If humanity were to make a most huggable animals list, pandas would most definitely make it up to the top 3. However, you might want to rethink your choice before you put your arms around a giant panda since they have perhaps one of the world's grossest habits: they love to rub horse manure on their necks and faces and roll around in it to cover their bodies.
Researchers at the Chinese Academy of Sciences’ Institute of Zoology wondered the reason behind this bizarre behavior, and now, they are saying that they've found an explanation.
The research was published in the journal Proceedings of the National Academy of Sciences.
A strange fecal attraction
It was in the winter of 2007 that the scientists in China first spotted the strange behavior: a wild giant panda (Ailuropoda melanoleuca) was smearing itself with horse poop until its fur was almost dripping with it. They'd see instances of that same behavior again and again after that.
No one knew why wild pandas were attracted to horse poop which meant some serious science was needed. In order to understand the reason why researchers analyzed 38 cases of poop-rolling which were captured on infrared cameras at the reserve from June 2016 to July 2017.
Possibly a protection from the cold
The first clue was the fact that the pandas preferred to roll in horse poop less than 10 days old which contained natural compounds called beta-caryophyllene (BCP) and beta-caryophyllene oxide (BCPO) which are reportedly scarce in older poop. When the researchers added this compound to the hay of pandas at the Beijing Zoo, they found that the animals inspected it closely and some rubbed it all over their bodies.
The second clue was more explanatory: the pandas tended to roll in horse poop in colder water, at temperatures between 23°F (-5°C) to 59°F (15°C).
In order to further their research, the scientists conducted experiments on mice since there are limitations to conducting research on giant pandas. It was seen that covering mice in a diluted BCP-BCPO solution boosted the animals' cold tolerance. Moreover, while they were seeking a molecular explanation for the effects, the researchers found the solution interacted with the TRPM8 thermoregulation channel which is a sort of all-body equivalent to the sensation of eating chilies and feeling hot.
Maintaining their body temperature is especially challenging for pandas due to their low-fat diet; so it doesn't come as a surprise that survival was the reason behind this behavior. However, it is still not clear how pandas discovered the warming effects of horse feces.