Ape

History of hominoid taxonomy

The history of hominoid taxonomy is somewhat confusing and complex. The names of subgroups have changed their meaning over time as new evidence from fossil discoveries, anatomy comparisons and DNA sequences, has changed understanding of the relationships between hominoids. The story of the hominoid taxonomy is one of gradual demotion of humans from a special position in the taxonomy to being one branch among many. It also illustrates the growing influence of cladistics (the science of classifying living things by strict descent) on taxonomy.

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As of 2005, there are eight extant genera of hominoids: Homo (humans), Pan (chimpanzees), Gorilla, Pongo (orangutans), and four genera of gibbons.

Related Topics:
As of 2005 - Genera - Homo - Pan - Gorilla - Pongo - Gibbon

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In 1758, Carolus Linnaeus, relying on second- or third-hand accounts, placed two species in Homo along with H. sapiens: Homo troglodytes ("cave-dwelling man") and the Homo caudatus ("tail-bearing man"). It is not clear to which animals these names refer, as Linnaeus had no specimen to refer to, hence no precise description. Linnaeus named the orangutan Simia satyrus ("satyr monkey"). He placed the three genera Homo, Simia and Lemur in the family of Primates.

Related Topics:
1758 - Carolus Linnaeus - Simia

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The troglodytes name was used for the chimpanzee by Blumenbach in 1775 but moved to the genus Simia. The orangutan was moved to the genus Pongo in 1799 by Lacépède.

Related Topics:
Blumenbach - Pongo - Lacépède

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Until about 1960 the hominoids were usually divided into two families: humans and their extinct relatives in Hominidae, the other apes in Pongidae.{{ref|Simpson1945}}

Related Topics:
1960 - Hominidae - Pongidae

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The 1960s saw the application of techniques from molecular biology to primate taxonomy. Goodman used his 1963 immunological study of serum proteins to propose a division of the hominoids into three families, with the (non-human) great apes in Pongidae and the lesser apes (gibbons) in Hylobatidae.{{ref|Goodman1963}} The trichotomy of hominoid families, however, prompted scientists to ask which family speciated first from the common hominoid ancestor.

Related Topics:
Molecular biology - Hylobatidae - Trichotomy - Speciated

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Within the superfamily Hominoidea, gibbons are the outgroup: this means that the rest of the hominoids are more closely related to each other than any of them are to gibbons. This led to the placing of the other great apes into the family Hominidae along with humans, by demoting the Pongidae to a subfamily; the Hominidae family now contained the subfamilies Homininae and Ponginae. Again, the three-way split in Ponginae led scientists to ask which of the three genera is least related to the others.

Related Topics:
Outgroup - Homininae - Ponginae

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Investigation showed orangutans to be the outgroup, but comparing humans to all three other hominid genera showed that African apes (chimpanzees and gorillas) and humans are more closely related to each other than any of them are to orangutans. This led to the placing of the African apes in the subfamily Homininae, forming another three-way split. This classification was first proposed by M. Goodman in 1974.{{ref|Goodman1974}}

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To try to resolve the hominine trichotomy, some authors proposed the division of the subfamily Homininae into the tribes Gorillini (African apes) and Hominini (humans).

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However, DNA comparisons provide convincing evidence that within the subfamily Homininae, gorillas are the outgroup. This suggests that chimpanzees should be in Hominini along with humans. This classification was first proposed (though one rank lower) by M. Goodman et. al. in 1990.{{ref|Goodman1990}}

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