Early Version of Giant Panda's 'False Thumb' Found in China
2022-07-05
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1Ancient bones unearthed in China are helping scientists better understand the development, or evolution, of modern pandas.
2Pandas are a kind of animal called bears that live in forests in the mountains of Southwestern China.
3Pandas' main food is a plant called bamboo.
4Currently, experts estimate the wild population of pandas is under 2,000.
5Researchers recently reported that they discovered fossils, or mineralized bones, from an extinct panda called Ailurarctos.
6The fossils were found near the city of Zhaotong in the northern Yunnan Province in China.
7They are about 6 million years old and are from an ancestor to the modern panda.
8The fossils helped scientists understand the evolution of a bone structure that helps pandas eat bamboo called a false thumb.
9The false thumb found on Ailurarctos is similar to those found on modern pandas.
10But, it is longer and lacks a hook that living pandas use to eat bamboo.
11The fossils are the oldest-known evidence of the false thumb, which is really an enlarged wrist bone called the radial sesamoid.
12The wrist is a joint of the body that permits the hand to move.
13The false thumb is an adaptation that helps the existing five fingers, or digits, hold objects.
14A bear's hand lacks an opposable thumb, a true digit.
15Humans and other related animals, called primates, possess opposable thumbs.
16They permit primates to hold and handle objects using fingers.
17The false thumb operates in a similar way.
18The researchers first found an Ailurarctos arm bone in 2010.
19They then discovered teeth and the false thumb in 2015, giving them a better understanding of the animal.
20Until now, the oldest-known evidence of this thumb-like structure was 102,000 to 49,000 years old.
21It came from the same kind of panda that is alive today.
22The false thumb was not present in another closely related bear that lived about 9 million years ago, the researchers said.
23Xiaoming Wang is the lead writer of the research published in the Scientific Reports.
24He studies fossils at the Natural History Museum of Los Angeles County.
25Wang said: "It uses the false thumb as a very crude opposable thumb to grasp bamboo, sort of like our own thumbs except it is located at the wrist and is much shorter than human thumbs."
26The modern panda's false thumb is more useful than the earlier version found in Ailurarctos.
27Wang said the hooked false thumb offers a better grasp and it comes out less from the body.
28That makes it easier for the panda to walk.
29Wang said scientists think that is the reason the false thumb in modern pandas has become shorter, not longer.
30The false thumb lets pandas hold bamboo to eat but not to turn the food as a thumb would permit.
31Tao Deng of the Chinese Academy of Sciences in Beijing is a paleontologist and co-writer of the study.
32He said, "The panda's false thumb is far less effective than the human thumb, but is enough to provide the giant panda with the grasping ability to eat bamboo."
33I'm Gregory Stachel.