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Rebutting Neanderthal Claims
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One of the continuing claims in the attack upon palaeoanthropology is that Neanderthals (Homo neanderthalensis) specimens were actually AMHs (Anatomically Modern Humans) afflicted with RA (Rheumatoid Arthritis). It is also claimed that the orbital torus is simply just due to "human variation".
A while ago I tackled this claim and I figured I'd share the information here with you fine folks. Enjoy.
Here is the actual claim I addressed:
“Neanderthal man was found to be pure human, whose brain was deformed by arthritis. [6] Neanderthal had arthritis and was crippled, that is why he would have walked stooped, but not because his whole civilization was like that, and not because he came from a monkey, he was a human. [7] Neanderthal and Homo Erectus had brain sizes like those of modern humans. Neanderthal fossils were found in the same layers as modern human fossils. The skulls of Neanderthal were the only ones with brow ridges, which is supposed to show it to be sub human. But, there are variations in human skulls, one of which is brow ridges. [8] Using the skull of Neanderthal man, an artist can draw either a human, or a monkey; this is not a method to rely upon.”
Source - http://www.freewebs.com/noevolutionguy/evolutionessay.htm
Homo neanderthalensis is not represented by a singular specimen. There are many specimens that have been found that represent the Neanderthals. Not all of them from many separate sites could all have arthritis. Also, rheumatoid arthritis (which is what the claim is) has specific pathology upon the skeleton. This does not explain the morphology of the Neanderthal specimens .
“Rheumatoid arthritis (RA) is a systematic autoimmune disease that causes chronic inflammation of connective tissue, primarily in the joints. The first joint tissue to be affected is the synovial membrane, which lines the joint cavity. Eventually, inflammation may spread to the articular cartilage, fibrous joint capsule, and surrounding ligaments and tendons, causing pain, joint deformity, and loss of function. The joints most commonly affected are in the fingers, feet, wrist, elbows, ankles and knees, but the shoulders, hips, and cervical spine also may be involved, as well as the tissue of the lungs, heart, kidneys and skin (Huether and McCance, 2000).”
Arthritis does not deform the brain. Neanderthals brains were, on average, equal to or larger than modern humans. Modern humans average approximately 1400 cc (Woolsey et al, 2003) with a range of approximately 1300 – 1500 cc. The Neanderthals brain size ranged between 1300 and 1640 cc (Poirier, 1999 and Klein, 2000). The claim that Neanderthals were human is both right and wrong, depending on how you look at it. They were human in the sense that they are part of the genus Homo.
The author references the work of Johanson and Shreeve (1989) and uses it as support for the arthritis assertion. The work does not support this claim at all. Johnason and Shreeve give the background of the first Neanderthal find described to the scientific community at the time (the mid 1800’s). A reaction to a paper written by the German anatomist who concluded that the specimens were ancient in origin although incorrectly speculated that they were from a barbarous race encountered by Roman armies (pp. 48). Johanson and Shreeve give the history of the finds, they do not claim that the Neanderthals were humans with arthritis or rather rickets which is the pathology discussed in the historical context of the reaction to the find. This means that the author has not actually read the work he cites, has taken this information from another work without properly referencing it or made a claim and cited the work knowing that Johanson and Shreeve did not take that position.
Any member of the genus Homo warrants being called a human. However, if the author is referring to modern humans, the Neanderthals were not the same as modern humans. The scientific community has come to the conclusion that Neanderthals are not a sub-species of Homo sapiens nor were they an ancestor of modern humans. The evidence warrants a classification of a separate species. This is a culmination of studies on the Neanderthal specimens ranging from general morphology to DNA analysis.
Back in 1997 Matthias Krings and his team extracted mtDNA from a Neanderthal specimen found in Germany. Using PCR techniques and control groups for comparison, Krings found that when compared to modern humans, Neanderthals show differentiation to the extent of being a separate species:
“DNA was extracted form the Neanderthal-type specimen found in 1856 in western Germany. By sequencing clones from short overlapping PCR products, a hitherto unknown mitochondrial (mt) DNA sequence was determined. Multiple controls indicate that this sequence is endogenous to the fossil. Sequence comparisons with human mtDNA sequences, as well as phylogenetic analyses, show that the Neanderthal sequence falls outside the variation of modern humans (19).”
Genetic analysis done by Scholz et al. (2000) showed that Neanderthals are not the ancestors of modern humans and not were differentiated enough to show they are not anatomically modern humans.
Using PCR amplification on two different samples of Neanderthal DNA (one from Germany and one from Croatia), they were compared to Homo sapiens DNA from a German sample and mammoth and reindeer DNA for controls (from Banks Island, Canada).
“The data presented in this study indicate that the composition of the genomes of Neanderthals and anatomically modern man is significantly different…(1930).”
Scholz continues to examine more in depth the genetics and concludes:
“…the mtDNA sequences provided by Krings et al. (1997, 1999) and the data presented here indicate a clear differentiation of Neanderthals and anatomically modern man and support the assumption that both taxa are discrete species. This also means Neanderthals cannot be the direct ancestor of anatomically modern humans. (1931).”
A unique study into the Neanderthal/modern human differentiation comes from an examination done by Grine (2004) and molar enamel. In examining the enamel thickness and molar morphology, Grine found:
“Evaluation of this purported synapomorphy through an examination of the permanent molars of recent Europeans and Africans reveals that they are indistinguishable from one another in enamel thickness. Thus, modern Europeans do not share relatively thin molar enamel with Neanderthals. Rather, thin tooth enamel would appear to represent an ostensibly autapomorophic feature by which they differ from modern as well as other fossil humans. (389).”
If Neanderthals and modern humans were the same species they would have been able to admix considerably. Currat and Excoffier’s (2004) research shows this did not happen during the modern humans expansion into Europe.
“…we estimate that maximum interbreeding rates between the two populations should have been smaller than 0.1%. We indeed show that the absence of Neanderthal mtDNA sequences in Europe is compatible with at most 120 admixture events between the two populations despite a likely cohabitation time of more than 12,000 y. This extremely low number strongly suggests an almost complete sterility between Neanderthal females and modern human males, implying that the two populations were probably distinct biological species. (2264).”
Currat and Excoffier’s work supports similar work previously done four years earlier by Ovchinnikov et al. in 2000.
Ovchinnikov and his team found that the genetic evidence shows that Neanderthals and humans are two separate species and Neanderthals did not contribute to the modern human gene pool. The examined a specimen from Mezmaiskaya Cave in northern Caucasus which was 29,000 years old.:
“The sequence shows 3.48% divergence from the Feldhofer Neanderthal. Phylogenetic analysis places the two Neanderthals [referring to a previous study by Ovchinnikov on a different specimen] from the Caucasus and western Germany together in a clade that is distinct from modern humans, suggesting that their mtDNA types have not contributed to the modern human mtDNA pool. Comparison with modern populations provides no evidence for the multiregional hypothesis of modern human evolution. (490).”
Harvati, Frost and McNulty (2004) focused on morphological differences between Neanderthals, modern humans, gorillas and chimps and some old world monkeys. Their analysis found:
“Morphological distances between model taxon pairs were compared to the distances between Neanderthals and modern humans obtained by using a randomization technique. Results strongly support a specific distinction for Neanderthals. (1147).”
Bruner et al. (2003) focused on a comparison of endocasts of Neanderthal and modern humans. One of the major events in our lineage’s evolution was the encephalization of the brain. The comparison of modern humans and Neanderthals showed marked differences:
“Enodcranial morphology was studied in a sample of fossil hominines by multivariate approaches using both traditional metrics and geometric morphometrics.
The main result was the identification of two different evolutionary trajectories, in which a similar expansion in endocranial size has been reach by different changes in shape. (15335).”
Caramelli et al. (2003) studied two Cro-magnon specimens and compared them with Neanderthal samples of DNA. They found what many others have and keep finding, more evidence that Neanderthals and modern humans are two distinct species:
“Following the most stringent current standards for validation of ancient DNA sequences, we typed the mtDNA hypervariable region I of two anatomically modern Homo sapiens sapiens individuals of the Cro-Magnon type dated at about 23 and 25 thousand years ago. Here we show that the mtDNAs of these individuals fall well within the range of variation of today’s humans, but differ sharply from the available sequences of the chronologically closer Neanderthals. (6593).”
Tattersall (1995) accentuates the findings of the status of Neanderthals being a separate species when discussing the cohabitation of modern humans and Neanderthals:
“…if the Neanderthals were a separate species from us – which the continuity people would deny, of course – significant interchange of genes would have not been possible (though, possibly, individuals might willingly or unwillingly have participated in attempts to hybridize). (226).”
The non-mixing of genetics has been shown and supported and therefore supports Tattersall’s contention that they were, indeed, a separate species. In fact, he was one of the first people to formally propose the separate species distinction which was originally determined in the early part of the 20th century:
“Specifically I urged that, at the very least, the Neanderthals be restored to separate species status as Homo neanderthalensis. (219).”
Kottak (2002) sums up the contention over the admixture vs. replacement hypothesis (replacement including the non-contribution of Neanderthals to the human gene pool which is supported many times over by genetic evidence):
“Current interpretations of the fossil evidence and dating seem to support the replacement hypothesis, which denies the Neanderthal ancestry of AMHs [anatomically modern humans] in Western Europe and the Middle East. AMHs seem likely to have evolved from an archaic H. sapiens African ancestor [Homo heidelbergensis – c.r.o.]. In Africa, as in the Middle East and Asia, the archaic H. sapiens fossils generally had flatter, less projecting faces than the Neanderthals did. Eventually, AMHs spread to other areas, including Western Europe…(175).”
There are many other differences between modern humans and Neanderthals in behavior and ecology from paleoanthropological evidence. As Klein notes:
“…archaeology also suggests important behavioral differences. Unlike Upper Paleolithic Cro-Magnons, Middle Paleolithic Neanderthals left little compelling evidence for art or jewelry.
Their cave sites are generally poorer in cultural debris and richer in bones of bears and other cave dwellers.
Finally, the Paleolithic artifact assemblages that Neanderthals produced varied little through time and space. The Upper Paleolithic assemblages that Cro-Magnons made varied far more and are the oldest from which we can infer identity-conscious ethnic groups (1526).”
Poirier and McKee (1999) discuss more morphological aspects of Neanderthals as they differ from modern humans:
“Face: Overall facial skeleton is massive; midfacial prognathism, large nasal apertures, well-developed but discontinuous brow ridges.
Skull: The cranial vault is long, low, and wide. The occipital bones have occipital ridges, and many have occipital buns. Perhaps differently shaped foramen magnum and middle ear bones.
Dentition and Jaws: No canine diastema in maxillary region; molars have large pulp cavity (taurodontism); large incisors, no chin.
Spinal Column: Heavily built; the cervical vertebrae have long projecting spinous processes.
Upper Limb Skeleton: Broad scapula, robust humerus with massive head.
Pelvis: More dorsally rotated ilia than in modern humans.
Lower Limb Skeleton: Massive femurs, short and strong tibiae, large and thick kneecaps. (271).”
In more recent research, genetic analysis of Y-Chromosomal DNA supports the separate species view as well as shown in a presentation by Svante Paabo (Dalton, 2006):
“One finding so far is that the Neanderthal Y chromosome is substantially more different from human and chimp Y chromosomes than are other chromosomes. This suggests that little interbreeding occurred, at least among the more recent Neanderthal species (260).”
The report was given at New York's Cold Spring Harbor Laboratory.
A study by Noonan, Coop, Kudaravalli, Smith, Krause, Alessi et al. (2006) examined a sequence of 65, 250 base pairs of Neanderthal DNA and estimate that the lineage of AMHs and Neanderthals diverged ~370,000 years ago which supports the previously proposed common ancestor of Neanderthals and AMHs in Homo heidelbergensis. The research also supports the non-admixture of the two genomes in a significant amount.
The Neanderthals were NOT the only ones with “brow ridges”. This part of the facial skeleton is called a supraorbital torus, is found in many hominids, Neanderthals, Homo erectus, Homo heidelbergensis, Homo habilis, Homo ergaster, et al.
The supraorbital tori of Neanderthals is distinct in that they are “extensively pneumatized by the frontal air sinuses, whereas those of Homo erectus are less so, often being composed of solid bone” and are still distinct from modern humans which lack this trait (Aiello and Dean, 2002, pp. 203). The “brow ridge” is not the single morphological trait by which the separation of modern humans and Neanderthals is made. To suggest such implies gross ignorance upon the subject.
References (In order of appeareance):
Huether, S. and McCance, K. (2000). Understanding Pathophysiology. (2nd ed.). St. Louis: Mosby.
Woolsey, T., Hanaway, J. and Gado, M. (2003). The Brain Atlas. (2nd ed.). Hoboken: John Wiley & Sons.
Poirier, F. and McKee, J. (1999). Understanding Human Evolution. (4th ed.). Upper Saddle River: Prentice Hall.
Klein, R. (2000). Whither the Neanderthals? Science, 299, 1525-1527.
Johanson, D. and Shreeve, J. (1989). Lucy’s Child: The Discovery of a Human Ancestor. New York: William Morrow and Co.
Krings, M., Stone, A., Schmitz, R., Krainitzki, H., Stoneking, M. and Paabo, S. (1997). Neanderthal DNA sequences and the origin of modern humans. Cell, 90, 19-30.
Scholz, M., Bachmann, L., Nicholson, G., Bachmann, J., Giddings, I., Ruschoff-Thale, B. et al. (2000). Genomic differentiation of Neanderthals and anatomically modern man allows a fossil-DNA-based classification of morphologically indistinguishable hominid bones. American Journal of Human Genetics, 66, 1927-1932.
Grine, F. (2004). Geographic variation in human tooth enamel thickness does not support Neanderthal involvement in the ancestry of modern Europeans. South African Journal of Science, 100, 389-394.
Currat, M. and Excoffier, L. (2004). Modern humans did not admix with Neanderthals during their range expansion into Europe. Public Library of Science - Biology, 2, 2264-2274.
Ovchinnikov, I., Gotherstrom, A., Romanova, G., Kharitonov, V. Liden, K. and Goodwin, W. (2000). Molecular analysis of Neanderthal DNA from the northern Caucasus. Nature, 404, 490-493.
Harvati, K., Frost, S. and McNulty, K. (2004). Neanderthal taxonomy reconsidered: Implications of 3D primate models of intra- and interspecific differences. Nature, 101, 1147-1152.
Bruner, E., Manzi, G. and Arsuaga, L. (2003). Encephalization and allometric trajectories in the genus Homo: Evidence from the Neanderthal and modern lineages. Proceedings of the National Academy of Sciences, 100, 15335-15340.
Caramelli, D., Lalueza-Fox, C., Vernesi, C., Lari, M., Casoli, A., Mallegni, F. et al. (2003). Evidence for a genetic discontinuity between Neanderthals and 24,000-year-old anatomically modern Europeans. Proceedings of the National Academy of Sciences, 100, 6593-6597.
Tattersall, I. (1995). The Fossil Trail. New York: Oxford U.P.
Kottak, C. (2002). Anthropology. (9th ed.). New York: McGraw-Hill.
Dalton, R. (2006). Neanderthal DNA yields to genome foray. Nature, 441, 260-261.
Noonan, J., Coop, G., Kudaravalli, S., Smith, D., Krause, J., Alessi, J. et al. (2006). Sequencing and analysis of Neanderthal genomic DNA. Science, 314, 1113-1118.
Aiello, L. and Dean, C. (2002). An Introduction to Human Evolutionary Anatomy. London: Elsevier Academic Press.
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