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Human taxonomy is the classification of the species Homo sapiens (Latin: "knowing man"), or the modern hominin, humans. Homo, the human genus, includes the past genetic tree of humanity, with Neanderthals, Denisovans, and other extinct species of hominin. H. sapiens is the only surviving species of the genus Homo. Extinct Homo species include archaic humans. Current humans have been designated as subspecies Homo sapiens sapiens, differentiated from the direct ancestor, Homo sapiens idaltu.
Prior to the current scientific classification of humans, philosophers and scientists have made various attempts to classify humans. They offered definitions of the human being and schemes for classifying types of humans. Biologists once classified races as subspecies, but today anthropologists reject the concept of race and view humanity as an interrelated genetic continuum. Taxonomy of the hominins continues to evolve.
Current issues in human taxonomy
Generally, humans are considered the only surviving representatives of the genus Homo.
Scientists have also debated whether any other branches of Homo, such as Neanderthals, should be classified as separate species or subspecies of H. sapiens. These distinctions are connected with two competing theories of human origins, the more common recent single-origin hypothesis (that modern humans represent a distinct gene pool) and the multiregional hypothesis (that modern humans spreading from Africa interbred with local Homo populations). Modern humans have some genes that originally arose in archaic human populations, composing perhaps 500% of our genetic inheritance. (For example, see microcephalin.)
History of human taxonomy
Human taxonomy has involved both placing humans within the hominid family (or within the animal kingdom in general) and classifying types of humans within the species.
History of classifying the human species
As recorded in the Hebrew Bible, ancient Hebrews classified humans as a kind of living soul (nephesh, roughly "breather"). Living things were said to beget their own kind, a group broader than the scientific species. Humans were said to comprise a single kind.
Humans have long been considered animals. Plato referred to humans as featherless biped animals, and Aristotle defined the human being as the "rational animal" or the "political animal". Classic and medieval taxonomy grouped living things according to characteristics, and classifying humans as animals meant that they have various animal characteristics (moving, eating, breathing, etc.). Modern taxonomy, on the other hand, classifies organisms according to evolutionary lines of descent. Current opposition to classifying humans as animals arises from this modern definition of what it means to be an animal (that is, a descendent of a common animal ancestor that lived over 500 million years ago).
When Linnaeus defined humans as Homo sapiens in 1758, they were the only members of the genus Homo. The first other species to be classified a Homo was H. neanderthalensis, classified in 1864. Since then, ten additional extinct species have been classified as Homo.
In a common misunderstanding of evolutionary theory, each species represents a stage in the evolutionary track, some "more evolved" and others further behind. Based on this misunderstanding, scientists thought of humans as having descended from modern apes and expected to find the "missing link," a living species halfway between apes and humans. Remnants of beliefs related to the Great Chain of Being were not only the origin of the term "missing link", but through the concept that a perfect creator would create things perfectly, extinction would be impossible and any species that ever lived would still be alive in some part of the world, awaiting discovery.
History of classifying types of humans
Races were once considered human subspecies, but genetic research shows that inherited differences do not accurately match common racial divisions. For example, since non-Africans are descended from a small population that emigrated from Africa about 100,000 years ago, non-Africans (even those representing different races) are more closely related to each other than Africans are to each other.
- Groves, C.P. (2005). Wilson, D.E.; Reeder, D.M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press. OCLC 62265494. ISBN 0-801-88221-4.