Giant panda bears evolved away from other bear species about 20 million years ago. Though they have similar characteristics, like body shape and digestive system, they greatly differ in preferred diets. Most bear species will happily feast on meat, fish, and berries, while pandas tend to stick to bamboo.
A new study published in Frontiers in Veterinary Science points out that pandas have evolved in specific ways to make eating bamboo easier, including a pseudo thumb for holding bamboo and flatter teeth for chewing it. The study set out to determine why pandas evolved to be more herbivorous when they have the system to be carnivorous. They answer, they found, may lay within the bamboo itself.
Pandas and Tasty Bamboo
There are over 1,000 species of bamboo, though pandas only snack on about 25 of them. The reedy, tree-like grass is a panda’s primary food source, especially the shoots. However, because bamboo has little protein, pandas can eat up to 12 hours a day, consuming roughly 26 to 84 pounds of the plant.
Within bamboo, as within all living organisms, is DNA and RNA. DNA stores genetic cell information, while RNA transfers it. They also have microRNAs (miRNA), or small non-coding RNAs that help with gene expression. According to the study, miRNA from plants can be absorbed through food.
With this information, the research team wanted to determine if absorbing this miRNA could regulate gene expression and aid pandas in adapting to consuming bamboo as a regular food source.
“We showed that plant-derived miRNAs are present in the blood of giant pandas,” said Feng Li, a researcher at China West Normal University and senior author of the study, in a press release. “Our study proved that bamboo used as food for giant pandas does affect the change of giant pandas’ feeding habits.”
Studying Adaptive Food
For this study, the research team took blood samples from seven giant pandas, including three females, three males, and one juvenile female. Within the samples, the team found 57 miRNAs that were likely from bamboo.
“MiRNA in bamboo can enter giant pandas’ bodies through diet, be absorbed by the intestine, enter the blood circulation, and then regulate when the giant panda’s RNA transfers information, thus playing a role in regulating the gene expression of giant pandas,” Li said in a press release.
According to the press release, the results show that the miRNAs from plants can “regulate different physiological processes.” These processes include growth and development, behavior, immune response, and biological rhythms.
“MiRNA in bamboo is also involved in the regulation of smell, taste, and dopamine pathways of giant pandas, all of which are related to their feeding habits,” Li said in a press release.
As pandas grow and consume more bamboo, the miRNA helps the pandas adapt to the taste and smell of bamboo so that they’re able to keep eating it. It’s likely why they are able to eat a more plant-based diet versus a carnivorous one.
From Food to Medicine
Researchers also found that there were different miRNA compositions in the blood, depending on the age and sex of the pandas.
“Only miRNAs that can specifically play a role in regulating gene expression can remain in the body, and those that do not play a role will be expelled,” said Li in a press release.
An example of this would be that miRNAs help with reproduction, so only a panda of a certain sex or age would have it. These test results are a key step in helping researchers understand how plant miRNA can transfer to animals, which may open the door to life-saving treatments of animal diseases.
“Plant miRNAs may also participate in regulating the animal immune system, enhancing animals’ disease resistance,” Li added in a press release.
Read More: Recent Findings Suggest Pandas Evolved To Eat Bamboo Six Million Years Ago
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A graduate of UW-Whitewater, Monica Cull wrote for several organizations, including one that focused on bees and the natural world, before coming to Discover Magazine. Her current work also appears on her travel blog and Common State Magazine. Her love of science came from watching PBS shows as a kid with her mom and spending too much time binging Doctor Who.
