Wednesday, June 23, 2010
There some interesting links in there, including Hawks contributing some thoughts on the 67kyo Callao metatarsal I discussed a little while back (and which has sparked some heated discussion, I'm glad to report!), and a really interesting post on why we seem to know so little about the Paleolithic and Mesolithic of Switzerland. Click over there for the actual links
Friday, June 18, 2010
The majority of hideworkers using chalcedony and milky
quartz begin production by heat treating the raw material to
make it more brittle for reduction. The hideworker places
the raw material on top of a broken piece of pottery with
an insulator such as leaves, domesticated animal hair, wool,
cotton, or additional pottery sherds in a pit under her hearth.
There she leaves the stone for as little as 12 hours and up to three months. Once she “cooks” the stone, she then lets
it cool for at least one day. Konso women knappers use
different heat-treating methods based on the size, type, and
quality of the raw material to increase the flakeability of the
stone. (Arthur 2010: 234, emphasis added)
If this account is at all a reflection of what went on in prehistory, this is a huge span of time during which material is exposed to heat. And this observation got me to thinking about the recent study by Brown et al. (2009), where they determined that Middle Stone Age hominins in southenr Africa by 72,000 years BP at the site of Pinnacle Point 5-6 (and maybe as far back as 164ky BP in the area as a whole), used 'pyrotechnology' to alter the properties of locally obtained silcrete to make it easier to work, notably to produce fine bifacial points. Brown et al.'s study is especially noteworthy in that they propose what are, to my knowledge, the first set of objective criteria that can be used to both identify heat treatment as well as to quantitatively assess how much more 'flakable' stone becomes after heat treatment. These include thermoluminescence, archaeomagnetism, and gloss/reflectance. This in itself is a big step forward for future studies of heat treatment as they set a new level of analytical rigor that now has to be matched by future studies interested in demonstrating that heat treating took place in the past. It also establishes the need for experimental protocols in such efforts.
Going back to the Arthur (2010) paper, though, I was struck by this section of the supplementary material provided for their study by Brown et al. (2009), in which they discuss their experimental protocol to replicate the effect of heat treating on silcrete:
Two methods were employed to heat treat experimental silcrete samples. In the first, we placed raw material and a thermocouple probe (type K) within a sand bath approximately 2-3 cm below the surface. A fire was then built over the sand containing the silcrete. The temperature of the silcrete was slowly built up to ~350º C over a period of approximately 5 hours and then gradually cooled to ~40º C (usually overnight) before the blanks were removed from the sand. Temperature was monitored and recorded using a J-Kem HHM-40 handheld temperature meter and data logger. Fires required approximately 20 kg of dried hardwood per 3 kg of stone. In the second method, we heated samples in a Gallenkamp muffle furnace fitted with an external J-Kem programmable temperature controller (Model 360/Timer-K). The controller was programmed to slowly ramp the temperature of the furnace to 350º C over 5 hours. This temperature was held constant for 12 hours and then dropped slowly to 40º C before removal of the blanks. (Brown et al. 2010: S2-3)Now, this is clearly a different setting under which to heat material. Further, Arthur's ethnoarchaeological observations don't indicate how hot is the fire that lithic nodules are exposed to, not whether or not the 12 hours is more frequent than the three months she mentions as one extreme of the spectrum of heating duration. She also doesn't describe how much better the stone was after heating, or after different lengths of exposure to heat, and the raw materials being heated in both studies are also very different. These factors mean that it's not possible to directly assess the comparability of the Konso observations to those from the MSA at Pinnacle Point. However, if they are at all comparable, it does suggest that the lengths of time employed in Brown et al.'s replicative work woulf fall at the lower end of the durations for which lithic raw material must be heated to acquire better properties.
Why does this matter? It matters because it has important implications for how long fires must have kept going in the past for heat treating to be effective. This, in turn, has implications for how much fuel must have been available for heat treatment to be a feasible undertaking. Perhaps most importantly, it also has implications about the labor that must have gone into tending these fires to make sure they didn't go out. If stone was heated continuously for, say, 24 or 48 hours, it implies that someone must have remained relatively close to that hearth for that duration, which imposes some limitations about how mobile that person (or those persons) might have been. If, as Arthur (2010) argues, women may have been in charge of some aspects of lithic production such as heat treating, it implies that males and females may have had different economic roles going back quite a ways in the Late Pleistocene, a topic we've discussed at AVRPI before.
Arthur, Kathryn Weedman (2010). Feminine Knowledge and Skill Reconsidered: Women and Flaked Stone Tools American Anthropologist, 112 (2), 228-243 : 10.1111/j.1548-1433.2010.01222.x
Brown, K., Marean, C., Herries, A., Jacobs, Z., Tribolo, C., Braun, D., Roberts, D., Meyer, M., & Bernatchez, J. (2009). Fire As an Engineering Tool of Early Modern Humans Science, 325 (5942), 859-862 DOI: 10.1126/science.1175028
Friday, June 11, 2010
That's all well and good, and the report provides a nice example of how observation and interpretation can be woven together during archaeological research to develop solid working hypotheses. What struck me most about the report, however, is how the material recovered during excavation will be put to use in the coming years and use the shape part of the school's own curriculum. It appears that the school administrators have very sagely decided to use this material to provide students with an awareness of the deep past.
So far the artifacts have been found in oval clusters. Goodby speculates that these areas were where the people pitched tents or other shelters.
Primarily, the explorers have found a variety of stone tools that would have been used for processing animal hides, such as scraping tools. They've also found tools for making things out of bone and antlers as well as tools for engraving and splitting. But what's even more significant is what the stone tells the archeologists about the people who used them.
"We're learning for one thing that they had connections that extended all over Northern New England," Goodby said. "They were getting their stone from quarries as far away as northern Maine. And from sources in far north New Hampshire." He said there's evidence some of the stone may have come from Berlin and Jefferson.
He said they may have gotten this by following the caribou migratory routes, as that was their main game animal. He also said it may indicate that they were connected to other bands of people at this time so the stone moved from family to family.
Goodby also believes the type of stone they are finding in Keene as compared to the stone found in Swanzey in the 1970s, will ultimately prove the Keene site is even older than the Swanzey site.
Another exciting find was a stone fireplace that still had remnants of burnt fire wood in it. Next to the hearth, the archeologists also discovered what they believe to be burnt caribou bone. Goodby said testing will be done on the bone to determine the animal and the wood to determine what species of trees were in the area when these people lived there.
He said school officials will be building the finds into the curriculum so that students will understand the importance of the history right there in their backyard. He also said replicas of the stone tools will be on permanent display inside the school.If you ask me, that's a really fantastic manner of both underscoring the importance of archaeology to a young audience as well as of introducing students to the fundamental principles that allow people to study the human past and, more broadly, an array of 'paleo' disciplines by familiarizing them, for starters, with how dating methods work and the long history of human-environment interactions. Given the recent rise of the worst of obscurantist tendencies in some quarters, this can only be a good thing.
"The curriculum has been a little bit lacking when it comes to the original inhabitants in New England," Gurney said. "Now the students will be able to hold replicas of the actual artifacts in their hands and see exactly what the real tools looked like and touch and hold them…. It's just great."
The authors emphasize that the peculiarities of the Callao metatarsal are unique in the panorama of known foot bones attributed to various Pleistocene Homo. Provocatively, they point out that the dimensions of the H. floresiensis third metatarsal from Liang Bua (LB 1) are very close to those of the Callao specimen (Mijares et al. 2010: 9). While they present this comparison as speculative, the implications of the exercise are clear: they're asking whether something like H. floresiensis could have been present at Callao ca. 67 kya, although they do cover their bases by emphasizing that the closest analog small-bodied humans known in the region today are Negritos.
What's a bit puzzling is their repeated discussion that the Philippines are east of Wallace's line. While I know there's a bit of debate over this, I've always understood the Philippines as being located west of Wallace's line, on the Asian side of things. Mijares et al.'s argument that the Philippines are "beyond Wallace's Line in Island Southeast Asia" appear to be a further manner of potentially linking the Callao specimen to those from Flores.
In any case, as the authors conclude, the Callao third metatarsal "documents the presence of a hominin species on the island of Luzon as early as 67 ka, and is testimony to a capability to colonize new territories across open sea gaps. The Philippine specimen also indicates that Flores was not the only island in Wallacea to be occupied by hominins more than 50,000 years ago" (Mijares et al. 2010: 9). Regardless of the precise taxonomic affiliation of that bone, it indicates a great time depth for human presence in that part of the Old World, and provides some thought-provoking evidence that seafaring must have been part of the hominin behavioral range by that time, something that seems to potentially have been the case in other parts of East Asia at that time.
Mijares, A., Détroit, F., Piper, P., Grün, R., Bellwood, P., Aubert, M., Champion, G., Cuevas, N., De Leon, A., & Dizon, E. (2010). New evidence for a 67,000-year-old human presence at Callao Cave, Luzon, Philippines Journal of Human Evolution DOI: 10.1016/j.jhevol.2010.04.008
Everyone and everything's jumping on the World Cup bandwagon, it seems (shot taken while I wasted 6 hours of my life at Paris CdG). It ended well (very well) four years ago, so let's see how it plays out this time around.... BTW, does anyone out there have a recommendation of where to watch the Italy games in Denver with like-minded people?
Thursday, June 10, 2010
I can’t help imagining some grouchy old-timer saying something like “Damn cave paintings. In my day, we told stories about the sacred mammoth hunt, and you really had to use your imagination. Kids these days just want to stare at a wall all night. No wonder they can’t throw a spear straight”.