What is the temporal bone from Darra-i-Kur, Afghanistan?
A bone from a historic excavation in Afghanistan raises the topic of genetic reanalysis of fragmentary fossils.
The original post here was published in 2010. In 2017, Katerina Douka and coworkers published the results of new analyses of the Darra-i-Kur specimen. These analyses are described in an update at the bottom of the post.
Wouldn't it be fun to compile a list of skeletal specimens that might prove interesting for DNA analysis? Near the top of my list is the only Middle Paleolithic-associated specimen from Afghanistan, a temporal bone from Darra-i-Kur. The bone was found in an excavation by Louis Dupree, prospecting the archaeology of the caves in northern Afghanistan in 1966. The bone was described in a brief report by J. Lawrence Angel (1972). A good short summary of its context was given by Bricker (1976):
Recent data from several sites indicate that some groups of anatomically modern man were making Mousterian tools.
One site that may very well fall into this category is the cave Darra-i-Kur, northeastern Afghanistan, excavated by Dupree. A fragmentary human temporal bone was found in a level containing a Mousterian industry of Levallois facies; some of the Levallois points are made on Levallois blad blanks, but the industry is clearly Middle rather than Upper Paleolithic. A radiocarbon date from the occupation level has a central value of ca 30,000 B.P., but both the nature of the sample and the lack of alkaline pretreatment indicate that the true age of the occupation is probably much older. According to Angel, the characteristics of the temporal bone contrast markedly with those of Neanderthal man, and the specimen can be considered at least transitional (in the sense of the Skhul population) and quite possibly modern. The difficulties of attempting a phyletic placement of such a fragmentary fossil are, of course, severe (Bricker 1976:138).
At the time, the Skhul hominins were generally thought to be contemporaries of the Würm Neandertals of Europe, making them a very apt comparison.
Angel decided that the bone represents a human of modern type, based on metric comparisons with Neandertals and living Americans of European ancestry. These observations really aren't equivocal, it doesn't look much like a Neandertal bone in any feature where they are different from later humans. The more interesting part of Angel's description is found in the final few paragraphs, where he opens himself to speculation about the pattern of Late Pleistocene evolution in the region:
It is tempting to infer further than [sic] the actual evolutionary transition from Neanderthal to modern man had taken place already in some area to the south, such as Sistan or India. The Skhul and Djebel Kafzeh skeletons from Israel (Mount Carmel), probably contemporary with Darra-i-Kur temporal bone show the kind of intermediate and variable state expected if a population of modern form, evolving between 100,000 and 40,000 B.C. in southern Asia, had absorbed a Classic Neanderthal group. But we cannot base this origin area for modern man on the Niah skull alone...
Hopefully not, since Niah is in Borneo. I suppose his point is that there are no representative skeletal specimens of the right age from nearby South Asia.
...We must not forget that the labels Neanderthal and modern each cover a whole array of varying and evolving populations at present inadequately sampled. For example, Swanscombe, Steinheim, and Ehringsdorf, and much later Skhul lack the "typical" Neanderthal occiput. The Darra-i-Kur temporal would fit into a partly Neanderthal population like Skhul just as well as a modern one. In this state of ignorance about man at the end of the Würm interstadial in Southern Asia, I dare not use Darra-i-Kur to pin up an hypothesis of modern intrusion from the south as opposed to one of general rapid evolution from Neanderthal forms to modern over the whole of western Asia.
I don't see any reason why the Darra-i-Kur temporal isn't just an ordinary human, post-dating 35,000 years ago. But I would have said the same about the Denisova pinky bone. We all know how that one turned out. I'm in favor of sequencing Upper Paleolithic-associated skeletal remains wherever we can, because they will significantly help us understand the interactions of populations prior to the massive population growth of the Neolithic—which distorts many of our attempts to see older events with genetic evidence. And this bone has been described as Middle Paleolithic in age, possibly contemporary with the European (and nearby) Neandertals.
Angel's speculative comments on the "actual evolutionary transition" are out of date, to be sure. But the dynamics of populations in West Asia, perhaps as far east as India, must be central to how we understand the interaction of African and Eurasian populations of the Late Pleistocene. There was a dispersal of genes from Africa, and there was mixture of populations before those genes reached their termini in Europe, Southeast Asia, and the New World.
Oh, and since the topic of the week is high altitude adaptation, Angel's final comment may be surprising:
Finally, I offer the equally unsupported speculation that Darra-i-Kur's increased size of vascular foramina may have a connection with the slight vascular hypertrophy needed at high altitude.
Not all that useful, as this is a very weak correlate of altitude. But, the bone does remind us that people have lived in high places since before the Upper Paleolithic.
What I didn't know when I wrote this original post is that a team of scientists were already interested in a genetic analysis of the Darra-i-Kur specimen. That work would eventually involve a full reanalysis of the radiocarbon age of the bone and its mtDNA sequence. Katerina Douka and coworkers published the results in 2017 in the Journal of Human Evolution.
While Angel had placed the temporal bone in the Mousterian, the radiocarbon age of the bone is actually only around 4500 years old. The authors suggest that the temporal is therefore intrusive from the overlying layer, described as “Goat Cult Neolithic”, which has the same radiocarbon age. The mtDNA sequence belongs to clade H2a, which is still found in this region of the world today.
One notable aspect of the study is that the researchers used a CT scan to guide their sampling of the bone for genetic and radiocarbon analysis. This meant that they could minimize the damage to the petrous portion of the temporal. It is unfortunate that more genetic studies have not pursued this kind of approach to maximize their knowledge of the internal anatomy and minimize the destruction of ancient material.
Angel, Lawrence J. (1972) A Middle Paleolithic temporal bone from Darra-i-Kur, Afghanistan. Transactions of the American Philosophical Society. 62, 54-56.
Bricker, H. M. (1976) Upper Palaeolithic archaeology. Annual Review of Anthropology. 5, 133-148.
Douka, K., Slon, V., Stringer, C., Potts, R., Hübner, A., Meyer, M., ... & Higham, T. (2017). Direct radiocarbon dating and DNA analysis of the Darra-i-Kur (Afghanistan) human temporal bone. Journal of Human Evolution, 107, 86-93. https://doi.org/10.1016/j.jhevol.2017.03.003
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