversity and typically lacked known cellulose-degrading bacteria. Study co-author Xiaoyan Pang, an associate professor at Shanghai Jiao Tong University says, "This result is unexpected and quite interesting because it implies the giant panda's gut microbiome may not have well adapted to its unique diet and places pandas at an evolutionary dilemma."

Giant pandas began to exclusively eat bamboo after they evolved from omnivorous bears about two million years ago. The evolution was the result of genetic mutations such as the loss of the umami taste receptor gene. Although the physical attributes of giant panda such as strong jaws, teeth, and an enlarged radial sesamoid support it for eating plants like bamboo, it has still retained the a simple stomach instead of the elongated ones found in other herbivores that can easily digest the plant polysaccharides.

The pandas have their natural habitat in the mountainous regions of southwest China. Their reproductive rate has dwindled with only about 1,600 pandas living in the wild and another 300 held in captivity in China. The researchers now fear that this might put the giant pandas among the list of endangered species who are at the verge of extinction. They concluded by saying that "Unlike other mammalian species that have evolved gut microbiome (and also digestive system anatomies) optimized for their specific diets, the aberrant coevolution of the giant panda, its dietary preferences, and its gut microbiota remains enigmatic."

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