AN EARLY UPPER PLEISTOCENE AND AFRICAN ORIGIN FOR THE NEANDERTHALS
1. February 1992
This contribution to the ongoing Neanderthal debate (Graves, 1991) postulates that the species Homo sapiens originated in Africa in the early Upper Pleistocene. This population then split into two groups. One group migrated to the Near East and Europe where it developed into Neanderthal. The other group stayed in Africa and developed into anatomically modern Homo sapiens. This latter group then migrated from Africa sometime later. The article will indicate that:
Rightmire (1990) discusses the following questions in relation to Homo erectus:
He presents a case for viewing Homo erectus as a real taxon. His description of this species lists many characters which are primitive and which are not shared with modern humans. It is also possible to identify some traits which are clearly derived for Homo erectus in comparison to earlier Homo or Australopithecus. These include a heavy brow, midline keeling and parietal tori, strong flexion of the occiput and development of a prominent transverse torus, features of the cranial base and expansion of cranial capacity. Such characters serve to diagnose the species in a more precise way, and it can be argued, he states, that Homo erectus is not simply an arbitrarily defined segment of a lineage. This paleospecies had ancestors and probably left descendants, but these groups can be distinguished from one another on the basis of morphological comparisons. Regarding ancestors he states that two taxa may be present, as both large and small-brained morphs are present.
Following the emergence of Homo erectus, he continues, systematic change is not easily documented. There is a trend towards endocranial expansion, which is apparent particularly in the later assemblages at Zhoukoudian and Ngandong. The growth of brain size with time depends on the date assigned to the Ngandong crania. If these crania are included then brain volume increases at a rate of about 180 ml/my. However, there is much doubt about the age of the Ngandong hominids, and assigning them a late Middle Pleistocene date biases the analysis. If a regression line is constructed without reference to Ngandong the slope drops to about 120 ml/my. This result cannot be distinguished from zero, and there is no evidence that the trend is statistically significant. Other characters change slowly or not at all. Towards the close of the Middle Pleistocene, there are signs that some of these traits begin to change more rapidly. It is during this period that populations of Homo erectus must have given way to the first representatives of a new species.
Rightmire states that early in the Middle Pleistocene, Homo erectus can be documented from fossils found in the South, Eastern and Northwestern parts of Africa, in the Far Eastern tropics and in the cooler reaches of Northern China. Populations inhabiting these far-flung regions of the Old World are anatomically similar, and the morphology of the species seems to have changed little over more than a million years. However, differences in behaviour are apparent. In Africa, Middle Pleistocene humans utilized an Acheulian technology, while at Zhoukoudian the chopping tools associated with Homo erectus do not include hand axes. In Java, few stone tools of any sort are found in the deposits yielding ancient hominids. This suggests that Homo erectus groups were adapting differently to local circumstances.
Rightmire states that late in the Middle Pleistocene a new form of Homo evolved. These hominids, which differ significantly from Homo erectus, are known from Europe, where some of the more spectacular discoveries have come from Petralona and Arago. Other localities such as Mauer, Bilzingsleben and Vertsesszöllös are less complete and consequently less informative, but are likely to be equally ancient. Dates are very approximate for all these European specimens. Even the oldest (Mauer?) may be less than 450,000 B.P. Crania which display an advanced morphology have turned up also in Africa at Bodo (Ethiopia), Lake Ndutu (near Olduvai Groge), Broken Hill (now Kabwe) and Elandfontein. In China important discoveries have been made at Dali and other sites. As in Europe dating is very imprecise, although it can be established that the fossils cover a substantial span of the Middle Pleistocene. Workers such as Weidenreich, Coon and Wolpoff argue that this change was continuous in different geographical regions. They assume that the change was gradual and that populations of late Homo erectus were succeeded by local populations of Homo sapiens in an unbroken progression. Few if any groups became extinct. The distinction between the two groups is seen as arbitrary or is simply ignored.
Rightmire himself adopts an opposing view. Homo erectus was a stable taxon, distinct in important ways from all later Pleistocene humans. It was pushed towards extinction and actually replaced by members of an anatomically advanced species. In some, probably many, regions such extinction was complete, and there was no local continuity. If this version of events is more or less correct then one would expect to see more abrupt changes in the record. Traits characteristic of Homo erectus would not always be carried into later populations of the same geographical area, where, instead, new trends in morphology should be established. Such novel features would be shared by all members of the descendant species, who would have dispersed widely following a later Middle Pleistocene origin. Rightmire presents evidence that the hominids from Lake Ndutu, Broken Hill, Petralona and Arago Cave differ in their morphology from Homo erectus. He refers to them as Homo sapiens although it is obvious that they display a number of archaic characteristics. In fact there is, he states, doubt about how the Broken Hill or the Arago people should be sorted and how these populations should be named. A number of authorities argue that the European specimens are Homo erectus, while other suggest that a name like Homo Heidelbergensis may be more appropriate.
In his comparison of the African specimens Rightmire states that they should all be grouped together on grounds of broadly similar morphology. The small size and relatively low cranial capacity estimated for Ndutu may indicate that this individual is female, whereas the larger specimen from Broken Hill is likely to be male. Characters of the occipital, mastoid and tympanic parts of the cranium, which are quite well preserved, seem to set these hominids apart from Homo erectus. In discussing the European fossils and comparing them to the African, Rightmire states that Petralona and Arago 21 are two of the best crania from the European Middle Pleistocene. Brows are large especially in Petralona where the torus is almost as thickened as in Broken Hill. In the Arago, Petralona and African faces the glabella is strongly projecting. Neither Petralona nor Arago exhibits any midline keeling. Petralona resembles the Broken Hill specimen in measurement of facial projection except at subspinale, which is slightly further forward relative to an axis through the auditory openings.
If these fossils are not Homo erectus, continues Rightmire, then it must next be agreed, whether multiple lineages of more modern Homo are to be recognized in the later Middle Pleistocene. Here very different views have been expressed. Wolpoff would include all of the hominids of Europe in a single highly dimorphic group. To him it is unimportant whether the root of this lineage is termed Homo erectus or Homo sapiens. All of its members are said to be connected in an unbroken evolutionary stream, both with the Neanderthals and with modern humans. Stringer (1983, 1985) has emphasized differences between later Middle Pleistocene hominids such as Swanscombe and Biache which clearly share apomorphic (derived) characters with the Neanderthals, and a more archaic assemblage including Arago and Petralona. These latter show few if any of the specialized traits associated with the Neanderthals of Europe and the Middle East. Instead they may be lumped broadly with archaic humans from other geographic regions, including sub-Saharan Africa. Stringer et al (1979) have suggested that fossils such as Petralona, Arago, Mauer, Broken Hill and Bodo may represent a primitive grade of our own species. Tattersall (1986) argues that taxic diversity within Homo has been seriously underestimated. He notes that legitimate species must be identified and described before the phylogeny of hominids can be investigated.
Rightmire states that on the basis of his own observations and measurements it is reasonable to assign Ndutu, Broken Hill, Petralona and the Arago remains to a single taxon distinct from Homo erectus and later Neanderthals, even if the Arago specimens display a few Neanderthal characters. There is no justification, he states, for separating the African and European assemblages. However, he endorses Tattersall's point that groups exhibiting the archaic morphology of Broken Hill or Petralona should be set apart from anatomically modern people. To lump all recent humans, Neanderthals, and an assortment of Middle Pleistocene fossils together in one taxon is to ignore important differences. If it is accepted that archaic Homo sapiens in Africa, Europe and Asia belongs to one taxon it must be determined where the taxon originated.
Anatomically modern humans must have evolved from archaic Homo sapiens. There is no other fossil candidate. Since archaic Homo sapiens fossils have been found in Africa, Europe and Asia, the AMH could have originated in one or more of these locations. Cavalli-Sforza et al (1988) have indicated that AMH diffused from Africa about 90,000 B.P. Fossils from African sites such as Border Cave and Klassies River Mouth Cave support this. The dating of the Border Cave finds are problematic, but the Klassies River site indicate that AMH flourished in Southern Africa about 100,000 B.P. As far as recent human evolution is concerned this article has indicated:
.An origin in Asian AHS is unlikely. If Rightmire is correct in saying that the African and European AHS are one species it would not seem to matter which AHS group Neanderthal emerged from. Further, it is accepted by many that AMH developed from African AHS. This would intimately bind AHS, Neanderthal and AMH, possibly in one species. However, there is another scenario. It has been argued by Stoneking et al (1989) that Homo sapiens originated in Africa about 200,000 B.P. (using the 3% mutation rate). This has recently been confirmed by Vigilant et al (1991) in a paper which avoided the confusion over certain conceptual issues in the Stoneking (1989) paper.
From fossil evidence this would make the common ancestor a member of an anatomically archaic group. Rightmire may very well be correct in saying that European and African AHS were one species, but this can only have been true up to about 200,000 when a new species emerged. It is possible to refer to a new species because of its lack of interbreeding with previous hominids. This is indicated in Stoneking's paper where it is argued that if interbreeding had taken place then the mtDNA of modern humans would be five times more divergent than actually observed so far. We must therefore refer to an old AHS group and a new AHS group (called AHS I and AHS II hereafter).Now the original question about Neanderthal origins becomes, did Neanderthal emerge from:
i) The old, pre 200,000 B.P. species (Africa, Europe) or
ii) the new, post 200,000 B.P. species (Africa only)?If Neanderthal were a member of the old AHS species then the hominid would be distantly related to AMH but of a different species, making inter-breeding questionable.
If Neanderthal were a member of the new AHS species, then the hominid and AMH would belong to the same species, making interbreeding possible. So, from which group did Neanderthal emerge:
It is postulated in this article that the source was the African AHS II group. This population, sometime after its emergence, split into two groups. One group migrated to Europe and Eastern Asia, probably through the Near East where it developed into Neanderthal. The other group stayed in Africa where it developed into AMH. This latter group then split into two further groups. One group stayed in Africa and the other group spread around the globe. This model implies that the European and African AHS I groups died out. The apparent continuity to Neanderthal in Europe being taken up by the African AHS II migrants.
Morphologically, the Neanderthals can be distinguished from all other people, fossil or living, primarily in the skull and face. Trinkaus (1986) and Klein (1989) has discussed the functional implications of this morphology:
.i) the relative shortness of the forearm and lower leg may have been an adaptation to the cold climates that many Neanderthals faced;
ii) the functional interpretation of the Neanderthal facial structure i.e. the forward placement of the jaws and the large size of the incisors may reflect the habitual use of the anterior dentition as a tool, perhaps mostly as a clamp or vice. This use could also account in whole or in part for such well known Neanderthal features as the long face, the well-developed supraorbital torus, and even the long, low shape of the cranium.
iii) The large, Neanderthal nose, located far in front of the brain could have functioned to warm cold air before it reached the lungs. It is also possible however that the large nose served to dissipate body heat during frequent periods of heightened activity.
The dates of the migration of African AHS II and the subsequent migration of AMH are of interest in this matter. The hypothesized early migrants would have brought their lithic technology with them. This technology is called Mousterian in Europe and the Near East, and the Middle Stone Age (MSA) in Sub-Saharan Africa. According to Deacon (1989) the MSA started in Southern Africa about 125,000 years B.P. Therefore the AHS II migration could only have occurred after that. According to Cavalli-Sforza et al (1986) anatomically modern man migrated from Africa about 92,000 years B.P. So based on this data, the initial migration of archaic man was between 125,000 B.P. and 92,000 years B.P. If the African AHS II migrated through the Middle East to Europe one would expect to find his earliest fossils in the Middle East. The earliest fossils from this area are:
A common Mousterian/Middle Stone Age covered Africa, the Near East and Europe starting about 125,000 years B.P. in Africa, a little later in the Near East and still later in Europe. This common culture included (after Klein 1989):
The present writer believes that the similarity between MSA and the European/Middle East cultures is best explained by African early Homo sapiens carrying that culture to Europe rather than a similar Mousterian culture developing independently there. The probability of two similar cultures developing independently in different areas seems rather remote. Because they belonged to the same species and shared a similar cognitive capacity and culture, the hypothesized second migration of AMH from Africa to the Near East would have allowed both groups to inter-breed. This need not necessarily have happened however. For a number of reasons they may have lived side by side without mating. This is a common occurrence as, for example, when modern Europeans met the original inhabitants of the Americas, Africa and Australia. The MSA differs from the succeeding Later Stone Age (LSA) in much the same way that the Mousterian differs from the succeeding Upper Palaeolithic.
The fate of the late Homo erectus/archaic Homo sapiens population, if they did not evolve into Neanderthal, must be addressed.
Although no Homo erectus fossils have been found in Europe, artifacts that he may have made can be identified by their contemporanity with Homo erectus elsewhere. These artifacts were part of the Acheulean tradition that was widespread both spatially and temporarily. However Binford (1989) states that the remarkable similarity in early hominid technology over vast areas calls to mind what we see in other species of animals, namely, a generic organizational basis of behaviour that is common to the species. There is nothing in the data of the Oldowan or the Acheulean to suggest in any way a "cultural" or extrasomatic mechanism of inheritance serving to make possible the occupation of varying niches by sub-populations of a single species. We are not looking at rudimentary or nascent cultural systems, instead we have a technologically aided, biologically based, panspecific form of adaptation.
In the same paper Binford also questions the hunting prowess of Homo erectus. There were, he argues, no mass kills at Torralba, no game drives, no activity areas in which large quantities of meat were processed by socially differentiated labour units. Also, the tool suite associated with bones from lower limbs and heads, association recognized from earlier sites as a tentative indication of scavenging, is the dominant one. It seems likely that, as elsewhere, these bones were accumulated by the hominids rather than representing animals killed there. Although there is a distinctive suite of tools that covaries with carcass indicators, there is no indication that the hominids hunted or caused the death of animals. In fact, the pattern of raw material use characteristic of this suite suggests that the hominids encountered the carcasses unexpectedly and were forced to produce the tools needed to deal with them using local sources and already present lithic remains. This behaviour is consistent, Binford argues, with scavenging, and little planning depth stands behind it. James (1989) rejects the use of fire by Homo erectus at Zhoukoudian. He states that what has passed for burnt bone in the past is in fact manganese staining. Binford and Ho (1985) point out that there are no structurally defined hearths there and that the so called ash layers appear to consist of owl droppings, hyena scats and other organic accumulations that have been decalcified and burned, perhaps as a result of spontaneous combustion or surface fires.
For these reasons, the present writer believes that serious doubt must be cast on the culture system of Homo erectus. Neither he nor AHS I show any cultural signs of an evolution to the culture possessed by the MSA sub-Saharan people and the Mousterian population of the Middle East and Europe. As already postulated the European late Homo erectus/AHS I died out as in East Asia. One population of Homo erectus had to evolve through AHS to AMH and Neanderthal. That population was in Africa.
PRESENT PROBLEMS REGARDING THE RELATIONSHIP OF NEANDERTHAL AND ANATOMICALLY MODERN HOMO
There are, currently, two spatial and temporal areas with an overlap of Neanderthal and AMH:
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