Genetic Tests Favor Ursine Family Theory : Are Pandas Raccoons? The Bear Facts

A bear is a bear is a bear is a bear. Unless it’s a panda.

It may never have crossed your mind that the giant pandas that visited the Los Angeles Zoo for the Summer Olympics last year may be members of the raccoon family. However, it has been an issue among scientists for more than a century.

The question is whether giant pandas should belong to either of the families, or if they should have a family of their own in the vast system of scientific classification that has a label for just about every animal in the world.

Giant pandas, according Stephen J. O’Brien, a research associate at the zoo, have been grouped with bears since their discovery by the Western world in the 1860s.

However, they have un-bearlike characteristics. Giant pandas are vegetarian, consuming mostly bamboo. Their forequarters are huge, like some bears, but their rear quarters are relatively small.

“Finally, the giant panda does not behave like a bear,” O’Brien and colleagues wrote in the scientific journal Nature. “Most bears hibernate, the giant panda does not; bears roar, whereas the giant panda bleats.”

The raccoon faction has argued that because of its skull and tooth structure, markings and other characteristics, the giant panda belongs in the same family from which raccoons and the lesser or red panda, which really does look like a raccoon, diverged millions of years ago.

To put the matter to rest, the National Zoo researchers called on the powers of genetic technology. They took some cell samples from a raccoon, a giant panda, a lesser panda and a trio of bruins: one American brown bear, a spectacled bear and a Maylayan sun bear.

Running the samples through three molecular tests that would reveal gene structure, they found the genetic similarities between bears and giant pandas far exceeded the number and extent of differences.

On the family tree, the bear group and procyonid group, to which the lesser panda belongs, probably split from a single ancestral line about 30 million to 50 million years ago.

The procyonids split into New World procyonids--represented by raccoons, coatis and kinkajous--and Old World procyonids, the aforementioned lesser pandas, 10 million years later.

Giant pandas branched off the bear family tree 15 million to 25 million years ago. Judging by the molecular tests, they should be considered a subgroup of the bear family.

The idiosyncrasies of giant pandas probably are the result of evolution and ancestral characteristics lost by bears after they split from the main line, the researchers wrote.

“It does prove the kid in the zoo knew what he was talking about,” said O’Brien, who is also chief of the section of genetics at the National Cancer Institute Frederick, Md., Research Facility.