Recent intron duplications16 Jan 2007
On the subject of recent genomic duplications, here's an interesting paper:
Modern origin of numerous alternatively spliced human introns from tandem arrays
Degen Zhuo, Richard Madden, Sherif Abou Elela, and Benoit Chabot
Despite the widespread occurrence of spliceosomal introns in the genomes of higher eukaryotes, their origin remains controversial. One model proposes that the duplication of small genomic portions could have provided the boundaries for new introns. If this mechanism has occurred recently, the 5' of contemporary Streletskian sites. At the same time, it has no peculiar tool types (fossiles directeurs), which would allow us to put the search for analogies on firmer ground. As a consequence, it is difficult to demonstrate convincingly that any other assemblage should be considered Spitsynian. Unlike the Streletskian, the Spitsynian at Kostenki 17/II lacks any "archaic" features. Despite its very early age, it looks to be a full-fledged Upper Paleolithic, with prismatic cores being the only form of nuclei and blades dominating among the blanks (Vishnyatsky and Nehoroshev 2004:87).
This passage goes on to describe other UP elements in the Spitsyn, such as retouched blades, blades made into endscrapers, burins, retouched microblades, a "few" bone tools, around 50 drilled pendants, shells and corals. They consider whether the industry is related to the Aurignacian:
It has recently been proposed that the Spitsynian may be considered one of the oldest Aurignacoid industries in Europe (Anikovich 1999). We are inclined to agree with Sinitsyn (2000), however, who argues that the term "Aurignacian" (in any form) to describe Kostenki 17/II is unwarranted (Vishnyatsky and Nehoroshev 2004:87).
In addition to these, Kostenki 14/IVb has a rich assemblage of worked bone tools, which are featured in the redating article. Vishnyatsky and Nehoroshev say only that it cannot be clearly assigned to either the Streletskian or Spitsynian -- it "has no parallels among contemporary sites," and is described by Sinitsyn (2000). I'll have to wait a bit to get my hands on this one, since my library doesn't subscribe to Stratum.
Vishnyatsky and Nehoroshev describe other initial Upper Paleolithic sites, which are mostly very sparse artifact accumulations that are difficult to diagnose, as well as the early Upper Paleolithic after 32,000 years ago. Included in the latter is Sungir, with a rich Streletskian artifact assemblage including bone tools, ornaments, and portable art. This site is apparently late, after around 25,000 years, which puts it as a contemporary of more similarly complex UP examples further to the west in the Danube basin.
Two other developments occur during the later EUP in this region. The first is the appearance of the actual Aurignacian, at a few sites, including Kostenki 1/III:
The collection consists of more than 4,500 stone and bone items. The technology is clearly blade-oriented. Tools (about two hundred) are dominated by retouched microblades, including those with alternate retouch (i.e., dorsal retouch on one edge and ventral on the opposite edge). There are also thick (carinated) end scrapers of typical Aurignacian appearance, end scrapers on large blades with retouched edges, various burins and scaled pieces, single perforators, and small side scrapers. Split-base bone points, characteristic of many Aurignacian industries, are absent; a surprising feature, given the rich bone inventory. It includes awls, polishers, a perforated pendant made from a fox canine, and engraved ivory rods and points. Of the thirteen radiocarbon dates obtained from different labs, eight are indicative of an age around 25-26 ka, whereas two dates suggest the assemblage may be as old as 32 ka. For the time being, it is impossible to choose between these two alternative age estimates, although palynological and stratigraphic data are thought to be more consistent with the earlier date. (Sinitsyn et al. 1997:29) (Vishnyatsky and Nehoroshev 2004:90).
Considering that these Aurignacian occurrences are late (even 32,000 is relatively late compared to the early Aurignacian), they had appeared contemporary with the later Aurignacian in central Europe, and may represent population expansion out of central Europe onto the Russian Plain. Vishnyatsky and Nehoroshev note that these Aurignacian sites are very "few in number and isolated" (90). But with the redating, Aurignacian is plausibly much earlier at Kostenki, as early as 40,000 years ago. In particular, Kostenki 14/III is apparently sealed at the ash horizon. Other Aurignacian occurrences may still be much later than this, however.
The other development is the appearance of a tradition called "Gorodtsovian" at Kostenki, around 30,000 years ago.
Despite their relatively late age, the Gorodtsovian, like the Streletskian, is characterized by a flake-oriented technology and contains many tools that would look more natural in the Middle Paleolithic. For example, Kostenki 14/II contains many retouched artifacts of Mousterian appearance, including diverse side scrapers, points, limaces, and knives, which altogether comprise about half of all tools (Sinitsyn 1996:282). Such tools are also well represented at Kostenki 15 and are still recognized at Kostenki 16, which is probably the latest known Gorodtsovian assemblage. In addition, all of the aforementioned sites contain diverse collections of scaled pieces and end scrapers, whereas burins and bifacially worked tools are either rare or absent. The Gorodtsov culture is famous for its bone inventory, consisting of many utilitarian and decorative objects, such as points (including one with a zoomorphic head), needles, pendants, and beads. Particularly characteristic are the so-called shovels with ornamented handles made on mammoth long bones or scapulae (Vishnyatsky and Nehoroshev 2004:89-90).
All in all, this leads to a complex and interesting situation. There are two plausible staging areas from which either populations, genes, and information can move into Central (and ultimately Western) Europe from Asia -- either here on the Russian Plain, or south of the Black Sea via Anatolia. Here, we see that the EUP on the Russian Plain includes at least four different industries before 25,000 years ago; there is no obvious sequence, with three different variants possibly occurring in the same time interval.
According to Vishnyatsky and Nehoroshev, the scarcity of Middle Paleolithic assemblages in the area makes it difficult to evaluate the origins of the industries with apparent technical similarities to Mousterian or other MP variants.
The later assemblages (post-32,000 in this context) are in some cases associated with skeletal remains of modern humans (e.g., at Sungir, Kostenki 14, Kostenki 15). The initial EUP has only a couple of isolated teeth. So there is no secure biological association for either the early Streletskian, the Spitsynian, or the Kostenki 14/IVb assemblage, whatever it represents.
Anikovich et al. (2007:225) argue that the appearance of worked bone tools represents "an intrusion of modern humans onto the central East European Plain several thousand years before their spread across western and eastern Europe." But with no apparent antecedents for this technology, it is increasingly difficult to see where these people were "intruding" from. With a date as old as 45,000 years ago or older, they surely weren't coming from the Caucasus, because there were Neandertals there then, as well as points further south. This leaves points further to the east across central Asia, or from the west out of Central Europe. But there is no evidence of UP in either of these areas early enough.
In my view, explaining the Streletskian is the central aspect of this problem. Anikovich et al. (2007) suggest that it may be an activity variant of the more "advanced" industry (they apparently ignore any possibility of distinction between Kostenki 14/IVb and Spitsynian Kostenki 17/II). Vishnyatsky and Nihoroshev (2004) cite Anikovich et al. (1999) as suggesting that the early Streletskian assemblages are a case of "acculturation" in which indigenous people using an MP variant observed and imported elements of a more advanced intrusive UP tradition.
After noting the lack of modern human remains in association with the early Aurignacian thorughout Europe, Vishnyatsky and Nehoroshev say this:
But, most importantly, all the Neanderthal eaerly Upper Paleolithic cutlures seem too original to have been simply borrowed. These observations necessarily exclude acculturation as a viable mechanism of culture change for the Neanderthal early Upper Paleolithic in Europe. On the Russian Plain, not only is there no reason to associated the "advanced" Spitsynian early Upper Paleolithic with anatomically modern humans and the "archaic" Streletskian early Upper Paleolithic with archaic humans, but there is also little evidence to suggest that the Spitsynian predates the Streletskian. As in western Europe, acculturation is thus a nonviable explanation for the genesis of te early Upper Paleolithic on the Russian Plain (Vishnyatsky and Nehoroshev 2004:96).
I think the presence of these different industries is important -- probably the best information we have about population dynamics. With respect to the origin of the "advanced" Kostenki 14/IVb or Spitsyn occurrences, it seems to me that we don't need to invoke an intrusive origin. The Russian Plain was evidently not inhabited very successfully by Neandertals, as reflected by the rarity of MP sites there. No plausible source population for non-Neandertals has similar ecological characteristics to this plain. In other words, if people came from Anatolia into the Russian Plain, they were not likely to arrive with tools that were already useful for the local ecology. To adapt successfully to this area, people had to innovate -- make new stuff. This innovation wouldn't be instantaneous, but there is no expectation that all the elements of an assemblage should have predecessors in some source population.
That might well include replacing an ancient wood technology with bone, since wood is not easily replaced on the plains, and bone is common. The use of bone in this way could be episodic in response to climatic changes, since sometimes trees would have succeeded in river drainages like the Don, while at other times the river flow or local temperatures might eliminate many trees.
With respect to "acculturation": I would like to see an argument clearly distinguishing "acculturation" from diffusion. Of course, it must be a type of diffusion, but all modern human material cultures have interactions with and pick up elements from their neighbors. The Streletskian may provide an interesting opportunity for comparisons considering its relatively long duration. Temporal changes are already known; how do these compare to the predictions of diffusion over time? Even similarities with earlier MP technological patterns may be relatively unsurprising, since these must to some extent represent highly stable technical patterns. If they hadn't been stable, they would not have lasted so long. A low-density population that conserves highly stable elements is in no sense surprising, no matter what its origin.
Anyway, this gives some background about the initial Upper Paleolithic at Kostenki and why the redating of the site has some relevance to the pattern of technological change in Europe. I don't think many of the interesting questions have good answers yet. But my impression is that answers depend on the dates only to the extent that they force better explanations than mass migration.
Vishnyatsky LB, Nehoroshev PE. 2004. The beginning of the Upper Paleolithic on the Russian Plain. Pp. 80-96 in Brantingham PJ, Kuhn SL, Kerry KW, eds, The Early Upper Paleolithic beyond Western Europe. University of California Press, Berkeley CA.
Anikovich MV and 14 others. 2007. Early Upper Paleolithic in Eastern Europe and implications for the dispersal of modern humans. Science 315:223-226. doi:10.1126/science.1133376
Sinitsyn AA. 2003. A Palaeolithic 'Pompeii' at Kostenki, Russia. Antiquity 77:9-14.