But their ancestors, like most bears, ate a much broader diet that included meat, and the exclusive diet of modern pandas was thought to have evolved relatively recently. However, a new study finds that pandas ’particular passion for bamboo may have originated at least 6 million years ago, possibly due to the plant’s wide availability throughout the year.
To survive only on low-nutrient bamboo, modern pandas (Ailuropoda melanoleuca) have developed a peculiar sixth finger, a kind of thumb that allows them to easily grab bamboo stems and cut leaves.
“Holding the bamboo stems firmly in order to crush them to bite sizes is perhaps the most crucial adaptation for consuming a prodigious amount of bamboo,” said study author Xiaoming Wang, a paleontologist. of vertebrates at the Los Angeles County Museum of Natural History, in a statement.
Wang and his team identified much earlier evidence that pandas had an extra finger and therefore a bamboo diet, in the form of a fossilized digit dating back 6 to 7 million years. The fossil, discovered in the southwestern province of Yunnan in China, belonged to a panda ancestor known as the Ailurarctos.
The new research published Thursday in the journal Scientific Reports.
Although the sixth digit of the giant panda is not as elegant or dexterous as human thumbs, the persistence of this “distinctive morphology” for millions of years suggested that it has an essential function for survival, he noted. study.
Evolutionary commitment
But what was especially disconcerting to the scientists involved in the study was that this fossilized structure was longer than that of modern giant pandas, which have a shorter, hooked sixth finger.
Wang and his colleagues think that the sixth shortest digit of modern pandas is an evolutionary compromise between the need to manipulate bamboo and the need to walk and carry their strong bodies.
“Five to six million years should be long enough for the panda to develop longer false thumbs, but it seems that the evolutionary pressure of the need to travel and bear its weight kept the ‘thumb’ short, strong enough to be useful without being big. enough to get in the way, “said study co-author Denise Su, an associate professor at the School of Human Evolution and Social Change and a scientific researcher at the Institute of Human Origins of Arizona State University, in a statement.