"One of the most important features of human beings and their primate relatives is the evolution of a thumb that can be held against other fingers for precise grasping. The false thumb lets pandas hold bamboo to eat but not rotate the food as a true thumb would allow. Until now, the oldest-known evidence of this thumb-like structure dated to fossils from about 102,000-49,000 years ago in the same panda species alive today. The researchers initially found an Ailurarctos arm bone in 2010, then discovered teeth and the false thumb in 2015, giving them a much better understanding of the animal. The panda's tight grip on bamboo acts against the jerking action of the mouth in order to quickly break food into bite-size chunks, Mr Wang added. Think of the false thumb as being stepped on every time the panda walks. "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 modern panda's false thumb has some advantages over the earlier version. "It uses the false thumb as a very crude opposable thumb to grasp bamboos, sort of like our own thumbs except it is located at the wrist and is much shorter than human thumbs," said Natural History Museum of Los Angeles County paleontologist Xiaoming Wang, lead author of the research published in the journal Scientific Reports.Ailurarctos was an evolutionary forerunner of the modern panda, smaller but with anatomical traits signalling a similar lifestyle including a bamboo diet. The false thumb serves a similar function. A bear's hand lacks the opposable thumb possessed by humans and various primates that enables the grasping and handling of objects using the fingers. The false thumb is an evolutionary adaptation to augment the existing five actual digits of the panda's hand.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |