"Lumping all giraffes into one species obscures the reality that some kinds of giraffe are on the brink" of extinction, said David Brown, a geneticist and the study's lead author. "Some of these populations number only a few hundred individuals and need immediate protection."
Today, there are fewer than 100,000 giraffes, whose numbers have seen a 30 percent drop in the last decade, Brown told the BBC.
Using molecular technology, Brown's team determined at least six groups of giraffes -- the world's tallest animals -- are reproductively isolated and different enough from each other to be classified as species, rather than subspecies as they now are classified.
Brown, who teaches at the University of California, Los Angeles, said giraffes in need of protection include the Nigerian giraffe, which number about 160, and the Rothschild giraffe, which has been reduced to only a few hundred.