This week I've been at the Vienna Natural History Museum to do some work. It's one of the great museums of the world, and they have a new human evolution exhibition with several great reconstructions of fossil specimens by Elizabeth Daynès. Several original hominin skeletal specimens are here on loan for a short time, including these:
Those are Qafzeh 11 and Qafzeh 9 from the Middle Paleolithic of the Levant, around 90,000 years old.
I was reading this morning an interesting paper from last year by Damien Flas [1], who considered the context of archaeological assemblages grouped as Lincombian-Ranisian-Jerzmanowician industry in northern Europe. This awkwardly-named archaeological grouping is one of the "transitional" initial Upper Paleolithic industries of Europe, plausibly made by Neandertals but involving artifacts built on a blade-based reduction strategy.
Flas tentatively concludes that LRJ was produced by Neandertals, mainly because of its early date, the late appearance of Aurignacian in northwestern Europe, and the lack of technical connections to traditions that were plausibly made by modern humans. I will share the portion of the text where he discusses the lack of such links:
Recently, maybe because an acculturation process related to the Aurignacian complex has been challenged on the basis of chronological and stratigraphic data (e.g. Bordes 2003; d'Errico et al. 1998; Zilhão 2006a), other industries have been proposed as proxies for the spread of AMH and as acculturators driving the last Neanderthals to develop the ‘transitional industries’ (Bar-Yosef 2007; Hoffecker 2009; Mellars 2005). In Central Europe, the Bohunician has been seen as a complex related to the spread of AMH from the Near East (Bar-Yosef and Svoboda 2003; Kozłowski 2004). Indeed, it shows similarities with the assemblages in layers 1–2 of Boker-Tachtit (Skrdla 2003; Tostevin 2003), and Tostevin (2007) has set out in a detailed way how the Szeletian assemblage from Vedrovice V may be seen as the result of acculturation of the local Middle Paleolithic (Keilmessergruppe from Kulna Cave) by the Bohunician complex.
However, the extension of this model to include a scenario whereby LRJ Neanderthals are acculturated by Bohunician AMH finds little support in the evidence, and is thus a weak hypothesis. There are no human remains, either in the Near East or in Central Europe, showing that this ‘Emireo-Bohunician’ complex is made by AMH, and it could alternatively correspond to the diffusion of technical ideas rather than to a population dispersal (Tostevin 2003). Moreover, the relationship between Boker Tachtit (in the Negev) and the Bohunician (in Moravia) is based on technological similarities, but intermediary assemblages between these two distant regions are rare (Bar-Yosef and Svoboda 2003; Kozłowski 2004) and sometimes show variability (as at Temnata and Bacho Kiro: Teyssandier 2008; Tsanova 2008). It would be also necessary to assess other European late Middle Paleolithic industries that could potentially play a role in the emergence of the Bohunician (Kozłowski 2001), such as the Polish sites of Piekary IIa and Ksiecia Jozefa (Sitlivy et al. 2007a, 2007b; Zilhão 2006a), as well as Korolevo I/IIb (Ukrainia: Monigal et al. 2006) and the Bulgarian Moustero-Levalloisian with leaf-points of Samuilitsa and Muselievo (Tsanova 2008). Even if the hypothesis that the Bohunician corresponds to an AMH dispersal from the Near East is accepted, the LRJ shows different objectives and reduction strategies from the Bohunician. More generally, it is difficult to see any lithic innovations in Bachokirian or Bohunician industries that could provide the stimulus for long-distance acculturation.
He posits a transformation from some Mousterian variant, based on the specialization toward "laminar blanks" (that is, cores suitable for striking blades). I find very interesting the implication of information exchange and possible dispersal among late Neandertals in the northern tier of Europe.
Related: my post from last year on Kent's Cavern dating, "The radiocarbon dating paper without a radiocarbon date". The Kent's Cavern maxilla overlies some artifacts attributed to LRJ traditions.
In reference to the post below about Quina Mousterian and reindeer specialization ("Paleoclimate and shifting Neandertal strategies"), let me add this great quote from Mark White. He addresses himself to the question of what kinds of strategies Neandertals employed against the cold of the MIS 4 winter in Britain and France.
Aiello and Wheeler hypothesize a very conservative 1 clo of insulation. The pelts of exploited Pleistocene mammals would have greatly exceeded this level (cf. Stenton 1991: 11), meaning that a clothed Neanderthal could have remained comfortable at temperatures far below those outlined above. Reindeer hides are particularly valued by modern arctic peoples because they are lightweight and their fur has excellent insulatory properties (clo value = 7: ibid.). The best time to procure reindeer hides is in the late summer, prior to the development of the heavy winter pelage and after the skin had repaired the damage caused by any summer parasites (ibid.: 6), which adds another interpretative dimension to the autumn mass killing of reindeer at Salzgitter-Liebenstedt (Gaudzinski and Roebroeks 2000); especially if Bocherens et al. (2005) are correct in their assertion that northern Neanderthals ate a lot of mammoth and rhino, but little reindeer (the reverse being true for hyenas). One wonders whether some species were targeted as much for their hides and sinews as for their meat value (see Burch (1998) for caribou), and whether the classic ‘scavenging’ pattern of heads and lower limbs found in Middle Palaeolithic sites is in fact a signature testifying to the preferential transport of hides away from the kill sites (cf. Chase 1986; Mellars 1996). Indeed, such patterns find obvious parallels in medieval tanneries (Serjeantson 1989; Gidney 2000). The broad association of scraper-rich Quina assemblages with colder environments and reindeer bones is highly suggestive in this regard (cf. Mellars 1996: 329; Dibble and Rolland 1992).
The quote is from another paper with an awesome title, "Things to do in Doggerland when you're dead" [1]. He adds that in Britain a a major limitation on Neandertals may have been the lack of wood -- not only for fire, but also for construction of long implements such as spears. The evidence for woodworking at some sites suggests they may have been located near stands of trees that persisted during the spread of periglacial steppes. All in all, it's a very interesting paper.
We have known for many years that Lower Paleolithic people were using shellfish, fish, and littoral resources at sites across the Old World, from Trinil [1], Koobi Fora [2], Gesher Benot Ya'aqov [3], and elsewhere. I've discussed the evidence several times (maybe most usefully in "The shells of Trinil"). As I wrote last year ("Fishy story at Koobi Fora"):
Aquatic animals aren't important because of their sheer numbers, but because they tell us about the flexibility of foraging behavior. Living hunter-gatherers eat turtles and reptiles when they can, and because they are usually small food packages, they often eat them where they find them instead of returning to a base camp first. Hunter-gatherers are flexible in what they eat and where they eat it. FwJj20 is showing at least a substantial taxonomic flexibility in the meat-eating of early Oldowan hunters.
So why do we keep seeing stories that make shellfish consumption look like news when it's done by Neandertals, MSA Africans, or anybody else?
I'm writing about this today because of a new paper in PLoS ONE by Miguel Cortés-Sánchez and colleagues, reporting on the shellfish remains in Bajondillo Cave, Spain [4].
Shellfish collecting has been well characterized in some Mousterian contexts. Mary Stiner treated it systematically in her 1993 monograph, Honor Among Thieves, which is part of the graduate education of most young Paleolithic archaeologists. Stiner spent a lot of text quantifying shellfish use and gave a good discussion of the biases that make archaeologists find less evidence of shellfish consumption than there probably was.
Most important, when you can walk along a shoreline and nosh shells, you're not very likely to haul many of them back to a cave several kilometers from the shore. In the Holocene, we find lots of archaeological localities where people were systematically collecting many shells and cooking them for large groups. For this purpose, the people carried baskets or sacks of shellfish for a good distance, and after they were consumed, the shells sometimes built up into large trash piles, or middens. We don't see shell middens in Mousterian or MSA contexts, but then we see very little of that kind of behavior with any kind of resources in MSA or Mousterian times. Here's what I wrote in 2008 ("Neandertal diet was not dolphin safe"):
[I]t was hard to understand the excitement that accompanied last year's paper by Curtis Marean and colleagues (2007), who found evidence for shellfish exploitation at Pinnacle Point, South Africa. The press reported the result as if there were a shell midden, with abundant evidence for consumption. But actually the number of shells is fairly small -- all the shells from all the layers reported weigh less than a kilogram. That looks similar to the pattern of exploitation that Stiner had reported for the Neandertals at Moscarini, and more or less like the pattern at Vanguard and Gorham's Caves.
The African MSA-era site with the most direct evidence of shellfish exploitation is at Abdur, Eritrea, where the stone tools are found in an ancient shore terrace, presumably at the very place where shellfish exploitation was happening [5]. That paper hinted at even earlier sites with similar evidence from Acheulean contexts along the Red Sea rift, where subsidence of the rift floor has left some ancient coral reefs exposed, Acheulean tools embedded within them. I should also point out indirect evidence on the basis of species abundance for human exploitation of giant clams in the Red Sea ("The ancient struggle for existence between humans and giant clams").
In other words, archaeologists have found quite a lot of evidence of coastal resource use by early people, despite the steep biases against it. In the case of aquatic animal exploitation, they've got it as early as the Oldowan, 1.95 million years ago [2].
Cortés-Sánchez and colleagues [4] add detail to this record but don't really broaden the picture. Mousterian shellfish acquisition around 150,000 years ago, well before the last interglacial, is earlier than many well-known instances of MSA shellfish utilization. But we know that much earlier humans were using these coastal resources, so it's hardly news. As at other sites, the mollusc remains are not very dense: a minimum of 16 shells in one layer, 66 shells in another, 80 in a third. If I were going to make a story out of it, I would direct more attention to the pearl, first I've ever heard of in a Neandertal site.
More important is the paper's demonstration that humans actually processed the shells. Cortés-Sánchez and colleagues contrast the condition of continental and marine molluscs in the same levels, to show the systematic breakage and burning of the marine species:
[A]lmost all of the marine mollusks exhibit intensive mechanical fracturing, with sharp edges on their shells suggestive of an absence of post-depositional transport, and very few appear complete (i.e., barely 7% at Bj19). Such fracturing, coupled with the absence of shells eroded by water, indicates that the marine mollusks from Bajondillo Cave, and in particular those from Bj19 do not represent “background fauna” from the nearby beach, a phenomenon that has recurrently caused problems in the association of early Middle Paleolithic shellfish deposits from the Mediterranean with paleo-human activities. In addition, a substantial percentage of the mussels exhibit burning marks (Figure 4: 1–6). These are recorded on 48% of the adult specimens from Bj19, the young mussels never exhibiting such traces. Thermo-alterations suggest consumption rather than passive burning, given that in most cases only the outer portions of the shells appear carbonized and/or flaked. An indirect line of evidence supporting this same hypothesis is provided by five of the epibiont barnacle remains that fire not only detached from the mussel shells but that in that process were thoroughly carbonized, as is the case of the four specimens from Bj18 (Figure 4: 8,11) or else calcined, as happens with the specimen from Bj19 (Figure 4: 12).
I appreciate the paper's list of 24 previously-published Neandertal sites that present mollusc remains. It would be useful to compile a broader list including MSA sites. Personally, I hope to never read again a headline about how surprising or significant was shellfish use by early humans.
Carles Lalueza-Fox and colleagues [1] have a new analysis of the mitochondrial DNA from El Sidrón, Spain. The site has a minimum number of 12 Neandertal specimens, dating to 49,000 years ago. The authors recovered mtDNA from all of the skeletal individuals, and additionally tested for the presence of Y chromosome to diagnose sex.
They found that all the adult males in the sample are close maternal relatives -- that is, they all share a single mtDNA haplotype. In contrast, the adult females and juveniles have a range of different haplotypes. Using some conclusions about the archaeological context (discussed below), they interpret the 12 individuals as part (possibly all) of a kin-structured group. They note that the relationships are then consistent with a patrilocal residence pattern: The men in the group are linked by kinship, the women have come from other kin networks, possibly transferred from other groups.
In the last paragraph of the paper, the authors suggest a further conclusion about life history:
Based on the ages of the El Sidrón group members and their mtDNA lineages, we speculate that juvenile 2 is the offspring (or close matrilineal relative) of female adult 5 and that juvenile 1 and the infant are the offspring of female adult 4. If correct, the latter relationship would indicate an interbirth interval of around 3 y for Neandertals. This period fits with the average 3-4-y interbirth interval reported for several modern hunter-gatherer groups (19).
That conclusion would be based on a single birth interval. It depends on the assumption that these juveniles are in fact siblings, which further depends on the proposed site deposition scenario. So although it is consistent with the data, I think it is very weak evidence. Still, it's a lot more evidence that I expected to have anytime soon. Moreover, it seems to me that the birth interval is testable with reference to dental development. A 3-4 year birth interval implies weaning in or before the fourth year of life, which ought to be reflected in enamel formation.
Awesome! We can now test hypotheses about Neandertal social organization directly from DNA evidence. The authors' hypothesis about patrilocality is consistent with the mtDNA, and I think it is likely to be the correct one.
Still, we have many reasons to be cautious about the interpretation. For one thing, Neandertals are already known to be relatively low in mtDNA variation, with very little regional population structure in the mtDNA. In such a population, it wouldn't be surprising to find individuals sharing the same mtDNA haplotype, even if they were not close kin. It might seem surprising that the individuals sharing the mtDNA haplotype are all men, but with a sample of only 12 individuals, that coincidence isn't really all that unlikely. The limited mtDNA variation would then be a sign of inbreeding at a regional level, not necessarily the kin structure of a particular group at a particular time.
Placing those individuals together as part of the same group is a forensic challenge. For most bones at archaeological sites, we would assume that the individuals lived at different times, possibly hundreds or thousands of years apart. The interpretation that they represent a single group requires several assumptions about the deposition of the remains, which amount to a detailed and surprising scenario. Lalueza-Fox and colleagues describe the El Sidrón skeletal assemblage as a result of systematic cannibalism:
The excavations to date have yielded > 1,800 hominin skeletal fragments and ∼400 Mousterian stone tools made in situ (3), but faunal remains are very scarce. The Neandertal bones are in a secondary position, and the original deposit, worn out by erosion, is thought to have been placed either on the surface or in an upper karst level (2). The present assemblage occurred shortly after the death of the individuals by the collapse of an upper gallery into the Ossuary Gallery triggered by a natural event, probably a violent storm that also dragged down pebbles and clay (Fig. S1). Given that (i) ≈18% of the lithic industry can be refitted, and (ii) the widespread spatial distribution of these refitted artifacts, it may be surmised that they result from a single and brief cultural activity. This likelihood lends even more support to the synchrony of the whole assemblage (2, 3), dating to around 49,000 y ago (4). Some evidence, such as skeletal parts still in anatomical articulation, indicates little site disturbance since formation. Ex hypothesis, the fact that all types of skeletal remains show evidence of anthropic activities associated to cannibalism (2) could indicate that the assemblage corresponds to a Neandertal group processed by other Neandertals on the surface. Although it is impossible to be sure that the individuals represent a contemporaneous group, alternative explanations, such as recurrent accumulation over time of cannibalized individuals that were closely related through the female line, seem less plausible.
If this interpretation is correct, it would be the most stunning example of intergroup violence known from the Pleistocene. Imagine the circumstance in which a group of hunter-gatherers would kill and butcher 12 individuals in one paroxysm of aggression. Certainly it was not mere survival, it was warfare.
Is it true? The problem is the "violent storm". How do we know that the existing assemblage is a good representation of the original deposition site? The high number of refits does imply that we're not looking at a random sample of an originally much larger assemblage, but it's hard to be more definitive. If we have the remains of 12 individuals, how many may have been involved in the act?
Naturally, if the remains had actually accumulated over a longer time, the conclusions about patrilocality would be unwarranted. In that case we would be back to a more general question of regional or local inbreeding among Neandertals, interesting from the point of view of population structure, but with less concrete information about social organization.
The forensic case provides a window into behavior that is potentially much broader. Krapina is another site with hundreds of skeletal fragments representing an even larger number of individuals, which may also represent one or more instances of cannibalism. In that case, the debate about cannibalism (versus secondary reburial of defleshed bones) has flared off and on for years. It is just very difficult to attain a reasonable certainty about such behaviors from the archaeological and skeletal evidence at hand.
I will be interested to read more about the context at El Sidrón as the research continues. The issues of kinship can be easily settled with nuclear DNA sequencing, and should in fact lead to some extremely interesting science, if that can be accomplished. The authors list some of the barriers to such sequencing, given a relatively low DNA yield in many of the specimens, but the field has rapidly progressed. Meanwhile, the archaeological interpretation of the site may allow us to revisit some other Neandertal assemblages, looking for other signs of aggression, violence, and social organization.
Well, I already snarked on the science headlines that have been claiming volcanoes "wiped out" the Neandertals. Some variation of this story, swapping in a different Neanderkiller, has been circulating since around 1890. But is there any truth to the headlines?
(see UPDATE below)
The source of the story is a paper in the October issue of Current Anthropology, by Golovanova and colleagues [1]. The paper reviews the chronology of Mezmaiskaya Cave, a site occupied by Neandertals and successive Upper Paleolithic peoples, in the Russian Caucasus. This site produced the skeleton of an infant, from which DNA evidence has been recovered. As Golovanova and colleagues describe, the deposit additionally contains volcanic ash from two eruptions that happened around 40,000 years ago.
The latter of the two eruptions appears to coincide with a long abandonment of the site:
Hominin occupation of Mezmaiskaya Cave changed dramatically after the later volcanic eruption represented in layer 1D. This eruption was probably more powerful than that in layer 2B-1. Layer 1D has a thickness up to 0.7 m and in some areas is composed of a relatively clean sediment lacking any inclusions (fig. A10). Limestone fragments, bones, and lithic artifacts are absent, and even pollen grains are rare. Pollen data show that extreme deterioration to a very cold and dry climate occurred in this time period....A chemical analysis of layer 1D indicates that the volcanic ash apparently derives from an eruption in the Kazbek volcanic province that occurred around 40,000 years ago. Because no Neanderthal specimens or MP lithic industries postdate layer 1D at Mezmaiskaya, this eruption seems to have significantly disrupted the ecological niche of local Neanderthals, possibly resulting in their rapid disappearance in this region.
The Kasbek volcanic province is in the Caucasus, so we're talking about a large eruption relatively local to the site. This is the sort of event you might well expect to have a strong impact on a dispersed hunter-gatherer population. The Middle Paleolithic people (presumably Neandertals) might have locally declined in numbers, or they might have moved on. The region need not have been abandoned entirely; a new population might have entered the area without using the same site. In this case, when new people began to use the site much later, the newbies were using an Upper Paleolithic industry.
A relatively local effect of volcanism in the Caucasus is one thing, but the extinction of Neandertals across western Eurasia is quite a bit more. How does the paper go from local event to a regional extinction?
The local eruption was the second event to leave ash in the Mezmaiskaya sequence. The first was a different eruption from Mt. Elbrus, which had a smaller impact than the second, as discussed below.
At issue in the paper is the possible coincidence of the second eruption and consequent abandonment of the site with a much larger volcanic event in Italy:
The CI [Campanian Ignimbrite] eruption from the Phlegrean Fields, southern Italy—the largest eruption documented in the Mediterranean region during the past 200,000 years (Wohletz, Civetta, and Orsi 1999)—drastically impacted European ecosystems. The most recent numerical (40Ar/39Ar) age determinations for CI eruption vary from to BP and cluster around 40,000 BP (Fedele, Giaccio, and Hajdas 2008:839).
This eruption produced the CI in Italy and Y5 tephra in Central and Eastern Europe and Eastern Mediterranean (Fedele et al. 2003; Fedele, Giaccio, and Hajdas 2008). High-altitude clouds of volcanic ash from this eruption had a significant effect on global climate. The resulting ash fall covered km2 of land and sea (fig. 1), and the Y5 tephra layer accumulated in the Eastern Mediterranean as far as Cyprus—more than 1,500 km from its source (Mussi 2001:191). The Y5 tephra is also identified in the EUP sequence at Kostenki in the Middle Don River in Russia (Holliday et al. 2007). In Eastern Europe, the ash layer varies from 1–2 cm in the eastern limit (between Penza and Rostov) to 5–8 cm in the west and southwest (southern Ukraine and Moldova) and averages about 3–4 cm (Laverov et al. 2005:51). Obviously, the area affected by this ash fall was much larger than the documented Y5 tephra sites.
Golovanova and colleagues propose the hypothesis that the climate effects of this CI event caused the demise of the Neandertals:
Our new data provide support for the hypothesis that the MUP transition in western Eurasia coincides with one of the most globally significant volcanogenic catastrophic events in the recent history of the earth. The large and coeval volcanic eruptions (from an unusually large CI eruption in the Apennines to a smaller eruption in the Caucasus) had a sudden and devastating effect on the ecology and forced the fast and extreme climate deterioration (so-called volcanic winter, perhaps comparable to the effect of nuclear winter) of the Northern Hemisphere in the beginning of Heinrich Event 4. We guess that this catastrophe likely may have both drastically destroyed the ecological niches of Neanderthals, possibly resulting in the mass death of hominins and prey animals and the severe alteration of foraging zones, and caused Neanderthal depopulation from Central Europe to the Caucasus.
That's a very clearly stated hypothesis. A volcanic eruption initiated climate effects that the regional population of Neandertals could not survive.
However, Golovanova and colleagues include in their paper several critical facts that run against this hypothesis:
1. The Mezmaiskaya sequence itself shows Middle Paleolithic people returning and proliferating after a large relatively local eruption. The Elbrus eruption apparently left ash in layer 2B-1, with a low density of bones and a very low frequency of bison compared to caprids. The excavators interpret the layer as a very low-intensity use of the cave. The pollen evidence suggests a "cold, dry climate". In other words, the paleoclimate and faunal evidence are both consistent with the hypothesis that the eruption had effects on Neandertal populations in the Caucasus. But then the Neandertals apparently returned in force:
The intensity of site use increased, however, during the accumulation of the upper MP layers 2A and 2 when the climate become cool and wet. Although the lithic industry changed slightly after the environmental crisis of layer 2B-1, it still remained typically MP Eastern Micoquian. Skeletal and mtDNA evidence indicates that Neanderthals produced both the earlier and the later MP industries at Mezmaiskaya (Briggs et al. 2009; Golovanova et al. 1999; Green et al. 2010; Ponce de Leon et al. 2008). Thus, the late MP environmental crisis at the cave had repercussions for local Neanderthals but did not cause a break in the continuity of occupation or technology.
That makes it seem pretty unequivocal. Neandertals survived and effectively adapted to at least one volcanic event in this area. That eruption did not kill them off, and it did not leave the area devoid of Neandertals in a way that facilitated a "modern human invasion."
It was only after the second volcanic event that Middle Paleolithic people declined at the site.
At issue is whether this second event was coincident with the CI eruption. The ash in the Mezmaiskaya sequence is not from the Y5 tephra, it is attributable to a much nearer source. I do not fully understand why the authors attribute this second event to the same time as the CI event; the time between layers 2 (terminal Mousterian) and 1C (early Upper Paleolithic) appears to have occupied a few hundred years, between 32,000 and 34,000 radiocarbon years BP. Calibration will move those dates older by a few thousand years (I discussed radiocarbon calibration a few years ago). But I think the CI eruption, around 40,000 years ago, doesn't fit well with this later event. It might fit with the earlier eruption, in my view, as Elbrus lava flows include 40,000 BP.
In any event, I think the associations of either local volcanic event with the larger CI event is at best uncertain. The record at the site makes it pretty clear that Neandertals were effectively adapting to the changing local climates and faunal abundance that coincided with the first eruption.
2. The initial Upper Paleolithic of Kostenki had appeared before the Y5 tephra was deposited. I wrote about the identification of this Y5 tephra at Kostenki a couple of years ago ("An earlier initial Upper Paleolithic at Kostenki"). As my post indicated, the identification of the ash layer with the Campanian Ignimbrite event suggested an earlier date for the initial Upper Paleolithic on the Russian Plain.
From the standpoint of the Neandertal volcanic winter hypothesis, this sequence of events is a problem, which Golovanova and colleagues discuss:
In any case, with or without the Kostenki addition, the few CI-bearing sites show that this eruption could have also extinguished the first wave (Proto-Aurignacian) of EMH expansion into Europe (Fedele, Giaccio, and Hajdas 2008): “At all key sites, where sedimentary resolution is good, the CI tephra directly seals archaeological layers that contain assemblages of the MUP mosaic, often variants of ‘Aurignacian’-like or so-called Early Upper Paleolithic Industries. … The layers above the CI tephra, where they are not culturally sterile, contain later and often much later properly defined Upper Paleolithic industries” (841). Thus, the CI-bearing sites demonstrate clear evidence of the break in habitation and culture change—a whole gamut of archaeological attributes for population replacement.
The volcano is supposed to explain the MUP transition, but occurs earlier than the MUP transition in some areas, but later in others. Golovanova and colleagues propose an ad hoc hypothesis to account for this mismatch: some early Upper Paleolithic modern humans were also wiped out.
Many researchers might find this idea tempting. It might, for example, explain why the (few) skeletal remains of the earliest Aurignacian people have such a high proportion of Neandertal features. We could propose that the initial Upper Paleolithic represents a degree of population mixture that later populations do not; the discontinuity between them could have been caused by climate extremes.
But we don't need climate or volcanism. Later Upper Paleolithic people retained similarities to Neandertals, which reduced in frequency over time. This is most readily explained by continued gene flow into a sparse European population from West Asia. A volcano-induced climate catastrophe is superfluous: It doesn't add to the explanation of a sustained genetic transformation of Europe that continued through the later Upper Paleolithic and Neolithic.
3. "Catastrophes" are not rare. The record of climate change during the last glaciation shows frequent strong oscillations. Some of these occurred at the same time as known eruptions, and so might be associated with them, but most climate oscillations have no obvious cause. Up to 40,000 years ago or so, the Neandertals survived them all. They survived the Toba event, largest eruption by volume in the Pleistocene, with no evidence of ill effects.
The "intensity of occupation" of archaeological sites naturally fluctuated for many reasons. In Paleolithic contexts, sites were almost never inhabited continuously. We usually don't know why a local population returned more often to a site, or why the later population may have used the site less often, but those changes in pattern will make a big difference to the occupation intensity. It's not enough to show that a fluctuation in occupation intensity was coincident with an eruption or climate event -- such coincidences are inevitable even when "occupation intensity" changed randomly.
Bad things happened in the past. Many of those bad things -- megadroughts, volcanoes, asteroid impacts, flesh-eating bacteria -- probably killed a lot of people.
But our ability to find the effects of these death-dealing events is a lot more limited than you might assume. Less than a thousand years after the Black Death, how many signs of it are still evident today? To the exceedingly clever, who know where to look, there are a few. If we discount historical records, which do not exist for the Pleistocene, and limit ourselves to very small samples of bone and stone remains, it becomes very difficult to demonstrate this widespread epidemic, which reduced the population of some parts of Europe by up to half.
Most Paleolithic sites document exceedingly low-intensity use of an area by ancient people, and have gaps of thousands of years. The hope of finding a single event with a short duration is near zero, unless it affected many sites in the same way.
The extinction of a widespread group of hominids would be one kind of event we might test. In the current example, I think the data point to a clear conclusion: Not all Neandertals were killed, starved, or slowly declined due to the effects of any single volcanic eruption. Too many of them clearly survived the time of the large eruptions, and the available archaeological indicators suggest that their populations tended to recover after climate extremes had been reached. They were very resilient to climate change, more than many other mammals.
It's not possible to rule out that one or more eruptions may not have had important effects, even ones that may have devastated some local populations. This is possibly the case at Mezmaiskaya. Nor is it possible to exclude the hypothesis that climate changes of greater and greater amplitude may have stressed their populations, contributing to the Neandertal demise.
That's one of the returning frustrations of the archaeological record. An event might have been a major tragedy in human terms, but essentially invisible to us today. Meanwhile, the large-scale dynamics of human populations, including speciation and extinction, do not appear to fit the record of catastrophic eruptions. I don't see that as the end of the story, but a more interesting prologue to our understanding of ancient human dynamics.
UPDATE (2010-10-16): I received a note from Golovanova and Doronichev, kindly pointing out a serious error in my post. I had misread their paper -- I described it as supporting a coincidence of CI with the first ash evidence at Mezmaiskaya, but the paper clearly argues that the CI event was "coeval" with the second ash, in layer 1D of the site.
I have extensively updated the part of the post that refers to the CI eruption.
I'm skeptical that the CI and Kazbek ashfalls could have happened near the same time, because the latter seems by radiocarbon evidence to be 2000 or more years later than 40,000 years ago. But the ESR dates are arguably consistent with the idea that the two eruptions coincided. I wouldn't push a chronology argument very far, not without a list of calibrated radiocarbon and ESR/TL dates from the relevant eruptions. But the multiplicity of events helps to reiterate the basic point that geological events happened, and fluctuations of site intensity happened, and it will take a coincidence across many sites to correlate the two.
Julien Riel-Salvatore has written more about the supposed Middle Paleolithic-age stone tools from Crete: "The final (?) word on those handaxes from Crete".
First, on the basis of the drawing of the handaxes, these implements do appear to be human-made. Second, they are not isolated occurrences: the authors identified nine localities where these quartz tools were found, only three of which also yielded Mesolithic tools. This leaves open the possibility that the 'Paleolithic' sites represent task-specific components of the Mesolithic toolkit on Crete, but this is unlikely based on the association of handaxes with some of the terrace deposits described in the quote above. Third, as the authors indicate, this was not a case of a H. heidelbergensis (or a couple of them) washing onto Crete: the fact that nine sites (defined by the presence of a minimum of 20 stone tools) were found in a relatively small area indicates a somewhat sustained human presence on the southern coast of Crete.
The comments have generated a lively discussion of the possibility that these are eoliths -- flaked by natural processes -- and how one would tell.
Today's sketchbook:
The mandible from the Kebara skeleton, top; Qafzeh 3, bottom.
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 [1]. A good short summary of its context was given by Bricker [2]:
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 is 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.
I wrote about Crete twice last month ("Crete: Pleistocene port of call?", "More tools from Crete"). Now John Noble Wilford writes about Strasser and Panagopoulou's work: "On Crete, New Evidence of Very Ancient Mariners". The article reviews the finds, and then gives space to a bunch of speculations.
The exposed uplifted layers represent the sequence of geologic periods that have been well studied and dated, in some cases correlated to established dates of glacial and interglacial periods of the most recent ice age. In addition, the team analyzed the layer bearing the tools and determined that the soil had been on the surface 130,000 to 190,000 years ago.
Dr. Runnels said he considered this a minimum age for the tools themselves. They include not only quartz hand axes, but also cleavers and scrapers, all of which are in the Acheulean style. The tools could have been made millenniums before they became, as it were, frozen in time in the Cretan cliffs, the archaeologists said.
Dr. Runnels suggested that the tools could be at least twice as old as the geologic layers. Dr. Strasser said they could be as much as 700,000 years old. Further explorations are planned this summer.
Ancient artifacts may be exposed to the elements once again and then re-incorporated into more recent sedimentary contexts, a process called "reworking". It happens. But it's a stretch, unless there is some independent evidence that the tools and surrounding rocks bear signs of battering from water transport or other contextual evidence of reworking.
Going out and saying that the tools could be "as much as 700,000 years old" is just overreaching -- it's like they're trying to say this is comparable to the "earliest" evidence of watercraft. And you really have to stretch the dates to get there: Flores was apparently inhabited by 800,000 years ago.
At the end:
But archaeologists and experts on early nautical history said the discovery appeared to show that these surprisingly ancient mariners had craft sturdier and more reliable than rafts. They also must have had the cognitive ability to conceive and carry out repeated water crossing over great distances in order to establish sustainable populations producing an abundance of stone artifacts.
Maybe. Maybe not. What evidence is there that the crossings were "repeated"? Imagine what would serve...finding Crete-derived rocks in a mainland site would do it, or vice-versa. Any evidence of transport. I don't imagine we'll find any earlier human-introduced fauna, and a human-induced extinction might result from a single invasion, not a "sustained" record of multiple crossings.
I pointed to one such faunal turnover in my last Crete post, which would point to a human invasion in the mid-Middle Pleistocene. Parallel technical change with Greece or North Africa after this time would show multiple contacts -- but such evidence would suppose a long archaeological record that we don't yet have.
I just don't think it helps to speculate so freely. Sure, we might find things that surprise us. But the actual facts are surprising enough to justify funding much more work.
