for National Geographic News
How do you miss a whole species of elephant? They are, after all, the largest living terrestrial mammals on Earth, with male African elephants reaching an astounding 6,500 kilograms (14,330 pounds). But that's just what has happened.
Up until recently, scientists believed there were two species of elephant: the African elephant and the Asian elephant. Geneticists conducting a comprehensive DNA sampling of elephants from across Africa recently found that there are in fact two species of African elephants.
Until this announcement, most zoologists had lumped all African elephants together into a single species, Loxodonta Africana, with four widely recognized sub-species. Now, genetics has proven that one of those sub-species, Loxodonta africana cyclotis, commonly known as the forest elephant, is in fact a distinct species.
The newly identified species, named Loxodonta cyclotis, means that Africa is home to both the "savanna" elephant and the "forest" elephant.
The announcement of a new species doesn't come as a total surprise. A few astute zoologists saw the forest elephant for the distinct species that it was years ago. German zoologist Paul Matschie described the species Loxondonta cyclotis in a paper published in 1900.
In 1931, a French zoologist named Frade also offered his support for the existence of a forest elephant species based on, of all things, the number of toenails elephants have. Frade observed that a typical savanna elephant has four toenails on each forefoot and three on each hind foot. In contrast, the forest elephant, Frade observed, typically has five toenails on each forefoot and four on each hind foot. Unfortunately for Frade, what he failed to realize is that all elephants, savanna and forest alike, have five nicely shaped toenails on each foot, fore and aft, at birth. Because of the rough terrain they traverse, savanna elephants tend to lose a greater number of toenails as they mature, leaving them with the statistically averaged four front and three rear toenails.
Other zoologists noticed more definitive characteristics, such as the shape of the mandible, which is short and wide in the savanna elephant while being long and narrow in the forest elephant, and the shape of the ears, which are rounded in the forest elephant and pointed in the savanna elephant. In addition, the forest elephant is smaller, with males only rarely reaching above 2.5 meters (8 feet) in height. A large male savanna elephant can reach nearly 4 meters (13 feet), with averages commonly above 3 meters (10 feet). Despite these observed distinctions, most scientists didn't generally go as far as suggesting that these differences were great enough to warrant a division into two species.
Conservation authorities have noted for decades an extreme difference between the confiscated illegal ivory of the forest elephant and that of the other sub-species of Africa elephant. In the forest elephant, the ivory is long, skinny, and straight, with a pinkish tinge, and is highly valued for its hardness. The savanna elephant has the more familiar thick, curved ivory shape.
The long-standing debate over one species or two was considered definitively "settled" with the publication of two studies in 1958 and 1974. Both found that the L.a. cyclotis and L. africana interbred where their ranges overlapped; thus their differences could, by the "mate-recognition" concept of a species, be only "sub" specific. Scientists have since found that the actual areas where the forest and savanna elephants habitats overlap are few and far between, making their opportunities to hybridise actually quite rare.
The recent genetic recognition of two species overturns this idea of sub-specificity, although the study alludes to low levels of interbreeding in the isolated cases where the ranges of the two species meet. What is most surprising about the finding is the extent of genetic differences observed between the two species. The forest elephant is more than half as different genetically from the savanna elephant as the African elephants are from the Asian elephant Elephas maximus. To place this in perspective, the African forest elephant and African savanna elephant are more distant from each other genetically than a tiger is from a lion or a horse is from a zebra.
Following the Ancestral Trail