The Giant Panda has an unusual paw, with a "thumb" and five fingers; the "thumb" is actually a modified sesamoid bone, which helps the panda to hold the bamboo while eating. Stephen Jay Gould wrote an essay about this, then used the title The Panda's Thumb for a book of essays concerned with evolution and intelligent design. The Giant Panda has a short tail, approximately 15 cm long. Giant Pandas can usually live to be 20-30 years old while living in captivity.
Until recently, scientists thought giant pandas spent most of their lives alone, with males and females meeting only during the breeding season. Recent studies paint a different picture, in which small groups of pandas share a large territory and sometimes meet outside the breeding season.[citation needed]
Like most subtropical mammals, but unlike most bears, the giant panda does not hibernate.
[edit] Diet
Pandas eating bamboo at the National Zoo in Washington, D.C.Despite its taxonomic classification as a carnivore, the panda has a diet that is primarily herbivorous, which consists almost exclusively of bamboo. This is an evolutionarily recent adaptation. Pandas lack the proper enzymes to digest bamboo efficiently, and thus derive little energy and little protein from it.
While primarily herbivorous, the panda still retains decidedly ursine teeth, and will eat meat, fish, and eggs when available. In captivity, zoos typically maintain the pandas' bamboo diet, though some will provide specially formulated biscuits or other dietary supplements.