Together with its black-and-white fur, slothful habits and cuddly attitude, bamboo is a specifying function of the critically-endangered huge panda (Ailuropoda melanoleuca. A single panda can take in between 26 and 84 pounds (12 to 38 kgs) of the greenery every day, and might invest as much as 16 hours daily consuming mouthful after mouthful of this fibrous, chewy plant.

These usage patterns are so extreme that Feng Lia scientist at China West Normal University, explains the panda as a “mobile shredder of bamboo.” Do panda bears ever broaden their diet plans and consume anything besides this fast-growing plant?

Usually, the response is no– although there are some uncommon exceptions. “There have been cases where wild giant pandas occasionally eat small animals,” Li informed Live Science in an e-mail. Li pointed out uncommon circumstances recorded in the Qinling Mountain area of China, where huge pandas were discovered gnawing the bones of a takin (Budorcas taxicolora goat-like wild ungulate. They have actually likewise been discovered periodically victimizing Chinese bamboo rats (Rhizomys sinensis.

John Speakmanthe chair of zoology at the University of Aberdeen in the United Kingdom, validates that these cases are opportunistic and uncommon: “There is a picture online of [a panda] in a zoo that captured and ate a peacock. But as far as I know these are really chance encounters.”

Aside from these unusual lapses into carnivorism, pandas stick specifically to bamboo. There’s an intriguing twist to this story, since there’s plenty of proof to reveal that pandas really ought to have much more varied diet plans. They’re not particularly appropriate to consuming bamboo.

Research study has actually revealed that the bears have a gut architecture that resembles predators, like their bear cousins, which their stomachs do not have the many-chambered structure that other herbivores utilize to process massive amounts of plants. What’s more, the microorganisms that occupy their gut plants are more like those of meat-eaters, and can processing and drawing out protein. Those microorganisms are inadequate to breaking down plants. Panda poop exposes this too: scientists on the research study discovered it consisted of pieces of undigested bamboo

Related: Why do chimpanzees toss poop?

The panda’s evolutionary increase

These ill-fitted qualities seem evolutionary hangovers from the huge panda’s ancestral past. Hints from the fossil record reveal that the forefathers of modern-day huge pandas taken in not just meat however likewise greenery. About 7 million years back, the fossil proof recommends that one forefather in specific, called Ailurarctos started to sample a little bamboo.

This significant “the starting point of the transition from omnivorous to herbivorous,” according to Li, which might have been sped up by a modification in the schedule of food. “The currently popular view is that environmental changes in ancient times led to a sharp decline in food resources. The ancestors of giant pandas competed fiercely with other carnivores,” Li stated.

Having currently began supplementing its diet plan with bamboo, Ailurarctos had an adaptive edge and was able endure the deficiency by occupying this eco-friendly specific niche, scientists think. “The evolutionary process of giant pandas changing from omnivorous to bamboo-exclusive is a classic case of ‘survival of the fittest, but not necessarily the best’ in evolutionary biology,” Li kept in mind.

While their evolutionary makeup might appear inadequately matched to their bamboo-intensive diet plans, huge pandas have actually likewise established a number of adjustments to fit their scenario. A gene that needs to allow them to taste the distinctively umami taste of meat has actually been suspended in their DNA, implying they likely do not have a natural hunger for fresh meat, Li stated. Pandas likewise have an extremely sluggish metabolic process, which assists them to make it through on their low-energy diet plan of bamboo. Pandas use up simply 38% of the everyday energy of other land mammals of a comparable size.

Speakman was included in research study that revealed a possible root of this slow metabolic rate: a gene anomaly that’s special to pandas and controls thyroid hormonal agents, which are type in controling metabolic process.

“We all pretty much expected their metabolic rates would be low because otherwise they wouldn’t be able to eat enough food to match their expenditure. The big insight was finding the genes that underlie that,” Speakman informed Live Science in an e-mail. “Since then we built mice with the same mutation and confirmed those mice also have lowered metabolic rates.”

Li led a research study that checked out how bamboo itself may even play an essential function in assisting pandas adjust to their uncommon diet plan. When Li took a look at blood samples drawn from panda bears, he determined particles called microRNAs, or miRNAs, distributing there. MiRNAs are particles that happen in animals and plants, which cells utilize to manage gene expression. These particles likewise take place in bamboo, from where they go into the panda’s body through diet plan, and can collect in its tissues in time.

When Li and coworkers analyzed numerous of the miRNAs taking place in panda blood, they discovered that they targeted particular genes that are otherwise associated with promoting hunger, managing sense of odor and reducing bitter tastes, to name a few things. It’s possible that these bamboo-derived particles have actually assisted establish and curate pandas’ cravings for the plant. This might be necessary for their survival, “ensuring that sufficient bamboo can be consumed every day to meet the energy intake requirements of the body,” Li described.

In other places, research studies have actually discovered that pandas’ gut germs aren’t entirely at chances with their vegan diet plan. Their gut plants modifications throughout the season when bamboo shoots– a more nourishing part of the plant than the leaves– appear, permitting pandas to save more energy throughout this quick window, throughout which time they noticeably put on weight

Pandas have actually likewise progressed a “pseudo-thumb” that permits them to grip bamboo stems firmly. Their molars are more comprehensive than in other bears– important for squashing sturdy bamboo stems, as are pandas’ distinctively effective jaws: “Their big round faces are because they have these massive jaw muscles that give them a bigger bite force than a polar bear,” Speakman stated.

Pandas are loved, however similarly buffooned as inadequately adjusted, evolutionary dead-ends. While it may appear like they simply loll around and consume bamboo all day, as Li put it, “the ‘laziness’ of pandas is survival wisdom.”

Emma Bryce is a London-based independent reporter who composes mostly about the environment, preservation and environment modification. She has actually composed for The Guardian, Wired Magazine, TED Ed, Anthropocene, China Dialogue, and Yale e360 to name a few, and has masters degree in science, health, and ecological reporting from New York University. Emma has actually been granted reporting grants from the European Journalism Centre, and in 2016 got an International Reporting Project fellowship to go to the COP22 environment conference in Morocco.