The carnivorous giant panda, unlike its siblings, has many "stunts" that allow it to adapt to a life that specializes in eating bamboo. Among these stunts, the giant panda's extra "thumb" is arguably the most famous but also the most mysterious. In addition to the normal five fingers on most mammalian forelimbs, giant pandas have a strongly enlarged wrist bone, the radial sesamoid bone, which acts as a sixth finger, forming a "thumb" that can be held oppositely to grasp the bamboo. The results of the study showed that the first panda had the earliest enlarged radial sesamoid bone, which had formed a "thumb" function of the opposite hand. However, since the late Miocene, the panda's "thumb" has not been further enlarged, because it must also take into account the load-bearing function of walking on foot while grasping bamboo, and cannot be abandoned by either side. The restriction of sharing weight may be the main reason why the panda's pseudo-thumb never evolved into a full finger, but this simple "thumb" suggests that the giant panda's habit of eating bamboo specifically originated at least 7-6 million years ago. (CCTV News, Shilong)
Source: Daily Economic News