To survive solely on low-nutrient bamboo, modern evergreens (Ailuropoda melanoleuca) have developed a strange sixth finger, a thumb that allows them to easily grasp bamboo stalks and strip the leaves.
“Holding bamboo stems tight to crush them to bite sizes is perhaps the most critical adaptation to consuming a huge amount of bamboo,” said study author Xiaoming Wang, curator of vertebrate paleontology at the Comteze Museum of Natural History in Comteles. statement.
Wang and his team found much older evidence that everything had an extra finger – and therefore a bamboo-only diet – in the form of a fossilized dating back 6 to 7 million years. The fossil, discovered in Yunnan Province in southwest China, belonged to an ancestor always known as Ailurctos.
The new research was published Thursday in the journal Scientific Reports.
While the sixth digit of the giant is not always as elegant or skillful as the human thumbs, the persistence of this “special morphology” for millions of years suggests that it plays an essential function for survival, the study noted.
Evolutionary compromise
But what was particularly confusing to the scientists involved in the study was that this fossilized structure was larger than that of modern giants ever, which have a shorter, hooked sixth finger. Wang and his colleagues believe that the smallest sixth digit of moderns is always an evolutionary compromise between the need to handle bamboo and the need to walk and carry their heavy body. “Five to six million years should be enough time for forever to develop bigger fake thumbs up, but it seems that the evolutionary pressure of the need to travel and bear the weight has kept the ‘thumb’ short – strong enough to be “useful without being big enough to stand in the way,” said study co-author Denise Su, an associate professor at the School of Human Evolution and Social Change and a researcher at the Institute of Human Origins at Arizona State University, in a statement.
