The peculiar anatomy transformations that made the ancestors of pandas (Ailuropoda melanoleuca) developed a “false thumb,” exclusively dedicated to grasping bamboo stems, happened at least 6 million years ago, a new study indicates.
The discovery, made by researchers from China and the USA, indicates that the lifestyle of these bears is extremely ancient and successful, despite the risk of extinction that the animals face today.
“Our fossil panda achieved the same functionality as a modern panda back then,” he told Sheet study coordinator Xiaoming Wang of the Natural History Museum of the Municipality of Los Angeles. In the work, which has just appeared in the online edition of the journal Scientific Reports, Wang and his colleagues compared the front paw bones of current pandas with those of a specimen of the genus. Illustrationsdiscovered in the Chinese province of Yunnan.
between the bones of Illustrations are teeth (a molar and a canine), part of a humerus (in humans, the part of the arm that articulates with the shoulder) and, of course, the pseudothumb, which corresponds to an elongation of a wrist bone, the sesamoid. radial. This means that modern pandas actually have five human-like fingers arranged in a “straight line” and a false sixth finger.
In the animals we know today, the false thumb is curved at the tip. The curious structure allows the animal to firmly hold the bamboo stalks while tearing the plant apart with its teeth.
In fact, more than the fluffy black and white coat that every child knows, it’s this anatomical feature that really defines these bears.
Pandas practically only feed on bamboo, and, as their intestines are still basically identical to those of other bears, which normally eat everything and consume a lot of meat, this means that the animal has to spend 15 hours of its day devouring bamboos non-stop. to meet your nutritional needs. That’s why the efficiency of the false thumb is so important to him.
The new study revealed that the pseudothumb of the Illustrations it is slightly longer than its modern relatives, and also relatively straight, without the curve at the tip. “The current species’ false thumb offers a slight advantage in allowing it to hold bamboo more stably in its hands, but the difference in this is probably not that big,” says Wang.
Another important issue is the animals’ locomotion – after all, unlike the character in the series “Kung Fu Panda”, real-life pandas are still quadrupeds and therefore the “new thumb” cannot interfere with their movements.
“When it became curved, the false thumb, because of the less prominent tip, also facilitated locomotion,” explains the study’s author. “Think about what happens when the animal steps on it every time it walks. So we think that’s the reason why it got shorter, not longer, even though a larger shape would theoretically be , most useful for grasping bamboo stalks.”
Although the plant is a relatively nutrient-poor food source, it is available all the time, even in winter, in the regions of China inhabited by the species today and in the past. Thus, depending on bamboo was a relatively safe evolutionary bet, although tedious from a human point of view, which explains the maintenance of this lifestyle for so long.