For pandas, it’s been two ‘thumbs’ up for millions of years

WASHINGTON

Scientists are able to use fossils found in China to help them understand one of the wonders of evolution: The giant panda’s false thumb. This false thumb allows the veggie-loving bear to eat the bamboo that is the bulk of its diet.

Researchers said on Thursday they discovered near the city of Zhaotong in northern Yunnan Province fossils about 6 million years old of an extinct panda called Ailurarctos that bore the oldest-known evidence of this improvised extra digit – actually a greatly enlarged wrist bone called the radial sesamoid.

It is very similar to the modern false thumb pandas, but it is longer and lacks an inward hook on the end of the extant species. This allows for greater manipulation of bamboo stalks, shoots, roots, and roots while you eat.

The false thumb was created by evolution to enhance the five existing digits on the panda’s hands. The opposable thumb, which humans and other primates possess, is absent from the bear’s hand. It allows the grasping and handling objects with the fingers. A false thumb performs a similar function.

“It uses the false thumb to grasp bamboos. It is a very crude opposable thumb, much like our thumbs, but it is located at the wrist. said Natural History Museum of Los Angeles County paleontologist Xiaoming Wang, lead author of the research published in the journal Scientific Reports https://www.nature.com/articles/s41598-022-13402-y.

Ailurarctos, a smaller evolutionary forerunner to the modern panda was smaller, but had anatomical traits that indicated a similar lifestyle, including a bamboo diet. The false thumb of the modern panda has some advantages over its predecessor.

“The hooked false thumb offers a tighter grasp of the bamboo and, at the same time, its less-protruded tip – because of the bended hook – makes it easier for the panda to walk. The false thumb is a foot that the panda steps on every time it walks. Therefore, we believe that the false thumb of modern pandas has become shorter and not longer.” Wang said.

Wang said that the tight grip of the bamboo by the panda protects against the jerking action from the mouth and allows it to quickly break down food in bite-size pieces.

In 2010, the researchers discovered an Ailurarctos bone in the arm. They then discovered teeth in 2015 and the false thumb in 2015. This gave them a better understanding of the animal. The oldest evidence of the thumb-like structure was found in fossils dating back to around 102,000-49,000 years ago, which is the same species of pandas that are alive today.

The false thumb allows pandas, in addition to holding bamboo to eat, to rotate the food as a true hand would.

“One of humanity’s most important features is the evolution of a thumb that can grip other fingers to allow for precise grasping. Although the false thumb of the panda is less effective than the human thumb it is sufficient to give the giant panda the ability to grasp bamboo. saidTao Deng, a paleontologist who is also a study co-author at the Chinese Academy of Sciences Beijing, is an author.

One of the eight species of bears in the world, the Panda, once inhabited vast swathes of Asia. They are now found mainly in temperate forests in the mountains in southwestern China with a wild population of less than 2,000.

A panda’s diet consists 99% of vegetarian food, but they may eat small animals or carrion occasionally. Because of their inefficient digestive system, pandas consume large amounts to meet their nutritional needs – 26-84 pounds (12-38 kg) of bamboo while eating up to 14 hours a day.

Researchers discovered that the false thumb did not exist in a close-related bear that lived around 9 million years ago. said.

“This is a great innovation – transformation of a minor bone into an element that is useful for a particular purpose,” saidLawrence Flynn, Harvard University paleobiologist and co-author of the study, is also an author.

(Reporting and Editing by Will Dunham, Editing By Rosalba O’Brien