The giant panda and his underactive thyroid

Scientists have long wondered how pandas whose bodies are equipped to eat meat can survive eating only low-nutrient food such as bamboo.


“Pandas save a lot of energy by being frugal with the energy they spend on physical activity”, explains Prof John Speakman, from the University of Aberdeen and Chinese Academy of Sciences. They found that the daily energy expenditure of these bears was only about 38 per cent of other similar-sized animals. “We found that their low metabolism is correlated with very low levels of thyroid hormones, which was linked to a genetic mutation in the thyroid synthesis pathway that is unique to the panda”.

“The on a regular basis potential fees ideals for big pandas are elegantly a lesser amount than those particular for koalas, just for example, and even more resembling all those of three-toed sloths”, the investigation, found in the document Science, said. The researchers believe that pandas’ small size of internal organs such as liver, brain and kidneys has the same function.

Taken together, these results suggest that particularly low energy expenditures and thyroid hormone levels enable the carnivorous-looking panda bears to munch on bamboo all day. The leader of the study was scientist Fuwen Wei who measured how much energy pandas consumed.

Finally, the team compared the giant panda genome to those of other mammals, identifying a panda-specific variation on the DUOX2 gene, loss of which is associated with underactive thyroids in humans. These critically endangered bears actually have a good reason for such lifestyle. The researchers found that pandas possess only a fraction of the total normal value of thyroid hormones in mammals, and that the values they exhibited are tantamount to that of a black bear going through hibernation. However, pandas dine nearly exclusively on bamboo, making them one of the eight bear species that have a plant-only diet. Nope. They can sustain high body temperatures due to their thick coat of fur, the researchers suspected. This may be partly responsible for the minimal energy demands of the pandas thus their survival with diet mainly consisting of bamboo.

There are roughly 1,800 giant pandas left in the wild according to the World Wildlife Fund, citing Chinese government figures.


How they achieve such low rates of energy use was the focus of the second part of our paper, published in the journal Science.

Giant panda taking a nap