Michelle Glantz, Sheela Athreya, and Terrence Ritzman have taken up yet another a reassessment of Teshik-Tash Neandertal child in the latest issue of the American Journal of Physical Anthropology. They’ve published the paper under the title, “Is Central Asia the Eastern Outpost of the Neandertal Range? A Reassessment of the Teshik-Tash Child.”
The child, Teshik-Tash 1, was found in 1938 in Uzbekistan. There’s been a lot of back and forth since the original publication on whether or not Teshik-Tash is really a Neandertal. I won’t be reviewing all the literature since the authors do a good job covering the discussion. The authors argue that one of the main reasons why Teshik-Tash is still considered a Neandertal is because of historical precedence. They also argue that this precedence has prevented people from fully appreciating variation.
They’ve found several things in the literature that may have affected its assessment, such as a reconstruction of the cranium. They claim that distortions and missing elements may have affected the morphology of the sample. For example, missing pieces of the fossil at the base of the cranium are parts that would affect the shape and size of the foramen magnum — a trait that has been used to attribute the Teshik-Tash child as a Neandertal. I’ve taken the liberty of highling an image, provided by the authors, to better illustrate the missing pieces.
But because of the not measuring reconstructions, there’s a lot of missing data. To compensate, expectation-maximization algorithms, a type of maximum likelihood estimations were deployed as well as multiple imputation, a technique for fitting models to incomplete data sets. Ultimately the data was analyzed under a principle component analysis and multinomial logistic regression. These statistical procedures are more fitting for small sample sizes with missing data.
The results suggest that Teshik-Tash share a lot of cranial and mandibular similarities to Upper Paleolithic modern humans, and fail to support the suggestion that Teshik-Tash is like its European Neandertal sub-adult comrades. But there really aren’t any other Central Asian Neandertal subadults to say for sure that this guy ain’t Neandertal. Until more specimens are found from that region, its really hard to say that the morphology swings either way.
Glantz et al. give about one sentence to the results of Krause et al.’s mtDNA analysis of Teshik-Tash from last year. A shame they play down the results. The results, which I covered, conclude that 190 base pairs from the Teshik Tash kid’s mtDNA is very similar to other Neandertals. The seqeunce can be found under this Genbank entry. I’ve decided to do a quick phylogenetic comparison of these 190bp to modern humans and other Neandertals. Here are the results, which clearly show Teshik-Tash, in these 190bp, is definitely Neandertal (the Teshik-Tash individual is the yellow, unknown item in the tree, and click thru to see a larger image):
I’m not saying the DNA analysis is definitive. If more DNA could be sequenced from the mitochondrion of Teshik-Tash, that would be better. But given that ancient DNA is fickle, what we have is pretty damn convincing. Despite the argument for distortion, previous morphological analysis (studies that didn’t rely on compensating for missing data) also support the claim that Teshik-Tash is a Neandertal. With these two lines of evidence, why then are we beating this dying horse?
- Glantz, M., Athreya, S., Ritzman, T. (2008). Is Central Asia the eastern outpost of the Neandertal range? A reassessment of the Teshik-Tash child. American Journal of Physical Anthropology DOI: 10.1002/ajpa.20897