Neanderthal DNA Research Articles

The Neander code

For a while, we were neck-and-neck in the human race. But we won, and they vanished. How like us were they? Dan Jones looks for the answers in Neanderthal DNA

Inconsistencies in Neanderthal genomic DNA sequences

Inconsistencies in Neanderthal genomic DNA sequences

Modern Humans Did Not Admix with Neanderthals during Their Range Expansion into Europe

The process by which the Neanderthals were replaced by modern humans between 42,000 and 30,000 before present is still intriguing. Although no Neanderthal mitochondrial DNA (mtDNA) lineage is found to date among several thousands of Europeans and in seven early modern Europeans, interbreeding rates as high as 25% could not be excluded between the two subspecies. In this study, we introduce a realistic model of the range expansion of early modern humans into Europe, and of their competition and potential admixture with local Neanderthals. Under this scenario, which explicitly models the dynamics of Neanderthals' replacement, 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.

Genetics and the Search for Modern Human Origins

Genetics and the Search for Modern Human Origins John H. Relethford Wiley-Liss, New York, 2001 ISBN 0-471-38413-5 The author, a population geneticist on the faculty of the State University of New York at Oneonta, has written a well-organized and most readable book which investigates what for well over a century has been one of the most hotly contested subjects in academe. As is well known, the study of anatomical traits early established the evolution of man from primate origins. By the middle of the twentieth century, what is today known as the Multi-Regional Theory of the origin of living humans was generally accepted. I choose to speak of "living humans" rather than of "modern humans" in this context, since the latter expression is poorly defined and is capable of many differing interpretations. Although the term "modern humans" is widely used by contemporary academic writers, there is a great deal of confusion as to when modern humans first appeared. This is because evolution is essentially a chicken-and-egg process; it is hardly possible to discover an anatomically modern child that was sired by parents who could be defined as non-modern. Even living human populations vary in so many details that it has been pointed out that virtually all the individual anatomical features which, taken as a whole, distinguish Classic Neanderthals can be found amongst one or other of the living varieties of man. Only when aggregated together in a single skeleton do they unequivocally mark that fossil to be Neanderthal. Implicitly acknowledging this problem, the author does not attempt to determine any set of traits that define either modern humans or Neanderthals but instead explains that the common approach is to take as many traits as possible to minimize statistical error and evolutionary fluctuations and get an estimate of the average degree of dissimilarity between the two arbitrarily chosen groups selected for the study. The radical essence of the Out of Africa theory, based on genetic and anatomical data of both fossils and living populations, argues that the ancestors of all living humans reached "modernity" in Africa, and that small populations moved out of Africa into Eurasia as recently as circa 120,000 years ago. Although there is massive evidence that other hominitis were already present in Eurasia at that time, the strict Out of Africa theory maintains that these "modern human" migrants totally replaced their non-modern predecessors in Eurasia instead of mixing their genes with them because of either mutual infertility or a primordial racist refusal on the migrants' part to interbreed with the "inferior" native stocks whom they supplanted. However, a few anatomists have persisted in pointing to the seemingly incontrovertible evidence of regional anatomical continuity from pre-modern into modern populations in certain parts of Eurasia, claiming that the human populations currently living outside Africa must have inherited at least some of their genes from earlier pre-modern populations of that area, if indeed they had not evolved quite independently from earlier non-African populations. The evidence advanced to support this view of Multi-Regional Evolution is strongest amongst the Mongoloids of Eastern Asia. During the last century, debate also centered on the theory that the Classic Neanderthals who occupied Western Eurasia down to around 40,000 years ago had evolved into modern Europeans or, more likely, had at least contributed some genes to the incoming, fully modern Cro-Magnon populations that supplanted them. Both views have now been rejected because of convincing DNA evidence acquired from Neanderthal fossils. This actually has less similarity to the DNA of modern European populations than with hat of contemporary East Asian, African and Australoid populations, although Neanderthal DNA is essentially dissimilar from that of all living humans. Similarly mitochrondrial DNA recovered from the remains of European Neanderthals does not show any reasonable degree of similarity to the mtDNA of contemporary modern Europeans, which is not surprising in light of the vast anatomical differences which separate them from the Cro-Magnon ancestors of living European Caucasoids. …

Neanderthal DNA. Not just old but old and cold?

The successful retrieval of ancient DNA from two geographically dispersed Neanderthal skeletons1,2 has fuelled a demand for more Neanderthal DNA sequences for analysis. However, these exceptionally well-preserved specimens were geologically young and the mean annual temperature of their cave sites low, so the survival of this ancient DNA could have been due to unusually favourable conditions. Here we calculate the thermal history of a range of Holocene and Pleistocene bones whose DNA quality has been tested and find that in only very few sites with Neanderthal remains is the preservation of DNA likely to match the quality of that from the skeleton found at Mezmaiskaya Cave2. We recommend that any additional Neanderthal destined for destructive analysis should be carefully selected, taking into account its integrated thermal history.

Genomic Differentiation of Neanderthals and Anatomically Modern Man Allows a Fossil–DNA-Based Classification of Morphologically Indistinguishable Hominid Bones

Southern blot hybridizations of genomic DNA were introduced as a relatively simple fossil-DNA-based approach to classify remains of Neanderthals. When hybridized with genomic DNA of either human or Neanderthal origin, DNA extracted from two Neanderthal finds-the Os parietale, from Warendorf-Neuwarendorf, Germany, and a clavicula, from Krapina, Croatia-was shown to yield hybridization signals that differ by at least a factor of two compared to the signals obtained with the use of fossil DNA of an early Homo sapiens from the Vogelherd cave (Stetten I), Germany. When labeled chimpanzee DNA was used as a probe, Neanderthal and human DNA, however, revealed hybridization signals of similar intensity. Thus, the genome of Neanderthals is expected to differ significantly from the genome of anatomically modern man, because of the contrasting composition of repetitive DNA. These data support the hypothesis that Neanderthals were not ancestors of anatomically modern man.

Neanderthal DNA confirms distinct history

Neanderthal DNA confirms distinct history

Molecular analysis of Neanderthal DNA from the northern Caucasus.

The expansion of premodern humans into western and eastern Europe approximately 40,000 years before the present led to the eventual replacement of the Neanderthals by modern humans approximately 28,000 years ago. Here we report the second mitochondrial DNA (mtDNA) analysis of a Neanderthal, and the first such analysis on clearly dated Neanderthal remains. The specimen is from one of the eastern-most Neanderthal populations, recovered from Mezmaiskaya Cave in the northern Caucasus. Radiocarbon dating estimated the specimen to be approximately 29,000 years old and therefore from one of the latest living Neanderthals. The sequence shows 3.48% divergence from the Feldhofer Neanderthal. Phylogenetic analysis places the two Neanderthals 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.

Svante Pääbo: pushing ancient DNA to the limit

Svante Pääbo: pushing ancient DNA to the limit

The DNA revolution in population genetics

Unprecedented clarity has come to our understanding of genetic variation by the analysis of DNA sequences. It is not surprising that the new DNA technologies are leading to a resurgence of interest in population genetics. In this review, I discuss recent progress and future directions towards reconstructing the history of human populations. There is increasing consensus on a recent `Out of Africa' origin of modern humans, which explains why the greatest fraction of genetic diversity is found within populations, rather than between them. The comparison of Y chromosome and mitochondrial DNA data shows remarkable sex differences in geographic variation. The analysis of Neanderthal DNA has been a major breakthrough in the study of fossil DNA. Among major hopes for the future are applications to polygenic diseases.

African Exodus--re-evaluating an hypothesis

African Exodus: The Origin of Modern Humanity Christopher Stringer dc Robin McKie Henry Holt, 1997 That the authors of this book are from two different backgrounds suggests there may be some tension in the book. Christopher Stringer (paleoanthropologist at London's Natural History Museum) is a well known scientist, but Robin McKie is a journalist (science editor of The Observer). African Exodus is a politically correct history of mankind, devoted to defending the Out of Africa theory of human origins, and incidentally arguing that therefore all humans are basically identical. One can speculate that Stringer supplied the basic facts while McKie was responsible for the political gloss. The organization of the book is chronological, tracing human history from its origins. However, the first chapter is autobiographical, recounting the Stringer's first work on human skulls (done as part of his PhD thesis). It then describes how the Kibish skull from Ethiopia looked modern to him. Yet it dated to about 130,000 years ago (i. e. when Europe was inhabited by Neanderthals with quite different looking skulls). This led him to develop the Out of Africa hypothesis that modern humans had evolved in Africa, probably in East Africa, some of whom later moved out of Africa to populate the world. This chapter is followed by one arguing for the East African ancestry of modern humans, and then a couple of chapters on the Neanderthals and their replacement by Cro-Magnons. The next two chapters deal with the genetic evidence on human evolution and how that points to an African origin for humans. A chapter is devoted to the apparent intellectual advantages of the Cro-Magnons, and speculation as to just what they had that the Neanderthals lacked that led to their replacement. The part of the book devoted to reviewing hominid origins appears competent and is certainly very readable. It differs little from other popular accounts. It has the advantage of being more up to date than older ones, carrying the evidence of research into 1996. For instance, it provides a vivid account of the discovery of a Neanderthal infant by Rak (for a scientific description see Rak, Kimbel, & Hovers, 1994), seemingly too different from current Homo sapiens infants to be the same species. In one case, an interview brings the story more up to date even though the published work was not yet available. The genetic work of Tishkoff and Kidd on a CTI-r repeat on chromosome 12 is described. It provides very powerful evidence for an African origin of the hominids. (A published report is now available in Tishkoff, et al. 1996). Of course, there is always new genetic work, too new to be cited, notably that concerning the Y chromosome (Zerjal, et al. 1997 is a recent example). Unfortunately, the book went to press too early to give the important finding (Krings, Stone, Schmitz, Krainitzki, Stoneking, & Paabo, 1997) that Neanderthal mitochondrial DNA is sufficiently different from modern humans to make modern Europeans descent from Neanderthals unlikely. This finding greatly weakens the case for any multi-regional hypothesis of human origins in the form advanced by its contemporary exponents, when they argue that Cro-Magnons evolved from Neanderthals. Since the book went to press further evidence suggesting the Neanderthals were not the ancestors of current Europeans has appeared (Richards, et al., 1996, Schwartz & Tattersall, 1966, Holliday, 1967, Armour et al, 1996). The major errors in the book arise when it moves beyond paleoanthropology and attempts to be politically correct. I suspect McKie (a journalist) may have written these sections, although a co-author such as Stringer certainly deserves to share the blame for obvious errors. Stringer is the author of another recent book on a similar subject (Stringer & Gamble, 1993) which seems free of the political correctness problems of African Exodus. African Exodus digresses from paleoanthropology (Stringer's area of expertise) to attack The Bell Curve (Herrnstein, & Murray, 1994). …