It was attention-grabbing reading about Charles Darwin’s theory on natural selection and evolution, as D. Dwight Davis’s perspective on the anatomy of a panda’s thumb. Before reading this article, I didn’t know any information regarding the structure of a panda bear’s hand, or the purpose of its phalanges.
Because Darwin first studied the structure of an orchid before examining a panda’s thumb, I enjoyed the comparison and contrast of these two species: The Marsh Epipactus and the panda’s “sixth finger”. I found it interesting that a panda developed a sixth finger due to Darwin’s theory of evolution.To put it bluntly, a panda’s thumb is not even considered a finger because it attaches at the wrist. This is called the radial sesamoid, which lies on the underside of the panda’s forepaw. The five regular digits of the panda’s hand provide the framework of another pad, while a shallow groove separates the two pads and serves as a passage for bamboo stalks, similar to the marsh Epipactus’s labellum, whose main purpose is to attract an insect and then trap it; this is the only plant’s source of food, similar to the panda’s reserve of bamboo.Not only does the panda have a sixth digit on its hand, or more so wrist, but it seems that this structure is also on its foot, which is the counter part of the radial sesamoid, called the tibial sesamoid.
I found it interesting that unlike the radial sesamoid, the tibial sesamoid does not have any advantage. In order for evolution to occur, the radial and tibial sesamoids would no longer be coordinated in development and would cause a corresponding modification where the panda would favor the thumb over the coordinating toe.I would think that because pandas have a sixth digit, other species related to them would also have one. However, that panda’s closest relatives: raccoons and bears use their forelegs for manipulating objects in feeding, unlike the panda that only uses its radial sesamoid for assistance while eating.
