Differences in Homo-erectus around the world?

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Sindhura

New member
Many paleoanthropologists still debate the definition of H. erectus and H. ergaster as separate species. Some call H. ergaster the direct African ancestor of H. erectus, proposing that it emigrated out of Africa and migrated into Asia, branching into a distinct species. Most dispense with the species-name ergaster, making no distinction between such fossils as the Turkana Boy and Peking Man. Though "Homo ergaster" has gained some acceptance as a valid taxon, these two are still usually defined as distinct African and Asian populations of the larger species H. erectus.

While some have argued (and insisted) that Ernst Mayr's biological species definition cannot be used here to test the above hypotheses, one can, however, examine the amount of morphological cranial variation within known H. erectus / H. ergaster specimens, and compare it to what one sees in disparate extant groups of primates with similar geographical distribution or close evolutionary relationship. Thus, if the amount of variation between H. erectus and H. ergaster is greater than what one sees within a species of, say, macaques, then H. erectus and H. ergaster may be considered two different species. The extant model of comparison is very important, and selecting appropriate species can be difficult. (For example, the morphological variation among the global population of H. sapiens is incredibly small, as attested by the Mitochondrial Eve hypothesis, and our own special diversity may not be a trustworthy comparison.) Another closely related, and possibly ancestral, species is Homo georgicus: fossils examples of this species were found in Dmanisi in the Republic of Georgia, and are considered to display traits intermediate between H. erectus and H. habilis.


Replica of lower jaws of Homo erectus from Tautavel, FranceH. erectus had a cranial capacity greater than that of Homo habilis (although the Dmanisi specimens have distinctively small crania): the earliest remains show a cranial capacity of 850 cm³, while the latest Javan specimens measure up to 1100 cm³ ,overlapping that of H. sapiens.; the frontal bone is less sloped and the dental arcade smaller than the australopithecines'; the face is more orthognatic (less protrusive) than either the australopithecines' or H. habilis's, with large brow-ridges and less prominent zygomata (cheekbones). These early hominins stood about 1.79 m (5 ft 10+1/2 in), and were robuster than modern humans. The sexual dimorphism between males and females was slightly greater than seen in H. sapiens, with males being about 25% larger than females. The discovery of the skeleton KNM-WT 15000, "Turkana boy"(see also Homo ergaster), made near Lake Turkana, Kenya by Richard Leakey and Kamoya Kimeu in 1984, is one of the most complete hominid-skeletons discovered, and has contributed greatly to the interpretation of human physiological evolution.
 
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bravozulu

Member
Before about 5 years ago it was more common to call African erectus ergastor and Asian "erectus" erectus. They found one in Africa with intermediate characteristics so most decided they must be variations of the same species. It is wise and necessary to look into what causes speciation and how that is determined in the fossil record to get a good feel for how valid that assessment is. Rather than looking at normal variation in an extant population of other animals, it is more logical to see if a shared set of traits is maintained throughout the fossil record. That is difficult with erectus because there is so much variability in erectus and it existed for such a long time but there are relatively few fossils.

We now have data that suggests that erectus lived alongside habilis about 1.5 million years ago near lake Turkana in Africa. One of the erectus was extremely small and another was Turkana boy who was very large and robust as an eight year old.(See recent NOVA Becoming Human for details). The habilis are much smaller than erectus but it has been and is still assumed that erectus evolved from habilis a few hundred thousand years prior to them cohabiting. Habilis also have much longer arms and other differences. The point is that seems highly unlikely for erectus to evolve in the same area as habilis so quickly unless speciation for hominids was quite rapid. We have an example of a hominid with features more primitive than erectus called floresiensis. That suggests that some of the Asian hominids are more primitive than what has been assumed to be erectus. There are examples of Asian hominids that are very distinct from erectus but have been called erectus largely because of nearby tools such as Sangarin 31. The link lists some of the erectus that outside of normal erectus ranges.
http://cameronmccormick.blogspot.com/2007/05/meganthropus.html

Other erectus in Asia are likely later waves and could be closer to antecessor in Europe or early heidelbergensis which I think were likely separate waves.. Otherwise there is considerable variation in a very short time.

We "know" there were multiple species so the designation based on tool use is dubious since more than one species likely existed to make the the tools. As far as their being one with intermediate features, that could be a hybrid or a third population. The ergastor or African erectus was generally described as being less robust with less protruding brow ridges than their Asian counterparts.
 
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