Homo erectus

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Homo erectus
Temporal range: Pleistocene
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Peking Man reconstruction
Scientific classification
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H. erectus
Binomial name
Homo erectus
Subspecies

Homo erectus palaeojavanicus
Homo erectus soloensis

Homo erectus ("upright man") is a hominin species that is believed to be an ancestor of modern humans (with Homo heidelbergensis usually treated as an intermediary step). The species is found from the middle Pleistocene onwards.

Eugène Dubois discovered Java Man in Indonesia in 1891, naming it Pithecanthropus erectus. The modern species name was initially proposed by Ernst Mayr in order to unify the classification of Asian fossils.

Anthropologists and geneticists throughout much of the last century have debated H. erectus' role in human evolution. Early in the century, it was believed the Asian continent was the evolutionary home of humans in contrast to naturalist Charles Darwin's prediction of humanity's African origins. However, during the 1950’s and 1970’s, numerous fossil finds in Africa yielded evidence of hominins far older. It is now believed that H. erectus is a descendent of more primitive ape-humans such as australopithecines and early Homo species. Before their settlement of South Eastern Asia, dating fewer than 500,000 and 300,000 years ago, H. erectus originally migrated during the Pleistocene glacial period in Africa roughly 2.0 million years ago and so dispersed throughout various areas of the Old World. Fossilized remains dating 1.8 and 1 million year old fossils have been found in India, China and Indonesia. H. erectus remains an important hominine since it is believed to be the oldest representation of early human migration. However, recent discoveries and analysis indicate that H. erectus situation on the human evolutionary tree may be phylogenetically akin to H. neanderthalensis, in that its lineage did not give rise to later variants of H. sapiens.

Description

The findings had fairly modern human features, with a larger cranial capacity than that of Homo habilis. The forehead is less sloping and the teeth are smaller (quantification of these differences is difficult however, see below). Homo erectus would bear a striking resemblance to modern humans, but had a brain about 75 percent (950 to 1100cc) of the size of modern human. These early hominins were tall, on average standing about 1.79 m (5 feet, 10 inches). The sexual dimorphism between males and females was almost the same as seen in modern Homo sapiens with males being slightly larger than females. The discovery of the skeleton KNM-WT 15000 (Turkana boy) made in near Lake Turkana, Kenya by Richard Leakey and Kamoya Kimeu in 1984 was a breakthrough in interpreting the physiological status of H. erectus.

Tool use and general abilities

Homo erectus used more diverse and sophisticated tools than its predecessors (ie. Homo habilis, Homo rudolfensis). One theory is that H. erectus first used tools of the Oldowan style and then later used tools of the Acheulean style. The surviving tools from both periods are all made of stone. Oldowan tools are the oldest known formed tools and date as far back as about 2.4 million years ago. The Acheulean era began about 1.2 million years ago and ended about 500,000 years ago. The primary innovation associated with Acheulean handaxes is that the stone was chipped on both sides to form two cutting edges.

Social aspects

Homo erectus (along with Homo ergaster) was probably the first early human to fit squarely into the category of a hunter gatherer society and not as prey for larger animals. Modern day anthropologists since the beginning of the 19th century have studied various aspects of modern day hunter group societies. Among the most studied have been the desert bushmen (Kun San) peoples of the Kalahari desert in Botswana, Angola and South Africa; these peoples have barely changed their hunter lifestyles for over 22,000 years. Anthropologists such as Richard Leakey believe that H. erectus was socially closer to modern humans than the more primitive species before it. The increased larger cranial capacity generally coincides with the more sophisticated tool technology occasionally found with the species remains. The discovery of Turkana boy in 1984 has so far proven that despite H. erectus's more human-like anatomy, the hominins were not capable of producing highly complex sound systems that would have been on a level comparable to modern speech.

H. erectus migrated all throughout the Great Rift Valley, even up to the Red Sea[1]. Early humans, in the person of Homo erectus, were learning to master their environment for the first time. Bruce Bower suggested that H. erectus may have built rafts and travelled over oceans, although this possibility is considered controversial. [2]

Some dispute that H. erectus was able to control fire. However, the earliest (least disputed) evidence of controlled fire is around 300,000 years old and comes from a site called Terra Amata, which lies on an ancient beach location on the French Riviera. This site seems to have been occupied by Homo erectus. There are older Homo erectus sites that seem to indicate controlled use of fire, some dating back 500,000 to 1.5 million years ago, in France, China, and other areas. A discovery brought forth at the Paleoanthropology Society Annual Meeting in Montreal, Canada in March of 2004 stated that controlled fires have been evidenced in excavations in Northern Israel from about 690,000 to 790,000 years ago. Regardless, it can at least be surmised that the controlled use of fire was atypical of Homo erectus until its decline and the rise of more advanced species of the Homo genus came to the forefront (such as Homo antecessor, H. heidelbergensis and H. neanderthalensis).

Classification

There is currently a great deal of discussion as to whether H. erectus and H. ergaster were separate species at all. This debate revolves around the interpretation of morphological differences between early African fossils (the classic H. ergaster) and those found in Asia (H. erectus; and late African sites). Since Erst Mayr's biological species definition cannot be tested, this issue may never be fully resolved.

Descendants and subspecies

Homo erectus remains one of the most successful and long-lived species of the Homo genus. It is generally consided to have given rise to a number of descendant species and subspecies.

Homo erectus
  |-> Homo erectus soloensis
  |-> Homo erectus palaeojavanicus
  |-> Homo floresiensis
  \-> Homo antecessor
         |  |-> Homo heidelbergensis
         |  \-> Homo neanderthalensis
         \-> Homo sapiens
               |  |-> Homo rhodesiensis
               |  \-> Homo cepranensis
               \-> Homo sapiens sapiens

The discovery of Homo floresiensis, and particularly its recent survival, has raised the possibility that numerous descendant species of Homo erectus may have existed in the islands of south-east Asia which await fossil discovery.

Individual fossils

Existing Homo erectus fossils include:

See also

References

  1. ^ Paolo Novaresio, The Explorers, published 1996 by Stewart, Tabori & Chang, ISBN 1-55670-495-X ; p. 13: "[Homo erectus] roamed the natural corridor of the Great Rift Valley as far as the Red Sea."
  2. Tattersall, Ian and Schwartz, Jeffrey. "Extinct Humans". Westview Press, Boulder, Colorado and Cumnor Hill, Oxford, 2000. ISBN 0-8133-3482-9 (hc)
  3. Erectus Ahoy