Fingering Species or Putting Your Foot In It.

I’m very pleased today to bring back the Subversive Archaeologist’s good friend, Iain Davidson. He’s voicing what, no doubt, some of you already suspect in regard to some of the most recent pronouncements having to do with our distant relatives, the Neanderthals, and us.

Since before Iain and I became acquainted in about 1988, we’ve shared what I facetiously refer to as an ‘intellectual pathology.’ We both think that a lot of the claims for modern-human behaviour in the Early and Middle Palaeolithic are misguided at best—misinterpretations for the most part—and, at worst, mythical.

Iain Davidson

Iain has recently retired from his Professorial duties at the University of New England, in Armidale, New South Wales, where he plied his trade for several decades. His research and fieldwork have spanned the length and breadth of Australia, from the dream time to the European occupation. He has expertise in, among other fields, animal bone archaeology, taphonomy, lithic replication and lithic analysis (including having to do with the Near Eastern Middle Palaeolithic).

He has published a good number of books, including a ground-breaking treatment of cooperative ties with Aboriginal groups in Australia. But the ones that are most closely connected with our favorite subject are one on the evolution of cognition and language and another on the relationship between lithic ‘technology’* and how we became human: Human Evolution, Language, and Mind and Stone Tools and the Evolution of Human Cognition.

In today’s oeuvre Iain has a bone to pick with the Neanderthal genome gang, who’ve lately been very vocal about your and my ancestors’ sexual behaviour in Europe about the time the Ns were checking out. It looks to me as if Iain has discovered another one of the rabbit holes that seem to abound in the land of subversive archaeology, down which we’re all being told to descend, and which leads to a bizarro world of fractured logic, Mad Hatter-like knowledge claims, and … well … before I give away the plot, I think I’ll turn the reins over to Iain.

Fingering Species or Putting Your Foot In It

Back in 2010 a modestly titled paper (1) announced that a whole sequence of ancient Mitochondrial DNA had been extracted from a pinky bone by the team who have been constructing the Neandertal genome (2): they called it “an unknown hominin”. This, despite the fact that this unknown hominin is known only from the pinky and perhaps a tooth from mixed sediments at the back of Denisova cave. The dating samples for the cave came from the better stratified sediments elsewhere, so the pinky and the tooth are effectively undated. The creature was subsequently dubbed “the Denisovans” on the assumption that, in life, more than one little finger was needed to reproduce a genetic sequence. The whole genome was subsequently presented (3) and it was shown that the distinctive sequences in the Denisovan genome could be found in present day people in Melanesia, Fiji and the Cook Island but not in modern Chinese or Native Americans (4). All of this is brilliant science and fascinating, but puzzling.

The bigpuzzle is what on earth we can do with this information in relation to everything we have known before. That is to say that the whole business of giving names to different species of hominins—in most cases it is not too much of a distortion to say “our ancestors”—has been done by identifying distinctive patches of variation in the skeletal remains from a particular time or place. But with the Denisovans we have a pinky and a tooth. People are bolder now about identifying teeth to species but it was once thought difficult. I am pretty sure that most people would be cautious about identifying a species from a pinky bone. So it is going to be difficult to classify any other fossil skeletal remains as Denisovans until ancient DNA has been extracted. Which is a big ask.

That puzzle means that it is really difficult to discuss population histories, say, of how the Denisovan genetic material got to Melanesia without leaving a trace in modern Han Chinese. I discussed this in my recent paper in Quaternary International (5). I suggested that it is highly likely that some of the presently known fossil specimens, especially those that have been difficult to classify, might end up to have been Denisovans, but until we have their DNA sequences we cannot know.

But wait there’s more. This week there have been two new studies which brought me up short.

First, a British team tried to assess the differences in structural organisation of the brains of Neandertals and humans (6). I do not want to go into the statistical manipulations that made that possible (well, I do, but that is not my point here—and the SA has already started that task). Rather, hidden away in the Supplementary Online Material, the samples were identified including the Chinese specimens from Dali and Jinniushan and the Indian specimen from Narmada as Denisovans. I could find no argument saying why they were so identified. In his recent book (which must have one of the best titles on human evolution ever—The origin of our species) Stringer, one of the team, emphasised the need for the DNA analysis (7). I wonder why he ignored that advice in the paper.

Second, yesterday the ancient DNA team from Leipzig released the full genome of the Neandertal, promising a paper on it would be coming out soon (8) [and see below]. That is not a surprise, as the original paper (2) only claimed to have a draft of the complete genome. What was surprising was that the genome included material from another very non-diagnostic bone, this time from the foot. But even more surprising was that this foot bone came from the same Denisova Cave as the pinky bone. I have not been able to access the paper in which the bone is described, but John Hawks (9) says that it found some similarities with Neandertals and some with recent humans. But here’s the thing: as Hawks pointed out, we could be about to witness a real confusion in the literature. We have two sets of evidence, from skeletal remains and from ancient DNA. I am not sure that they are compatible even in the most straightforward of cases. After all the original draft genome sequence was obtained from non-diagnostic leg bones. 

Press release from the Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology. 

A high-quality Neandertal genome sequence

The genome sequence was generated from a toe bone discovered in Denisova Cave in southern Siberia in 2010.  The bone is described in Mednikova (Ethnology & Anthropology of Eurasia 2011. 39: 129-138). DNA sequences were generated on the Illumina HiSeq platform and constitute an average 50-fold coverage of the genome. 99.9% of the 1.7GB of uniquely mappable DNA sequences in the human genome are covered at least ten times. Contamination with modern human DNA, estimated from mitochondrial and nuclear DNA sequences, is around 1%. The figure shows a tree relating this genome to the genomes of Neandertals from Croatia, from Germany and from the Caucasus as well as the Denisovan genome recovered from a finger bone excavated at Deniosva Cave. It shows that this individual is closely related to these other Neandertals. Thus, both Neandertals and Denisovans have inhabited this cave in southern Siberia, presumably at different times.

What we actually have is skeletal and behavioural variation on one side which has been partitioned into species by physical anthropologists and on the other side we have variation in ancient and modern DNA and a capacity to identify distinctive sequences of DNA attributed to a couple of ancient species in living populations suggesting low levels of admixture. The DNA variation will yield vast amounts of information. I am not sure the skeletal variation will yield so much, particularly if a typological approach is the best we can do. Certainly, giving the name Denisovan to skeletal remains is going to be a very counter-productive activity until DNA has been extracted from some more diagnostic parts of the skeleton.

And at the back of my mind is the crisis in physical anthropology caused by the difficulties of agreement about the most fundamental aspects of classification of the remains from Liang Bua in Flores. There are claims in the literature that one or more characters are most like hominins from Australopithecus afarensis, Homo habilis, H. rudolfensis, H. georgicus, H. erectus, H. antecessor, or that the creatures were the remains of modern humans either with one pathology or another, or with no pathology (this is summarised in ref 10). If it is so difficult to classify a nearly complete skeleton into an appropriate place right across the range of hominin variation then I am not sure I am going to be convinced by extending a classification from a pinky bone to a whole skeleton or even a skull. And I am going to remain puzzled by the presence of two bones of the extremities from different species in the same cave. Dare I say we need to proceed with caution, perhaps on tippy toe.

1) Krause, J., Fu, Q., Good, J. M., Viola, B., Shunkov, M. V., Derevianko, A. P., & Pääbo, S. (2010). The complete mitochondrial DNA genome of an unknown hominin from southern Siberia. [doi: 10.1038/nature08976]. Nature, 464(7290), 894-897. http://www.nature.com/nature/journal/v464/n7290/full/nature08976.html

2) Green, R. E., Krause, J., Briggs, A. W., Maricic, T., Stenzel, U., Kircher, M., . . .  & Pääbo, S. (2010). A draft sequence of the Neandertal genome. Science, 328(5979), 710-722. doi: 10.1126/science.1188021 http://www.sciencemag.org/content/328/5979/710.abstract?sid=4f93e3a0-e172-4994-b57f-178bdf78d8f0

3) Meyer, M., Kircher, M., Gansauge, M.-T., Li, H., Racimo, F., Mallick, S., . . . & Pääbo, S. (2012). A High-Coverage Genome Sequence from an Archaic Denisovan Individual. Science, 338(6104), 222-226. doi: 10.1126/science.1224344 http://www.sciencemag.org/content/338/6104/222

4) Reich, D., Patterson, N., Kircher, M., Delfin, F., Nandineni, Madhusudan R., Pugach, I., . . . Stoneking, M. (2011). Denisova admixture and the first modern human dispersals into Southeast Asia and Oceania. The American Journal of Human Genetics, 89(4), 516-528. doi: 10.1016/j.ajhg.2011.09.005 http://genetics.med.harvard.edu/reich/Reich_Lab/Welcome_files/2011_AJHG_Stoneking_Denisova_Impact.pdf [free access]

5) Davidson, I. (2013). Peopling the last new worlds: The first colonisation of Sahul and the Americas. Quaternary International, 285(0), 1-29. doi: http://dx.doi.org/10.1016/j.quaint.2012.09.023 http://www.sciencedirect.com/science/article/pii/S1040618212031965

6) Pearce, E., Stringer, C., & Dunbar, R. I. M. (2013). New insights into differences in brain organization between Neanderthals and anatomically modern humans. Proceedings of the Royal Society B: Biological Sciences, 280(1758). doi: 10.1098/rspb.2013.0168 http://rspb.royalsocietypublishing.org/content/280/1758/20130168.abstract

7) Stringer, C. (2011). The origin of our species. London: Allen Lane. 

8) http://www.eva.mpg.de/neandertal/index.html 

9) http://johnhawks.net/weblog/reviews/neandertals/neandertal_dna/altai-denisova-neandertal-high-coverage-2013.html 

10) Aiello, L. C. (2010). Five years of Homo floresiensis. American Journal of Physical Anthropology, 142(2), 167-179. doi: 10.1002/ajpa.21255 http://onlinelibrary.wiley.com.oca.ucsc.edu/doi/10.1002/ajpa.21255/abstract

~Iain Davidson


* Sorry! I had to put technology in inverted commas, because technology is a word that implies mindedness, and as you know, it’s still an open question whether it existed throughout the history of stone artifact production.

SA announces new posts on the Subversive Archaeologist‘s facebook page (mirrored on Rob Gargett’s news feed), on Robert H. Gargett‘s Academia.edu page, Rob Gargett‘s twitter account, and his Google+ page. A few of you have already signed up to receive email when I post. Others have subscribed to the blog’s RSS feeds. You can also become a ‘member’ of the blog through Google Friend Connect. Thank you for your continued patronage. You’re the reason I do this.

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