zinjanthropus

Robust australopithecines Fossil range: Pleistocene
Skull of Paranthropus boisei
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Primates Family: Hominidae Subfamily: Homininae Tribe: Hominini Subtribe: Hominina Genus: Paranthropus Broom, 1938
Species
†Paranthropus aethiopicus †Paranthropus boisei †Paranthropus robustus

The robust australopithecines, members of the extinct hominin genus Paranthropus (Greek para "beside", Greek anthropos "human"), were bipedal hominids that probably descended from the gracile australopithecine hominids (Australopithecus). ^[1]

Description

Paranthropus boisei reconstruction

All species of Paranthropus were bipedal, and many lived during a time when species of the genus Homo (which were possibly descended from Australopithecus), were prevalent. Paranthropus first appeared roughly 2.7 million years ago. Most species of Paranthropus had a brain about 40 percent of the size of a modern human. There was some size variation between the different species of Paranthropus, but most stood roughly 1.3-1.4 m (4.26 to 4.59 feet) tall and were quite well muscled. Paranthropus is thought to have lived in wooded areas rather than the grasslands of the Australopithecus.

The behavior of Paranthropus was quite different from that of the genus Homo, in that it was not as adaptable to its environment or as resourceful. Evidence of this exists in the form of its physiology which was specifically tailored to a diet of grubs and plants. This would have made it more reliant on favorable environmental conditions than members of the genus Homo, such as Homo habilis, which would eat a much wider variety of foods.

Disputed taxonomy

Dawkins notes "perhaps several different species" of robust hominids, and "as usual their affinities, and the exact number of species, are hotly disputed. Names that have been attached to various of these creatures...are Australopithecus (or Paranthropus) robustus, Australopithecus (or Paranthropus or Zinjanthropus) boisei, and Australopithecus (or Paranthropus) aethiopicus."^[1] Opinions differ whether the species P. aethiopicus, P. boisei and P. robustus should be included within the genus Australopithecus. The emergence of the robusts could be either a display of divergent or convergent evolution. There is currently no consensus in the scientific community whether P. aethiopicus, P. boisei and P. robustus should be placed into a distinct genus, Paranthropus, which is believed to have evolved from the ancestral Australopithecus line. Up until the last half-decade, the majority of the scientific community included all the species of both Australopithecus and Paranthropus in a single genus. Currently, both taxonomic systems are used and accepted in the scientific community. However, although Australopithecus robustus and Paranthropus robustus are used interchangeably for the same specimens, some researchers, beginning with Robert Broom, and continuing with people such as Bernard A. Wood, think that there is a difference between Australopithecus and Paranthropus, and that there should be two genera.^{[2] [3]} On Wikipedia, this approach is utilised, and for the sake of consistency, the genus Paranthropus is used for all articles which mention the species P. aethiopicus P. boisei and P. robustus.

Occurrence

Paranthropus aethiopicus skull replica

For the most part the Australopithecus species A. afarensis, A. africanus, and A. anamensis either disappeared from the fossil record before the appearance of early humans or seem to have been the ancestors of Homo habilis, yet P. boisei and P. aethiopicus continued to evolve along a separate path distinct and unrelated to early humans. Paranthropus shared the earth with some early examples of the Homo genus, such as H. habilis, H. ergaster, and possibly even H. erectus. Australopithecus afarensis and A. anamensis had, for the most part, disappeared by this time. There were also significant morphological differences between Australopithecus and Paranthropus, although the differences were found on the cranial remains. The postcranial remains were still very similar. Paranthropus was more massively built craniodentally and tended to sport gorilla-like sagittal crests on the cranium which anchored massive temporalis muscles of mastication.^[4]

Intelligence

Species of Paranthropus had smaller braincases than Homo, yet they had significantly larger braincases than Australopithecus. Paranthropus is associated with stone tools both in southern and eastern Africa, although there is considerable debate whether they were made and utilized by these robust australopithecines or contemporaneous Homo. Most believe that early Homo was the tool maker.^[5] Most Paranthropus species seem almost certainly not to have used language nor to have controlled fire, although they are directly associated with the latter at Swartkrans, South Africa.^[5]

Discovery

A partial cranium and mandible of Paranthropus robustus was discovered in 1938 by a schoolboy, Gert Terblanche, at Kromdraai B (70 km south west of Pretoria) in South Africa. It was described as a new genus and species by Robert Broom of the Transvaal Museum. The site has been excavated since 1993 by Francis Thackeray of the Transvaal Museum. A date of at least 1.95 million years has been obtained for Kromdraai B.

Replica of the skull found by Mary Leakey

Paranthropus boisei was discovered by Mary Leakey on July 17, 1959, at the FLK Bed I site of Olduvai Gorge in Tanzania (specimen OH 5). Mary was working alone, as Louis was ill in camp. She rushed back to camp and at the news Louis made a remarkable recovery. They refrained from excavating until Des Bartlett had photographed the site.

In his notes Louis recorded a first name, Titanohomo mirabilis, reflecting an initial impression of close human affinity. Louis and Mary began to call it "Dear Boy". Recovery was halted on August 7. Dear Boy was in context with Oldowan tools and animal bones.

The fossil was published in Nature dated August 15, 1959, but due to a strike of the printers the issue was not released until September. In it Louis placed the fossil in Broom's Australopithecinae family, creating a new genus for it, Zinjanthropus, species boisei. "Zinj" is an ancient Arabic word for the coast of East Africa and "boisei" referred to Charles Boise, an anthropological benefactor of the Leakeys. Louis based his classification on twenty differences from Australopithecus.

Broom had died in 1951 but Dart was still living. He is said to have wept for joy on Louis' behalf on being personally shown Zinj, which Louis and Mary carried around in a tin (later a box). Louis had considered Broom's Paranthropus genus, but rejected it because he believed Zinj was in the Homo ancestral stock but Paranthropus was not. He relied heavily on the larger size of Zinj's canines.

At that time palaeoanthropology was in an overall mood to lump and was preaching against splitting. Consequently, the presentation of Zinj during the Fourth Pan-African Congress of Prehistorians in July in the then Belgian Congo, at which Louis was forced to read the delayed Nature article, nearly came to grief for Louis over the creation of a new genus. Dart rescued him with the now famous joke, "... what would have happened if Mrs. Ples had met Dear Boy one dark night."

The battle of the name raged on for many years and drove a wedge between Louis and LeGros Clark, Sir Wilfrid from 1955, who took the Paranthropus view. On the other hand it brought the Leakeys and Dr. Melville Bell Grosvenor of the National Geographic Society together. The Leakeys became international figures and had no trouble finding funds from then on. The Zinj question ultimately became part of the Australopithecus/Paranthropus question (which only applied to the robust Australopithecines).

See also

Paleontology portal

• Cranial capacity

References

External links

Wikibooks has a book on the topic of Introduction to Paleoanthropology

• "Hominidae". Mikko's Phylogeny Archive. http://www.fmnh.helsinki.fi/users/haaramo/Metazoa/Deuterostoma/Chordata/synapsida/Eutheria/Primates/Hominoidea/Hominidae.htm. 
• "Early Human Phylogeny". Smithsonian Institution. http://www.mnh.si.edu/anthro/humanorigins/ha/a_tree.html. 
• "Paranthropus". Human Evolution—A Look At Our Ancestors. Humboldt State University. http://www.humboldt.edu/~mrc1/paranthro.shtml. 
• "What Killed Paranthropus?" (Abstract). New Scientist (2434). 2004-02-14. http://www.newscientist.com/article/mg18124342.700-what-killed-paranthropus.html.