Hominin or Hominid? What s in a Name!

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1 Hominin or Hominid? What s in a Name! Philip L. Stein Los Angeles Pierce College The first step in wisdom is to call things by their right name. Confucius The classification of humans has always been problematical for one very important reason they are us! From the very beginning of scientific classification humans tended to be set apart from other animals, although through time the breech became smaller and smaller. Early biologists such as Johann Friedrich Blumenbach and Georges Cuvier placed humans into their own distinct order which emphasized what they considered to be the unique place of humans in the natural scheme of things. Charles Darwin commented in The Descent of Man (1871), If man had not been his own classifier, he would never have thought of founding a separate order for his own reception. It is an interesting footnote to history that Carolus Linnaeus in the 18th century believed that humans were a subspecies of monkey. Later Linnaeus classified humans into a new animal group, the primates, along with the monkeys, and bestowed on humankind the name Homo sapiens or wise man. However, he seems to have been having second thoughts, alternating between Homo sapiens and Homo diurnus or day man. The choice of words we use when communicating information can be essential to the understanding of that information. This is especially critical in selecting the words we use in discussing human evolution. Should we use the term human to refer to all members of the genus Homo? Or should we restrict the term to anatomically modern Homo sapiens? Most of us probably use semi-popular names that are derived from formal scientific designation. Thus Australopithecus becomes australopithecines; apes become pongids; and humans and their ancestors the lived following the split from the common ancestor are the hominids. The term hominid is derived from the name of the family Hominidae. This term is very valuable in that it lets us get along just fine without having to resort to man, people, or human when we want to include extinct forms. Hominid is also neutral. For example, it does not suggest any advanced cognitive abilities such as language or the ability to utilize symbols. We tend to think of the Linnaean system of naming and classification as being stable. In fact, it was precisely because of this perceived stability that it was adapted by the biological community. But in fact it is far from stable. Even in the days of Linnaeus, when species represented divinely-creating types, the grouping of species into higher taxonomic categories was open to considerable debate. Once the decision had been made that the classification scheme was to represent evolutionary relationships, however, debates over the proper assignment of taxa became very important. The placement of a species into a particular taxon is in effect making a scientific statement about

2 2 how that species fits into the evolutionary history of life. However, our understanding of our evolutionary past is constantly changing. We can illustrate this problem by looking at the classification of the hominoids over the past 50 or so years. In all humility, let us examine the history of the classification over the nine editions of Stein and Rowe, Physical Anthropology. The first edition was published in 1974, and the classification of the primates that was used was based upon the classification scheme of the Napiers in A Handbook of the Living Primates (1967). Family: Pongidae (orangutan, chimpanzee, gorilla, bonobo) Family: Hominidae (humans) From this taxonomy we derived the following useful terms: Taxon Name of Taxon Nontechnical Form of Name Included Living Primates Suborder Anthropoidea anthropoid all monkeys, apes, and humans Superfamily Hominoidea hominoid all apes and humans Family Hylobatidae hylobatid gibbons Family Pongidae pongid great apes Family Hominidae hominid humans However, evolutionary theory and the specific evidence of a particular evolutionary history are continually changing. Colin Groves, in his review of primate classification (Primate Taxonomy, 2001) writes: Because of new discoveries or hypotheses about interrelationships, alterations in classification are necessary. Taxonomy, like other fields of biology is a dynamic science. Classifications are not engraved in stone, nor should they be. Continuing our stroll down memory lane, a change in the classification of primates in Stein and Rowe appears in the fourth edition (1989). Family: Pongidae (orangutan)

3 3 Family: Panidae (chimpanzee, gorilla, bonobo) Family: Hominidae (humans) In this classification notice is given to the fact that the orangutans branched off of the lineage leading to the hominids significantly earlier than the branching among the African great apes. A new term was introduced panid. This change was largely in response to the work of the molecular biologists who were using molecular evidence to work out the evolutionary ties among various primate forms. While the classification of primates in the text remained constant through the eighth edition, a table was added in the sixth edition (1996) that presented as alternative classification those of Andrews and Cronin (1982) and Andrews (1990). Many biologists and paleoanthropologists were beginning to talk about abandoning the Linnaean system altogether and replacing it with an entirely new system such as the proposed PhytoCode. Let s look at the classification of Andrews: Family: Hominidae Subfamily: Ponginae (orangutan) Subfamily: Homininae Tribe: Gorillini (chimpanzee, gorilla, bonobo) Tribe: Hominini (humans) This latter taxonomy emphasizes the close relationships between humans and the African great apes and introduces the term hominin after tribe Hominini. Of historical interest is the more extreme classification of Morris Goodman, also published in This taxonomy emphasis the fact that the gorillas branched off the evolving ape line before the separation of the chimpanzees and bonobos and humans. Family: Hominidae Subfamily: Hylobatinae Subfamily: Homininae Tribe: Pongini (orangutan) Tribe: Hominini (humans) Subtribe: Gorillina (gorilla) Subtribe: Hominina (chimpanzee, bonobo, humans) This latter classification reflects a strong reliance upon molecular data, which after all is Goodman s area of research. It emphasizes the close evolutionary relationship between the chimpanzee and bonobo on one hand and humans on the other. Others go to even a greater extreme placing the chimpanzee and bonobo into the genus Homo, but this has not caught on.

4 4 Although the use of the term hominid for the lineage leading to ourselves remains in use throughout the 1980s and 1990s, it has been slowly replaced by the term hominin, based upon the tribe name Hominini. The term hominin today is the standard in the research world, and it is working its way into the more popular and textbook world. To complete the study to date, the ninth edition of Stein and Rowe (2006) has adopted a consensus classification. Family: Hominidae Subfamily: Ponginae (orangutan) Subfamily: Gorillinae (gorilla) Subfamily: Homininae Tribe: Panini (chimpanzee, bonobo) Tribe: Hominini (humans) If the popular terms are to be derived from the technical terms, we now have the following: Taxon Name of Taxon Nontechnical Form of Name Included Living Primates Superfamily Hominoidea hominoid All apes and humans Family Hominidae hominid Great apes and humans Subfamily Hominin hominine Chimpanzee, bonobos, and humans Tribe Hominini hominin Humans Today, several textbooks have adopted the new terminology, both in physical anthropology and in general anthropology. Some authors discuss the issue in their Preface or Introduction. For example, Agustin Fuentes, in the first edition of Core Concepts in Biological Anthropology (2007) writes: Under the methodology of science, when data do not support a hypothesis (such as the Pongidae/Hominidae taxonomy), we must alter our hypothesis to fit the current data sets. That is why in this book we used the classifications Homininae (chimpanzees, humans, and gorillas), Ponginae (orangutans), and Hominini (humans and ancestors in our lineage since the split with the other African apes.)

5 5 Bernard Campbell, et al., in the ninth edition of Humankind Emerging, writes the following in the Preface where the significant changes to this new edition are enumerated: A thorough taxonomic revision of the human lineage that brings this text into agreement with most modern paleoanthropological theories. The term hominid is widened to include members of the human lineage as well as all great apes. Living humans and their ancestors since the split from the apes are placed in the Tribe Hominini and are called hominins. Hominins are divided further into two Subtribes: Australopithecina (containing the australopiths of Africa) and Hominina (containing all living and extinct members of the genus Homo). Not all textbook authors accept the new taxonomy. Alan Park is very explicit in his discussion of two different forms of taxonomy. The classification discussed above is ultimately based upon cladistics or the order of branching. On the other hand, Park recognizes what he calls phenetic taxonomy, a classification system based on existing phenotypic features and adaptations. Chimpanzees and gorillas resemble one another and are different from humans, and this is reflected in the older taxonomy which he continues to use. However, it is clear that hominin is going to replace hominid. In fact, of the 8 specialized physical anthropology textbooks with copyright dates of 2004 or later, half use hominin in place of hominid. Textbooks Using Hominin Boyd & Silk, How Humans Evolved, 4th ed., 2006 Campbell, Humankind Emerging, 9th ed., 2006 Fuentes, Core Concepts in Biological Anthropology, 2007 Stein & Rowe, Physical Anthropology, 9th ed., 2006 Textbooks Using Hominid Jurmain & Nelson: Introduction to Physical Anthropology, 10th ed., 2006 Park, Biological Anthropology, 4th ed., 2005 Relethford, Fundamentals of Biological Anthropology, 6th ed., 2004 Stanford, Biological Anthropology, 2006 The hominid/hominin debate has already entered the public arena. In 2001 The National Geographic referred to the Kenyapithecus platyops fossils as hominins. At the same time, the report in the New York Times referred to the fossils as hominids, and several hundred s were received by National Geographic pointing out what the writers perceived as poor editorial work. In an essay written by Lee Berger for the National Geographic News (December, 2001). Lee notes that Modern-day genetic research is providing evidence that morphological distinctions are not necessarily proof of evolutionary relatedness. He further points out that: In the long run, hominin is likely to win out against term hominid. It is more precise and recognizes the biological reality that moves beyond physical morphology.

6 6 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. One could argue that the introductory student really doesn t need to be aware of these technical debates. After all, it confuses an already confusing subject. But I disagree. I strongly feel that as long as our students are taking Physical Anthropology to meet a science requirement and as long as our course may be the only science course required we must be aware of the appalling lack of science literacy among our students. Among our most important student learning objects is the development of an understanding of the scientific method. For example, the gulf that is widening between evolution and creationism is largely fueled by the failure of creationists to understand just how science works. This terminological debate is a great opportunity to discuss the nature of science and the nature of science debates. In contrast to the Creationist worldview, the world of science is not a static one.