Giant pandas have a special bone that extends from their wrists called a "pseudo-thumb," which they use to hold and manipulate bamboo. They are also very good tree climbers and can swim.
They also have strong jaws and teeth like most bears. They are not as docile as many zoo animals, though.
To survive solely on low-nutrient bamboo, modern giant pandas have developed a peculiar sixth finger. This "thumb" allows them to grasp and crush bamboo stalks into bite-size pieces.
It's not clear how this digit evolved, but Wang and his team say that the ancient panda ancestor Ailurarctos (Ailuropoda melanoleuca) had a similar thumblike structure six million years ago.
This digit was longer and straighter than the one in modern giant pandas, researchers found. This suggests that it had an essential role in the evolution of the species, they wrote in the journal Scientific Reports.
The earliest evidence of this thumblike feature was discovered in a fossil from about 100,000 years ago. But the latest research shows that this extra finger was already in place at about 6 million years ago, according to researchers from China and the US.
The scientists said that it may have been an adaptation to help the pandas travel and bear their hefty weights. They also think that the digit's length was optimum for its usefulness, not big enough to get in the way or slow down their fast-paced diet.