In recognition of these and other genetic relationships, some argue that we must overhaul the present morphologically based classification system for one that is more representative of our true evolutionary relationships as evinced by our genes.
Reworking the Family Tree
This is where the term hominin comes into play. Under the new classification model, hominoids would remain a primate superfamily, as has always been the case. Under this hominoid umbrella would fall orangutans, gorillas, chimps, and humans, all in the Family Hominidae.
In recognition of their genetic divergence some 11 to 13 million years ago, the orangutans would be placed in the sub-family Ponginae and the African apes, including humans, would all be lumped together in the sub-family Homininae. The bipedal apesall of the fossil species as well as living humanswould fall into the tribe Hominini (thus hominin). All of the fossil genera, such as Australopithecus, Ardipithecus, Kenyanthropus, and Homo, would fall into this tribe.
A few evolutionary biologists want a more extreme classification, which would include humans and chimpanzees within the same genus, the genus Homo.
Old Versus New
So hominid or hominin? Is it just a matter of semantics that only purists should be worried about? The New York Times' use of "hominid" and National Geographic's use of "hominin" were both right in the broadest sense. In either the "old" or "new" classification system, hominid works, it just means different things.
In the old system, hominid refers solely to the bipedal ape lineage. In the new classification system it refers to the broader grouping of all the great apes, which would by definition certainly include the new Kenyanthropus fossils.
The use of hominin by National Geographic is technically more correct in that it recognizes the relationship of Kenyanthropus to the other bipedal apes and distinguishes it from other living and fossil African apes which are not so closely related to us based on the molecular evidence we have to date.
In the long run, hominin is likely to win out against the term hominid. It is more precise and recognizes the biological reality that moves beyond physical morphology.
Do I like it? Well, I would never try to stand in the way of the advancement of science, but just try saying Hominidae, Homininae, Hominini three times fast in front of a first year Introduction to Anthropology class and you will have some sympathy for the scientist who clings to the term hominid for a few more years.
So what's in a name? The classification debate is not just a debate for the purist; it cuts to the very core of our understanding of human's place in nature and our evolutionary relationships with our closest living relatives. All hominins are hominids, but not all hominids are hominins.
Lee R. Berger is director of the paleoanthropology unit for research and exploration at the University of the Witwatersrand in Johannesburg, South Africa. He has written for National Geographic and has appeared in many documentaries on human evolution. He received the National Geographic Society Prize for Research and Exploration in 1997.
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