The Neanderthal Debate Essay

The Neanderthal Debate

Introduction

According to Green, Krause et al in their Nature article of 2006 ‘Comparison with the human and chimpanzee genomes reveals that modern human and Neanderthal DNA sequences diverged on average about 500,000 years ago.’ Our knowledge of the Neanderthals is of course based upon a limited number of species, but from these it is possible to make a number of suppositions about their genetic makeup and physiology, their habits and their relationship to modern humans. However these are only supposition because of the unavailability of enough suitable specimens. The articles cited all seem to follow different methods of obtaining data and so this makes true comparisons difficult.

Thesis

From the limited number and type of specimens available it is impossible to prove definitively whether or not Neanderthals have contributed to the ancestry for modern man, but logic and anthroplogy tells me that they are likely to have survived in some cases.

The fossil record

It was more than 150 years ago that Neanderthals were first distinguished as a species from remains found in Germany. They seem to appear some 400,000 years ago, and make their exit from the fossil record comparatively recently, some 30,000 years ago,.( page 330) though as pointed out later, dating is not as exact a science as some would like But did they all disappear or can it be possible that Neanderthal genes are walking in the cities of earth in the 21st century? Green and Krause state that they gradually evolved traits in their morphology that distinguished them more and more from the ancestors of modern man. For instance their mid faces bulged and there are obvious differences in the base of the skull, inner ears and jaws. There seems to be no known evidence of communal habitation of the two groups, although it is known that in some instances their territories overlapped.

Modern Mitochondrial DNA Research

Green, Krause et al discuss ( page 330) how modern research has shown that the various Neanderthals from scattered areas show more likenesses with each other than they do with modern humans. It also seems to show that if Neanderthals did contribute to the  modern gene pool the donation was minimal or even non-existent. However Noonan and Coop et al in their November 2006 article in ‘Science’ ‘Sequencing and Analysis of Neanderthal Genomic DNA’, point out that any genetic material found would only show half the picture as it could only refer to the mating of a female Neanderthal with a male Homo Sapien because mitochondrial DNA is only passed on in the maternal line. They also stipulate that any firm hypothesis would depend upon the finding of lots more data and point out the lack of both material and evidence for an admixture of the two groups.

They discuss the number of matching sequences between Neanderthals and chimpanzees where human sequences are absent, which seems to deny the possibility of Neanderthals being included in the ancestry of modern man.

Homo Adoramus.

Yet despite all the scientific there are those who would point out that there are likenesses between the two – for instance both groups practiced body decoration and it has been surmised that this points to interaction between the two groups. Also body decoration may mean religion, which is why it is sometimes suggested that, whatever the physical differences, the two might be grouped together as ‘Homo adoramus’. According to Tattershall and Schwartz in their article of 1999, ‘Hominids and Hybrids: The place of Neanderthals in Human Evolution’, there are those who still view Neanderthals as merely a variation of modern man. The authors are of the opinion that if the Neanderthals are a separate species (page 7117) then they deserve close study in their own right, but that if they are simply a side issue as far as the human race is concerned then they are less important, though there would be those who would debate their point. They discuss an article in the same issue of ‘The Proceedings’ by Duarte et al about the discovery of a small child’s skeleton in Portugal which is said to bear both Neanderthal and human characteristics. The fact that she was found in Portugal is important as it was in Iberia that the Neanderthals lasted for the longest time. Duarte et al seem to believe that she was born as the result not of a casual meeting, but as the result of many years, perhaps even several millennia, of interaction between the two groups and mention the geological barriers to dispersal. According to Tattershall and Schwartz the Neanderthals disappeared within 10,000 years of the arrival of Homo Sapiens in northern Europe, which means that there was no time for the millennia of interaction that Duarte et al propose. They post either direct conflict between the two or economic ascendancy of Homo Sapiens. Alternatively they suggest that either the Neanderthals evolved into modern man, which does not fit with the DNA evidence mentioned earlier, or that the groups merged, but the Homo Sapien DNA somehow ‘swamped’ that of the northern group. Although they do not agree with the Duarte findings Tattershall and Schwartz are glad, because they believe they will inspire even more research as they undoubtedly will.

Claims of Transition

Such claims are mentioned by Tattershall and Schwartz, but are dismissed as being because of wrong dating or, they state, have later been found to belong to one group or the other. However Duarte, Mauricio et al state in their November 2006 article  mentioned above, that the child’s skeleton, found buried with red ochre and pierced shell, another pointer towards both groups being classed as worshipping man, is  a ‘morphological mosaic’ which ‘ indicates admixture between regional Neanderthals and early modern humans dispersing into southern Iberia’ and on page 7608, because of the late dating of this specimen, conclude a long period of a joint culture. They base a lot of their hypothesis upon limb length and sturdiness, though others, including Tattershall and Schwartz prefer to think that it could just be a very sturdy modern child and point out that  the symphysis pubis in particular has only modern characteristics rather than the plate like symphysis found in Neanderthals.

The Replacement Theory

Wolpoff and Hawks et al discuss the idea that new populations, coming out of Africa, replace d the more established hominid populations elsewhere as already suggested by Tattershall and Schwartz et al. The Wolpoff article looks at early modern populations of both Australians and Central Europeans. The conclusion the researchers came to was on of dual ancestry, which would fit in with the Duarte hypothesis. They mention the two, opposite, ideas that have come about in recent years. One theory states that there must have been complete replacement of the older population. The second idea is of multiregional evolution which asserts that the modern human population has come about as the result of various scattered populations coming together, both genetically and by the exchange of ideas. The first idea would classify these older populations as belong to a different, now extinct species such as the Neanderthals.

They chose Australia and Central Europe in order to study the possible transition because of the ready availability of species. However they do say ‘so-called transition’ which seems to imply that they doubt the whole idea of multiregional evolution. Also, when it comes to dating species used, there are discrepancies. The Australian specimen is perhaps 15,000 years old or as old as 30,000 years depending upon which results are taken as valid. They point out that it resembles Javan fossils, yet the former is classed as human and the latter have been classed as Homo Erectus. Both cannot be true.

From Europe they were able to use many scattered cranial fragments. Some of these had already been likened to early Neanderthal like specimens and they suppose from this that these are ancestors of the local present population.

Obstacles to Exact Diagnosis

Various obstacles to proving any theory are discussed in the Wolpoff and Hawks’  document. These include the small number of early human craniums available for study, the small size of the specimens that are available and the fact that they have been preserved in many different ways  – the researchers describe the preservation as haphazard. They admit that some traits may be unobservable.

Scientific Methods

In Wolpoff et al’s case the researchers go into great detail about how they went about comparing the species in pairs – likes and unlikes. This is described as ‘pair-wise differences.’ Where there is missing data it was recorded as an absence of differences. Is this allowable? If not what else could they have done one must ask. They found on average that the Australian skull was most different from that from Africa and was closer to the Javan specimens already classed as Homo Erectus. The arguing is quite complicated, but in the end the conclusion is that, from the specimens so far studied, the dual evolutionary theory is not disproved. They expected to find the same from the Czech results. Finally there conclusion are that, although they admit that in many cases ancient populations would have been overrun but :-

             We conclude that the hypothesis that all living humans descended from a

single geographically isolated group during the Late Pleistocene is false, and

that the replacement explanation for the origin of these early modem Australians and Europeans can be ruled out. ( Wolpoff et al, page 296)

Conclusion

All the groups admit that they are working with incomplete data, scattered small specimens in various states of preservation. This obviously makes it very difficult to make definitive statements, yet this is what occurs in several cases. There are instances where findings are stated as perhaps being more definite than another group, analyzing the same data, would find as is proved by the Duarte findings being criticized by Tattershall et al.

Carl Bergman, a German biologist, stated in the 19th century that in a warm-blooded, polytypic, wide-ranging animal species, according to their varied geographical group and therefore their average environmental temperature, the body size and physical configuration of individual groups would vary too with those in the colder climates tending to be larger than those in the warmer areas of the world. If this principle is accepted then people would have changed gradually over the generations as they moved into new climatic areas, so as humans moved out of Africa they would change.

Another point is that J.A.Allen said that animals adapt to cold climates by having shorter limbs and protruding body parts. Daurte’s finding for instance would fit in with body types found in modern human groups who live in very cold climates such as the Inuit’s and Lapps. It would be interesting to know more about what animal bones were found alongside the European species studied –were there any cold weather creatures such as reindeer?

Each of these papers, despite going into great detail in each case, does not cover the whole question. Science is moving at a very fast rate when it comes to mitochondrial DNA analysis. This method does not depend upon putting together broken bones in order to prove a point and it seems to be the way that the various aspects of the Neanderthal debate will eventually be settled – until that is, someone comes up with another and newer theory.

Another point is that, although in one case the possibility of conflict and economics is mentioned, there is really almost no acknowledgement of what takes place when modern populations clash and meet. For instance when there is a large migration of a particular group, for examples Jews after the persecution in Eastern Europe at the turn of the 19th and centuries, or the large number of West Indians who came to the U.K. in the 1950’s.Of the first generation in both cases very few married those from another group, but in each case, over time, this has occurred, yet the majority have remained within their own racial group. If we consider what happened during the Holocaust, surely one occasion when a population might have totally succumbed, we know that there were many survivors and so their genes live on. In the midst of all the minute measuring by the various researchers there seems to be too little acknowledgement of what is the most likely occurrence, that is that it is highly unlikely that all Neanderthals were eliminated in a relatively short period, though some smaller and more isolated groups may have been.

From the reading of these articles none seem to really prove the matter one way or the other, despite all the measuring, comparisons and charts. The debate is not over.

References

Allen, J.A. ( 1877), The Influence of Physical Conditions in the Genesis of Species.
Radical Review, , 1: 108-140.

Electronic Sources

Bergman,C. quoted in The American Dictionary of the English Language, Fourth Edition, retrieved 17th October 2008 from

http://www.bartleby.com/61/98/B0199800.html

Duarte, C., Mauricio, J. et al, The Early Upper Paleolithic Human Skeleton from the Abrigo do Lagar Velho (Portugal) and Modern Human Emergence in Iberia, Proceedings of the National Academy of  Sciences of the United States of America, volume 96 pages 7604-7609.

Green, R., Krause, J. et al, (November 2006) Analysis of one million base pairs of

Neanderthal DNA, Nature volume 444,

Noonan, J. and Coop, G. et al, (November 2006) Sequencing and Analysis of Neanderthal Genomic DNA, Science, Volume 314

Tattershall, I and Schwartz, J.( 1999) Hominids and Hybrids: The Place of Neanderthals in Human Evolution, Proceedings of the National Academy of  Sciences of the United States of America, volume 96 pages7117- 7119,

Wolpoff, M. ,Hawks, J. et al, ( January 2001) Modern Human Ancestry at the Peripheries: A Test of the Replacement Theory, Science, Volume 291, pages 293 – 297, The American Association for the Advancement of Science