Extinct and ancient panda species were not exclusive bamboo eaters, and most likely had a more varied and complex diet, according to a study. The giant pandas we know today live only in the understory of particular mountains in southwestern China, where they subsist on bamboo alone. In support of their tough and fibrous bamboo diet, pandas have distinctive teeth, skull, and muscle characteristics along with a special pseudo-thumb to grasp and hold bamboo stems, leaves, and shoots.
"It has been widely accepted that giant pandas have exclusively fed on bamboo for the last two million years," said Fuwen Wei of Chinese Academy of Sciences. However, the study, published in the journal Current Biology, shows the opposite.
The researchers first analysed bone collagen of modern pandas (1970s-2000s) and other mammals from the same mountains. The stable isotopic composition of carbon and nitrogen from modern panda and other modern mammal bone samples indicated three obvious groups: carnivores, herbivores, and giant pandas.
Isotopes are different forms of the same element that contain equal numbers of protons but different numbers of neutrons. The giant pandas were clearly unique, on account of their habit of eating bamboo, researchers said.
The team measured bone collagen isotopes of 12 ancient pandas collected from seven archaeological sites in southern and southwestern China and compared them to the patterns they observed in modern giant pandas. The data comparison showed that ancient and modern pandas are isotopically distinct from one another, suggesting differences in their dietary habits.
There was also more variation among ancient panda species, suggesting that the niche they occupied was about three times wider than that of modern pandas. Ancient pandas most likely had a varied diet, similar to that of other mammalian species that lived alongside them.
They were "probably not exclusive bamboo feeders," researchers said. The study suggests that pandas' dietary habits have evolved in two phases. First, the pandas went from being meat eaters or omnivores to becoming dedicated plant eaters. Only later did they specialise on bamboo, researchers said.