Why do pandas eat bamboo? Is it an ancestral trait or something they acquired later? Based on years of research and analysis, I have come to the following conclusion: eating bamboo is not an ancestral trait.
In the winter of 1993, while observing pandas' chewing function at the Beijing Zoo, a visitor asked a zookeeper, "Why do pandas have such a strong preference for bamboo?"
The zookeeper readily replied, "Eating bamboo is its nature."
In 1975, large areas of *Phyllostachys edulis* and *Phyllostachys pubescens* growing in the Tangjiahe and Wanglang areas of the Minshan Mountains in Sichuan Province flowered, and the bamboo quickly withered and died after flowering. According to statistics from reserve staff, more than 100 pandas starved to death in the withered bamboo thickets because their food source was destroyed. This shows that bamboo forests are indeed a vital food source for pandas, essential for their survival.
However, tracing the evolutionary history of pandas back to the era of their "grandfather," the early panda, 8-7 million years ago in its native habitat, you'll find that the early panda was quite different from its descendants. As mentioned above, apart from the premolars showing early bamboo-eating features, the early panda's dental structure was similar to that of omnivorous bears. It goes without saying that the early panda was an omnivore.
Looking at their ecological environment, pandas live in wet swamps, eating everything from tender branches and mountain fruits to grass roots and insects. If there is a disaster in one place, they will flee to another place and will never starve to death.
The Panda ba's descendant, the Ailuropoda basilicas, also lived in a superior ecological environment, with mountains and rivers complementing each other and lush vegetation. However, the Panda ba's did not inherit the omnivorous nature of its ancestor, instead developing a picky and selective diet. Such feeding habits often could not withstand the selection of nature; once the bamboo flowered and withered, it was equivalent to cutting off their food source, ultimately leading to them becoming emaciated and starving, their fate sealed.
From a microscopic perspective, the enamel structures of the teeth of the panda, the red panda, the Panda basilica, and the extant panda are also different.
The structure of a panda's teeth consists of an outer layer of enamel, also known as enamel, and an inner layer of chalk, also known as dentin. The enamel layer is composed of several enamel prisms and is hard and wear-resistant.
In 1999, Huang Wanbo, Ouyang Lian, and others, in a paper titled "Analysis of Enamel Structure in Panda Teeth," discussed how the teeth of *Ailuropoda melanogaster* had coarse, few, and weakly coiled enamel prisms with thick interstitial tissue, while those of *Panda simonii*, *Panda basilica*, and modern pandas had fine, numerous, and strongly coiled enamel prisms with thin interstitial tissue. This phenomenon is related to their diet. As mentioned above, *Ailuropoda melanogaster* ate a varied diet of soft foods, resulting in coarse, few, and weakly coiled enamel prisms with thick interstitial tissue. *Panda simonii*, *Panda basilica*, and modern pandas ate a more monotonous diet, mainly bamboo, which is hard. Therefore, their teeth had fine, numerous, and strongly coiled enamel prisms with thin interstitial tissue.
In conclusion, the panda's ability to eat bamboo is neither "innate" nor inherited, but acquired later in life.
